The larger black flour beetle Cynaeus angustus (Leconte) thrives in cotton gin trash piles on the Southern High Plains of Texas and sometimes becomes a nuisance after invading public and private structures. For better understanding of the basic larger black flour beetle ecology in gin trash piles, we conducted a series of laboratory and semirealistic field trials. We showed (1) in naturally infested gin trash piles, that similar trap captures were obtained in three cardinal directions; (2) in a laboratory study, late-instar larvae stayed longer in larval stage in moist soil compared with drier soil; (3) in both horizontal and vertical choice experiments, late instars preferred soil with low moisture content; and (4) specifically larger black flour beetle adults, but most larvae as well, responded negatively to high moisture content in gin trash. The results presented are consistent with reports of larger black flour beetle living in decaying yucca palms in deserts and suggest that maintaining gin trash piles with high moisture content may be an important component in an integrated control strategy.

The alfalfa root weevil, Sitona discoideus (Coleoptera: Curculionidae), is an important pest of alfalfa. The developmental rates of the embryo development were recorded at eight constant temperatures ranging from 8.5 to 30°C. Using 10 models (1 linear and 9 nonlinear), we evaluated the relationship between constant temperature and developmental rate. Embryo development was shortest (8.5 d) and longest (69 d), at 28 and 8.5°C, respectively. The threshold temperature (T₀) and the thermal constant (K) were estimated using linear regression to be 4.7°C and 207.7 DD, respectively. The two most efficient nonlinear models, the Lactin and the Sharp and DeMichele, gave estimates of T_min and T_max of 4.4 and 3.9 and 30.0 and 30.9°C, respectively. This information has potential application in predicting the suitability and optimal time of release of an egg parasitoid of S. discoideus.

The sensitive stage for switching migrant oriental armyworm, Mythimna separata (Walker), into residents was determined under the stresses of starvation and cold (5°C) in a laboratory population. Presumed migrants developing from gregarious larvae oviposited significantly earlier when adults were starved or shocked by cold only during the first 24 h after emergence. In contrast, preoviposition periods for migrants starved or cooled on days 2–6 of adult life were not significantly affected. The preresponse period of male migrants starved on day 1 of adult life was also significantly shortened, whereas those treated on following days were not significantly influenced. Similarly, total lifetime fecundity of migrants, which were starved or cooled on day 1 after emergence, was significantly increased; however, the same effect was not observed in migrants that were stressed later. Although preoviposition periods of presumed residents, developing from solitary larvae, starved or shocked by cold during the first several days of adulthood were significantly prolonged, this delay was not related to migratory strategy, because lifetime fecundity was not significantly reduced. The results suggest that the first day of adult life in this species is a sensitive stage during which migrants can shift into residents, although residents cannot shift to migrants. Thus, starvation and cold experienced in this stage induces migrants to modify their developmental path into reproduction and residency.

Effects of photoperiod on development, survival, feeding, and oviposition of boll weevils, Anthonomus grandis grandis Boheman, were assessed under five different photophases (24, 14, 12, 10, and 0 h) at a constant 27°C temperature and 65% RH in the laboratory. Analyses of our results detected positive relationships between photoperiod and puncturing (mean numbers of oviposition and feeding punctures per day), and oviposition (oviposition punctures/oviposition feeding punctures) activities, and the proportion of squares attacked by boll weevil females. When boll weevil females developed in light:darkness cycles, they produced a significantly higher percentage of eggs developing to adulthood than those developed in 24-h light or dark conditions. In long photoperiod (24:0 and 14:10 h), the number of female progeny was significantly higher and their development time was significantly shorter than those developed in short photoperiod (0:24 and 10:14 h). Lifetime oviposition was significantly highest at 12- and 14-h photophase, lowest at 0- and 10-h photophase, and intermediate at 24 h of light. Life table calculations indicated that boll weevil populations developed in a photoperiod of 14:10 and 12:12 (L:D) h will increase an average of two-fold each generation (R_o) compared with boll weevils developed in 24:0- and 10:14-h photoperiods and 15-fold compared with those at 0:24 h. Knowledge of the photoperiod-dependent population growth potential is critical for understanding population dynamics to better develop sampling protocols and timing insecticide applications.

