Colony collapse disorder (CCD), a syndrome whose defining trait is the rapid loss of adult worker honey bees, Apis mellifera L., is thought to be responsible for a minority of the large overwintering losses experienced by U.S. beekeepers since the winter 2006–2007. Using the same data set developed to perform a monofactorial analysis (PloS ONE 4: e6481, 2009), we conducted a classification and regression tree (CART) analysis in an attempt to better understand the relative importance and interrelations among different risk variables in explaining CCD. Fifty-five exploratory variables were used to construct two CART models: one model with and one model without a cost of misclassifying a CCD-diagnosed colony as a non-CCD colony. The resulting model tree that permitted for misclassification had a sensitivity and specificity of 85 and 74%, respectively. Although factors measuring colony stress (e.g., adult bee physiological measures, such as fluctuating asymmetry or mass of head) were important discriminating values, six of the 19 variables having the greatest discriminatory value were pesticide levels in different hive matrices. Notably, coumaphos levels in brood (a miticide commonly used by beekeepers) had the highest discriminatory value and were highest in control (healthy) colonies. Our CART analysis provides evidence that CCD is probably the result of several factors acting in concert, making afflicted colonies more susceptible to disease. This analysis highlights several areas that warrant further attention, including the effect of sublethal pesticide exposure on pathogen prevalence and the role of variability in bee tolerance to pesticides on colony survivorship.

With the threat of new plant diseases on the increase, plant disease epidemiology requires research on pathogen vector movement. Here, releases were performed in planted potato fields of different ages and canopy structures, located in the Texas Panhandle, to evaluate the range of movement of the potato psyllid Bactericera cockerelli (Sulc). This insect is a known causative agent of psyllid yellows disease, and is a vector of the reported etiological agents of zebra chip disease of potato, ‘Candidatus Liberibacter solanacearum/psyllaurous.’ Based on collections of B. cockerelli immatures along transects 9 m long radiating in four cardinal directions from release points, adult females dispersed considerable distances, regardless of plant age or canopy structure. Immature abundance declined along transects and were well described by linear and nonlinear models, but abundance patterns did not differ among the different planting dates and canopy structures. However, unequal immature abundance was detected among the four cardinal directions, with more immatures generally collected along transects to the north and west of release points, opposite of prevailing winds in the area at the time of release. Plots where B. cockerelli were released had significantly lower mean potato tuber weights than control plots with no B. cockerelli. However, few plots with B. cockerelli released in them had declining trends in tuber weights with increasing distance from release points.

The purpose of this investigation was to evaluate acquisition and inoculation (together, transmission) efficiency of Candidatus Liberibacter asiaticus (Las), the pathogen associated with citrus huanglongbing (HLB) by the Asian citrus psyllid, Diaphorina citri (Kuwayama) (Hemiptera: Psyllidae). In laboratory studies, nymphs reared on Las infected plants were more likely to acquire the bacterium than adults. Acquisition by nymphs ranged from 60 to 100%, whereas acquisition by adults only reached 40% after 5 wk of feeding on Las-infected plants. Similar rates of pathogen acquisition by psyllids after nymphal and adult feeding were observed in the field. Transmission of Las from parent to offspring (transovarial) occurred at a rate of 2–6%. One year after psyllid inoculations, successful transmission by individual D. citri ranged from 4 to 10%, whereas groups of 100 or more D. citri transmitted the pathogen at a rate of ≈88%. In addition, the proportion of Las-positive adult psyllids, determined using quantitative real-time polymerase chain reaction, decreased over time when held on healthy plants. Due to the low rate of pathogen acquisition and long time period required for successful inoculation by adult D. citri, experiments designed to determine the latent period required for replication and successful inoculation of Las by D. citri did not result in Las-infected plants after >1 yr of incubation after inoculation. Collectively, these results indicate that adult D. citri which acquire the HLB pathogen as adults are poor vectors of the pathogen compared with adults that acquired the pathogen as nymphs.

Sanitation being an important component of chemical-free management of stored-products pests, the nutritional stress on insects that results from a clean environment may prove advantageous to the use of microbial controls. Dietary stress by food deprivation or suboptimal diet increased susceptibility of the red flour beetle, Tribolium castaneum (Herbst), larvae to Beauveria bassiana (Balsamo) Vuillemin. Fungus-related mortality increased linearly with the number of days of food deprivation. Rearing of larvae on a rice meal diet resulted in slower development and greater susceptibility to B. bassiana than rearing on whole wheat flour with brewer's yeast. Larvae that were fed for 24 h on flour with B. bassiana conidia consumed significantly less and weighed significantly less than those that were fed fungus-free flour. Thus, the presence of B. bassiana conidia is itself a cause of dietary stress.

Bacillus thuringiensis japonensis strain Buibui (Btj) has the potential to be an important control agent for pest scarabs. Bioassays using autoclaved and nonautoclaved soil showed there were always lower LC₅₀ values associated with nonautoclaved soil. We identified five other bacteria found in the hemolymph of insects killed by Btj and used them in bioassays to see whether we could enhance the control achieved with Btj alone. One bacterium, designated NFD2 and later identified as a Bacillus sp., showed the greatest enhancement of Btj in preliminary experiments and was used in bioassays with Btj versus oriental beetle, Anomala orientalis (Waterhouse), and northern masked chafer, Cyclocephala borealis Arrow (Coleoptera: Scarabaeidae), larvae. This bacterium alone was nontoxic to grubs in bioassays. A combination of this bacterium with Btj in nonautoclaved soil resulted in a significantly lower LC₅₀ value (0.23 µg toxin per g soil) from all other treatments for A. orientalis with one exception; the LC₅₀ where NFD2 was added back into autoclaved soil (0.29 µg toxin per g soil). A combination of this bacterium with Btj in nonautoclaved soil resulted in a significantly lower LC₅₀ value (48.29 µg toxin per g soil) from all other treatments for C. borealis with the exception of the treatment where Bacillus sp. NFD2 was added back to autoclaved soil (96.87 µg toxin per g soil) with Btj. This research shows that other soil bacteria can be used to enhance the toxicity of Btj and possibly other Bts.

Golf courses are a potential market for microbial insecticides, but how intensive management of such sites interacts with efficacy of entomopathogens is poorly known. We evaluated Agrotis ipsilon nucleopolyhedrovirus (AgipMNPV) for suppressing black cutworms, Agrotis ipsilon Hufnagel (Lepidoptera: Noctuidae), in turf representative of golf course habitats and on whole tees under actual play. In independent trials on sand- or soil-based putting greens and surrounds, or fairway-height creeping bentgrass (Agrostis stolonifera L.), ≤1-wk-old AgipMNPV residues (10 × 10⁸ occlusion bodies [OBs] per m²) typically gave 50–60% lethal infection of introduced third instars. In most cases, however, there was no residual control beyond 2–4 wk. Spraying fairway-height bentgrass with AgipMNPV alone (10 × 10⁹ OBs per m²) gave 90, 85, and 7% infection of second instars introduced 4 d, 3 wk, or 5 wk later, but adjuvants (optical brightener, lignin, or both) intended to synergize and protect the virus from UV degradation did not extend infectivity. Fresh (<1-wk-old) AgipMNPV residues killed 76–86% of neonates hatching from eggs on tees under play, but levels of control plummeted within a few weeks. Three species of braconids, an encyrtid Copidosoma bakeri (Howard), and a tachinid, Bonnetia comta (Fallen) collectively killed 24–31% of larvae recovered from those tees. AgipMNPV seems better suited for targeted control of early instars than for season-long control. Golf turf is a severe environment for baculoviruses so several applications per growing season would probably be needed to maintain high enough titers on grass foliage to effectively control caterpillar pests.

The use of flightless strains of the multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), established via artificial selection, can be highly effective as a biological control agent for aphids. However, flightless H. axyridis must depend on walking for dispersion. Therefore, data on the walking activity levels in flightless strains are important for the development of effective methods when releasing these agents in the field. Results of measurement of walking activity levels using an infrared actograph showed that walking activity levels during the daytime (but not nighttime) in both sexes of pure flightless strains tended to be lower than those of control strains. We also found that walking activity levels during the daytime for the Ff generation of hybrid strains, produced by reciprocal crossing between two pure flightless strains, were approximately equal to those of pure strains; the reduction in walking activity levels was not recovered by hybrid vigor. Our results indicate that the reduction in walking activity levels in the pure flightless strains was not caused merely by inbreeding depression stemming from the artificial selection process. Instead, potentially flight ability and walking activity levels in this species may be controlled by the pleiotropic effect of a gene.

