Neutral molecular markers are gene sequences where variants are considered to confer no fitness advantage, such as microsatellites and mitochondrial haplotypes. Several types of neutral marker are easy to develop, cheap to use, and have found extensive application for addressing ecological questions. In biocontrol, these markers are used to simplify identification of cryptic species and of prey remains in predators. Here, we address the potential of neutral molecular markers for determining the relative performance of a “superior” strain of a species after release into an already established conspecific population. We used modeling to show that only under very limited conditions can traditional neutral markers be used to demonstrate that beneficial genetic variation was successfully introgressed into the existing population. However, new population genomic methods do make it possible to track alleles at a large number of loci and consequently make it possible to show if alleles from a superior strain spread in an already established conspecific population.

Evolution of pest resistance to pesticides is an urgent global problem with resistance recorded in at least 954 species of pests, including 546 arthropods, 218 weeds, and 190 plant pathogens. To facilitate understanding and management of resistance, we provide definitions of 50 key terms related to resistance. We confirm the broad, long-standing definition of resistance, which is a genetically based decrease in susceptibility to a pesticide, and the definition of “field-evolved resistance,” which is a genetically based decrease in susceptibility to a pesticide in a population caused by exposure to the pesticide in the field. The impact of field-evolved resistance on pest control can vary from none to severe. We define “practical resistance” as field-evolved resistance that reduces pesticide efficacy and has practical consequences for pest control. Recognizing that resistance is not “all or none” and that intermediate levels of resistance can have a continuum of effects on pest control, we describe five categories of field-evolved resistance and use them to classify 13 cases of field-evolved resistance to five Bacillus thuringiensis (Bt) toxins in transgenic corn and cotton based on monitoring data from five continents for nine major pest species. We urge researchers to publish and analyze their resistance monitoring data in conjunction with data on management practices to accelerate progress in determining which actions will be most useful in response to specific data on the magnitude, distribution, and impact of resistance.

The honey bee parasite Varroa destructor Anderson & Trueman can disperse and invade honey bee colonies by attaching to “drifting” and “robbing” honey bees that move into nonnatal colonies. We quantified the weekly invasion rates and the subsequent mite population growth from the end of July to November 2011 in 28 honey bee colonies kept in two apiaries that had high (HBD) and low (LBD) densities of neighboring colonies. At each apiary, half (seven) of the colonies were continuously treated with acaricides to kill all Varroa mites and thereby determine the invasion rates. The other group of colonies was only treated before the beginning of the experiment and then left untreated to record Varroa population growth until a final treatment in November. The numbers of bees and brood cells of all colonies were estimated according to the Liebefeld evaluation method. The invasion rates varied among individual colonies but revealed highly significant differences between the study sites. The average invasion rate per colony over the entire 3.5-mo period ranged from 266 to 1,171 mites at the HBD site compared with only 72 to 248 mites at the LBD apiary. In the untreated colonies, the Varroa population reached an average final infestation in November of 2,082 mites per colony (HBD) and 340 mites per colony (LBD). All colonies survived the winter; however, the higher infested colonies lost about three times more bees compared with the lower infested colonies. Therefore, mite invasion and late-year population growth must be considered more carefully for future treatment concepts in temperate regions.

Varroa destructor (Anderson and Trueman) trapped on bottom boards were assessed as indirect measurements of colony mite population differences and potential indicators of mite resistance in commercial colonies of Russian and Italian honey bees (Apis mellifera L.) by using 35 candidate measurements. Measurements included numbers of damaged and nondamaged younger mites, nymphs, damaged and nondamaged older mites, fresh mites, and all mites, each as a proportion of total mites in the colonies and as a proportion of all trapped mites or all trapped fresh mites. Several measurements differed strongly between the stocks, suggesting that the detailed characteristics of trapped mites may reflect the operation of resistance mechanisms in the Russian honey bees. Regression analyses were used to determine the relationships of these candidate measurements with the number of mites in the colonies. The largest positive regressions differed for the two stocks (Italian honey bees: trapped mites and trapped younger mites; Russian honey bees: trapped younger mites and trapped fresh mites). Also, the regressions for Italian honey bees were substantially stronger. The largest negative regressions with colony mites for both stocks were for the proportion of older mites out of all trapped mites. Although these regressions were statistically significant and consistent with those previously reported, they were weaker than those previously reported. The numbers of mites in the colonies were low, especially in the Russian honey bee colonies, which may have negatively influenced the precision of the regressions.

Two types of honey bees, Apis mellifera L., bred for resistance to Varroa destructor Anderson & Trueman, were evaluated for performance when used for honey production in Montana, and for almond pollination the following winter. Colonies of Russian honey bees and outcrossed honey bees with Varroa-sensitive hygiene (VSH) were compared with control colonies of Italian honey bees. All colonies were managed without miticide treatments. In total, 185 and 175 colonies were established for trials in 2010–2011 and 2011–2012, respectively. Survival of colonies with original queens or with supersedure queens was similar among stocks for both years. Colony sizes of the Varroa-resistant stocks were as large as or larger than the control colonies during periods critical to honey production and almond pollination. Honey production varied among stocks. In the first year, all stocks produced similar amounts of honey. In the second year, Russian honey bees colonies produced less honey than the control colonies. V. destructor infestations also varied among stocks. In the first year, control colonies had more infesting mites than either of the Varroa-resistant stocks, especially later in the year. In the second year, the control and outcrossed Varroa-sensitive hygiene colonies had high and damaging levels of infestation while the Russian honey bees colonies maintained lower levels of infestation. Infestations of Acarapis woodi (Rennie) were generally infrequent and low. All the stocks had similarly high Nosema ceranae infections in the spring and following winter of both years. Overall, the two Varroa-resistant stocks functioned adequately in this model beekeeping system.

The pupal development of Aethina tumida Murray (Coleoptera: Nitidulidae) was studied at various combinations of thermo-hygrometric soil conditions (temperatures of 16, 18, and 20°C and soil water content levels of 0.37, 0.56, and 0.73 m³ water per cubic meter of dry soil) representative of southeastern Canada. Survivorship and development duration of A. tumida pupae, as well as sex ratio and life span of emerging adults, were assessed. Assays were conducted in growth chambers on an average of 50 third-instar larvae per thermo-hygrometric combination. Results show that survivorship of pupae decreased with lower temperature and higher soil water content. Pupal development time shortened as temperature increased (69–78 d at 16°C, 47–54 d at 18°C, and 36–39 d at 20°C), but was longer in dryer soil. Optimal soil water content for pupal development was 0.56 m³ water per cubic meter of soil. We estimated that the minimum development temperature for pupae is between 10.2 and 13.2°C, depending on soil water content. The sex ratio of emerging adults was influenced by soil water content. We measured one female to one male for dry and intermediately wet soils and three females to one male for wet soils. Higher soil water content reduced the life span of emerging adults by half. This study contributes to a better understanding of A. tumida population dynamics in eastern Canada.

Myzus persicae (Sulzer) is an efficient vector of potyviruses in sweet potato, Ipomoea batatas (L.). These potyviruses also infect members of the morning glory family Ipomoea cordatotriloba Dennstedt and Ipomoea hederacea Jacqin commonly found within or around sweet potato fields. Infection of sweet potato with potyviruses increases the intrinsic rate of increase of M. persicae. Thus, from the epidemiological stand point, virus infection can modify vector population dynamics, and therefore increase virus spread. To better understand this, stylet penetration behaviors of M. persicae on virus infected and noninfected sweet potato cvs. ‘Beauregard’ and ‘Evangeline’, as well as morning glory plants I. cordatotriloba and I. hederacea were monitored. Stylet penetration behaviors associated with nonpersistent virus transmission such as time to first intracellular puncture (potential drop), number of potential drops, duration of potential drop, duration of potential drop subphase II-3, and number of potential drops with subphase II-3 pulses were significantly increased on virus-infected compared with noninfected Beauregard, but greatly reduced on virus-infected compared with noninfected I. hederacea plants. Stylet penetration behaviors associated with host acceptance such as reduced nonprobing duration and nonprobing events were greater on virus-infected compared with noninfected Beauregard plants. In contrast, on Evangeline, I. cordatotriloba and I. hederacea stylet penetration behaviors by M. persicae indicate it had less preference for virus-infected compared with noninfected plants.

