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Noctuid pests, including tobacco budworm (Chloridea virescens (Fab.)) and bollworm (Helicoverpa zea (Boddie)), are significant pests of southern row crops including cotton (Gossypium hirsutum L.), corn (Zea mays L.), and soybean (Glycine max (L.) Moench.). This pest complex is seasonally monitored through Hartstack traps that are baited with synthetic lepidopteran pheromones across the southern United States. We examined bycatch from the noctuid traps deployed across the Mississippi Delta in 2015, 2016, and 2017 for the presence of bees. The most abundant species collected were honey bees (Apis mellifera L.), bumble bees (Bombus spp.), and long-horned bees (Melissodes spp.); these three genera accounted for 82.4% of specimens collected. We also evaluated the proportion of local- and landscape-level habitats on the abundance and richness of the bees caught as bycatch. The proportion of natural and semi-natural habitat affected the abundance and richness of bees collected at the landscape level, but not at more local scales. Additional research is needed to better understand these interactions between bycatch and landscape factors to minimize non-target collections.

Rearing bollworm, Helicoverpa zea (Boddie), on synthetic diets for use in laboratory bioassays is a common practice around the world. Little is known about how insect diets currently utilized for bollworm rearing have been altered from their original nutrient composition and the implications this might have on insect fitness. Therefore, this study assessed notable shortcomings of a commonly used meridic diet by exposing bollworms to cotton (Gossypium hirsutum L) leaf tissue for short periods during early development to determine effect on larval and pupal survival and weights. Mean survival of larvae ranged from 60% when bollworms were exposed to Bt cotton leaves for 7 days to 100% on meridic diet. Mean pupation ranged from 58 to 97%, which closely mimicked survival of larvae at 7 days. Insect larvae reared on meridic diet through 7 days were fitter relative to those exposed to cotton leaf tissue, having greater larval weight and survival than other treatments. Conversely, pupal weight of bollworms exposed to meridic diet for the same 7-day period tended to lag behind those exposed to cotton leaf tissue. However, any fitness benefit gained from rearing larvae on leaf tissue might be offset by increased mortality before the pupal stage. The experiment demonstrated that larval and pupal fitness were impacted by supplementing meridic diet with leaf tissue, but additional research is needed to further investigate effects through multiple generations.

Laboratory measurements of susceptibility to Bt toxins can be a poor indicator of the ability of an insect to survive on transgenic crops. We investigated the potential of using leaf tissue for evaluating heliothine susceptibilities to two dualgene Bt cottons, Gossypium hirsutum L. A preliminary study with different cotton leaf disk combinations was performed to determine the best procedure for using cotton tissue to assay bollworm, Helicoverpa zea Boddie, and tobacco budworm, Heliothis virescens F. Neonate larvae from a laboratory colony were assayed simultaneously on leaf disks of non-Bt and two dual-gene transgenic cottons in addition to meridic diet overlaid with discriminating doses of a commerciallyformulated Bt product. The bollworm colony in the laboratory was more tolerant than tobacco budworm to the commercially-formulated Bt product. When corrected for the non-Bt check, percentage of bollworm larval mortality was 42.1 and 71.9 on leaf disks of the two dual-gene Bt cottons. No tobacco budworm survived on dualgene Bt cotton leaf disks in the study. Assays using transgenic cotton leaf disks may compliment current meridic diet-based methods by providing a linkage to insect survival on Bt cotton plants.

Supplemental control with diamides for bollworm, Helicoverpa zea (Boddie), in Bt cotton is becoming more frequent, but there is little information on net returns to growers. The value of spraying Bt cotton with commercially available diamides was evaluated at seven locations in the Mississippi Delta cropping region in 2014 and 2015. Plots of Bollgard II®, Widestrike 3®, and non-Bt cotton varieties planted at each location were divided into five subplots. Treatments randomly assigned to subplots of each cotton cultivar were: 1) lowest labeled rate of chlorantraniliprole applied at threshold, 2) lowest labeled rate of flubendiamide applied at threshold, 3) lowest labeled rate of λ-cyhalothrin + chlorantraniliprole applied at threshold, 4) sprayed check, which was the maximum labeled rate of chlorantraniliprole applied on a 3-week schedule and initiated before first bloom to minimize damage from heliothines, and 5) nontreated check. Each plot was monitored weekly for larval abundance and plant dama...