Redbay ambrosia beetle, Xyleborus glabratus Eichhoff, is a native of Southeast Asia recently established in coastal forests of Georgia, SC and Florida. It vectors a wilt fungus, Raffaelea sp., lethal to redbay trees, Persea borbonia L. Spreng, and certain other Lauraceae. No practical monitoring system exists for this beetle so we conducted studies to identify host attractants and develop lures. Volatiles were collected from redbay wood and bark by steam distillation, direct solvent extraction, and dynamic headspace sampling with a Poropak Q cartridge. Steam, methanol, and pentane extracts were tested as baits in trapping trials but were not attractive to X. glabratus. Major constituents in Poropak aerations identified by gas chromatography-mass spectrometry included α-pinene, β-pinene, δ-3-carene, eucalyptol, p-cymene, α-copaene, terpinene-4-ol, linalool, calamenene, and nonanoic acid. We assayed several of these compounds (including eucalyptol, p-cymene, terpinene-4-ol, linalool, nonanoic acid, and caryophyllene oxide) both individually and in combination, but none were attractive at tested doses. Two other redbay odor components, α-copaene and calamenene, were unavailable in sufficient quantities commercially so we substituted manuka oil, the essential oil extracted from Leptospermum scoparium Forst. and Forst., which contains high proportions of both compounds. Manuka oil was equally attractive as redbay wood to X. glabratus, but increasing release rates >10-fold did not enhance its activity. Phoebe oil, an extract of Brazilian walnut (Phoebe porosa Mez.), which contains significant quantities of α-copaene and calamenene, was also attractive. Fractions of manuka oil were not more attractive than the whole oil. Manuka and phoebe oil are readily available and are good alternatives to redbay wood as a trap bait for monitoring X. glabratus distribution and population trends.

Seven synthetic herbivore-induced plant volatiles (HIPVs) and a mixture of nonanal (Z)-3-hexen-1-ol were field tested for their ability to attract beneficial insects in an open cotton field. Eleven species of the main natural enemies of insect pests in cotton fields were studied. Significantly greater numbers of the ladybird beetle Coccinella septempunctata were trapped on (Z)-3-hexenyl acetate-baited cards than on others that were HIPV baited or the control cards. Erigonidium graminicolum was attracted to traps baited with nonanal, (Z)-3-hexenyl acetate, and methyl salicylate (MeSA). The predatory bug Deraeocoris punctulatus was only attracted to traps baited with octanal. The predatory bug Orius similis responded to traps baited with 3,7-dimethyl,1,3,6-octatriene, nonanal, (Z)-3-hexenyl acetate, nonanal (Z)-3-hexen-1-ol, and MeSA. Dimethyl octatriene, nonanal (Z)-3-hexen-1-ol, and octanal significantly attracted the syrphid fly Paragus quadrifasciatus. The ladybird beetle Propylaea japonica, the green lacewing Chrysopa sinica, the bigeyed bug Geocoris pallidipennis, the syrphid fly Epistrophe balteata, and the parasitic wasp Campoletis chlorideae did not respond to any of the HIPVs tested. These results are discussed with regard to the potential of HIPVs as tools for recruiting natural enemies into cotton fields.

Responses of the tea mosquito, Helopeltis theivora (Waterhouse) (Hemiptera: Miridae), a major pest of tea, to female sex pheromone compounds were measured using wind tunnel and electroantennogram (EAG) bioassays. In the wind tunnel, male tea mosquitoes were found to be most attracted to a dichloromethane extract of the female thorax. Gas chromatography-mass spectrometry (GC-MS) analysis of female thoracic extracts and dynamic head space samples of virgin females showed the presence of five compounds: (Z)-3 hexenyl acetate, (Z)-3 hexenyl butanoate, (E)-2 hexenyl pentanoate, 2,4 dimethyl pentanal, and (E)-2-hexenol. Male tea mosquitoes were attracted to blends of (Z)-3 hexenyl acetate and (E)-2-hexenol in the wind tunnel with a 1:5 ratio eliciting the greatest response. EAG recordings of male antenna confirmed the ability of this blend to evoke antennal responses in male insects. Similarly active EAG responses were recorded toward female thoracic extract and a blend of (Z)-3 hexenyl acetate and (E)-2-hexenol. Behavioral responses of adult males are mediated by a blend of volatile female sex pheromone compounds, (Z)-3 hexenyl acetate and (E)-2-hexenol, at a ratio of 1:5. This female sex pheromone blend may be useful for tea mosquito control and management programs.