Bemisia tabaci (Gennadius) whitefly populations produce economically important damage to crops by their direct feeding and also by transmitting plant viruses. Although there are several methods to reduce B. tabaci damage, most growers rely on the use of insecticides to decrease populations of this pest. Insecticides that reduce feeding of whitefly adults may also reduce the transmission of viruses that are harmful to crop plants. However, demonstrating the feeding reduction has proved challenging. In this study, water-sensitive paper was used to determine whitefly adult feeding, indirectly through honeydew production, when insects were placed on insecticide-treated and untreated plants. Plant treatments with two formulations of cyantraniliprole (Cyazypyr) showed a reduction in the amount of honeydew produced by B. tabaci adults equivalent to imidacloprid. The reduction in the amount of honeydew produced indicates reduced insect feeding and the possibility for a reduction in virus transmission. Plant treatments with two formulations of cyantraniliprole also resulted in higher mortality than imidacloprid.

In addition to being used increasingly as a model system in modern molecular biology studies, the free-living nematode Caenorhabditis elegans (Maupas, 1900) is an important pathogen in fungi and straw mushrooms. In this study, Bacillus thuringiensis strain 010 was found to have significantly detrimental activity against C. elegans. To further characterize this activity, the toxicological mechanism was elucidated at molecular level. Genes encoding for crystal protein and chitinase were isolated, cloned, and sequenced. However, the toxicity was detected only in the chitinase. Under transmission electron microscopy, change in the body wall and gut structures of C. elegans was observed, and thus degeneration of body wall and gut in the worms was also investigated. Further bioassay also confirmed the mortality of C. elegans fed with Escherichia coli TB1 strain. These observations suggest great potential for B. thuringiensis 010 as a biocontrol agent against C. elegans and other nematodes.

The current study investigated the characteristics and mechanism of the invertebrate immune priming using Galleria mellonella (L.) (Lepidoptera: Pyralidae) larvae (host) and Photorhabdus luminescens TT01 (pathogen) as a model. The following parameters of the G. mellonella larvae primed by hemocoel injection of heat-killed cells of TT01 or Bacillus thuringiensis HD-1 were determined at designated times after priming and then compared and analyzed systematically: mortality of the primed larvae against TT01 infection (immune protection level), hemocyte density, phagocytosis and encapsulation abilities of hemocyte, and antibacterial activity of cell free hemolymph (major innate parameters). The results showed that 1) immune priming increased survival of the larvae against a lethal infection of TT01 and the levels and periods of protection correlated positively to the priming dose; 2) the changes on the levels of protection and the major innate parameters of the larvae primed with either TT01 or HD-1 followed a similar pattern of the convex curve, although the levels and the timing of changes differed significantly among the four innate immune parameters and between two priming bacteria; and 3) the immune protection level at a time after priming was correlated to the overall level of four innate immune parameters of the primed larvae. The current study demonstrated that the immune priming phenomenon of G. mellonella larvae has low level of specificity, and it was achieved mainly by the regulation on the quantity and activity of major innate immune parameters, such as hemocytes, antimicrobial peptides, and enzymes.

The temporal development of biological control of arthropod pests in perennial cropping systems is largely unreported. In this study, the development of biological control of twospotted spider mite, Tetranychus urticae Koch, and hop aphid, Phorodon humuli (Schrank), in a new planting of hop in Oregon is described over a period of 9 yr (2005–2013). Both the abundance and diversity of natural enemies increased over time. Known predators of hop aphid (Coccinellidae and Anthocoridae) were present in all years; however, stable biological control of hop aphid was not achieved in most years and aphicides were required to suppress populations at commercially acceptable levels in 5 of 9 yr. Populations of aphidophagous coccinellids developed synchronously with hop aphid populations, and temporal correlations indicated these are the primary predatory insect associated with hop aphid regulation. However, sampling methods did not assess levels of aphid parasitoids and hyperparasitoids and their contribution to biological control was unquantified. Spider mite biological control was associated primarily with predatory mites (Phytoseiidae) and Stethorus spp. (Coccinellidae). The magnitude of temporal correlations of abundance of these predators with spider mites was found to be greatest on the same sampling dates and at lags of 7–14 d. Stable biological control of spider mites occurred after four field seasons, suppressing spider mites to levels similar to those commonly achieved with chemical control. A survey of 11 commercial hop yards in Oregon documented pest and natural enemy densities under commercial management practices over a period of 4 yr (2008–2011). Natural enemy abundance in commercial hop yards was similar to that of a 2- to 3-yr-old hop yard with limited disturbance. Whereas total reliance on biological control for hop aphid is unlikely to be successful, there appears to be unrealized potential for biological control of spider mites in commercial production. Dynamic action thresholds that consider the value of natural enemies are needed for both pests.

New liquid fermentation techniques for the production of the bioinsecticidal fungus Metarhizium brunneum strain F-52 have resulted in the formation of microsclerotia (MS), a compact, melonized-hyphal structure capable of surviving desiccation and formulation as dry granules. When rehydrated, these MS granules germinate to produce conidia that can infect susceptible insects. Fermentation media containing cottonseed or soy flours as nitrogen sources and formulated at two carbon to nitrogen ratios (C:N), 30:1 or 50:1, were evaluated for production of microsclerotia. Dry MS granule samples were compared for storage stability based on conidia production, and insecticidal activity against larvae of the lesser mealworm, Alphitobius diaperinus (Panzer), using a potting soil bioassay. Cottonseed and soy flours were equivalent for production, MS granule viability, and insecticidal activity. Fermentation media containing higher nitrogen concentrations (30:1 C:N) resulted in greater biomass accumulation and greater production of conidia from granules regardless of the nitrogen source. MS granules made with M. brunneum cultures grown in media with 30:1 C:N produced 8.5 × 10⁹ conidia per gram of granules after 8-d incubation, significantly higher than MS granules made using fungus produced using 50:1 C:N media (5.5 × 10⁹ conidia per gram dry MS granules). The LC₅₀ for larval mortality was 8.05 × 10⁵ conidia per cup, equivalent to applications of 94 or 147 µg granules per cup for granules made from high and low nitrogen media, respectively. Measurements of water activity were not significantly different among granule samples (0.28–0.29) even though granules made from high nitrogen media had higher moisture content (>5.2%) compared with granules made from low nitrogen media (<4.6%). Higher initial conidial production was reflected in longer storage stability at 25°C, with half-lives estimated at 3.7 and 1.7 wk for 30:1 and 50:1 C:N ratios, respectively. These results support further evaluation of MS granule formulations for the control of soil-inhabiting insect pests.

