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This study evaluated the impact of four cover crop species and their termination timings on cover crop biomass, weed control, and corn yield. A field experiment was arranged in a split-plot design in which cover crop species (wheat, cereal rye, hairy vetch, and rapeseed) were the main plot factor, and termination timings [4, 2, 1, and 0 wk before planting corn (WBP)] was the subplot factor. In both years (2021 and 2022), hairy vetch produced the most biomass (5,021 kg ha –1 ) among cover crop species, followed by cereal rye (4,387 kg ha –1 ), wheat (3,876 kg ha –1 ), and rapeseed (2,575 kg ha –1 ). Regression analysis of cover crop biomass with accumulated growing degree days (AGDDs) indicated that for every 100 AGDD increase, the biomass of cereal rye, wheat, hairy vetch, and rapeseed increased by 880, 670, 780, and 620 kg ha –1 , respectively. The density of grass and small-seeded broadleaf (SSB) weeds at 4 wk after preemergence herbicide (WAPR) application varied significantly across termination timings. The grass and SSB weed densities were 56% and 36% less at 0 WBP compared with 2 WBP, and 67% and 61% less compared with 4 WBP. The sole use of a roller-crimper did not affect the termination of rapeseed at 0 WBP and resulted in the least corn yield (3,046 kg ha –1 ), whereas several different combinations of cover crops and termination timings resulted in greater corn yield. In conclusion, allowing cover crops to grow longer in the spring offers more biomass for weed suppression and impacts corn yield.

Spotted cucumber beetle ( Diabrotica undecimpunctata howardi ; also known as southern corn rootworm) is a pest feeding on many crops, including cucurbits, corn (maize), peanuts, beans, and other crops and wild plants in North America. On cucurbit crops, where it co-occurs with striped cucumber beetle ( Acalymma vittatum ), both are key pests that vector Erwinia tracheiphila, a destructive pathogen that causes bacterial wilt. Here we deployed synthetic vittatalactone, the male-produced aggregation pheromone of A. vittatum , as lures in the field, to measure attraction of the target and non-target insects. Both sexes of D. u. howardi were strongly attracted to the vittatalactone lures (5–7.5-fold compared to blank trap) throughout the growing season in Maryland and Virginia, USA. Moreover, D. u. howardi was more attracted to live A. vittatum males feeding on squash plants than to plants with females or without any beetles, confirming the genuine organismal cross-attraction between these two key pests. The kairomonal attraction to vittatalactone suggests that it functions as a “keystone semiochemical,” mediating the colonization of cucurbits by multiple herbivore species. Such cross attraction could allow for use of vittatalactone in management of multiple pest species, with potential reduction of pesticide use in cucurbit crops.

The invasive brown marmorated stink bug Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) has become a serious economic pest in parts of the USA, and control tactics are often needed in order to avoid crop losses in tree fruit and other crops. Chemical control is usually the most effective and efficient tactic for preventing damage in crops. Researchers have tested a wide range of insecticides using laboratory and field experiments to determine the best options for H. halys control in the USA. This review summarizes that work and describes current practices with regard to insecticide options for H. halys .

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive pest of numerous agricultural crops with an increasing global distribution. Finding simple and reliable monitoring tools for H. halys agricultural and surveillance programs is imperative. In 2016, we compared standard pyramid traps to clear sticky cards attached atop wooden stakes and evaluated two commercially formulated lures (Trécé and AgBio) with low and high rates of the H. halys aggregation pheromone (PHER) and pheromone synergist (MDT) at 12 sites (low: 5 mg PHER + 50 mg MDT; high: 20 mg PHER + 200 mg MDT). In 2017, we reevaluated lure efficacy using only the clear sticky traps at six locations. Sites were classified as having low, moderate, or high relative population densities of H. halys in 2016, and as very low or low densities of H. halys in 2017. Although clear sticky traps captured fewer adults and nymphs than pyramid traps, their captures were generally correlated at all population levels indicating that clear sticky traps can reliably monitor H. halys presence and relative abundance regardless of relative population density. During both years, adult and nymphal captures were significantly greater in traps baited with Trécé lures than with AgBio lures. Captures were greater in traps baited with high loading rate lures for each lure type, and with the exception of traps baited with AgBio lures at high relative density sites in 2016, H. halys captures in traps with low and high loading rates of each lure type were correlated for both years. Comparison of yellow and clear sticky cards indicated they performed equally, but yellow cards captured more nontargets. In summary, clear sticky traps attached atop wooden posts and baited with H. halys pheromone and pheromone synergist lures are an effective option for this pest monitoring and detection.