Insects in the order Thysanoptera are known for their haplodiploid reproduction, with most species reproducing by arrhenotoky. A few species, however, have only female populations and reproduce by thelytoky. Seven thrips species reproducing either by arrhenotoky [Frankliniella occidentalis (Pergande), Echinothrips americanus Morgan, Suocerathrips linguis Mound and Marullo, Gynaikothrips ficorum (Marchal)] or thelytoky [Hercinothrips femoralis (O.M. Reuter) and Parthenothrips dracaenae (Heeger)] or showing both reproduction modes (Thrips tabaci Lindeman) were screened for the presence of Wolbachia using 16S rDNA and ftsZ gene primers. The arrhenotokous reproducing species E. americanus, G. ficorum, and S. linguis tested positive for Wolbachia. The bacterium was not detected in F. occidentalis or T. tabaci; even the thelytokous population of T. tabaci was free of Wolbachia. Wolbachia was found in the thelytokous reproducing species H. femoralis and P. dracaenae. Antibiotic treatment of H. femoralis induced the production of males that copulated with females. The results confirmed Wolbachia to be present in thelytokous reproducing thrips species and proved the presence of the bacterium for the first time in some arrhenotokous reproducing thrips species.

Scant attention has been paid to invasive species whose range and abundance has decreased after an initial range expansion. One such species is the browntail moth Euproctis chrysorrhoea L, which was discovered in the eastern United States in 1897. Its range expanded until 1914; after 1915, however, its range contracted and now it persists in only two isolated coastal locations. Although a biological control agent has been implicated in this range collapse, cold inland winter temperatures may also help to restrict browntail moth populations. We surveyed coastal versus inland habitats in Maine and Massachusetts for browntail moth overwintering mortality and larval density per web. We also performed an experiment assessing these same variables in coastal versus inland habitats on different host plant species and at different initial larval densities. We also analyzed temperature records to assess whether winter temperatures correlated with changes in the invasive range. Overwintering mortality was lower in coastal populations for both the experimental populations and in the Maine field survey. Experimental populations in Cape Cod coastal areas also had lower rates of fall mortality and higher larval densities, suggesting that coastal areas are better year-round habitats than inland areas. There were no consistent differences between coastal and inland populations in their response to larval density or host plant, although overall survival in both areas was higher at low initial larval densities and affected by host identity. There was also no difference in two measures of the coldest winter temperatures during browntail moth’s expansion and contraction. Our results show that climate affects browntail moth, but suggest that winter temperatures cannot explain both the rapid expansion and subsequent collapse of this pest.

Listronotusmaculicollis (Kirby) is a burgeoning pest of Poaannua L. in the northeast United States. To develop an understanding of its spatial and temporal association with golf course landscapes, we described the patterns of variation in certain population parameters across site (Fayetteville and Ithaca, NY), year (2004–2006), and management habitat (fairway, intermediaterough, rough). In weekly surveys along fairway transects, we sampled larvae (identified to instar) by soil core extraction and adults (identified to sex and maturation)by hand collection. Five instars were confirmed based on head capsule width measurements; there was no overlap among instars. Sex ratio was significantly male-skewed on the rough versus the fairway. Insect load, a measure of population size based on cumulative insect-days, varied from 3.0- to 18.5-fold across sites and years and averaged 8.7- and 8.0-fold greater on the fairway than rough for larvae and adults, respectively. Visual assessment of stage-specific population fluctuation curves revealed no divergence in adult males and females, i.e., no evidence of protandry. Variation was greater by year than by site in terms of overall shape of the fluctuation curves, relative abundance of overwintered to spring and summer adults, population synchrony, and number of generations (two to three). Evidence of bimodal spring generations showed that early season population synchrony may be linked to the pattern of adults transitioning from overwintering to developmental habitats. The magnitude of variation in population dynamics underscores the relevance of decision-making strategies and has implications for improving both the spatial and temporal targeting of intervention tactics.