Early research investigating attractants for the Mexican fruit fly, Anastrepha ludens Loew, during the 1930s indicated that fermentation products were effective attractants for Mexican fruit flies and other tropical Tephritidae, but that attraction to fruit components was only of academic interest. Tests reported here were carried out on populations of Mexican fruit flies from 2004 to 2011. Trapping experiments carried out at sites in the states Nuevo Leon and San Luis Potosi compared grape juice, reconstituted grape concentrate and powdered grape mixes, and torula yeast extract in orchards at each site. The Nuevo Leon orchard was mixed with alternate rows of pears and surrounded by alternate hosts. The San Luis Potosi site was surrounded by other orange orchards or nonhosts. Each test was run for at least 10 mo and included highest and lowest trapping periods. Results showed that grape juice captured the most total flies and had the fewest samples with zero flies. However, in the series of experiments, each product had the most captures in at least one experiment. Hydrolyzed torula was superior in one of the six experiments. In five of the tests, polyethylene glycol was tested as an additive to the grape products but never improved capture rate compared with the product without the additive. These results indicate that grape juice is superior to grape concentrate or powder and grape juice is at least equal to torula yeast hydrolysate for trapping pest populations of Mexican fruit flies in commercial citrus orchards.

Bactrocera tau (Walker) is one of the most harmful pests to fruits and vegetables. To counteract this pest, the development of phytosanitary treatment is required to comply with the pest regulation requirements of certain countries. This study investigated the toxicity of phosphine fumigation against B. tau under low temperature conditions. Different growth stages (eggs and instars) of B. tau were exposed to 1.07 mg/liter phosphine for 1–10 d at 5°C, and compared with unfumigated flies at 5°C. The results showed that tolerance to cold treatment alone or phosphine fumigation at low temperatures generally increased with the stage of insect development. However, eggs incubated for 12 h at 25°C represented the most tolerant growth stage to phosphine fumigation at 5°C. Furthermore, 8.56- to 2.18-d exposure periods were required to achieve 99% mortality with a range of phosphine concentrations from 0.46 to 3.81 mg/liter. C^0.62 t = k expression was obtained from the LT₉₉ values, indicating that the exposure time was more important than the phosphine concentration.

High-pressure processing (HPP) combined with heat or cold has been proposed as an alternative quarantine process for Mexican fruit fly Anastrepha ludens Loew (Diptera: Tephritidae). HPP conditions at levels higher than 100 MPa applied to destroy eggs and larvae can also affect the postharvest physiology of the fruits. HPP at pressure levels in the range of 50–100 MPa is recommended. Eggs have been reported as being more resistant to HPP than larvae. Therefore, the objective of this study was to assess the effect of a precooling treatment on the biological viability of A. ludens eggs treated by HPP at 0°C. The capability of nondestroyed eggs to develop and reproduce was also evaluated. One-, 2-, 3-, and 4-d-old eggs were precooled in ice water for 0 (control) 3, 6, 12, or 24 h and then pressurized at 50, 70, or 90 MPa for 0, 3, 6, or 9 min at 0°C. The hatching capability of pressurized eggs was evaluated. The most lethal effect of HPP on nonprecooled eggs (0 h) was obtained at 90 MPa for 9 min, destroying all eggs except for the 3-d-old ones, which showed an 11.8% hatch rate. Precooling treatment improved the hatch rate of eggs ranging from 4 to 50% depending on precooling conditions. The main effect was observed after 6 h. These results suggest that precooling modified the biochemistry and physiology of eggs, improving their resistance to HPP treatments.

It is well recognized that the quality of host plants affects the development and survival of twospotted spider mite Tetranychus urticae Koch. The life table parameters of T. urticae, on six cultivars of common bean (Phaseolus vulgaris L.) (chiti Khomein, chiti Ks21189, red Akhtar, red Ks31169, white Pak, and white G11867) were studied at constant laboratory conditions (27 ± 2°C, 70 ± 5% RH and 16:8 L:D). Total development times of immature males and females were significantly influenced by bean cultivar. T. urticae laid significantly more eggs per day on red Akhtar (16.16) than on the other cultivars. The mean generation time ranged from 23.37 to 34.82 d, and a significant varietal effect was seen. Percentage of egg hatchability of twospotted spider mite ranged from 88.25 to 94.20%. The highest intrinsic rate of increase, was recorded on red Akhtar (0.269 ± 0.031) and the lowest value was obtained on white Pak (0.129 ± 0.048). In addition, net reproductive rate and finite rate of increase of the twospotted spider mite had the highest value on red Akhtar: 62.38 ± 1.05 and 1.30 ± 1.02, respectively. The lowest values of these parameters were recorded on white Pak as 26.11 ± 1.40 and 1.13 ± 1.10, respectively. Doubling time varied significantly on different cultivars and the lowest and highest values were obtained on red Akhtar and white Pak, respectively. Our findings revealed that white beans (Pak and G11867) were less suitable cultivars, suggesting that they are more resistant to the twospotted spider mite than the other cultivars.

The invasive fruit fly, Bactrocera invadens Drew, Tsuruta & White, is a highly polyphagous fruit pest that occurs predominantly in Africa yet has its origins in the Indian subcontinent. It is extremely morphologically and genetically similar to the Oriental fruit fly, Bactrocera dorsalis (Hendel); as such the specific relationship between these two species is unresolved. We assessed prezygotic compatibility between B. dorsalis and B. invadens using standardized field cage mating tests, which have proven effectiveness in tephritid cryptic species studies. These tests were followed by an assessment of postzygotic compatibility by examining egg viability, larval and pupal survival, and sex ratios of offspring produced from parental and subsequent F1 crosses to examine for hybrid breakdown as predicted under a two-species hypothesis. B. dorsalis was sourced from two countries (Pakistan and China), and each population was compared with B. invadens from its type locality of Kenya. B. invadens mated randomly with B. dorsalis from both localities, and there were generally high levels of hybrid viability and survival resulting from parental and F1 crosses. Furthermore, all but one hybrid cross resulted in equal sex ratios, with the single deviation in favor of males and contrary to expectations under Haldane's rule. These data support the hypothesis that B. dorsalis and B. invadens represent the same biological species, an outcome that poses significant implications for pest management and international trade for sub-Saharan Africa.

The intensification of agriculture has caused a decline in the complexity of agricultural landscapes because of the expansion of arable lands and the removal of natural habitats. These landscape changes, which have substantial effects on natural enemies (e.g., parasitoids) and on biological control services, have received considerable attention recently. In the current study, we analyzed the effects of landscape complexity on cereal aphids and their parasitic wasps in 24 sites during a period of 3 yr. In total, 11 primary parasitoid species and 6 hyperparasitoid species, comprising 5,220 individuals, were collected in our experiments. With the exception of two primary parasitic wasps (Trioxys asiaticus Telenga and Toxares sp.) and one hyperparasitic wasp (Dendrocerus carpenteri [Curtis]), most species were sensitive to landscape complexity after ≥1 yr. Species diversity, primary parasitism, and hyperparasitism increased with increasing landscape complexity. However, the relationship between the population density of active primary parasitoids (effective primary parasitoids) and landscape complexity was indicated by a quadratic function, not a linear function. The effective population density of primary parasitoids was maximal (2.04 individuals per 100 wheat stems) if the percentage of noncrop habitat was 38%. The hypothesis that landscape complexity may enhance the activity or higher diversity of primary parasitoids and hyperparasitoids was well-supported by our study. However, the hyperparasitoids had a more sensitive response to landscape complexity than the primary parasitoids. Further studies should aim to enhance the biological pest control of primary parasitoids and suppress hyperparasitoids by habitat manipulation. This technique could be used effectively for pest management in mosaic landscapes through habitat rearrangement and reorganization.