Firewood can serve as a vector in the transport of non-native species, including wood-boring insects that feed within the wood and thus can be transported accidentally. Governments have enacted limitations on the movement of firewood in an effort to limit the anthropogenic movement of non-native species through, for example, recreational camping. Although the movement of invasive species through firewood is a documented invasion pathway, it is not trivial for governments to determine a “safe” allowable distance for moving firewood. We were motivated by this challenge and developed a theoretical simulation to determine the campgrounds that could be potentially exposed to infested firewood based upon the hypothetical distribution of an invasive species and the allowable distance for moving firewood. We extend this concept to the known distributions of emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) and Asian longhorned beetle, Anoplophora glabripennis (Motschulsky) Coleoptera: Cerambycidae). We illustrate, based upon theoretical and empirical observations, that as the distribution of an invasive species increases, more rigid constraints on the movement of firewood would be required relative to those species that are distributed over a smaller scale. Also, on the level of management within a state, smaller states have far less margin for error than larger ones, as even extremely rigid restrictions on the movement of firewood could have little management effect unless the infested area is spatially limited. These results collectively suggest the potential for a dynamic management strategy that adjusts allowable distances for firewood movement based upon the distribution of the non-native species.

Sternochetus mangiferae (F.) (Coleoptera: Curculionidae) is a quarantine pest of mango, Mangifera indica L., in South Africa. The aim of the study was to test cultural and chemical control measures in a systems approach for risk mitigation of S. mangiferae in South Africa. A large-scale experiment, using a randomized block design with three replicates, was undertaken on ‘Tommy Atkins’ mangoes in South Africa. Five treatment combinations were applied over two seasons: 1) untreated control; 2) sanitation and physical removal of egg-infested fruit (P S); 3) thiamethoxam, P S; 4) thiamethoxam, fipronil, P S; and 5) thiamethoxam, two fenthion applications, P S. A weekly random sample of eight fruit from 40 trees per orchard was taken from 5 wk to harvest over two harvest periods. In total, 57,600 fruit were sampled. In a separate experiment, the same variety was used to test the efficacy of covering fruit with paper bags over one season in a completely randomized design. In both trials, all the pests were recorded from internal and external fruit inspections. In trial 1, results after the first season showed >98% control in the three chemical combination treatments. In the second season, treatment 2 provided 19% and treatment 3 99.9% control, whereas no fruit were infested with S. mangiferae in treatments 4 and 5. Trial two showed that fruit bagging significantly reduced S. mangiferae infestation. The data showed that a systems approach for S. mangiferae control in South Africa can be effective and that bagging can be an effective organic control option.

In a field test to examine attractancy of Mediterranean fruit fly, Ceratitis capitata (Wiedemann), relative to release rates, equal moles of racemic ceralure B1 and trimedlure isomer C were compared on cotton wicks. Data were collected at 2, 4, and 7 d. The substrates were analyzed for longevity and overall persistence in the field. Ceralure B1 was equally attractive as trimedlure C for the first 2 d and significantly more so at 4 and 7 d based on trap counts of captured male Mediterranean fruit flies. Residue analysis of weathered wicks showed that the trimedlure C lasted for just 2 d in our field evaluations, whereas ceralure B1 had measurable material present after 7 d. Thus, based on the amounts of chemicals released, ceralure B1 was more active even in the first 2 d. Ceralure B1 also was formulated in a plastic matrix (ceralure coin) at three different dosages and tested for attractancy in the field against a 2-g trimedlure plug. A 150-mg ceralure B1 coin was equally attractive as a commercial 2-g trimedlure plug, whereas a 300-mg coin was significantly more attractive during a 6 – 8-wk deployment. Although our results clearly show that ceralure B1 is a superior attractant to trimedlure, costs of synthesis need to be considered as part of an overall program management strategy.

Studies were conducted in Hawaii to measure attraction of male melon fly, Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae), to SPLAT-Cue-Lure (C-L) and SPLAT-Melo-Lure (M-L) (raspberry ketone formate). Direct field comparisons of SPLAT-C-L and SPLAT-M-L at low (5%) and high (20%) concentrations indicated few differences in attraction over a 15-wk period. Subsequently, only SPLAT-Spinosad-C-L (5%) was compared with Min-U-Gel C-L with naled (standard used in California) in weathering studies. Treatments were weathered for 1, 2, 4, and 8 wk in Riverside, CA, and shipped to Hawaii for attraction/toxicity tests under field and semifield conditions by using released males of controlled ages, and for feeding tests in the laboratory. In terms of attraction, SPLAT-Spinosad-C-L compared favorably to, or outperformed the current standard of Min-U-Gel-C-L with naled. In terms of toxicity, the cumulative 24-h mortality did not differ between the two insecticide-containing C-L treatments in field cage studies after 8 wk. However, in feeding studies in which individual males were exposed for 5 min to the different C-L treatments after 4 wk of weathering, SPLAT-Spinosad-C-L demonstrated reduced mortality compared with the Min-U-GelC-L with naled, suggesting reduced persistence of the spinosad material. Spinosad has low contact toxicity and when mixed with SPLAT and C-L offers a reduced risk alternative for control of B. cucurbitae and related C-L—responding species, without many of the negative effects to humans and nontargets of broad-spectrum contact poisons such as naled.

In field trials, adult Chlorochroa uhleri (Stål) (Heteroptera: Pentatomidae) of both sexes were caught in significant numbers in cylindrical screen traps baited with gray rubber septum lures loaded with the main component of the male-produced pheromone, methyl (E)-6-2,3-dihydrofarnesoate. Addition of the two possible minor components of the pheromone, methyl (E)-5-2,6,10-trimethyl-5,9-undecadienoate and methyl (2E,6E) -farnesoate, did not affect attraction. Combining the pheromone with different concentrations of volatiles mimicking the odors of a known host plant, alfalfa (Medicago sativa L.), had no significant effect on attraction of adult bugs, whereas combining the pheromone with the pheromones of two sympatric stink bug species, Chlorochroa sayi (Stål) and Euschistus conspersus Uhler, decreased trap captures, suggesting interference between the pheromones. Small numbers of Chlorochroa ligata (Say) adults also were attracted, but numbers caught were too low to allow statistical comparisons between lure blends. In field trials with C. sayi, all three of the male-specific pheromone compounds [methyl geranate, methyl citronellate, and methyl (E) -6-2,3-dihydrofarnesoate] were required for optimal attraction. As with C. uhleri, adults of both sexes were attracted to pheromone lures in approximately equal numbers. Because of the decreased volatility (=release rate) of methyl (E)-6-2,3-dihydrofarnesoate in comparison with the other two, lower molecular weight pheromone components, lures needed to be loaded with a disproportionately high amount of methyl (E)-6-2,3-dihydrofarnesoate to obtain the best trap catch. There was no indication that the pheromone components of C. uhleri or E. conspersus interfered with the attractiveness of the C. sayi pheromone in lures containing a blend of all three pheromones.

The flight take-off activity of Colorado potato beetles, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), was significantly higher at a landscape-protected than at semiexposed and exposed sites in a 2-yr field study. In both years, mean daylight temperature, solar radiation, and relative humidity were generally similar at all sites, but wind speed was lower at the protected site than at the exposed sites. Results suggest that wind was the limiting abiotic factor for flight take-off at the exposed site. Caged beetles exposed to constant wind speeds of 3.4, 4.7, and 7.0 m/s showed a significant corresponding decrease in number of flight take-off. There was no cumulative effect of wind exposure on the readiness of the beetles to fly, suggesting that wind acts as a physical barrier to flight take-off. It should be possible to reduce Colorado potato beetle flight dispersal by selecting fields most exposed to wind over landscape-protected fields when rotating potato, Solanum tuberosum L., crops.