Aleochara bilineata Gyllenhal (Coleoptera: Staphylinidae) is an important natural enemy of root maggots (Delia spp.) (Diptera: Anthomyiidae), which are serious pests of brassicaceous crops in North America and Europe. Adults of A. bilineata feed on eggs and larvae of root maggots, and A. bilineata larvae parasitize Delia spp. pupae. Emergence and seasonal activity patterns of A. bilineata were investigated during 2003–2005 in canola (Brassica rapa L. and Brassica napus L.) in central Alberta, Canada, in relation to degree-day (DD) accumulations and Julian date. Captures of A. bilineata adults from pitfall traps within emergence cages situated over canola stubble from the previous year indicated that ≈428, 493, and 455 DD (soil base 5.57°C) and 187, 189, and 180 Julian days were required for 50% emergence in 2003, 2004, and 2005, respectively (3-yr mean = 185.1 ± 2.8 Julian days [SEM]). Captures of A. bilineata adults from pitfall traps placed in current canola crops determined that 50% levels of activity density required 379 DD and 180 Julian days in 2004. A logistic model that described the relationship of degree-days and Julian days with emergence of adult beetles was appraised, and good correspondence was evident between predicted and observed cumulative emergence patterns. Emergence and seasonal activity periods of A. bilineata in canola were well synchronized with occurrence of preimaginal life stages of its principal hosts, Delia radicum (L.) and Delia platura Meigen, with beetle emergence beginning shortly after the onset of root maggot oviposition.

Many ecological studies of tropical insects are based on small sample sizes or lack sampling scheme rigor, which prevents testing ecological hypotheses and comparing samples from different sites and times. Here we present the results of quantitative trapping of bark and ambrosia beetles over 2 yr at two localities in northern Thailand separated by 5 km, 1,100 m in altitude, and in different forest types. Beetles were collected using a spatially and temporally standardized sampling scheme, followed by a quantitative analysis of community composition and its responses to environmental variables and trapping techniques. In total, 118 species were collected, but the species accumulation curves show little sign of leveling off. Based on slightly different species accumulation rates, the more humid site has a little higher species richness. Species composition was significantly different between the sites, which was not a result of undersampling of rare species. α diversity at each site contributes to the regional diversity more than the turnover of species between the sites (β diversity). Mean annual temperature and humidity have larger effects on the community species composition than seasonal fluctuations of temperature and humidity at each site—beetles do choose their environment but are aseasonal. The site with greater humidity supported significantly more species living in a symbiosis with fungi (ambrosia beetles), whereas the drier and more disturbed site hosted a greater number of circumtropical colonizer species. Each of the different types of trap had a bias for certain taxonomic groups. The results show that even modest samples, if properly structured and analyzed, can answer many ecological questions and can serve in biodiversity comparisons on broad scales.

The myrmecophilous five-spotted gamagrass leafhopper, Dalbulus quinquenotatus DeLong and Nault, and its tending ants on gamagrass Tripsacum dactyloides L. were examined to determine the influence of shade and ant-constructed shelters on the population sizes of D. quinquenotatus and ants. Gamagrass plants hosting ants and leafhoppers were exposed to 50, 30, or 0% artificially constructed shade. The greatest numbers of leafhoppers and ants were found on plants that received 50% shade. Shelters made by the ant Solenopsis geminata (F.) contained large numbers of leafhoppers and ants but were found only on T. dactyloides exposed to 50% shade in artificially constructed habitats. Additional sampling was conducted on wild gamagrass plants in the field to explore the presence of ants tending leafhoppers in shelters and to evaluate whether ant-constructed shelters protect leafhopper nymphs from parasitoid wasps. Large aggregations of S. geminata in shelters were also found in natural gamagrass habitats. Leafhopper nymphs living in shelters made by S. geminata may be protected against the dryinid wasp parasitoid Anteon ciudadi Olmi. No sheltered nymphs were parasitized by dryinids, whereas 24% of unsheltered nymphs had dryinid parasitism.