Transgenic crops containing the bacterium Bacillus thuringiensis (Bt) genes reduce pests and insecticide usage, promote biocontrol services, and economically benefit growers. Area-wide Bt adoption suppresses pests regionally, with declines expanding beyond the planted Bt crops into other non-Bt crop fields. However, the offsite benefits to growers of other crops from such regional suppression remain uncertain. With data spanning 1976–2016, we demonstrate that vegetable growers benefit via decreased crop damage and insecticide applications in relation to pest suppression in the Mid-Atlantic United States. We provide evidence for the regional suppression of Ostrinia nubilalis (Hübner), European corn borer, and Helicoverpa zea (Boddie), corn earworm, populations in association with widespread Bt maize adoption (1996–2016) and decreased economic levels for injury in vegetable crops [peppers (Capsicum annuum L.), green beans (Phaseolus vulgaris L.), and sweet corn (Zea mays L., convar. saccharata)] compared with the pre-Bt period (1976–1995). Moth populations of both species significantly declined in association with widespread Bt maize (field corn) adoption, even as increased temperatures buffered the population reduction. We show marked decreases in the number of recommended insecticidal applications, insecticides applied, and O. nubilalis damage in vegetable crops in association with widespread Bt maize adoption. These offsite benefits to vegetable growers in the agricultural landscape have not been previously documented, and the positive impacts identified here expand on the reported ecological effects of Bt adoption. Our results also underscore the need to account for offsite economic benefits of pest suppression, in addition to the direct economic benefits of Bt crops.

The productivity and survival of managed honey bee colonies is negatively impacted by a diverse array of interacting factors, including exposure to agrochemicals, such as pesticides. This study investigated the use of volatile heterocyclic amine (HCA) compounds as potential short-term repellents that could be employed as feeding deterrents to reduce the exposure of bees to pesticide-treated plants. Parent and substituted HCAs were screened for efficacy relative to the repellent N,N-diethyl-meta-toluamide (DEET) in laboratory and field experiments. Additionally, electroantennogram (EAG) recordings were conducted to determine the level of antennal response in bees. In video-tracking recordings, bees were observed to spend significantly less time with an HCA-treated food source than an untreated source. In a high-tunnel experiment, the HCA piperidine was incorporated in a feeding station and found to significantly reduce bee visitations relative to an untreated feeder. In field experiments, bee visitations were significantly reduced on melon flowers (Cucumis melo L.) and flowering knapweed (Centaurea stoebe L.) that were sprayed with a piperidine solution, relative to untreated plants. In EAG recordings, the HCAs elicited antennal responses that were significantly different from control or vehicle responses. Overall, this study provides evidence that HCAs can deter individual bees from food sources and suggests that this deterrence is the result of antennal olfactory detection. These findings warrant further study into structure–activity relationships that could lead to the development of short-term repellent compounds that are effective deterrents to reduce the contact of bees to pesticide-treated plants.

The brown marmorated stink bug, Halyomorpha halys (Stål), is an invasive pest introduced to North America in the mid-1990's that has caused economic losses to a wide range of commodities. In vegetables, H. halys feeding damage has been well described, but the effect of different vegetable hosts on H. halys fitness is less understood. We caged 2nd instar H. halys on different vegetable hosts (e.g., tomato, sweet corn, eggplant, bell pepper, and snap bean) and monitored their development until adulthood to compare the effects of vegetable host type on H. halys nymph survival and development time. Experiments were replicated nine times over a two-year period. Survival of 2nd instars from F1 generation (early-season) eggs was low (<30%) on all vegetables resulting in no significant treatment effect. However, H. halys nymphs collected from F2 generation (late-season) eggs had higher survivorship on all vegetables except tomato. The percentage of H. halys 2nd instars that reached adulthood was greatest on corn (53%) and pepper (45%), followed by snap bean (24%), and significantly lower on eggplant (9%) and tomato (2%). Total development time from 2nd instar to adult was fastest on corn and slowest on peppers, although tomatoes were not tested due to the low survival. Trends in development rate were not seasonally-dependent. Our study compares H. halys survivability on several vegetable commodities, and provides insights into H. halys developmental success and dependence on various host plants over the season.