The leopard moth, Zeuzera pyrina (L.) (Lepidoptera: Cossidae), is a damaging pest for many fruit trees (e.g., apple [Malus spp.], pear [Pyrus spp.] peach [Prunus spp.], and olive [Olea]). Recently, it caused serious yield losses in newly established olive orchards in Egypt, including the death of young trees. Chemical and biological control have shown limited efficiency against this pest. Field tests were conducted in 2005 and 2006 to evaluate mating disruption (MD) for the control of the leopard moth, on heavily infested, densely planted olive plots (336 trees per ha). The binary blend of the pheromone components (E,Z)-2, 13-octadecenyl acetate and (E,Z)-3, 13-octadecenyl acetate (95:5) was dispensed from polyethylene vials. Efficacy was measured considering reduction of catches in pheromone traps, reduction of active galleries of leopard moth per tree and fruit yield in the pheromone-treated plots (MD) compared with control plots (CO). Male captures in MD plots were reduced by 89.3% in 2005 and 82.9% in 2006, during a trapping period of 14 and 13 wk, respectively. Application of MD over two consecutive years progressively reduced the number of active galleries per tree in the third year where no sex pheromone was applied. In all years, larval galleries outnumbered moth captures. Fruit yield from trees where sex pheromone had been applied in 2005 and 2006 increased significantly in 2006 (98.8 ± 2.9 kg per tree) and 2007 (23 ± 1.3 kg per tree) compared with control ones (61.0 ± 3.9 and 10.0 ± 0.6 kg per tree, respectively). Mating disruption shows promising for suppressing leopard moth infestation in olives.

Life tables of the planthopper Nilaparvata lugens (Stål) (Hemiptera: Delphacidae) on two wild rice species, Oryza officinalis Wall, ex Watt, and Oryza rufipogon Griff, and on ‘Taichung Native 1’ (O. sativa indica TN1) were studied at 27°C in the laboratory. The raw data were analyzed based on the age-stage, two-sex life table to take both sexes and the variable developmental rate among individuals and between sexes into consideration. The intrinsic rate of increase (r), the finite rate (λ), the net reproduction rate (R₀) and the mean generation time (T) of N. lugens on O. officinalis were -0.0616 d^-1, 0.9402 d^-1, 0.10 offspring, and 36.7 d, respectively, showing that the species is resistant to N. lugens. The resistance of O. officinalis is expressed in the long developmental time from first to fifth instar of N. lugens, the reduced preadult survival rate, the short adult longevity, and low fecundity. However, the population parameters of the N. lugens on O. rufipogon and TN1 were 0.1096 d^-1, 1.1158 d^-1, 67.82 offspring, and 38.6 d and 0.1340 d^-1, 1.1434 d^-1, 144.77 offspring, and 37.2 d, respectively. These population parameters showed that N. lugens can successfully survive and reproduce on both O. rufipogon and TN1.

Crawling and scraping activity of three stored-product pests, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), and Stegobium paniceum (L.) (Coleoptera: Anobiidae), and two urban pests, Blattella germanica (L.) (Blattodea: Blattellidae) and Cimex lectularius L. (Hemiptera: Cimicidae), were monitored individually by infrared sensors, microphones, and a piezoelectric sensor in a small arena to evaluate effects of insect locomotory behavior and size on the ability of an inexpensively constructed instrument to detect insects and distinguish among different species. Adults of all species could be detected when crawling or scraping. The smallest insects in the study, first-fourth-instar C. lectularius nymphs, could not be detected easily when crawling, but could be detected when scraping. Sound and vibration sensors detected brief, 3-10-ms impulses from all tested species, often grouped in distinctive trains (bursts), typical of impulses in previous acoustic detection experiments. To consider the potential for targeting or focusing detection on particular species of interest, indicators were developed to assess the likelihood of detection of C. lectularius. Statistically significant differences were found between C. lectularius and other species in distributions of three measured variables: infrared signal durations, sound impulse-burst durations, and sound pressure levels (energy) of impulses that best matched an averaged spectrum (profile) of scraping behavior. Thus, there is potential that signals collected by an inexpensive, polymodal-sensor instrument could be used in automated trapping systems to detect a targeted species, 0.1 mg or larger, in environments where servicing of traps is difficult or when timeliness of trapping information is important.

In the interest of developing interventions to infestations by Formosan subterranean termites, Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae), several rare sugars were tested for effects on the termites and symbionts. Among these, the D-galactose analog, 2-deoxy-D-galactose (2deoxyGal) showed promise as a potential control chemical. At a test concentration of 2deoxyGal (320.4 µg/mm³) in water applied to 5-cm filter paper, in bioassays with 20 termite workers, we found that worker termite mortality was significantly affected over a 2-wk period. Subsequent dose—mortality feeding studies confirmed these findings. In addition, consumption of the sugar-treated filter paper by termites caused a significant decrease in hindgut protozoan populations. 2deoxyGal caused dose-dependent termite mortality, taking on average 1 wk to begin killing workers, indicating that it may have promise as a delayed action toxin, which, if added to baits, could allow time after bait discovery for an entire colony to be affected.

A common goal of conservation biological control is to enhance biodiversity and increase abundance and effectiveness of predators and parasitoids. Although many studies report an increase in abundance of natural enemies, it has been difficult to document increases in rates of biological control. To enhance parasitism of the tufted apple bud moth, Platynota idaeusalis (Walker) (Lepidoptera: Tortricidae), alternate food was provided by interplanting peaches bearing extrafloral nectaries into apple (Malus spp.) orchards. Laboratory studies showed that the presence of nectar increased longevity and parasitism rates by Goniozus floridanus (Bethylidae), the dominant parasitoid of tufted apple bud moth in West Virginia. In orchard studies, we found the total number of hymenopteran parasitoids was higher on peach (Prunus spp.) trees than on adjacent apple trees. Abundance of parasitic Hymenoptera also was significantly higher on the side of traps facing away from rather than toward peach trees, indicating attraction to peach trees. However, total parasitism rates of tufted apple bud moth were not affected by the presence of peach extrafloral nectar in any field studies. Insect injury to fruit at harvest showed that fruit from orchards with interplanted peach trees had less injury from San Jose scale, Quadraspidiotus perniciosus (Comstock) and stink bugs (Pentatomidae) than fruit from an apple monoculture. Although interplanting with peach trees did not produce the hypothesized result of increased biological control, the experiment did have beneficial results for pest management. These results demonstrate the importance of collecting data on variables beyond the targeted species when evaluating habitat manipulation experiments to fully assess the impact on the ecosystem.

Bioassay of nitenpyram was conducted on the planthopper Nikparvata lugens (Stål) (Hemiptera: Delphacidae) in the laboratory by using the rice-stem dipping method. The resulting data were analyzed using the complementary log-log time—concentration—mortality modeling technique, yielding the parameters for time and concentration effects of nitenpyram against N. lugens instars. The LC₅₀ values to instars I and II estimated for 24, 48, and 72 h after treatment were 1.03, 0.27, and 0.11 mg/liter, respectively. These values were lower than those for instars III and IV and instars V at the same times. The estimates of LT₅₀ for instars I and II were decreased from 69.06 to 16.22 h with the increasing concentration from 0.125 to 2 mg/liter; the same estimates for both instars III and IV and instars V at the concentrations of 1–2 mg/liter were close to each other, ranging from 33.11 to 44.16 h, much higher than the values of instars I and II at the same concentration. Based on the time—concentration—mortality relationships fitted and the virulence indices (LC₅₀ and LT₅₀) estimated, nitenpyram is a promising pesticide for N. lugens control.

The occurrence of aphid-transmitted viruses in agricultural crops of the Midwest and northeastern United States has become more frequent since the arrival and establishment of the soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae). A. glycines is a competent vector of plant viruses and may be responsible for recent virus epidemics in Wisconsin snap bean, Phaseolus vulgaris L., fields. To determine whether vegetation surrounding crop fields could serve as sources of virus inocula, we examined the settling activity of A. glycines and other aphid species in agricultural crops and noncrop field margins adjacent to snap bean fields. Noncrop field margins were made up of numerous virus-susceptible plant species within 10 m from snap bean field edges. During summers 2006 and 2007, horizontal pan traps were placed in commercial soybean [Glycine max (L.) Merr.], snap bean, and surrounding field margins to characterize aphid flight activity patterns in the different habitat types. Alate abundance and peak occurrence across years varied between crop and noncrop field margins and differed among patches of plants in field margins. Overall aphid activity peaked late in the season (21 August in 2006 and 28 July in 2007); with the majority (52%) of total aphids trapped in all habitats being A. glycines. Susceptibility to viral infection and confirmed visitation of A. glycines to these forage plants suggests the importance of noncrop habitats as potential sources of primary virus inoculum. Viral disease onset followed peak aphid flights and further implicates A. glycines as a likely vector of viruses in commercial bean and other crops in Wisconsin.