The use of neonicotinoid insecticides in the United States has grown by about a factor of four since the mid-2000s. Seed treatments account for a significant fraction of overall insecticide application to crops, and a large proportion of major U.S. crops are now planted using seed treated with neonicotinoids. Neonicotinoid insecticidal seed treatments are primarily intended to protect crops against sporadic or minor early-season pests. A better understanding of factors that influence the risk of economic infestations and extent of crop damage by sporadic pests is needed to target neonicotinoid insecticidal seed treatments use based on expected pest pressure. In a series of papers, we review the distribution, ecology, and historical management of seed and seedling pests targeted by neonicotinoid seed treatments in U.S. corn (Zea mays), soybean (Glycine max), wheat (Triticum aestivum), and cotton (Gossypium hirsutum L.). This information is key to region-specific management practices that reduce the risks and increase the benefits of neonicotinoid seed treatments.

The use of insecticides at planting has been a common crop management practice in cotton for several decades. Historically, U.S. cotton growers relied on in-furrow applications of insecticides, such as aldicarb, to control early-season insect pests. In-furrow applications have largely been replaced with insecticide-treated seed. Since 2012, more than 60% of the U.S. cotton crop is planted with seed treated with insecticide, primarily the neonicotinoids imidacloprid or thiamethoxam. Several insects or insect groups are included on the labels of these neonicotinoids for use as seed treatments. An increased understanding of the risks associated with economically injurious populations of insect pests is needed to optimize use of early-season insecticides and reduce over-reliance on them in cotton, especially when initial decisions for insect control before planting have subsequent influence on future pest abundance. Existing literature pertaining to these early-season cotton insect pests was examined to identify factors favoring their distribution and abundance and the importance of insect control tactics used at planting. The relative importance of some of these pests is dependent on the cotton-growing region and impacted by local production practices. Thrips (predominantly Frankliniella spp.) (Thysanoptera: Thripidae) are the most prevalent early-season insect group in cotton across the United States and the primary target of initial insect control. Other targeted insects include the black cutworm, Agrotis ipsilon (Hufnagel) (Lepidoptera: Noctuidae), aphids (predominantly Aphis gossypii Glover) (Hemiptera: Aphididae), plant bugs (Hemiptera: Miridae), and wireworms (Coleoptera: Elateridae).

Soybean faces potential economic damage from a wide variety of early-season invertebrate pests. The objective of this article was to determine the extent and intensity of nine early-season soybean insect pests targeted for control by insecticidal seed treatments in the United States and to identify various management options for them: bean leaf beetle (Cerotoma trifurcate Förster, Coleoptera: Chrysomelidae); grape colaspis, Colaspis brunnea (F.) (Coleoptera: Chrysomelidae); leafhoppers (Hemiptera: Ciccadellidae); seedcorn maggot, Delia platura (Meigen) (Diptera: Anthomyiidae); soybean aphid (Aphis glycines Matsumura, Hemiptera: Aphididae); threecornered alfalfa hopper, Spsistilus festinus (Say) (Hemiptera: Membracidae); thrips (Thysanoptera: Thripidae); white grubs (Coleoptera: Scarabaeidae); and wireworms (Coleoptera: Elateridae). Seedcorn maggot, white grubs, and wireworms have been limited to a relatively small proportion of soybean fields with readily defined factors regarding their risk. However, questions about the pest status of the other six pests were identified. Bean leaf beetle, which vectors Bean pod mottle virus to soybean, has been present across major soybean-production regions, but frequency and proportion of soybean fields that economically impacted is not adequately documented. The impact of threecornered alfalfa hopper and thrips on soybean productivity varied within regions, but specific reasons for the variation were unclear. Early-season management of grape colaspis and leafhoppers has been infrequent, but factors that promoted economic injury and the need for management in specific fields were undetermined. Although early-season management of soybean aphid has not proven feasible for individual fields, questions remain regarding its management in fields near overwintering stands and the possibility for areawide suppression.