Habrobracon hebetor Say is an ectoparasitoid of larval stage of various lepidopteran pests. Lethal and sublethal effects of azadirachtin and cypermethrin were evaluated on adult and preimaginal stages of H. hebetor under laboratory conditions. Contact exposure bioassays with adults indicated that the lethal concentration (LC₅₀) of two commercial azadirachtin-containing formulations, NeemGuardand BioNeem, were 43.5 and 10.2 µg a.i./ml, respectively. The LC₅₀ of cypermethrin was 5.4 µg a.i./ml. When larval stage of H. hebetor was exposed to these insecticides with a field recommended concentration of NeemGuard, BioNeem, or cypermethrin by a dip protocol, the emergence rate was reduced by 39.0, 36.6, and 97.6%, respectively. To assay the sublethal effects of these insecticides, adult wasps were exposed to an LC30 concentration of the insecticides, and then demographic parameters of the surviving wasps were determined. Fecundity, fertility, and parameters including the intrinsic rate of increase (r_m) were affected negatively. The r_mvalues following exposure to NeemGuard, BioNeem, cypermethrin, or mock treatment were 0.143, 0.149, 0.160, and 0.179, respectively, female offspring per female per day, respectively. The current study showed that cypermethrin had more acute toxicity on larval and adult stages of H. hebetor compared with azadirachin. The commercial formulations of azadirachtin and cypermethrin negatively affected most of the life table parameters of the parasitoid. Semifield and field studies are needed for obtaining more applicable results on combining H. hebetor and the tested insecticides for an integrated pest management-based strategy for crop protection.

Phytophagous stink bugs are economically important pests of annual and perennial crops in the southeastern United States. Because of insecticide resistance and risk of secondary pest outbreaks, there is interest in identifying cultural practices that could lead to reduced insecticide applications. The objective of this project was to assess the importance of cotton planting date on stink bug damage to cotton. Unsprayed cotton plots with biweekly planting dates were established at three locations in southern Georgia in each of two crop years. During the bloom cycle, stink bug-induced boll injury was estimated weekly in each plot. Plots were subsequently defoliated, mechanically harvested, and ginned to assess differences in fiber yield and quality attributable to stink bug injury. Results show that the rate of boll damage generally increased more rapidly through the bloom cycle for planting dates in June compared with May. Similarly, estimates of boll damage from June-planted cotton more frequently exceeded the stink bug treatment threshold compared with May-planted cotton. In 2011, mean lint yield and economic returns from May planting dates were significantly greater than June planting dates. In 2012, lint yield and economic returns were greater in plots established in early May compared with later planting dates. Estimates of HVI color b, a measure of fiber yellowness, were lower in early May-planted cotton compared with June planting. These data show that growers need to be aware of increased stink bug damage potential when planting late.

Orange mint moths, Pyrausta orphisalis (Walker) (Crambidae), were initially trapped in a study of noctuid moth attraction to floral volatiles. A subsequent series of trapping experiments in commercial mint fields determined that phenylacetaldehyde and 4-oxoisophorone were attractive to P. orphisalis, whereas benzyl acetate, eugenol, cis-jasmone, limonene, linalool, methyl-2-methoxybenzoate, methyl salicylate, β-myrcene, and 2-phenylethanol were not. When used in combination with phenylacetaldehyde, 4-oxoisophorone and methyl-2-methoxybenzoate increased catches of P. orphisalis in traps by ∼50%, and β-myrcene tripled the trap catch. A second crambid species, the false celery leaftier moth, Udea profundalis Packard, was also attracted to phenylacetaldehyde, but was not attracted to any other single-chemical lure. Cis-jasmone, limonene, and 4-oxoisophorone increased catches of U. profundalis by β50% when presented in traps with phenylacetaldehyde, while linalool increased the catch 2.5-fold, and β-myrcene tripled the trap catch. Both sexes of each species were similarly attracted to most of these lures. These findings provide chemical lures for trapping males and females of both P. orphisalis and U. profundalis.

The crucifer flea beetle, Phyllotreta cruciferae (Goeze) (Coleoptera: Chrysomelidae), has recently emerged as a serious pest of canola (Brassica napus L.) in Montana. The adult beetles feed on canola leaves, causing many small holes that stunt growth and reduce yield. In 2013, damage to canola seedlings was high (≈80%) in many parts of Montana, evidence that when flea beetles emerge in large numbers, they can quickly destroy a young canola crop. In the current study, the effectiveness of several biopesticides was evaluated and compared with two insecticides (deltamethrin and bifenthrin) commonly used as foliar sprays as well as seed treatment with an imidacloprid insecticide for the control of P. cruciferae under field conditions in 2013. The biopesticides used included an entomopathogenic nematode (Steinernema carpocapsae), two entomopathogenic fungi (Beauveria bassiana and Metarhizium brunneum), neem, and petroleum spray oils. The control agents were delivered in combination or alone in a single or repeated applications at different times. The plant-derived compound neem (azadirachtin), petroleum spray oil, and fatty acids (M-Pede) only showed moderate effect, although they significantly reduced leaf injuries caused by P. cruciferae and resulted in higher canola yield than the untreated control. Combined use of B. bassiana and M. brunneum in two repeated applications and bifenthrin in five applications were most effective in reducing feeding injuries and improving yield levels at both trial locations. This indicates that entomopathogenic fungi are effective against P. cruciferae, and may serve as alternatives to conventional insecticides or seed treatments in managing this pest.

The spectral sensitivity of the compound eye in three gypsy moth species from six different geographical regions (Lymantria dispar asiatica Vnukovskij [Asian gypsy moth], Lymantria dispar japonica Motschulsky [Japanese gypsy moth], and Lymantria dispar dispar L. [North American gypsy moth]) was tested electrophysiologically in the wavelength region 300–700 nm. For all moths examined, a maximum response occurred in the 480–520-nm range (blue-green region) with a shoulder peak occurring at 460 nm. A smaller, secondary peak was observed for both sexes at the 340–380-nm range, which is in the region considered behaviorally maximal in night-flying insects. No peaks in sensitivity were observed between 520 and 700 nm (red region) for any of the moths tested. Based on our retinal recording data, a short wavelength blocking filter with a transition wavelength near 500 nm should reduce gypsy moth attraction to artificial lighting sources. This would help reduce the number of Lymantria-infested ships traveling to and from foreign ports.

A new species of xyleborine ambrosia beetle has been found to attack balsa, Ochroma pyramidale (Cavanilles ex Lamarck) Urban, in Ecuador. Coptoborus ochromactonus Smith & Cognato is described and its biology is reported. Large-scale surveys were conducted between 2006 and 2009, and observational studies were carried out between 2010 and 2013 in Ecuadorian commercial plantations to determine life history and host preference characteristics. C. ochromactonus attacked balsa between 1.5 and 3 yr in age. Successful attacks were more prevalent in smaller diameter trees and unhealthy trees. In general, attacks and beetle-caused mortality were more prevalent during the dry summer months when trees were under more moisture and light stress. Fungal mycelia were consistently observed coating beetle galleries and are likely the true damaging agent to balsa trees.

For >20 yr, Bemisia tabaci Gennadius persists as a begomovirus vector and is a serious problem in tomato production in many parts of the world. In tropical countries, the use of netting to protect horticultural crops has proven to be an effective and sustainable tool against Lepidoptera but not against small insects. This study evaluated the repellent effect of AgroNet 0.9T, a 0.9-mm pore diameter and 40-mesh size netting treated with alphacypermethrin insecticide against B. tabaci. This pyrethroid insecticide is known to have toxic and repellent effects against mosquitoes and has been used for treatment of mosquito nets. Two nontreated netting materials were used as control: AgroNet 0.9NT with 0.9-mm pore diameter and 40-mesh size and AgroNet 0.4NT with 0.4-mm pore diameter and 80-mesh size. The behavior of B. tabaci and its parasitoid Encarsia formosa Gahan as they progressed through the treated netting was studied in the laboratory in choice and no-choice tests. The development of wild B. tabaci population on tomato plants protected by the same nets was followed in two field trials implemented in Njoro, Kenya. Results obtained with the no-choice tests showed a significant reduction of movement on the treated net with 40-mesh (19%) compared with nontreated netting (35 and 46% with 80- and 40-mesh, respectively). The mortality of B. tabaci was significantly higher (two-fold) in the test tube containing only the treated netting compared with the nontreated one. The repellent effect of the treated netting was also demonstrated against E. formosa, but it did not have this toxic effect. Unlike for B. tabaci, the treated and nontreated nets appeared to have a similar repellent effect on E. formosa in the choice test, which suggests a learning behavior of the parasitoid. In both field tests, B. tabaci population was significantly lower on tomato protected by the treated net compared with the same nontreated net. However there was no significant difference in B. tabaci population between the treated 0.9-pore diameter and the nontreated 0.4-pore diameter. We discussed these findings and their implications for the use of repellent netting in integrated pest management in horticulture and more specifically in vegetable production.