In western North America, infestations of the hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), are common on orchard, ornamental, and roadside western hemlock, Tsuga heterophylla (Raf.) Sargent. However, these infestations rarely cause T. heterophylla mortality. Host tolerance and presence of endemic predators may be contributing to the relatively low levels of injury to T. heterophylla caused by A. tsugae. Field surveys of the arthropod community associated with A. tsugae infestations on 116 T. heterophylla at 16 sites in Oregon and Washington were conducted every 4–6 wk from January 2005 through November 2006. Fourteen uninfested T. heterophylla were also surveyed across 5 of the 16 sites. Immature A. tsugae predators collected in the field were brought to the laboratory for rearing. Eight species of hymenopterous parasitoids were reared from pupae of predators of A. tsugae in the laboratory. Two Pachyneuron spp. (Pteromalidae) and a Melanips sp. (Figitidae) were reared from Leucopis spp. (Diptera: Chamaemyiidae) puparia. Syrphoctonus pallipes (Gravenhorst) (Ichneumonidae), Woldstedtius flavolineatus (Gravenhorst) (Ichneumonidae), Syrphophagus sp. (Encyrtidae), and Pachyneuron albutius Walker were reared from Syrphidae (Diptera) puparia. A Helorus sp. (Heloridae) was reared from a Chrysoperla sp. (Neuroptera: Chrysopidae) cocoon. Laboratory rearing did not show any direct association between parasitoids and A. tsugae. In the field survey, a total of 509 adult parasitic Hymenoptera representing 19 families and at least 57 genera were collected from T. heterophylla. Nonparametric analysis of community structure showed Pachyneuron spp. were strongly correlated to abundance of their Leucopis spp. hosts and to A. tsugae population score in the field. The possible impact of parasitism on Leucopis spp., potential A. tsugae biological control candidates for the eastern United States, is discussed.

We assessed the relationships between diversity patterns of Iberian Calathus and current environmental gradients or broad-scale spatial constraints, using 50-km grid cells as sampling units. We assessed the completeness of the inventories using nonparametric estimators to avoid spurious results based on sampling biases. We modeled species richness and beta diversity, using spatial position, and 23 topographical, climatic, and geological variables as predictors in regression and constrained analysis of principal coordinates modeling. Geographical situation does not seem to affect Calathus species richness, because no spatial pattern was detected. The environmental variables only explained 23% of the variation in richness. Spatial and environmental predictors explained a large part of the variation in species composition (58%). The fraction shared by both groups of variables was relatively large, but the pure effect of each model was still important. Our results show that it is necessary to assess the completeness of inventories to avoid drawing false conclusions. Also, Iberian Calathus represent a clear example of the need for combined analyses of species richness and beta diversity patterns, because the lack of patterns in the former does not imply the invariance of biotic communities.

Synchrony and impact of the predators Laricobius nigrinus Fender and Laricobius rubidus LeConte, on hemlock woolly adelgid, Adelges tsugae Annand, were studied in an eastern hemlock field insectary in Virginia. First, a field insectary for propagation of the introduced L. nigrinus was established by planting hemlocks in 2001, infesting them with hemlock woolly adelgid in 2002 and 2003, followed by releasing 258 L. nigrinus in 2003. Initial sampling showed that the native L. rubidus was present in the area. Hemlock woolly adelgid and both Laricobius species populations increased annually, from which 305 F₃ L. nigrinus adults were collected and redistributed to forests in 2007. Second, the phenology of hemlock woolly adelgid and Laricobius spp. life cycles were monitored in 2005 and 2006. Adult L. nigrinus (F₂) and L. rubidus were active on hemlock from fall through mid-spring and overlapped with second-instar sistentes nymphs through progredientes eggs. The predators’ eggs were oviposited and larvae developed (i.e., F₃ L. nigrinus) from late winter to mid-spring on progredientes eggs, indicating synchrony with suitable prey life stages. Third, a predator exclusion experiment was used to examine the relationships between the predators and prey in 2005 and 2006. When exposed to L. nigrinus (F₂ adults and F₃ larvae) and L. rubidus, hemlock woolly adelgid survival and ovisac density were lower and ovisac disturbance was higher than hemlock woolly adelgid protected in cages. The establishment and production of L. nigrinus at a field insectary, synchronization with, and impacts on hemlock woolly adelgid after a small release 2 yr earlier makes it an important potential biological control agent of hemlock woolly adelgid.