A preventative insecticide treatment is a tactic compatible with an integrated pest management (IPM) strategy for a particular pest only when a rescue treatment is not a realistic option, and if there is a reasonable expectation of economic damage by that pest. Most corn, Zea mays L., planted in the United States is protected from several sporadic early-season insect pests by neonicotinoid seed treatments, usually without the knowledge of the threat posed in a given field. We undertook an extensive literature review of these sporadic pests to clarify the prevalence of economic infestations in different regions of the United States, and the agronomic, biotic, and abiotic factors that affect the likelihood of attack. The summaries of the prevalence and risk factors presented here should help farmers and consultants better assess the value of preventative protection of seedling corn under local conditions, and provide others with a better understanding of the complexities farmers face in assessing risks posed by potential pests. The profiles suggest that, in general, pressure from most sporadic pests on seedling corn is rare or local, seldom high enough to decrease yield. However, this is not true in all regions for all sporadic pests. An important issue exposed by the profiles is that the value of preventative insecticide protection of seedling corn depends on understanding the likely combined pressure from multiple species. While such risk may often still be negligible, there is a great need for robust methodology to assess the risk posed by multiple pests. This represents a significant challenge for future research.

The Hessian fly, Mayetiola destructor (Say) (Diptera: Cecidomyiidae); cereal aphids (Hemiptera: Aphididae); and wireworms (Coleoptera: Elateridae) are three common and important insect pests of seedling wheat, Triticum aestivum L., in the United States. Though less common as pests, false wireworms (Coleoptera: Tenebrionidae) may also be problematic in situations that favor wireworms. In addition, cereal aphids vector viruses that cause barley yellow dwarf, a serious and widespread wheat disease. Scientific journal publications, review articles, and management guidebooks on wheat insect pests were consulted to determine the extent and intensity that these pests impose on wheat production in the United States. Widespread outbreaks occur infrequently, but local outbreaks happen nearly every year for the three major pests and cause several millions of dollars in crop losses annually. Hessian fly perennially threatens wheat in the southeastern United States, and wireworms are persistent pests in northwestern wheat-production systems. Otherwise, the particular location and severity of outbreaks vary yearly and are largely unpredictable. However, particular agronomic practices can greatly reduce risk of infestation such as elimination of volunteer wheat and weedy hosts and planting wheat during periods of reduced pest abundance. In addition, resistant cultivars can limit Hessian fly and Russian wheat aphid (Diuraphis noxia [Kurdjumov]) damage in some areas, but virulent biotypes of each pest complicate their management. Although several preemptive tactics reliably suppress infestations and barley yellow dwarf severity, they are not compatible in all agricultural systems. Consequently, insecticides are necessary in certain areas and within particular production systems to manage major early-season insect pests of wheat.

Tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), populations were collected from field locations in the Mississippi River Delta of Arkansas, Louisiana, and Mississippi. Third-instar F(1) nymphs from each field location, in addition to a laboratory colony, were screened for susceptibility to novaluron. Both a glass vial bioassay and a diet-incorporated bioassay used dose-response regression lines to calculate LC(50) and LC(90) values for novaluron. Mean LC(50s) for glass vial bioassays ranged from 44.70 ± 3.58 to 66.54 ± 4.19 μg/vial, while mean LC(50s) for diet-incorporated bioassays ranged from 12.10 ± 0.77 to 17.63 ± 2.42 μg/200 ml of artificial diet. A comparison of LC(50) values from the same field population screened using both bioassay methods failed to show a relationship. LC(50) values from field locations were compared with a historically susceptible population from Crossett, AR. Results indicated that considerable variability in susceptibility to novaluron exists within field populations of tarnished plant bugs across the Delta, including some locations with lower LC(50) values than a historically susceptible population.