Firewood is a major pathway for the inadvertent movement of bark- and wood-infesting insects. After discovery of Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) in southeastern Michigan in 2002, quarantines were enacted including prohibition of transporting firewood across the Mackinac Bridge between Michigan's Lower and Upper peninsulas. Drivers are required to surrender firewood before crossing the bridge. We surveyed recently surrendered firewood in April, July, and September 2008 and categorized it by genus, cross-sectional shape (whole, half, or quarter), approximate age (years since it was a live tree), presence of bark, and evidence of bark- and wood-boring insects. The 1,045 pieces of firewood examined represented 21 tree genera: primarily Acer (30%), Quercus (18%), Fraxinus (15%), Ulmus (12%), Betula (5%), and Prunus (5%). Live borers (Bostrichoidea, Brentidae, Buprestidae, Cerambycidae, Cossidae, Curculionidae [Scolytinae and non-Scolytinae],and Siricidae) were found in 23% of the pieces and another 41% had evidence of previous borer infestation. Of the 152 Fraxinus firewood pieces, 13% had evidence of past A. planipennis infestation, but we found no live A. planipennis. We discuss national “don't move firewood” campaigns and U.S. imports of fuelwood. During 1996–2009, the United States imported fuelwood valued at >$US98 million from 34 countries.

Our research used a combination of passive traps, funnel traps with lures, baited trees, and surveys of long-term thinning plots to assess the impacts of different levels of stand basal area (BA) on bark beetle tree attack and on trap captures of Ips spp., Dendroctonus spp., and their predators. The study occurred at two sites in ponderosa pine, Pinus ponderosa Dougl. ex Laws., forests, from 2004 to 2007 during low bark beetle populations. Residual stand BA ranged from 9.0 to 37.0 m²/ha. More predators and bark beetles were collected in passive traps in stands of lower BA than in stands of higher BA; however, significance varied by species and site, and total number of beetles collected was low. Height of the clear panel passive traps affected trap catches for some species at some sites and years. When pheromone lures were used with funnel traps [Ips pini (Say) lure: lanierone, 03/-97 ipsdienol], we found no significant difference in trap catches among basal area treatments for bark beetles and their predators. Similarly, when trees were baited (Dendroctonus brevicomis LeConte lure: myrcene, exo-brevicomin and frontalin ), we found no significant difference for days to first bark beetle attack. Surveys of long-term thinning treatments found evidence of bark beetle attacks only in unthinned plots (≈37 m²/ ha basal area). We discuss our results in terms of management implications for bark beetle trapping and control.

The responsiveness of male codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), exposed to surfaces treated with the ecdysteroid agonist methoxyfenozide, toward lures loaded with the synthetic sex pheromone codlemone and/or the pear ester kairomone were investigated in wind tunnel experiments. Five different kinds of commercially available codling moth monitoring lures (obtained from Trécé Inc., Adair, OK) were used in the bioassay: Pherocon CM Standard lure (loaded with 1 mg of codlemone), Pherocon CM Long-Life L2 (loaded with 3.5 mg of codlemone), Pherocon CM 10X (loaded with 10 mg of codlemone), Pherocon CM-DA Combo (loaded with 3.0 mg of codlemone and 3.0 mg of pear ester), and Pherocon DA (loaded with 3.0 mg of pear ester). Results from the study revealed that male codling moth exposed to surfaces treated with methoxyfenozide and the surfactant exhibited a significant decline in responsiveness toward lures loaded with either codlemone or pear ester. The full impact of how this negative effect might alter current moth monitoring procedures in orchards receiving ecdysone agonist sprays requires further investigation.

The systemic neonicotinoid insecticide imidacloprid, Admire Pro, was applied to 3- and 4-yr-old nonbearing ‘Rio Red’ grapefruit, Citrus × paradisi Macfad., trees in 2006 and 2007, respectively, to determine its effects in the control of two major citrus pests, the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), and a citrus leafminer Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae). Young flush shoots were randomly collected weekly for 13 and 11 wk in 2006 and 2007, respectively, to determine the infestation levels and densities of immature stages of both Asian citrus psyllid and P. citrella. Additional flush shoot samples were collected in 2007 and titers of imidacloprid in leaf tissue were determined using an enzyme-linked immunosorbent assay. Soil application of imidacloprid significantly reduced the infestation levels and densities of both pests on flush shoots, starting from the second week post application. The effects of the neonicotinoid insecticide were similar in both years. Analysis of imidacloprid concentration in leaf tissue showed a gradual increase during the first 3 wk, and titers remained well above 200 ppb for 11 wk postapplication. Significant positive correlations were obtained between imidacloprid titers in leaf tissue and the percentage of control levels achieved for both pests. A high level of suppression of both P. citrella and Asian citrus psyllid populations on citrus trees was associated with imidacloprid titer in leaf tissue >200 ppb, which was reached 2 wk after soil treatment. Although soil application of imidacloprid did not provide rapid knockdown of Asian citrus psyllid and P. citrella populations, it resulted in chronic residues in leaf tissue and long-term suppression of both pests.

Laboratory and semifield bioassays were conducted to determine the life-stage activity of insecticides for controlling cranberry fruitworm, Acrobasis vaccinii Riley (Lepidoptera: Pyralidae), a key lepidopteran pest of highbush blueberry, Vaccinium corymbosum L. The organophosphates azinphosmethyl and phosmet, the pyrethroid esfenvalerate, and the carbamate methomyl were lethal to all life stages. The neonicotinoids thiacloprid and acetamiprid demonstrated strong larvicidal and ovicidal activity but were somewhat weaker adulticides than the conventional broad-spectrum compounds. Bacillus thuringiensis, indoxacarb, and emamectin benzoate were shown to control A. vacinii primarily through their larvicidal activity. Spinosad was toxic to all life stages, including eggs laid on top of residues and those that were treated topically, but larvicidal activity was short lived. The growth regulators pyriproxyfen and novaluron had strong ovicidal activity when eggs were laid on top of residues but had limited larvicidal activity. Tebufenozide was not directly toxic to eggs, but demonstrated larvicidal activity, and ovilarvicidal activity when topically applied to eggs. Azinphosmethyl, phosmet, indoxacarb, thiacloprid, and acetamiprid were all toxic to the egg parasitoid Trichogramma minutum Riley. In contrast pyriproxyfen, emamectin benzoate, methomyl, novaluron, and spinosad did not negatively affect the survival of T. minutum within Acrobasis vacinii eggs. These results help inform the ongoing development of integrated strategies for insect management in blueberry.

Effective management of potato ‘Zebra Chip’ (ZC) disease caused by Cadidatus Liberibacter psyllaurous (syn. solanacearum) depends on the management of its insect vector insect, potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Psyllidae). To elucidate the age-specific population dynamics of B. cockerelli, the life-table parameters were determined on potato, Solanum tuberosum L., under both laboratory and field conditions in the Lower Rio Grande Valley (LRGV) of Texas. Generally, survival, fecundity, and longevity of B. cockerelli were significantly greater under laboratory than under field conditions. The mortality under laboratory conditions was mainly due to natural intrinsic mortality. However, under field conditions, most (83.2%) B. cockerelli were missing, and of those that were not, they developed slower, and had shorter preoviposition period, shorter oviposition period, shorter longevity, lower fecundity, and higher mortality than those under laboratory conditions. As a result, most of the life-table parameters of B. cockerelli, including the intrinsic rate of increase, finite rate of increase, and net reproductive rate, were significantly lower in the field under the environmental conditions of the LRGV of Texas than in the laboratory. The information could help increase our understanding of the epidemiology of the ZC diseases associated with the pathogens transmitted by this insect pest.