Although many studies have been conducted on the development and reproductive potential of Diaphorina citri Kuwayama, 1908 (Hemiptera: Liviidae) in different host species, few have evaluated these parameters on different varieties of the same host species. This study evaluated the influence of five commercial varieties of citrus (Citrus spp. L.)—Hamlin, Natal, Pêra, Ponkan, and Valencia—and orange jasmine [Murraya exotica (L.) Jack] on the development of D. citri. Survival rates for the egg stage were highest on orange jasmine (85.7%) and on Valencia (83.3%). The lowest viability of the nymphal stage was also observed on Hamlin, averaging 57.4%. Values for total viability ranged from 65.9 to 32.6%, and were highest on Valencia. The longest egg-adult development time was on Natal, with a mean of 18.4 d; the shortest total development time was on orange jasmine, with a mean of 17.3 d. Based on the fertility life table, the net reproductive rate (Ro) of D. citri was 2.5 times higher when reared on Valencia than on Hamlin. The other parameters (duration of each generation [T], finite rate of increase [λ], and innate capacity to increase in number [r_m]) also demonstrated that Valencia is best suited to this insect. The results obtained for the biological parameters and the fertility life table indicate that Valencia and orange jasmine were the most suitable hosts, whereas Hamlin was least suitable for the development of D. citri. These results provide information for the installation of new citrus groves, especially in the choice of varieties to be planted and the location of different varieties within the groves, with a view toward the management of Huanglongbing or HLB.

Foxglove aphid, Aulacorthum solani (Kaltenbach) (Hemiptera: Aphididae), has recently undergone a status change from an occasional pest to a serious pest in greenhouses of North America and the United Kingdom. Little nonanecdotal information exists on the ecology of this insect in greenhouse crops. To help improve integrated pest management decisions for A. solani, the within-plant distribution of this pest was explored on a variety of common greenhouse plants in both the vegetative and flowering stage. This aphid generally was found on lower leaves of vegetative plants, but was found higher in the canopy on reproductive plants (on flowers, flower buds, or upper leaves). Aphid numbers were not consistently positively correlated with total leaf surface areas within plant strata across plant species. Thus, the observed differences in preferred feeding sites on vegetative versus flowering plants are possibly a response to differences in nutritional quality of the various host-plant tissues. Despite being anecdotally described as a “stem-feeding aphid,” A. solani was rarely found feeding on stems at the population densities established in our tests, with the exception of racemes of scarlet sage (Salvia splendans). Although some previous reports suggested that A. solani prefers to feed on new growth of plants, our results indicate that mature leaves are preferred over growing tips and young leaves. The implications of the within-plant feeding preferences of A. solani populations with respect to both biological and chemical control are discussed.

Insecticides used against potato leafhopper, Empoasca fabae (Harris) (Homoptera: Cicadellidae), have been reported to cause problems with maple spider mite, Oligonychus aceris (Shimer) (Acarina: Tetranychidae), on nursery-grown ‘Red Sunset’ red maple and ‘Autumn Blaze’ Freeman maple. To test this, we conducted two experiments on field-grown trees in nurseries. In the first, the effects of early-season pesticide applications were examined during 2009. The second experiment was conducted in 2010 to compare effects of using threshold levels of one, three, or six leafhoppers per branch to time applications. Pesticide applications reduced abundance and damage by leafhoppers in both cultivars, but increased populations of O. aceris on Autumn Blaze during 2009. In contrast, on Red Sunset, populations of O. aceris did not increase after insecticide applications. In 2010, insecticide applications did not increase abundance of O. aceris on Autumn Blaze because use of treatment thresholds to manage leafhoppers greatly reduced numbers of trees requiring treatment for leafhoppers. Two phytoseiid mites, Neoseiulus fallacis (Garman) and Typhlodromus caudiglans (Schuster), and one stigmaeid, Zetzellia mali (Ewing), were identified as the principal predators of O. aceris on maple leaves. Insecticide applications had no significant effects on the total abundance of predatory mites on either Red Sunset or Autumn Blaze maples in 2009 or 2010. However, populations of predator Z. mali were higher during both years on Red Sunset than on Autumn Blaze. These results suggest that both early-season pesticide use and cultivar can affect the likelihood of secondary outbreaks of spider mites on maples.

The leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), is a global pest of citrus and contributes to the incidence and severity of citrus bacterial canker. SPLAT CLM (ISCA Technologies, Riverside, CA) is an emulsified wax that provides sustained release of (Z,Z,E)-7,11,13-hexadecatrienal, the major component of P. citrella sex pheromone. Trials in commercial orchards demonstrated that SPLAT CLM applied to plots of varying width resulted in disruption of trap catch of male P. citrella within treated rows and across untreated rows adjacent to treated rows. SPLAT CLM applied to plots of constant width (10 rows) disrupted trap catch across an untreated gap as the square of the width of the gap. Similarly, the ability of the pheromone source in treated rows to disrupt trap catch across untreated gaps of constant size declined as the square of the width of adjacent treated areas. A coverage pattern of 4 rows skipped for every 10 treated rows resulted in a 4% reduction of trap shutdown, and reduced the product and application costs by 29%. Mining incidence by P. citrella in treated rows was reduced by 53% compared with untreated areas. Intentional coverage gaps can significantly reduce the cost of mating disruption. Commercial lures for P. citrella used in this study were highly potent with respect to attracting males. Each lure was ≈10³ times as attractive as an individual P. citrella female. Disruption of trap catch using commercial lures may underestimate actual mating disruption achieved in the field.

This field study investigated the colony effect of a fipronil spot treatment applied to active infestations of Formosan subterranean termite, Coptotermes formosanus Shiraki. Spot treatments were applied to a single active independent monitor from each of four colonies in which multiple independent monitors were established. All treated monitors were abandoned, and the contents of the treated monitors were replaced with untreated wood at the ≈30-d posttreatment inspection. All colonies survived treatment and only one colony exhibited long-term effects, which included significant reductions in termite collections and increased worker size. The affected colony was treated within 1 m of its primary nest. Two colonies exhibited a correlation between monitor termite production and distance from treatment. Distance appears to be a factor limiting fipronil's colony effects. The Formosan subterranean termite may not be a good candidate for the exterior perimeter and localized interior treatment label option because of the large range and size of the colony.