The southern United States has a long growing period between corn, Zea mays L., harvest and first winter frost, so volunteer corn which germinates after harvest has a growing period sufficient for corn earworm, Helicoverpa zea (Boddie) and fall armyworm, Spodoptera frugiperda (J. E. Smith) to feed on these plants. However, lower air temperatures can limit larval development on late season volunteer corn and thereby successful pupation. Here we explore the suitability of late season volunteer corn for larval development and the potential contribution of H. zea larvae to the overwintering population. Our survey revealed the occurrence of volunteer corn in high densities, with monthly mean densities ranging from 56,000 to 143,000 plants ha−1. H. zea larvae were found feeding on both vegetative and reproductive stage plants while S. frugiperda were only found on vegetative stage plants. An analysis of H. zea growing degree day (GDD) accumulations based on Mississippi weather data from 1980 to 2010 revealed that sufficient GDD to reach prepupation would always be accumulated before first frost if oviposition occurred by 9 September, with the probability of successful pupation decreasing rapidly thereafter. However, most of the H. zea larvae were oviposited after this, and could not reach pupation. Because S. frugiperda cannot overwinter in Mississippi, their ability to pupate was not examined. Low suitability of whorl stage corn for H. zea development coupled with low larval densities during this stage effectively diminish the number of larvae that complete development on late season volunteer transgenic corn expressing genes from the soil bacterium, Bacillus thuringiensis (Bt). This limits the Bt resistance risk posed by larvae developing on late season volunteer corn in all but the most southern locations in the US.

Nuclear polyhedrosis viruses have been labeled for use as microbial insecticides in agronomically-important crops in the U.S. since the 1970s. New products developed from viral isolates of different species in the heliothine genera Helicoverpa, Heliothis, and Chloridea have been introduced to the market and are receiving renewed attention for controlling heliothine pests. Two laboratory assays were used to evaluate comparative activities among the first nuclear polyhedrosis viruses registered in the U.S. and two commercially-available baculovirus products for controlling bollworm, Helicoverpa zea (Boddie), and tobacco budworm, Chloridea virescens (F.). Based on comparisons of LC50s of formulated products from laboratory overlay assays at 7 days, Gemstar was 2.4 and 3.7 fold less active than Elcar against bollworm and tobacco budworm, respectively. Heligen was 2.9 and 7.1 fold more active than Elcar against bollworm and tobacco budworm, respectively. However, once corrected for concentration of polyhedral occlusion bodies, susceptibility of bollworm did not differ to any of the three products tested. Tobacco budworms were more susceptible to Heligen than Gemstar in laboratory overlay assays following correction for differences in concentration of polyhedral occlusion bodies, which might be caused by interrelatedness of the species with the Old World bollworm. No discernable difference in death of bollworms or tobacco budworms was detected among the greatest labeled rate of any formulated microbial insecticide sprayed on leaves of non-Bt cotton (Gossypium hirsutum L.) at 14 days and percentage of pupation at 20 days post-treatment. Although the activity of wild-type baculovirus has changed little during the past four decades, use of the products should be encouraged whenever possible. Potential ecological benefits of preserving beneficial insects and reducing selection for resistance to insecticides should be promoted as long as effectiveness and costs are reasonable.

Interpreting variable laboratory measurements of Helicoverpa zea Boddie susceptibility to toxins from Bacillus thuringiensis Berliner (Bt) has been challenging due to a lack of clear evidence to document declining field control. Research that links laboratory measurements of susceptibility to survival on Bt crops is vital for accurate characterization and any subsequent response to the occurrence of an implied H. zea resistance event. In this study, H. zea survival and the resultant damage to plant fruiting structures of non-Bt, Bollgard II, and Bollgard III cottons from two insect colonies with differing levels of laboratory susceptibility to Bt toxins were evaluated in large field cages. Laboratory bioassays revealed resistance ratios of 2.04 and 622.14 between the two H. zea colonies for Dipel DF and Cry1Ac, respectively. Differences between the two H. zea colonies measured via bioassays with Bollgard II and Bollgard III cotton leaf tissue in the laboratory were not statistically discernable. However, there was 17.6% and 5.3% lower larval mortality in Bollgard II and Bollgard III for the feral relative to the laboratory colony of H. zea, respectively. Although H. zea larval numbers in cages infested with the laboratory susceptible colony did not differ between the two Bt cottons, there were fewer larvae per 25 plants in Bollgard III than in Bollgard II cotton in cages containing tolerant insects. Cages infested with tolerant H. zea moths had higher numbers of total larvae than those containing the laboratory susceptible colony in both Bollgard II and Bollgard III cottons. Bollgard II and Bollgard III cottons received 77.4% and 82.7% more total damage to total plant fruiting structures in cages infested with tolerant insects relative to those containing the laboratory susceptible colony. The damage inflicted to fruiting structures on Bollgard III cotton by a feral H. zea colony with decreased measurements of laboratory susceptibility to Dipel DF and Cry1Ac indicate that the addition of Vip3A to third generation Bt cottons may not provide sufficient control in situations where infestations levels are high.