An examination of oviposition choices by the lesser peachtree borer, Synanthedon pictipes (Grote and Robinson) (Lepidoptera: Sesiidae), showed that wounded peach, Prunus persica (L.) Batsch, bark was attractive to females for oviposition. Females responded to bark that was injured mechanically (e.g., hammer blows, knife cuts, pruning wounds), infested by lesser peachtree borer larvae or injured by disease. In fact, there was no difference in female oviposition response to knife cut wounds and knife cut wounds infested with lesser peachtree borer larvae. Oviposition on wounded bark from three different high chill peach cultivars was similar and strongly suggests that the narrow genetic base of high chill peach cultivars grown in the southeastern United States has little inherent resistance to the lesser peachtree borer. In stark contrast, when provided different Prunus spp., i.e., exotic peach and the native species P. angustifolia and P. serotina, the exotic peach was highly preferred for oviposition by the native lesser peachtree borer.

Pyriproxyfen has been an important insecticide used as part of an integrated pest management (IPM) program for the sweetpotato whitefly, Bemisia tabaci (Gennadius) (B biotype), in Arizona cotton. We used a simulation model to examine the effects of pyriproxyfen concentration, insecticide action thresholds, crop diversity, planting date, and pyriproxyfen decay on evolution of resistance to pyriproxyfen in B. tabaci. In the model, pyriproxyfen use was restricted to cotton with a limit of one application per season. Other model parameters were based on data from laboratory and field experiments. Whitefly population densities and the number of insecticide applications per year increased as resistance evolved. Resistance evolved slowest with a low pyriproxyfen concentration. Lower action thresholds for pyriproxyfen and higher action thresholds for insecticides other than pyriproxyfen also slowed the evolution of resistance. However, lower action thresholds for pyriproxyfen resulted in more insecticide sprays per year with a high pyriproxyfen concentration. Resistance to pyriproxyfen evolved fastest in cotton-intensive regions and slowest in multicrop regions. In regions with noncotton crops, increasing immigration to cotton slowed resistance. Resistance evolved faster with earlier planting dates, although fewer insecticide sprays were needed compared with fields planted later in the year. Faster rates of pyriproxyfen decay slowed resistance. In some cases, strategies that delayed resistance were effective from an IPM perspective. However, some strategies that delayed resistance resulted in higher population densities. Results suggest that modification of operational and environmental factors, which can be controlled by growers, could prolong the efficacy of pyriproxyfen.

Escherichia coli labeled with a green fluorescent protein was inoculated into sterile dairy manure at 7.0 log cfu/g. Approximately 125 black soldier fly larvae were placed in manure inoculated and homogenized with E. coli. Manure inoculated with E. coli but without black soldier fly larvae served as the control. For the first experiment, larvae were introduced into 50, 75, 100, or 125 g sterilized dairy manure inoculated and homogenized with E. coli and stored 72 h at 27°C. Black soldier fly larvae significantly reduced E. coli counts in all treatments. However, varying the amount of manure provided the black soldier fly larvae significantly affected their weight gain and their ability to reduce E. coli populations present. For the second experiment, larvae were introduced into 50 g manure inoculated with E. coli and stored for 72 h at 23, 27, 31, or 35°C. Minimal bacterial growth was recorded in the control held at 35°C and was excluded from the analysis. Black soldier fly larvae significantly reduced E. coli counts in manure held at remaining temperatures. Accordingly, temperature significantly influenced the ability of black soldier fly larvae to develop and reduce E. coli counts with greatest suppression occurring at 27°C.