This study describes the behavioral and histological changes of the molting process in Coptotermes formosanus Shiraki caused by the chitin synthesis inhibitor noviflumuron. Termites exposed to noviflumuron initiated ecdysis as untreated individuals did; however, peristalsis contractions were weak and the expansion of the dorsal breach of the exoskeleton did not occur. Treated termites could not complete their molting process and died after the initiation of the ecdysis. Histological observations showed that the process of voiding the gut protozoa during premolting was not affected by the noviflumuron treatment. However, the formation of the new cuticle was disrupted resulting in the loss of integrity of the cuticle. The alteration of the cuticle was visible in the gizzard (foregut), the thoracic pleurons, and most of the exoskeleton. Muscles were partially able to reattach to the incompletely formed new cuticle, and muscle contractions resulted in tearing off the cuticle. Because the integrity of the newly formed cuticle was compromised by the noviflumuron treatment, we concluded that termites' death was caused primarily by the loss of hemolymph as a result of the damage done by the muscle contractions on the exoskeleton during the peristalsis. As the physiological homeostasis was disrupted, termites were too weak to shed their old cuticle, ultimately resulting in termite dying during the molting process.

Ant management in urban and natural areas often relies on toxic baits. Liquid baits are highly attractive to pest ants because they mimic natural food sources such as honeydew and nectar, the principal dietary components of many ants. However, liquid bait use has been limited owing to the lack of bait dispensers that are effective, inexpensive, and easy to service. The current study evaluated the potential of water-storing crystals (Polyacrylamide spheres) to effectively deliver liquid thiamethoxam baits to laboratory colonies of Argentine ants, Linepithema humile Mayr. Results of laboratory trials show that bait crystals saturated in 25% sucrose solution containing 0.007% thiamethoxam are highly attractive to Argentine ants and highly effective against all castes and life stages, including workers, queens, and brood. Fresh bait crystals were highly effective and required ≈2 d to kill all workers and ≈6 d to achieve complete mortality in queens and brood. Results of bait aging tests show that the crystals lose ≈70% of moisture in 8 h and the duration of outdoor exposure has a significant effect on moisture loss and subsequently bait acceptance and bait efficacy. A gradual decrease in mortality was observed for all castes and life stages as bait age increased. In general, fresh baits and those aged for <8 h retained their efficacy and caused substantial mortality. Baits aged longer than 8 h were substantially less attractive and less effective. Horizontal transfer tests examined the transfer of thiamethoxam from live treated donors to live untreated recipients. The results show that donor ants that obtain thiamethoxam by feeding on bait crystals effectively transfer it to untreated recipient ants. The level of secondary mortality depended on the donor:recipient ratio, with ≈40% recipient worker mortality with the 1:5 ratio and 15% recipient worker mortality with 1:10 or 1:20 ratios. However, no queens died in any transfer tests, suggesting that multiple feedings from multiple donors may be necessary to produce queen mortality. The results of the transfer tests demonstrate the role of trophallaxis in the distribution of thiamethoxam and confirm that thiamethoxam is effectively transferred in Argentine ant colonies. The distribution of thiamethoxam within Argentine ant colonies was further examined using protein marking coupled with an enzyme-linked immunosorbent assay to detect the marker. The distribution of thiamethoxam was highly efficient, with 79 ± 13% of workers testing positive at 15 min and 100 ± 0% of workers testing positive at 6 h. In summary, the results of this study demonstrate that water-storing crystals effectively deliver thiamethoxam to all castes and life stages of Argentine ants and may offer an effective tool for Argentine ant management.

Topical and fumigant toxicity of saturated aliphatic fatty acids with chain lengths of C1 through C14 were determined against the German cockroach, Blattella germanica (L.). In the C1 to C11 series, topical toxicity (LD₅₀ in milligram per adult male) ranged from 0.145 (C1) to 0.322 mg (C2). Toxicity declined dramatically with C12 and C14 acids whose LD₅₀ values could not be calculated. The relative fumigation toxicity (LC₅₀ in microliter per liter) of C1 through C5 acids was positively correlated with topical toxicity with values ranging from 6.159 (C3) to 12.302 µl/liter (C2). Fumigant toxicity decreased sharply with C6 (LC₅₀ = 37.691 µl/ liter) and there was no mortality of cockroaches exposed to vapors from C7 to C14 acids. The low fumigant toxicity of the C6 to C11 acids was correlated with their relatively low vapor pressure, but differences in diffusion of the vapors into the spiracles and subsequent passage to the target sites may have also been involved.

Crops producing insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) are widely planted and enable management of key insect pests while reducing the use of conventional insecticides. However, the evolution of Bt resistance could diminish these benefits. Fitness costs of Bt resistance occur in the absence of Bt toxin when individuals with resistance alleles show a reduction in fitness relative to susceptible individuals, and they can delay the evolution of resistance. Ecological factors including host-plant variety can affect the magnitude of fitness costs, and consequently, the degree to which fitness costs delay resistance. In this study, we measured fitness costs of resistance to Bt toxin Cry1F in the European corn borer Ostrinia nubilalis Hübner (Lepidoptera: Crambidae) using Cry1F-resistant and Cry1F-susceptible strains sharing a similar genetic background. Fitness costs were tested on three lines of maize, Zea mays L., by measuring larval survival and development in two greenhouse experiments with plants in either the vegetative or reproductive stage. Both experiments showed that maize line significantly affected larval survival and developmental rate. However, larval survival, mass, and developmental rate did not differ between the Cry1F-resistant and susceptible strains, indicating a lack of fitness costs of resistance to Cry1F for the larval fitness components measured in this experiment. Future experiments should test for fitness costs of Cry1F resistance affecting survival to adulthood and adult life-history parameters.

Baseline toxicity levels to foliarly applied spirotetramat were established for 19 field populations of whiteflies, Bemisia tabaci (Gennadius) B biotype (= Bemisia argentifolii Bellows & Perring) (Hemiptera: Aleyrodidae) from Arizona and California in 2008 and 2009. The susceptibility data were determined against the second instar of B. tabaci field collections before the registration and widespread use of spirotetramat in California. Three strains of whitefly, resistant to either bifenthrin, imidacloprid, or pyriproxyfen, were also tested to determine the potential for cross-resistance to spirotetramat. No significant geographic variation in susceptibility to spirotetramat was observed among regions within Arizona. The LC₅₀ values for the Arizona populations spanned a 14-fold range between populations during the 2 yr sampling tests including a low LC₅₀ of 0.91 (µg [AI] ml^-1) and a high LC₅₀ of 13.47 (µ [AI] ml^-1), while the LC₉₀ values showed a seven-fold range. The field populations from California exhibited limited variation in susceptibility to spirotetramat in general (1.02–7.02 µg [AI] ml^-1) with one exception (27.98 µg [AI] ml^-1). Variation in susceptibility among the resistant strains was about eight-fold at the LC₅₀ level with the PYR-strain, showing the highest susceptibility to spirotetramat at 3.79 (µg [AI] ml^-1). In addition, comparisons of relative susceptibilities among three older immature instars of two field populations showed no significant differences. These results establish a regional baseline that can serve as a reference for future monitoring and management of B. tabaci resistance to spirotetramat.

The genetically modified maize expressing Vip3Aa20 insecticidal protein from Bacillus thuringiensis Berliner is a biotechnological option for the control of Spodoptera frugiperda (J.E. Smith) and Diatraea saccharalis (F.) in Brazil. To support an Insect Resistance Management program, we conducted studies of baseline susceptibility and monitoring of Brazilian populations of S. frugiperda and D. saccharalis to the Vip3Aa20 insecticidal protein. Neonates were exposed to Vip3Aa20 applied on artificial diet surface. Mortality and growth inhibition were assessed after 7 d. All populations were susceptible to Vip3Aa20. The LC₅₀ ranged from 92.38 to 611.65 ng Vip3Aa20/cm² for 16 populations of S. frugiperda (6.6-fold variation), and between 61.18 and 367.86 ng Vip3Aa20/cm² for 6 populations of D. saccharalis (sixfold variation). The EC₅₀ ranged from 21.76 to 70.09 and 48.65 to 163.60 ng Vip3Aa20/cm² for S. frugiperda and D. saccharalis, respectively. There was a low interpopulation variation in susceptibility to Vip3Aa20, which represents the natural geographic variation in the response, and not the variation caused by previous exposure to selection pressure. For these two pests, the diagnostic concentrations of 2,000 and 3,600 ng of Vip3Aa20/cm² caused high mortality. These diagnostic concentrations will be used in resistance monitoring programs in Brazil.