Insects use a diverse array of specialized terpene metabolites as pheromones in intraspecific interactions. In contrast to plants and microbes, which employ enzymes called terpene synthases (TPSs) to synthesize terpene metabolites, limited information from few species is available about the enzymatic mechanisms underlying terpene pheromone biosynthesis in insects. Several stink bugs (Hemiptera: Pentatomidae), among them severe agricultural pests, release 15-carbon sesquiterpenes with a bisabolene skeleton as sex or aggregation pheromones. The harlequin bug, Murgantia histrionica, a specialist pest of crucifers, uses two stereoisomers of 10,11-epoxy-1-bisabolen-3-ol as a male-released aggregation pheromone called murgantiol. We show that MhTPS (MhIDS-1), an enzyme unrelated to plant and microbial TPSs but with similarity to trans-isoprenyl diphosphate synthases (IDS) of the core terpene biosynthetic pathway, catalyzes the formation of (1S,6S,7R)-1,10-bisaboladien-1-ol (sesquipiperitol) as a terpene intermediate in murgantiol biosynthesis. Sesquipiperitol, a so-far-unknown compound in animals, also occurs in plants, indicating convergent evolution in the biosynthesis of this sesquiterpene. RNAi-mediated knockdown of MhTPS mRNA confirmed the role of MhTPS in murgantiol biosynthesis. MhTPS expression is highly specific to tissues lining the cuticle of the abdominal sternites of mature males. Phylogenetic analysis suggests that MhTPS is derived from a trans-IDS progenitor and diverged from bona fide trans-IDS proteins including MhIDS-2, which functions as an (E,E)-farnesyl diphosphate (FPP) synthase. Structure-guided mutagenesis revealed several residues critical to MhTPS and MhFPPS activity. The emergence of an IDS-like protein with TPS activity in M. histrionica demonstrates that de novo terpene biosynthesis evolved in the Hemiptera in an adaptation for intraspecific communication.

Corn wireworm, Melanotus communis Gyllenhal (Coleoptera: Elateridae), is an economically important larval pest of root and tuber crops in the United States. Previous work to estimate field-level abundance of M. communis has focused on grain-based larval baits placed in soil. However, this sampling method is labor intensive and may not estimate population size accurately. Recent discovery of the M. communis sex pheromone, 13-tetradecenyl acetate, provides a new method to monitor this pest during the adult stage. Early studies with this pheromone showed that different trapping methods might enhance catch and improve trap servicing. We hypothesized that placing lures on elevated traps would increase M. communis capture relative to the in-ground pitfall trapping that is currently used. We had 2 objectives for this study: (a) to compare pheromone captures among in-ground pitfall traps, on-ground pitfalls, elevated pitfalls (1 m), or elevated sticky cards (1 m) and (b) test lure longevity by aging the lures outdoors at 8-, 6-, 4-, 2-, and 0-wk intervals prior to trap deployment in the field. Experiments were conducted in North Carolina, Virginia, South Carolina, and Florida during the 2021 and 2022 field seasons. Results highlight large variation in M. communis abundance across the 4 states. We showed that 1 m elevated pheromone traps caught the most beetles. The age of the lure prior to deployment had a significant effect on trap catch. The lures that were aged for fewer weeks attracted significantly more beetles, with 0- and 2-wk-old lures capturing the greatest numbers. Graphical Abstract

Squash bug, Anasa tristis DeGeer (Hemiptera: Coreidae), is a major pest of squash and pumpkins in the United States. In order to better understand the importance of natural egg parasitism of this species in Virginia, we conducted a 2-yr statewide survey. In total, 1,127 squash bug egg masses (∼20,000 total eggs) were sampled from squash and pumpkins from 43 counties in Virginia from 2014 to 2015. Egg masses were brought back to the lab to record levels of squash bug nymphal emergence or adult parasitoid eclosion and identification. Over 50% of the total squash bug eggs collected statewide were parasitized. Gryon pennsylvanicum Ashmead (Hymenoptera: Scelionidae) was the predominant egg parasitoid accounting for over 98% of all parasitoid adults recovered. The only other species emerging from squash bug eggs was Anastatus reduvii Howard (Hymenoptera: Eupelmidae), which is a generalist parasitoid. G. pennsylvanicum was found in 75% of the counties surveyed with the highest levels of parasitism occurring in the Northern, Southwestern Mountain, and Western Piedmont regions of the state and the lowest levels of parasitism occurring in theTidewater region in the southeastern portion of the state. Based on this 2-yr survey, G. pennsylvanicum was determined to be a major natural enemy of squash bug, significantly reducing the number of nymphs that emerge from deposited eggs. Conservation of this natural enemy should therefore be a priority for integrated pest management programs in cucurbits.