We evaluated the influence of six different citrus rootstocks on the incidence of the citrus leafminer, Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), and the aphid species, Aphis gossypii Glover and A. spiraecola Patch (Hemiptera: Aphididae), on ‘Clementine de Nules’ trees (Citrus clementina Hort. ex Tan.). Sampling was conducted during 2005 and 2006 in a grove of 3-yr-old trees in southern Spain with six rootstocks arranged in a completely randomized block design. Incidence (i.e., degree of infestation) and availability of resources for herbivores were assessed bi-weekly, and in addition, a “flushing index” was estimated as the number of young shoots (as a percentage of total shoots) susceptible to herbivore injury. Our results showed that contrasting factors affected the incidence of populations of P. citrella, A. gossypii, and A. spiraecola on ‘Clementine de Nules’. Incidence of P. citrella was significantly dependent on the flushing pattern observed throughout the study, whereas the reverse was true for the aphid species. Among these, A. spiraecola had similar levels of incidence regardless of rootstock, whereas A. gossypii were found almost exclusively on leaves of ‘Clementine de Nules’ grafted on ‘Cleopatra mandarin’ (Citrus reshni Hort. ex Tan). Potential implications of these results on pest control are discussed.

Heliothis virescens F. is an important polyphagous pest that can develop on >100 plant species, including 20 economic crops. Populations of this insect are believed to be locally maintained on a few crops and weed hosts in Washington County, MS. To find the intrinsic value of these plants for the development of H. virescens populations, we fed different laboratory and wild colonies with fresh and lyophilized plant tissue under a constant temperature. Development time of this insect under laboratory conditions varied up to 10 d between plant hosts and was dependent on the type of plant tissue provided: fresh or lyophilized. Life table parameters such as net reproductive rate, finite rate of increase, and generation time indicated that Trifolium repens, a wild host growing around agricultural fields year round, could be one of the most suitable local plant hosts for the development of H. virescens. Two species of Geranium, previously reported as the source of the first H. virescens generation in the region, had lower intrinsic value as a food source than did T. repens. Gossyipium hirsutum, perhaps the most important crop source of H. virescens in the region, produced low net reproductive rate and finite rate of increase parameters. Sampling conducted in agricultural fields during 2006 and 2007 found no larvae on the above mentioned wild hosts as it was previously reported. Results indicated that H. virescens populations in this region were not supported by the wild plant species growing around agricultural fields during the time when the survey took place.

The Japanese beetle, Popillia japonica Newman, has an unusually broad host range among deciduous woody plants, yet it feeds only sparingly, or not at all, on certain species in the field. We evaluated beetles’ preference, survival over time and fecundity on eight woody plant species historically rated as susceptible or resistant and, after verifying those ratings, tested whether resistance is correlated with so-called quantitative defense traits including leaf toughness, low nutrient content (water, nitrogen, and sugars), and relatively high amounts of tannins or saponins, traditionally associated with such plants. We further tested whether species unsuitable for Japanese beetles are also rejected by fall webworms, Hyphantria cunea (Drury) (Lepidoptera: Arctiidae), the expected outcome if the aforementioned traits serve as broad-based defenses against generalists. Choice tests supported historical resistance ratings for the selected species: tuliptree, lilac, dogwood, and Bradford callery pear were rejected by Japanese beetles, whereas sassafras, cherry plum, Virginia creeper, and littleleaf linden were readily eaten. Rejected species also were unsuitable for survival over time, or egg-laying, indicating beetles’ inability to overcome the resistance factors through habituation, compensatory feeding, or detoxification. None of the aforementioned leaf traits was consistently higher or lower in the resistant or susceptible plants, and plant species rejected by Japanese beetles often were not rejected by fall webworms. Specialized secondary chemistry, not quantitative defenses, likely determines the Japanese beetle’s dietary range among deciduous woody plant species it may encounter.

The effects of maize (Zea mays L.) phenology on establishment and adult emergence of the western corn rootworm (Diabrotica virgifera virgifera LeConte) and plant damage to maize was evaluated in field trials in 2001 and 2002 and in the greenhouse. Although neonate western corn rootworm larvae were able to initially establish on maize roots during anthesis and early reproductive stages, these older roots were apparently unsuitable for complete western corn rootworm larval development. The number of western corn rootworm beetles that emerged from eggs that hatched during anthesis to early reproductive stages was significantly fewer than the number of beetles that eclosed from V4 to V11. Plant damage was also lowest from larvae that eclosed during anthesis to early reproductive stages. Potential causal mechanisms and implications of these data in terms of potential management strategies in the future are discussed.