The armored scales Fiorinia externa Ferris and Aspidiotus cryptomeriae Kuwana (Hemiptera: Diaspididae) are increasingly damaging to Christmas tree plantings in southern New England. The systemic insecticide dinotefuran was investigated for selectively suppressing armored scale populations relative to their natural enemies in cooperating growers' fields in 2008 and 2009. Banded soil application of dinotefuran resulted in poor control. However, a dinotefuran spray applied to the basal 25 cm of trunk resulted in its absorption through the bark, translocation to the foliage, and good efficacy. The basal bark spray did not significantly impact the activity of predators Chilocorus stigma (Say) or Cybocephalus nipponicus Enrody-Younga and in 2009 showed a dosage-dependent improvement in the percentage of scales parasitized by Encarsia citrina Craw. A field dosage—response factorial experiment revealed that a 0.25% (vol:vol) addition of a surfactant with dinotefuran did not enhance insecticidal effect. Probit-transformed scale population reduction relative to the untreated check was subjected to linear regression analysis; reduction of scale populations was proportional to the log of insecticide dosage, whereas basal bark spray efficacy declined in proportion to the cube of tree height. The regression equation can be used to optimize dosage relative to tree height. Excellent efficacy resulted from basal bark spray application dates of 28 April (prebud break) to mid-June, but earlier spray timing within that treatment window had fewer crawlers discoloring new growth with their short-lived feeding. A basal bark spray of dinotefuran is well suited for integration with natural enemies to manage armored scales in Christmas tree plantations.

Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is a major pest of strawberry, causing substantial yield loss through direct feeding on the flowers and fruit. Insecticides are the main method used for its control; however, F. occidentalis has developed resistance to insecticides from all major chemical classes. Chemical control is not a long-term strategy and integrated pest management is required. This study determined whether F. occidentalis damage could be reduced by host plant resistance or tolerance in three commercial strawberry cultivars (Fragaria × ananassa [Rosaceae]: ‘Albion’, ‘Camarosa’, and ‘Camino Real’). Determination of resistance or tolerance to F. occidentalis was based on olfactory response, feeding damage, ovipositional preference, and host suitability for reproduction on leaves. F. occidentalis adults preferred to feed on Camarosa; however, if leaves had been fed on previously by conspecifics, there was no difference in feeding preference. Camarosa was the most preferred cultivar for oviposition, and more eggs were laid by F. occidentalis on Camarosa than either Albion or Camino Real. More larvae hatched and adults were reared from Camarosa than either Albion or Camino Real. The percentage of unhatched eggs, larvae, and pupae that died was highest on Camino Real. Survival rate was highest on Camarosa. Egg incubation, prepupation, pupation, and total developmental periods were shortest on Camarosa, but the larval period was longest on Camarosa. Camarosa was the most favorable cultivar for F. occidentalis population growth on leaves.

The aim of our study was to investigate the intra- and interspecific agonistic behaviors exhibited by the worker and soldier castes of the subterranean termite Microcerotermes crassus Snyder (Isoptera: Termitidae). Aggression between M. crassus colonies from different field locations and also against three termite species—Coptotermes gestroi (Wasmann), Globitermes sulphureus Haviland, and Odontotermes sp.—were observed in the laboratory. Termite responses were tested in paired combination of castes (soldiers versus soldiers, soldiers versus workers, and workers versus workers) consisting of 10 individuals each. Significant agonistic behaviors were observed only in encounters between pairings of different termite species. M. crassus was aggressive toward individuals from different species but not toward individuals from different M. crassus colonies. Mortality of M. crassus reached 100% in most of the interspecific encounters. However, no or low mortality was recorded in the intraspecific pairings.

A novel bait station referred to as a virtual bait station was developed and tested against field populations of the invasive Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), at White Beach, Camp Pendleton, in Oceanside, CA. White Beach is a nesting habitat for an endangered seabird, the California least tern (Sterna antillarum browni Mearns). The beach is heavily infested with Argentine ants, one of the threats for the California least tern chicks. Conventional pest control strategies are prohibited because of the existence of the protected bird species and the site's proximity to the ocean. The bait station consisted of a polyvinyl chloride pipe that was treated on the inside with fipronil insecticide at low concentrations to obtain delayed toxicity against ants. The pipe was provisioned with an inverted bottle of 25% sucrose solution, then capped, and buried in the sand. Foraging ants crossed the treated surface to consume the sucrose solution. The delayed toxicity of fipronil deposits allowed the ants to continue foraging on the sucrose solution and to interact with their nestmates, killing them within 3–5 d after exposure. Further modification of the bait station design minimized the accumulation of dead ants in the sucrose solution, significantly improving the longevity and efficacy of the bait station. The virtual bait station exploits the foraging behavior of the ants and provides a low impact approach to control ants in environmentally sensitive habitats. It excluded all insects except ants, required only milligram quantities of toxicant, and eliminated the problem of formulating toxicants into aqueous sugar baits.

The objective of this study was to evaluate the suitability of heat- and freeze-killed oothecae of Periplaneta americana (L.) (Dictyoptera: Blattidae) as hosts for parasitoid Aprostocetus hagenowii (Ratzeburg) (Hymenoptera: Eulophidae). The oothecae were subjected to -20, 45, 48, 50, and 55°C at different exposure times (15, 30, 45, and 60 min). The effects of heat- and freeze-killed oothecae on several biological parameters (e.g., parasitism and emergence rates, developmental times, progeny number, and sex ratio) of A. hagenowii were determined. Embryonic development of 2-d-old oothecae was terminated by either freezing at -20°C or heating at ≥48°C for ≥30 min. A. hagenowii parasitized live oothecae as well as both heat- and freeze-killed oothecae. Percentage parasitism, emergence rates, and developmental times of A. hagenowii in both heat- and freeze-killed oothecae were not significantly different from those of the live oothecae. Both heating and freezing did not influence progeny number (male and female) and sex ratio of A. hagenowii emerged from killed oothecae.

The longlegged ant, Anoplolepis gracilipes (Fr. Smith) (Hymenoptera: Formicidae), is a highly invasive species that can aggressively displace other ant species. We conducted laboratory assays to examine interspecies aggression of A. gracilipes versus 15 sympatric ant species found in the urban environment and disturbed habitat in Malaysia: Monomorium pharaonis (L.), Monomorium floricola (Jerdon), Monomorium orientale Mayr, Monomorium destructor (Jerdon), Pheidole parva Mayr, Crematogaster sp., Solenopsis geminata (F.), Tapinoma indicum (Forel), Tapinoma melanocephalum (F.), Technomyrmex butteli Forel, Dolichoderus thoracicus (Smith), Paratrechina longicornis (Latrielle), Oecophylla smaragdina (F), Camponotus sp., and Tetraponera rufonigra (Jerdon). A. gracilipes showed aggressive behavior toward all opponent species, except the smallest M. orientale. Opponent species size (body size, head width, and mandible width) was significantly correlated with A. gracilipes aggression level and mortality rate. We also found a significant positive relationship between A. gracilipes aggression level and the mortality of the opponent species. The results suggest that invasive populations of A. gracilipes would have the greatest impact on larger ant species. In addition, we examined the intraspecific aggression of A. gracilipes. We found that A. gracilipes from different localities in Malaysia showed intraspecific aggression toward one another. This finding differs from the results of studies conducted in Christmas Island earlier. Differences in the genetic variability among populations may explain these differing results.

Previous short-term experiments showed that trail following behavior of the Argentine ant, Linepithema humile (Mayr) (Hymenoptera: Formicidae), can be disrupted by a high concentration of synthetic trail pheromone component (Z)-9-hexadecenal. In this study, a long-term field trial was conducted in 100-m² plots of house gardens in an urban area of Japan to see whether the control effect on Argentine ants can be obtained by permeating synthetic trail pheromone from dispensers. The dispensers were placed in the experimental plots during the ant's active season (April–November) for 2 yr with monthly renewal. To estimate Argentine ant population density, foraging activity of Argentine ants in the study plots was monitored by monthly bait surveys. Throughout the study period, Argentine ant foraging activity was suppressed in the presence of the dispensers, presumably via trail forming inhibition. In contrast, the level of foraging activity was not different between treatment and no-treatment plots when the dispensers were temporarily removed, suggesting that treatment with pheromone dispensers did not suppress Argentine ant density in the treatment plots. Population decline may be expected with larger-scale treatment that covers a significant portion of the ant colony or with improvement in the potency of the disruptant.