Recent Environmental Protection Agency (EPA) decisions regarding resistance management in Bt-cropping systems have prompted concern in some experts that dual-gene Bt-corn (Cry1A.105 and Cry2Ab2 toxins) may result in more rapid selection for resistance in Helicoverpa zea (Boddie) than single-gene Bacillus thuringiensis (Bt)-corn (Cry1Ab toxin). The concern is that Bt-toxin longevity could be significantly reduced with recent adoption of a natural refuge for dual-gene Bt-cotton (Cry1Ac and Cry2Ab2 toxins) and concurrent reduction in dual-gene corn refuge from 50 to 20%. A population genetics framework that simulates complex landscapes was applied to risk assessment. Expert opinions on effectiveness of several transgenic corn and cotton varieties were captured and used to assign probabilities to different scenarios in the assessment. At least 350 replicate simulations with randomly drawn parameters were completed for each of four risk assessments. Resistance evolved within 30 yr in 22.5% of simulations with single-gene corn and cotton with no volunteer corn. When volunteer corn was added to this assessment, risk of resistance evolving within 30 yr declined to 13.8%. When dual-gene Bt-cotton planted with a natural refuge and single-gene corn planted with a 50% structured refuge was simulated, simultaneous resistance to both toxins never occurred within 30 yr, but in 38.5% of simulations, resistance evolved to toxin present in single-gene Bt-corn (Cry1Ab). When both corn and cotton were simulated as dual-gene products, cotton with a natural refuge and corn with a 20% refuge, 3% of simulations evolved resistance to both toxins simultaneously within 30 yr, while 10.4% of simulations evolved resistance to Cry1Ab/c toxin.

Insecticidal control of the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), is targeted at the adult and nymphal stages, but there is little information on relative susceptibilities of these insects to insecticides. Tarnished plant bug adults were collected from various locations in Mississippi during 2008–2009, and different life stages of their progeny were tested for susceptibilities to three classes of insecticides. A glass vial bioassay was used to evaluate four populations of tarnished plant bugs for susceptibility to the pyrethroid insecticide, permethrin, and two populations to the organophosphate insecticide, methamidophos. Additionally, a diet-incorporated bioassay was used to evaluate the susceptibility of the various life stages of a single population of tarnished plant bugs to a neonicotinoid insecticide, thiamethoxam. For all but one population and insecticide combination, the estimated LC50 values ranked from least to greatest were: 1st instars, 2nd instars, 3rd insta...

Pheromone trap captures of Helicoverpa zea (Boddie) and Heliothis virescens (F.) from 2002 - 2005 were used to examine the distribution of these species across a multiple crop environment in southeast Arkansas. The greatest number of H. virescens moths was collected during 2003, but densities were low compared with H. zea throughout the study. Overall, fewer H. virescens moths were captured next to Bt corn and Bt cotton than next to nonBt cotton and early-maturing soybean. A significant relationship was not detected between pheromone trap captures of H. virescens and the percentage of these moths that fed on cotton as larvae. More H. zea moths were captured in traps located next to Bt corn and nonBt corn during the month of June than in traps located next to cotton, sorghum, or soybean, whereas traps located adjacent to early- and late-maturing varieties of soybean, Bt cotton, nonBt cotton, and grain sorghum captured greater numbers of moths than those traps located next to corn during July. Therefore, th...

The influence of maize, Zea mays L., and pigweed, Amaranthus spp., on the abundance of tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), adults infesting cotton, Gossypium hirsutum L., in the Mississippi Delta was studied using stable-isotope analyses. Cotton fields adjacent to maize and those farther than 1.6 km from maize were identified in four counties of the Mississippi Delta. Tarnished plant bug adults were collected from the cotton fields weekly throughout the growing season and analyzed with stable-carbon and nitrogen isotopes to determine the natal host. The proportion of tarnished plant bug adults collected from cotton that developed as nymphs on plants that used the C4 photosynthetic pathway, primarily maize and pigweed, peaked from 79–92% during 2008–2009. Distance of cotton fields from maize did not influence the peak proportion of tarnished plant bug adults with a C4 signature from cotton fields, the peak time, or peak duration. Time of the C4 peaks occurred from 28 June...