The Asiatice stem borer, Chilo suppressalis (Walker), an important rice insect pest in China, has developed resistances to several classes of insecticides. To control C. suppressalis, chlorantraniliprole has been introduced as a novel insecticide in rice field since 2008. It is an anthranilic diamide insecticide that binds and activates ryanodine receptors (RyR). The susceptibility of field populations of C. suppressalis to chlorantraniliprole was determined in this study. The hypotheses of equality and parallelism showed that regression lines in the tested five populations were neither equal nor parallel. The Ruian, Cangnan, and Liangyungang populations (RA12, CN12, and LYG12) collected in 2012 had lower LD₅₀ values, whereas the Zhuji populations (ZJ12 and ZJ13) collected in 2012 and 2013 were ≈15 times more tolerant than the RA12 population. To determine the potential mechanisms involved in this tolerance variation, synergism bioassays were performed. Significant differences in susceptibility were found between without synergist and with synergist for the three populations (RA12, LYG12, and ZJ13), based on the tests for the hypotheses of equality. In RA12 and LYG12 populations with chlorantraniliprole, the addition of piperonyl butoxide (PBO) significantly synergized the activity, with synergism ratios of 2.68- and 2.33-fold, respectively, whereas addition of S,S,S-tributyl phosphorotrithioate (DEF) and diethyl maleate (DEM) had no synergist effect. In ZJ13 population with chlorantraniliprole, the addition of PBO and DEF increased synergism ratios by 12.43- and 6.31-fold, respectively, whereas addition of DEM had no significant effect on the toxicity against ZJ13 larvae. These susceptibility and synergism data suggested that detoxification enzymes might be involved in the tolerance variation to chlorantraniliprole in field populations of C. suppressalis.

Dillapiol, the main constituent in dill Anethum sowa Roxb. ex Fleming (Apiaceae) oil and wild pepper, Piper aduncum L. (Piperaceae), is an effective cytochrome P450 inhibitor similar to piperonyl butoxide (PBO). Laboratory and field trials with pyrethrum Chrysanthemum cinerariifolium (Trevir.) vis. extracts combined with dillapiol (1:5 and 1:16 ratio) were effective against both insecticide-susceptible and -resistant Colorado potato beetle Leptinotarsa decemlineata (Say). In the laboratory, pyrethrum efficacy was increased 2.2-fold with the SS strain and 9.1-fold with the RS strains by using pyrethrum dillapiol. Two field trials with the pyrethrum dillapiol formulation demonstrated efficacy ≥10 times than that of pyrethrum alone. The residual activity (half-life) of the combination exposed to direct sunlight was 3 h but it increased to 10.7 h by adding 2% of the sunscreen octylmethoxycinnamate.

The wide application of chlorantraniliprole, which selectively targets insect ryanodine receptors (RyR), for control of the diamondback moth, Plutella xylostella (L.), has led to increasingly prominent development of resistance to this insecticide. Although much work has been carried out on the structure and function of RyR, the molecular mechanisms of resistance to chlorantraniliprole in diamondback moth still needs further investigation. P. xylostella strains with medium and high resistance to chlorantraniliprole were obtained by laboratory selection and field collection. The biological activity of chlorantraniliprole against the third-instar larvae of susceptible and resistant strains was tested, and resistance development and biological fitness were investigated. The realized heritability (h²) of resistance showed the diamondback moth has a high risk of resistance to chlorantraniliprole. RyR transcript levels were lower in resistant strains than in susceptible strains, indicating that decreased expression of PxRyR may be associated with chlorantraniliprole resistance in P. xylostella. A 4,400 bp fragment of the RyR cDNA, which encodes most of the functional domains of RyR, was cloned and characterized from four strains (S, F₁₈, BY, and ZC). A 14 amino acid (Q⁴⁵⁴⁶-S⁴⁵⁵⁹) deletion was found in three resistant strains (F₁₈, BY, and ZC). A point mutation resulting in a glycine to glutamate substitution, as reported in a previously published article, was also found in the carboxyl-terminal region of two resistant strains (BY and ZC). These results indicated that decreased transcriptional level of RyR mRNA and combined with the site mutation might be related to chlorantraniliprole resistance in P. xylostella.

The control of rice leaffolder, Cnaphalocrocis medinalis (Guenée), depended mainly on the insecticide application in China for a long time, and the resistance development impacted the effects of insecticide application. In this study, 13 conventional and new chemistry insecticides were assayed for the toxicities to the larvae of rice leaffolder collected from Nanning, Changsha, and Nanjing, China, with rice seedling dip method during 2011–2013. Among the tested chemicals, macrolide insecticides spinetoram, spinosad, abamectin, and emanectin benzoate have the highest toxicities, whereas monosultap and Bt have the least toxicities to this insect. Comparing with the baseline data established in 2010, the susceptibilities of rice leaffolder to chlorantraniliprole, metaflumizone, and tebufenozide are declining simultaneously and gradually in the three regions from 2011 to 2013, and C. medinalis are becoming resistance to chlorantraniliprole, metaflumizone, and tebufenozide. The synchronous decreases of susceptibility in three geographic populations were not observed for macrolide insecticides, indoxacarb, chlorpyrifos, monosultap, and Bt. The synchronous insecticide susceptibility declines in field populations of the migratory insect collected from different areas indicated resistance evolution, and the sequence application patterns of different insecticides should be scheduled to delay the further development of resistance along the migratory pathway of the rice leaffolder in China.

Because of its importance as a pollinator and its potential economic usefulness for the biodegradation of organic animal waste, the genetic and phenotypic diversity of the drone fly, Eristalis tenax L. (Diptera: Syrphidae), was studied in both wild and captive populations from southeastern Europe. Wild specimens from a natural protected habitat (with low human impact), field crop habitat (semisynanthropic condition), and intensive pig farming habitat (synanthropic condition) were compared with a laboratory colony reared on artificial media. An integrative approach was applied based on allozyme loci, cytochrome c oxidase I mitochondrial DNA, wing traits (size and shape), and abdominal color patterns. Our results indicate that the fourth and eighth generations of the laboratory colony show a severe lack of genetic diversity compared with natural populations. Reduced genetic diversity in subsequent generations (F4 and F8) of the laboratory colony was found to be linked with phenotypic divergence. Loss of genetic variability associated with phenotypic differentiation in laboratory samples suggests a founder effect, followed by stochastic genetic processes and inbreeding. Hence, our results have implications for captive bred Eristalis flies, which have been used in crop pollination and biodegradation of organic waste under synanthropic conditions.

Wireworms (Coleoptera: Elateridae), the subterranean larval stage of the click beetle, are becoming more prevalent in many cropping systems and posing an increasing economic threat to wheat growers in the Pacific Northwest following the cancellation of the insecticide lindane in 2006. Current insecticide seed treatments alone are not adequate for wireworm control. The objective of this study was to evaluate a diverse set of 163 wheat genotypes for tolerance to wireworm feeding. Entries were planted in replicated field trials over 3 yr and evaluated for their performance when grown in the presence of wireworms. Entries were rated based on survival and given a tolerance score. Results indicated that differences exist among wheat genotypes in their level of tolerance to wireworm feeding. In particular, consistently high-ranking genotypes of interest may be ‘BR 18’, ‘Sonalika’, ‘Safed Lerma’, and ‘Hollis’. These genotypes, used in conjunction with other cultural or chemical control methods, may help provide an economic means of controlling wireworms.