The invasive Argentine ant, Linepithema humile (Mayr), has become a worldwide problem capable of inflicting significant ecological and economic injury on urban, agricultural, and natural environments. The mobility of this pest ant has long been noted, rapidly moving nests to new food resources and then away as resources are depleted. This ant, like many pest ant species, has a special affinity for honeydew excreted by phloem-feeding Hemiptera. We investigated the effect of various hemipteran control strategies on terrapin scale densities and measured their indirect effect on local Argentine ant densities and foraging effort. We then determined whether this indirect treatment strategy improved the performance of an ant bait. We predicted that Argentine ants would move nests away from trees treated for Hemiptera and then move nests back when a liquid bait was offered, followed by a decline in ant numbers due to intake of the toxicant. A horticultural oil spray and soil application of the systemic insecticide, imidacloprid, had no effect on terrapin scale numbers. However, trunk-injected dicrotophos caused a reduction in scale and a decline in local Argentine ant nest density and canopy foraging effort. We also recorded a reduction in local Argentine ant ground foraging when large amounts of liquid bait were applied, and we found no evidence that combining dicrotophos with liquid ant bait performed better than each treatment alone. We suggest that a strategy of combined hemipteran control plus application of liquid ant bait can reduce local Argentine ant densities, when both components of this system are highly efficacious.

The occurrence of resistance in Varroa mite populations is a serious threat to the beekeeping industry and to crops that rely on the honey bee for pollination. Integrated pest management strategies for control of this pest include the judicious use of insecticides. To monitor field populations of Varroa mite for insecticide resistance, a glass vial bioassay procedure was developed to use in the development of a resistance management strategy. Diagnostic concentrations needed to separate susceptible genotypes from resistant individuals were determined for Cypermethrin (0.1 µg per vial), fluvalinate (5.0 µg per vial), malathion (0.01 µg per vial), coumaphos (10.0 µg per vial), diazinon (5.0 µg per vial), methomyl (0.5 µg per vial), propoxur (0.1 µg per vial), and endosulfan (2.5 µg per vial). Resistance to organophosphorus insecticides (malathion, coumaphos) and pyrethroids (cypermetrhrin, fluvalinate) was widespread in both La Media Ranch, TX, and Wewahitchka, FL, from 2007 to 2009. There was no resistance to endosulfan, diazinon, methomyl, and propoxur in field populations of Varroa mite in the two locations where resistance was monitored. The seasonal patterns of resistance in Wewahitchka were different from those of La Media Ranch. In the former location, the frequency of resistance to all insecticides tested decreased significantly from 2007 to 2009, whereas it increased in the latter location. Resistance levels were unstable, suggesting that resistance could be successfully managed. The results validate use of the glass vial bioassay to monitor for resistance in Varroa mite and provide the basis for the development of a resistance management strategy designed to extend the efficacy of all classes of insecticides used for control of Varroa mite.

The large-scale cultivation of transgenic crops producing Bacillus thuringiensis (Bt) toxins have already lead to the evolution of Bt resistance in some pest populations targeted by these crops. We used the F₂ screening method for further estimating the frequency of resistance alleles of the European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), to Bt maize, Zea mays L., producing the CrylAb toxin. In France, Germany, and Italy, 784, 455, and 80 lines of European corn borer were screened for resistance to Mon810 maize, respectively. In Slovakia, 26 lines were screened for resistance to the CrylAb toxin. The cost of F₂ screen performed in the four countries varied from US$300 to $1,300 per line screened. The major difference in cost was mostly due to a severe loss of univoltine lines during the screen in Germany and Slovakia. In none of the screened lines did we detect alleles conferring resistance to Mon810 maize or to the CrylAb toxin. The frequency of resistance alleles were <1.0 × 10^-3, <1.6 × 10^-3, <9.2 × 10^-3, and <2.6 × 10^-2 in France, Germany, Italy, and Slovakia, with 95% probability, respectively. The average detection probability over all lines was ≈90%. Making the assumption that European corn borer populations in these countries belong to the same genetic entity, the frequency of alleles conferring resistance to the CrylAb produced by the Mon810 maize in western and central Europe was 1.0 × 10^-4, with a 95% confidence interval of 0–3.0 × 10^-4.

In 2007–2008, the “annual bluegrass weevil,” Listronotus maculicollis Kirby (Coleoptera: Curculionidae), a serious pest of Poa annua L. (Poales: Poaceae) on U.S. golf courses, was shown to be resistant to two pyrethroids, bifenthrin and lambda-cyhalothrin. In 2008, we showed that bifenthrin resistance was principally mediated by oxidase detoxification (cytochrome P450 [P450]). P450s can be inhibited by demethylation inhibitor fungicides and gibberellin inhibitor plant growth regulators, both of which are commonly used on golf courses. We tested these compounds for synergistic activity with bifenthin against a pyrethroid-resistant population of L. maculicollis. The LD₅₀ value for bifenthrin was significantly reduced from 87 ng per insect (without synergists) to 9.6–40 ng per insect after exposure to the fungicides fenarimol, fenpropimorph, prochloraz, propiconazole, and pyrifenox and the plant growth regulators flurprimidol, paclobutrazol, and trinexapac-ethyl. Simulated field exposure with formulated products registered for use on turf revealed enhanced mortality when adult weevils were exposed to bifenthrin (25% mortality, presented alone) combined with field dosages of propiconizole, fenarimol, flurprimidol, or trinexapac-ethyl (range, 49–70% mortality).

To determine their baseline susceptibility to chlorantraniliprole, spinetoram, spinosad, and acetamiprid, oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), neonates were placed on diet cubes containing a range of concentrations of each insecticide. Mortality was assessed after 96 h. Two populations—a long-term laboratory colony from Rutgers University and a colony established in 2007 from a southwestern Illinois (Calhoun County) field population—were tested. We used probit and logit analyses to compare the responses of Calhoun colony neonates from parents reared on ‘Gala’ apples (Malus spp.) with those of Calhoun colony neonates from parents reared on lima bean, Phaseolus lunatus L., diet. We also compared the responses of Calhoun colony neonates with those of Rutgers colony neonates (all from parents reared on apples). LC₅₀s (ppm in diet) for Calhoun colony progeny of adults reared on apples were 0.08, 0.06, 0.41, and 0.30, respectively, for chlorantraniliprole, spinetoram, acetamiprid, and spinosad. Parental food source (apples versus lima bean diet) did not consistently influence the concentration-mortality relationships for neonates. Based on LC₅₀S and toxicity ratio tests, Calhoun colony neonates were slightly but significantly less susceptible to spinetoram and acetamiprid than were Rutgers colony neonates. Similarly, LC₉₀S and toxicity ratio tests indicated that Calhoun colony neonates were slightly but significantly less susceptible to chlorantraniliprole as well. However, toxicity ratios (Calhoun/Rutgers) were low in all instances, and the highest ratio was 1.73 at LC₉₀ for chlorantraniliprole. Overall, the two colonies responded similarly to these insecticides. Results reported here provide baseline data for future monitoring of resistance development.

Evolution of resistance by pests can reduce the efficacy of transgenic crops that produce insecticidal toxins from the bacterium Bacillus thuringiensis Berliner (Bt). In conjunction with refuges of non-Bt host plants, fitness costs can delay the evolution of resistance. Furthermore, fitness costs often vary with ecological conditions, suggesting that agricultural landscapes can be manipulated to magnify fitness costs and thereby prolong the efficacy of Bt crops. In the current study, we tested the effects of four species of entomopathogenic nematodes (Steinernematidae and Heterorhabditidae) on the magnitude and dominance of fitness costs of resistance to Bt toxin CrylAc in pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae). For more than a decade, field populations of pink bollworm in the United States have remained susceptible to Bt cotton Gossypium hirsutum L. producing CrylAc; however, we used laboratory strains that had a mixture of susceptible and resistant individuals. In laboratory experiments, dominant fitness costs were imposed by the nematode Steinernema riobrave Cabanillas, Poinar, and Raulston but no fitness costs were imposed by Steinernema carpocapsae Weiser, Steinernema sp. (ML18 strain), or Heterorhabditis sonorensis Stock, Rivera-Orduño, and Flores-Lara. In computer simulations, evolution of resistance to CrylAc by pink bollworm was substantially delayed by treating some non-Bt cotton refuge fields with nematodes that imposed a dominant fitness cost, similar to the cost observed in laboratory experiments with S. riobrave. Based on the results here and in related studies, we conclude that entomopathogenic nematodes could bolster insect resistance management, but the success of this approach will depend on selecting the appropriate species of nematode and environment, as fitness costs were magnified by only two of five species evaluated and also depended on environmental factors.