Diaprepes abbreviatus L. is a highly polyphagous root weevil that causes damage to several fruit crops, ornamental plants, and other naturally occurring plants in Florida. Haeckeliania sperata Pinto is a gregarious endoparasitoid that attacks D. abbreviatus eggs. We hypothesized that the reproductive success of H. sperata is affected by the host plant of D. abbreviatus. Six host plants with varying degrees of pubescence were used to determine the effect of leaf trichomes on the searching behavior and success of parasitism by H. sperata. No-choice tests showed that H. sperata was able to parasitize Diaprepes eggs laid on the six host plants. However, the plants with a high trichome density on their leaves had a lower percent of parasitism than the plants with smoother leaves. Removing trichomes from a host plant showed that the presence of some leaf trichomes had a negative effect on the overall searching efficiency of H. sperata. The presence of trichomes decreased the total distance traveled and increased the total search time of H. sperata females, resulting in a lower searching speed. Multiple regression analysis was used to establish the relationship between percent parasitism and leaf trichome density, leaf thickness, and the searching speed of H. sperata. Searching speed was the best predictor of percent parasitism; this parameter could be used to predict the suitability of host plants for the establishment of H. sperata. Our findings suggest that the reproductive success of H. sperata is affected by the host plant of D. abbreviatus.

Aphids can respond both positively and negatively to virus-induced modifications of the shared host plant. It can be speculated that viruses dependent on aphids for their transmission might evolve to induce changes in the host plant that attract aphids and improve their performance, subsequently enhancing the success of the pathogen itself. We studied how pea aphids [Acyrthosiphon pisum (Harris)] responded to infection of tic beans (Vicia faba L.) by three viruses with varying degrees of dependence on this aphid for their transmission: pea enation mosaic virus (PEMV), bean yellow mosaic virus (BYMV), and broad bean mottle virus (BBMV). BYMV has a nonpersistent mode of transmission by aphids, whereas PEMV is transmitted in a circulative-persistent manner. BBMV is not aphid transmitted. When reared on plants infected by PEMV, no changes in aphid survival, growth, or reproductive performance were observed, whereas infection of beans by the other aphid-dependent virus, BYMV, actually caused a reduction in aphid survival in some assays. None of the viruses induced A. pisum to increase production of winged progeny, and aphids settled preferentially on leaf tissue from plants infected by all three viruses, the likely mechanism being visual responses to yellowing of foliage. Thus, in this system, the attractiveness of an infected host plant and its quality in terms of aphid growth and reproduction were not related to the pathogen’s dependence on the aphid for transmission to new hosts.

Fifteen silver birch (Betula pendula Roth) lines carrying a sugar beet chitinase IV gene and eight wild-type birch clones were grown in a field trial. The composition and density of the insect population and the leaf damage caused by insects were monitored and compared between transgenic and wild-type trees. The most abundant insect group in all trees was aphids, and the variation in total insect densities was mainly explained by the variation in aphid densities. Insect densities were generally higher in the transgenic than in the control trees, indicating that the expression of the sugar beet chitinase IV gene had an influence on the suitability of birch leaves to aphids. The level of leaf damage was higher among transgenic than among control trees. Chewing damage was the most common type of leaf damage in all trees. The number of different damage types was higher among the wild-type clones than among the transgenic lines or their controls. The results indicate that the chitinase transgenic trees are more susceptible to aphids and suffer higher levels of leaf damage than the control trees. In the composition of the damage types, the control trees were more similar to the transgenic than to other wild-type trees, indicating that the composition was mostly linked to the genotype of the tree and not to the expression of the transgene. This study provides important information on the ecological interactions of chitinase transgenic trees in the field trial. No clear harmful effects of transgenic chitinase on the biodiversity of insect population were detected.