The tomato—potato psyllid Bactericera cockerelli (Šulc) (Hemiptera: Triozidae) is a pest of many solanaceous plants, including tomato (Solanum lycopersicum L.) and potato (Solanum tuberosum L.). In tomato, feeding by nymphs is associated with “psyllid yellows.” B. cockerelli also vectors “Candidatus Liberibacter psyllaurous,” an infectious bacterium that causes “vein greening” disease. Decisions about management action are much more effective when guided by robust sampling. However, there are few previous studies of potato psyllid spatial distribution in tomato fields, and no published sequential sampling plans for the pest in tomato. We studied B. cockerelli in various tomato fields in California and used these data to generate a sequential sampling plan. We found that juvenile B. cockerelli in tomato fields exhibit an edge effect, an aggregated distribution, and individuals are primarily located on the bottom of leaves. Psyllids were concentrated in the upper segments of plants, but this changed over time. Finally, we present three binominal sequential sampling plans for managing tomato psyllids in tomato fields. These plans differed from both those for bell pepper (Capsicum annum L.) and potato, indicating that B. cockerelli needs to be sampled using crop-specific sampling plans.

Panicle caterpillars comprise an economically important insect pest complex of sorghum throughout the Great Plains of the United States, particularly in Kansas, Oklahoma, and Texas. The sorghum panicle caterpillar complex consists of larvae of two polyphagous lepidopteran species: the corn earworm, Helicoverpa zea (Boddie), and fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). Sampling for panicle caterpillars in sorghum fields is usually accomplished by the beat bucket sampling technique with a fixed sample size of 30 beat bucket samples of one sorghum panicle each per 16.2 ha of field. We used Wald's sequential probability ratio test for a negative binomial distribution to develop a sequential sampling plan for panicle caterpillars. In total, 115 sorghum fields were sampled in Kansas, Oklahoma, and Texas from June to August 2010. Panicle caterpillars had an aggregated distribution of counts confirmed by Pearson's chi-square statistic for lack of fit to the negative binomial distribution for each sampled field. A sequential sampling plan was developed using a high threshold (an economic threshold) of 0.5 caterpillars per sorghum panicle, a low threshold (a safe level) of 0.20 caterpillars per panicle, and fixed error rates (α = 0.10 and β = 0.05). At caterpillar densities >0.45 and <0.12 per panicle, the average number of panicles inspected to make a decision was less than the current recommendation of 30. In a 2013 validation test of 25 fields, the expected number of samples taken from average sample number curve was in close agreement with the number of samples required using the sequential plan (r² = 0.93), and all fields were correctly classified when compared with a fixed sample size result. The plan improved upon current sampling recommendations for panicle caterpillars in sorghum because at known acceptable fixed error rates fewer samples were required when caterpillars are scarce or abundant, whereas more samples were required to make decisions with the same acceptable error rates when densities were near the economic thresholds.

The residual effect of chlorfenapyr (Phantom) was evaluated for residual control of three stored-product psocid species: Liposcelis bostrychophila Badonnel, Liposcelis entomophila (Enderlein), and Liposcelis paeta Pearman (Psocoptera: Liposcelididae). Chlorfenapyr was applied to individual arenas with a concrete surface at rates of 0, 2.8, 13.8, 20.6, 27.5, 55, and 110 mg active ingredient (AI)/m². Adults were exposed on the treated arenas and mortality assessed after 1, 2, and 3 d. The procedures were repeated weekly on the same treated arenas for 3 wk to assess residual efficacy. At each week, mortality of all species was low after 1 d of exposure but notably increased after 2 or 3 d. L. entomophila was the most susceptible species, with 99–100% mortality at rates of 13.8 mg/ m² or higher. Similarly, mortality of L. paeta after 3 d of exposure at the same concentration ranged from 92 to 100%. L. bostrychophila was the least susceptible species, with mortality of <60% during the third week after application at rates ≤27.5 mg/m². However, even for this species, mortality after 3 wk was 90% or higher at rates >27.5 mg/m². Complete mortality of all species occurred after 3 d exposure at the highest rate tested of 110 mg/m². Thus, our results show that chlorfenapyr is effective against major psocid species at the application rates evaluated in this study.

Insecticides can have lethal or sublethal effects upon targeted pest species, and sublethal effects may even favor pest outbreaks if insecticide-induced hormesis occurs. Hormesis is a biphasic dose—response of a given chemical compound that is stimulatory at low doses and toxic at high doses. The former response may result from the disruption of animal homeostasis leading to trade-off shifts between basic ecophysiological processes. A growing interest in the use of biorational insecticides, such as azadirachtin to control stored-product pests, raises concerns about potential sublethal effects. In this study, we explored the hypothesis that azadirachtin can negatively impact the reproductive capacity of the Mexican bean weevil, Zabrotes subfasciatus (Boheman) (Chrysomelidae: Bruchinae), a key pest of stored beans. In addition,weinvestigated whether adults of this species could compensate for any sublethal effect that might have affected any of their reproductive parameters by adjusting the allocation of its reproductive efforts. The results showed that females of Z. subfasciatus increased fecundity daily to compensate for azadirachtin-induced decreased longevity. In addition, a stage-structured matrix study revealed that populations of Z. subfasciatus engendered from females exposed to azadirachtin exhibited a higher rate of population increase (r) and a higher net reproductive rate (Ro). Finally, a projection matrix analysis showed notably higher densities along the generations for azadirachtin-exposed Z. subfasciatus populations. Thus, our study provides empirical evidence for the capacity of Z. subfasciatus to adapt to sublethal effects caused by biorational insecticides; consequently, this study highlights the importance of understanding this phenomenon when devising pest management strategies.

The psocid, Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae), can cause significant damage to stored commodities, and its pest status in the United States has been increasing over the last decade. Because L. bostrychophila is difficult to control with conventional methods, it is critical to explore alternative approaches such as the use of attractants that can be incorporated into integrated pest management programs for monitoring psocids. The orientation response of several L. bostrychophila life stages (first and second instars, third and fourth instars, 0- to 7-d-old adults, 21- to 28-d-old adults, and adults of mixed ages) to a range of potential attractants (including whole and cracked grains, grain-based oils, wheat germ, brewer's yeast, and commercially available kairomone lures) was studied using a two-choice pitfall test to identify candidates for further development as lures in traps. Amongthe potential attractants evaluated, the strongest response by all stages of L. bostrychophila was to brewer's yeast. Other materials for which there was consistently a strong response were psocid diet, wheat germ, and wheat germ oil. These results show the potential for developing monitoring tools for integrated pest management programs for L. bostrychophila and other psocid species.

The hop looper, Hypena humuli Harris, is a reemergent pest of hop that often requires treatment to mitigate crop damage. In 4 yr of field trials, plots treated with fungicides were observed to sustain less hop looper defoliation compared with nontreated plots. Further investigation revealed that abundance of hop looper and associated defoliation were reduced when the fungicide pyraclostrobin was applied in late July to early August.Twoother fungicides possessing active ingredients in thesamechemical family (quinone outside inhibitor) did not reduce abundance of hop looper or its defoliation. Pyraclostrobin is efficacious against powdery mildew diseases, and the application timing evaluated in these studies corresponds with a period of juvenile susceptibility of hop cones to the disease. Use of fungicides containing pyraclostrobin at this time may have the ancillary benefit of reducing hop looper damage, potentially obviating the need for broad-spectrum insecticides later in the season. Follow-up studies are warranted to determine whether pyraclostrobin may inhibit other lepidopteran species.