The objective of the current study is to investigate the bacterial colonization within the gut of the house fly, Musca domestica L. (Diptera: Muscidae), at the larval stage and the bacterial community of the gut of the house fly at the newly emerged adult stage. After using ethidium monoazide to inhibit recovery of nucleic acids from dead bacteria, three polymerase chain reaction (PCR)-amplified 16S rDNA libraries from wheat bran, larvae, and newly emerged adults was constructed, analyzed, and compared. In total, 24, 11, and four phylotypes in the 16S rDNA libraries of wheat bran and the gut of larvae and adults, respectively, were found and assigned to three phylogenetic phyla of the domain Bacteria: Firmicutes, Proteobacteria, and Bacteroidetes. In the wheat bran library, 76% of the total number of sequences were affiliated to the genera Pseudomonas, Halomonas, Providencia, and Ignatzschineria. The three genera Morganella (79.05%), Providencia (8.78%), and Ignatzschineria (9.46%) dominated the library of the larval gut. Compared with the wheat bran library, the relative abundance of Morganella morganii (Winslow) was significantly higher (79.05 versus 0.8%), whereas that of Ignatzschineria larvae and of Providencia spp. was similar. These results demonstrate that M. morganii, Providencia spp., and I. larvae colonized the gut of the house fly larvae. Live bacteria of M. morganii, Providencia spp., and Proteus spp. were found in the gut of newly emerged adults. Therefore, the bacteria M. morganii and Providencia spp. colonized the larval gut could survive in the gut from larval metamorphosis to adult eclosion of the house fly.

Several different taxa within the genera Dacus and Ceratitis (Diptera: Tephritidae) are important agricultural pests in Sub-Saharan Africa. Although the status of many of these taxa as distinct species and their phylogenetic relationships is unclear, it is clear that these pests use a wide range of host plants and are highly invasive. The great potential for economic damage inflicted by these pests requires the ability to make accurate and reliable taxonomic identification of specimens. However, many limitations and uncertainties are encountered when these species are examined using traditional approaches based on morphological identification techniques. We describe here the amplification and analysis of DNA sequences from the mitochondrial cytochrome oxidase II (COII)-tRNA_lys-tRNAAsp genes from individuals of various Dacus and Ceratitis species and populations from Sub-Saharan Africa. The variation detected in the DNA sequences of these individuals is used both for clarification of their taxonomic status and the analysis of phylogenetic relationships of these taxa.

Wolbachia, a bacterial symbiont, is maternally transmitted in arthropods and nematodes. We report a systematic survey of Wolbachia taxonomy in the sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), and in some of its natural enemies. For the first time, Wolbachia infections in B. tabaci are correlated with various whitefly genetic groups, host plants, and natural enemies as well as with geographical regions. Polymerase chain reaction using 16S rDNA and ftsZ genes revealed two Wolbachia supergroups, A and B, exist as single or double infections in B. tabaci as well as in some of its aphelinid parasitoids and predatory beetles. Approximately 89% of B. tabaci sampled were infected by Wolbachia, among which 34% were infected by A, 51% were infected by B, and 5% were infected by both A and B supergroups. These infection frequencies differed among B. tabaci genetic groups and locations. The invasive B. tabaci genetic group from the Middle East Asia Minor 1 (also referred as B biotype) and Mediterranean (also referred as Q biotype) was more likely to harbor A than B, whereas native genetic groups in AsiaI and AsiaII were more likely to harbor B than A. Although 60% of aphelinid parasitoids and 72% of coccinellid beetles also were infected by Wolbachia, they were more likely to host B than A. Furthermore, for the first time we report Wolbachia in B biotype from specimens collected outside of China. Construction of a phylogenetic tree clearly indicated that the Wolbachia sequences from different genetic groups of B. tabaci were not only similar to each other but also to sequences from beetles and parasitoids, which may provide evidence of coevolution and horizontal transmission of Wolbachia populations.

Both nymphal and adult spittlebugs (Hemiptera: Cercopidae) cause serious economic damage to susceptible brachiariagrass [genus Biachiaria (Trin.) Griseb], pastures in tropical America. Both life stages are xylem feeders: nymphs feed primarily on roots and stems, whereas the adults feed mainly on foliage. Numerous interspecific brachiariagrass hybrids with high levels of antibiosis resistance to nymphs of several important spittlebug species have been obtained. Recent studies revealed major inconsistencies between reaction to nymphs and reaction to adults on the same host genotype. Because both insect life stages can cause severe economic damage on susceptible brachiariagrass pastures, a cultivar development strategy must take into account resistance to both life stages. To assess the degree of association between resistance to spittlebug nymphs and to adult feeding, we tested 164 hybrids and six check genotypes for resistance to both life stages of three spittlebug species: Aeneolamia varia (F.), Aeneolamia reducta (Lallemand), and Zulia carbonaria (Lallemand). Most hybrids tested were classified as resistant to nymphs. On the contrary, for all three species, the overall mean damage score of the 164 hybrids did not differ from the mean score of the susceptible checks. None of the hybrids was classified as resistant to adult feeding damage. Correlations between percentage nymph survival and adult damage scores were consistently low (r = 0.0104–0.0191). Correlations between nymphal and adult damage scores were also low (0.109–0.271), suggesting that resistances to the different life stages are largely independent. Chi-square analyses comparing frequency distributions of responses of the 164 breeding hybrids to nymphs or adults confirmed essential genetic independence of these two traits. We conclude that attention to improving genetic resistance specifically to adult feeding damage is warranted.

Twenty-one cabbage (Brassica oleracea capitata group) varieties, including 16 local varieties and five commercial hybrids, were screened for resistance to the moth Mamestra brassicae L. under natural and artificial conditions in northwestern Spain. Resistance was assessed as the proportion of damaged plants and damaged leaves, leaf feeding injury, and number of larvae present. Correlation coefficients among damage traits showed that a visual scale (general appearance rating) should be a useful indicator of resistance. Most local varieties were highly susceptible to M. brassicae, whereas the commercial hybrids tested were resistant in terms of head foliage consumption and number of larvae per plant. Performance of varieties was similar under natural and artificial infestation although some of them performed differently at each year. Three local varieties (MBG-BRS0057, MBG-BRS0074, and MBG-BRS0452) were highly susceptible at both natural and artificial infestation conditions being MBG-BRS0074 the most damaged variety. Two local varieties (MBG-BRS0402 and MBG-BRS0535) and commercial hybrids were identified as resistant or moderately resistant to M. brassicae. Among them, ‘Corazon de Buey’ and ‘Cabeza negra’ were the most resistant and produced compact heads. These varieties could be useful sources of resistance to obtain resistant varieties to M. brassicae or as donors of resistance to other Brassica crops. The possible role of leaf traits, head compactness, and leaf glucosinolate content in relation to M. brassicae resistance is discussed.

The Russian wheat aphid, Diuraphis noxia Kurdjumov, is an introduced species first identified in 1986 into the United States. It has since become a major pest of wheat, Triticum aestivum L_., and other small grains in the western United States. Three other Diuraphis species, Diuraphis frequens (Walker), Diuraphis mexicana (McVicar Baker), and Diuraphis tritici (Gillette), were already endemic to the United States before the introduction of D. noxia. The objective of this study was to determine the occurrence and host associations of these four Diuraphis spp. in the Rocky Mountain region that borders the western Great Plains to better understand their distribution and ecological interactions. In addition, a key to these species with photographs of live or fresh preparations of specimens is presented to aid in their identification. D. noxia was the most widely distributed species in the study area spanning the Rocky Mountain areas of Wyoming, New Mexico, Utah, and Colorado. This species was most common in the cereal-producing areas of the Colorado Plateau ecoregion. D. frequens was found to be the predominant species in the Alpine/Aspen Mountain areas of the South Central Rockies and Colorado Rockies ecoregions. The other Diuraphis species were rarely encountered even though their plant hosts occurred in the ecoregions sampled. D. noxia shared common hosts and was found co-infesting grasses with other Diuraphis species. Therefore, the potential exists for D. noxia to impact the other native Diuraphis species.

Studies were conducted in Honduras to determine effective sampling range of a female-targeted protein-based synthetic attractant for the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae). Multilure traps were baited with ammonium acetate, putrescine, and trimethylamine lures (three-component attractant) and sampled over eight consecutive weeks. Field design consisted of 38 traps (over 0.5 ha) placed in a combination of standard and high-density grids to facilitate geostatistical analysis, and tests were conducted in coffee (Coffea arabica L.), mango (Mangifera indica L.), and orthanique (Citrus sinensis × Citrus reticulata). Effective sampling range, as determined from the range parameter obtained from experimental variograms that fit a spherical model, was ≈30 m for flies captured in tests in coffee or mango and ≈40 m for flies captured in orthanique. For comparison, a release-recapture study was conducted in mango using wild (field-collected) mixed sex C. capitata and an array of 20 baited traps spaced 10–50 m from the release point. Contour analysis was used to document spatial distribution of fly recaptures and to estimate effective sampling range, defined by the area that encompassed 90% of the recaptures. With this approach, effective range of the three-component attractant was estimated to be ≈28 m, similar to results obtained from variogram analysis. Contour maps indicated that wind direction had a strong influence on sampling range, which was ≈15 m greater upwind compared with downwind from the release point. Geostatistical analysis of field-captured insects in appropriately designed trapping grids may provide a supplement or alternative to release-recapture studies to estimate sampling ranges for semiochemical-based trapping systems.

Insects can cause substantial damage to stored grain. In addition, consumers and therefore food processors are increasingly interested in chemical-free products. Integrated pest management (IPM) may increase farmers' profits while reducing their use of pesticides. This study uses a stochastic dynamic programming framework to model the economics of optimal insect control in corn, Zea mays L., stored on-farm with multiple controls conditional on the biophysical conditions of the grain in the bin. We find that for farmers who have a contract with a food processor, where there are quality premiums, the optimal management strategy depends on monitoring the biophysical conditions of the grain and the time period under consideration. For farmers who deliver to the commodity market, their current practices are optimal.

The drugstore beetle, Stegobium paniceum (L.) (Coleoptera: Anobiidae), is a pest of stored medicinal and aromatic plants. Generally, mortality of each stage increased with an increase of temperature and exposure time. Heat tolerance for different stages from highest to lowest was young larvae, old larvae, eggs, adult, and pupae. The mortality after 7 h at 42°C for young larvae, old larvae, eggs, adults, and pupae, respectively, was 16 ± 5, 31 ± 6, 48 ± 3, 63 ± 8, and 86 ± 2% (mean ± SEM). Similar trends for stage specific mortality were seen with the lethal time for 90% mortality (LT₉₀) at 42°C; 773,144,12, and 11 h for old larvae, eggs, adults, and pupa respectively. Mortality was too low with young larvae to estimate LT₉₀. The LT₉₀ for young larvae at 42, 45, 50, 55, and 60°C was 25, 20, 3.9, 0.18, and 0.08 h, respectively. The cold tolerance of different stages at 0°C from highest to lowest was adults, old larvae, young larvae, pupae, and eggs. The LT₉₀ at 0°C was 298,153,151, 89, and 53 h, respectively. The LT₉₀ for adults at 5, -5, -10, and -15°C was 792, 58, 2, and 0.8 h, respectively. The supercooling point of adults was -15.2 ± 2°C; young larvae, -9.0 ± 0.8°C; old larvae, -6.5 ± 0.5°C; and pupae, -4.0 ± 1.4°C. Heat treatments that control young larvae should control all other stages of S. paniceum. Cold treatments that control adults should control all other stages of S. paniceum. Dried plants stored at 5°C for 45 d or 42°C for 30 h and then kept below 18°C throughout the rest of the year, should remain pest-free without any chemical control.

Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), the red flour beetle, is a common cosmopolitan pest exploiting a variety of stored products. We experimentally manipulated diet nutritional quality by using non-nutritive filler to examine how this influenced pheromone production and olfactory attractiveness of T. castaneum adult males. Volatiles released by individual males reared on high versus low nutrition diets were collected using solid phase microextraction, and gas chromatography coupled to mass spectrometry was used to identify and quantify the Tribolium aggregation pheromone 4, 8-dimethyldecanal (DMD). Males kept on high nutrition diet showed a three-fold increase in daily DMD production, which suggests the possibility that this pheromone could act as a condition-dependent mating signal. In pitfall trap assays, there was no significant difference in the mean response of virgin females to discs kept with low versus high nutrition males, although discs carrying male cues were significantly more attractive than blank discs. These results suggest that DMD production rates by T. castaneum males will depend on the nutritional quality of various stored products, but such differences may not alter males' ability to attract females.

We investigated the effects of eight temperatures (22.5, 25.0, 27.5, 30.0, 32.5, 35.0, 37.5, and 40.0°C) and four relative humidities (43, 55, 63, and 75%) on population growth and development of the psocid Liposcelis rufa Broadhead (Psocoptera: Liposcelididae). L. rufa did not survive at 43% RH, at all temperatures tested; at 55% RH, at the highest four temperatures; and at 63% RH and 40.0°C. The greatest population growth was recorded at 35.0°C and 75% RH (73-fold growth). At 40.0°C, L. rufa populations declined or barely grew. L. rufa males have two to four nymphal instars, and the percentages of males with two, three, and four instars were 31, 54, and 15%, respectively. Female L. rufa have two to five instars, and the percentages of females with two, three, four, and five instars were 2, 44, 42, and 12%, respectively. The life cycle was shorter for males than females. We developed temperature-dependent developmental equations for male and female eggs, individual nymphal, combined nymphal, and combined immature stages. The ability of L. rufa to reproduce at a relative humidity of 55% and temperatures of 22.5–30.0°C and at relative humidities of 63–75% and temperatures of 22.5–37.5°C, in addition to being able to survive at 40.0°C, suggests that this species would be expected to have a broader distribution than other Liposcelis species. These data provide a better understanding of L. rufa population dynamics and can be used to help develop effective management strategies for this psocid.

The number of adult male and female house flies, Musca domestica L. (Diptera: Muscidae), near varying levels of (Z)-9-tricosene alone (5, 50, or 100 µl) or combined (50 µl) with sugar was determined using conical screened traps on a dairy in southern California. Overall, significantly more males than females were collected in the traps. Significantly more flies (male and female) were collected in traps with (Z)-9-tricosene. There were no significant differences among doses of (Z)-9-tricosene alone, but numbers of both sexes were significantly higher in traps baited with (Z)-9-tricosene and sugar compared with the 5- and 50-µl doses without sugar. The age of female flies collected in traps was determined by pterin analysis. Mean female ages ranged from 94.7 to 99.6 degree-days (6.3–6.8 d of age) and did not differ significantly among treatments. Dissections of a subset of females from each treatment determined that collected females were primarily nongravid (86.3%). Proportions of gravid females that were collected did not differ among treatments.

The house fly, Musca domestica L. (Diptera: Muscidae), continues to be a primary pest of livestock facilities worldwide. This pest also has shown a propensity for pesticide resistance development when under high selection pressures. In this study the house fly strain FDm was created by a 20% contribution from each of five colonies collected from dairies in Florida with known imidacloprid resistance. The FDm strain was used to evaluate the level of imidacloprid resistance after five selections near the LC₇₀ value of each selected generation. Overall, the mean selection mortality was 72.7, with males being considerably more susceptible than females. The unselected (F₀) FDm strain showed considerable susceptibility to imidacloprid after its creation, compared with the five parental strains. Between 9,500 and 14,000 virgin house flies were used in each selection. After the fifth and final selection, a 331-fold increase in imidacloprid resistance at the LC₇₀ was observed over the parental FDm strain. In parallel studies, the FDm strain showed increasing tolerance of the commercial imidacloprid product QuickBayt. These results suggest that livestock producers should use caution when choosing pesticides and consider rotating fly baits, as is encouraged with other pesticide treatment regimes on farms.