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Control of cucurbit pests, such as striped cucumber beetle (Acalymma vittatum), spotted cucumber beetle (Diabrotica undecimpunctata howardi) and squash bug (Anasa tristis), in organic systems is difficult due to a lack of effective insecticide options. This has led to the development of many integrated pest management techniques, such as use of row covers, crop rotation and cover crops. This study explored the novel use of strip tillage and row covers to reduce pest pressure in summer squash (Cucurbita pepe) and muskmelon (Cucumis melo) production systems. Results showed that although strip tillage reduced striped cucumber beetle and squash bug numbers, there was a yield reduction in both crops compared with the plasticulture system. Row cover increased marketable yield in both systems, with the highest yield being in the plasticulture system. Unmarketable fruit directly attributed to insect damage was higher in the plasticulture systems, but was not significantly different when compared with the strip tillage system. Although there are many documented positive attributes of strip tillage, results from this study indicate that a combination of plasticulture and row cover may be a superior system for organic cucurbit production.

Specialized host–microbe symbioses canonically show greater diversity than expected from simple models, both at the population level and within individual hosts. To understand how this heterogeneity arises, we utilize the squash bug, Anasa tristis , and its bacterial symbionts in the genus Caballeronia . We modulate symbiont bottleneck size and inoculum composition during colonization to demonstrate the significance of ecological drift, the noisy fluctuations in community composition due to demographic stochasticity. Consistent with predictions from the neutral theory of biodiversity, we found that ecological drift alone can account for heterogeneity in symbiont community composition between hosts, even when 2 strains are nearly genetically identical. When acting on competing strains, ecological drift can maintain symbiont genetic diversity among different hosts by stochastically determining the dominant strain within each host. Finally, ecological drift mediates heterogeneity in isogenic symbiont populations even within a single host, along a consistent gradient running the anterior-posterior axis of the symbiotic organ. Our results demonstrate that symbiont population structure across scales does not necessarily require host-mediated selection, as it can emerge as a result of ecological drift acting on both isogenic and unrelated competitors. Our findings illuminate the processes that might affect symbiont transmission, coinfection, and population structure in nature, which can drive the evolution of host–microbe symbioses and microbe–microbe interactions within host-associated microbiomes.

In response to herbivory, plants emit volatile compounds that play important roles in plant defense. Herbivore-induced plant volatiles (HIPVs) can deter herbivores, recruit natural enemies, and warn other plants of possible herbivore attack. Following HIPV detection, neighboring plants often respond by enhancing their anti-herbivore defenses, but a recent study found that herbivores can manipulate HIPV-interplant communication for their own benefit and suppress defenses in neighboring plants. Herbivores induce species-specific blends of HIPVs and how these different blends affect the specificity of plant defense responses remains unclear. Here we assessed how HIPVs from zucchini plants (Cucurbita pepo) challenged with different herbivore species affect resistance in neighboring plants. Volatile “emitter” plants were damaged by one of three herbivore species: saltmarsh caterpillars (Estigmene acrea), squash bugs (Anasa tristis), or striped cucumber beetles (Acalymma vittatum), or were left as undamaged controls. Neighboring “receiver” plants were exposed to HIPVs or control volatiles and then challenged by the associated herbivore species. As measures of plant resistance, we quantified herbivore feeding damage and defense-related phytohormones in receivers. We found that the three herbivore species induced different HIPV blends from squash plants. HIPVs induced by saltmarsh caterpillars suppressed defenses in receivers, leading to greater herbivory and lower defense induction compared to controls. In contrast, HIPVs induced by cucumber beetles and squash bugs did not affect plant resistance to subsequent herbivory in receivers. Our study shows that herbivore species identity affects volatile-mediated interplant communication in zucchini, revealing a new example of herbivore defense suppression through volatile cues.

Mating with the wrong species is surprisingly common in nature. Interspecific mating can lead to reproductive interference, where wasted time, energy, nutrients, or gametes reduces the fitness of one or both of the interacting species. However, the ecological and evolutionary forces that maintain this seemingly maladaptive behavior remain poorly understood, in part because the natural complexity of heterospecific encounters is often not considered experimentally. The goal of this study was to directly test if the negative effects of heterospecific mating can be mitigated by conspecific mating. We used two closely related species of squash bug, Anasa tristis and Anasa andresii, which are known to readily mate with each other despite clear negative fitness consequences. We gave all females opportunities to mate with conspecific males before and after encountering heterospecific males. We found that A. tristis females can alleviate temporary bouts of heterospecific interference when given opportunities to mate with conspecifics. However, we found the opposite for A. andresii females. Mating with conspecifics did not shelter female A. andresii from the consequences of heterospecific mating. Our study reveals the complex dynamics of reproductive interference and highlights scenarios where mating with the wrong species can have either minimal or long-lasting effects on fitness. We emphasize the benefit of assessing reproductive interference using experiments that not only vary heterospecific encounter rates, but that also quantify lifetime measures of fitness. Our study adds to the growing body of research highlighting the importance of reproductive interference and sheds light on why this seemingly paradoxical behavior continues to persist.

Plant structural defenses such as trichomes exert a significant selection pressure on insect herbivores. However, whether variation in structural defense traits affects common herbivores in related plant species is less understood. Here, we examined the role of trichomes in plant–herbivore interactions in two commonly cultivated members in Cucurbitaceae: bottle gourd ( Lagenaria siceraria ) and cucumber ( Cucumis sativa ). In common garden experiments when the two species were grown together, we observed that they differed in their attractiveness to four major herbivore species ( Trichoplusia ni , Acalymma vittatum , Diaphania indica , and Anasa tristis ) and, consequently, their feeding behavior. We found that L. siceraria consistently harbored less herbivores, and the two lepidopteran herbivores ( T. ni and D. indica ) were found to take significantly longer time to commence feeding on them, a primary mode of pre-ingestive defense function of trichomes. To tease apart structural and chemical modes of defenses, we first used scanning electron microscopy to identify, quantify, and measure trichome traits including their morphology and density. We found that C. sativa has significantly lower number of trichomes compared to L. siceraria , regardless of trichome type and leaf surface. We then used artificial diet enriched with trichomes as caterpillar food and found that trichomes from these two species differentially affected growth and development of T. ni showing cascading effects of trichomes. Taken together, we show that trichomes, independent of chemical defenses, are an effective pre- and post-ingestive defense strategy against herbivores with negative consequences for their feeding, growth, and development.

The squash bug, Anasa tristis (De Geer), is a serious pest of cucurbit crops across the United States, especially within summer squash (Cucurbita pepo L.) systems. Using their piercing sucking mouthparts, squash bugs feed on both leaf tissue and fruits, often leading to leaf necrosis, marketable fruit loss, and even plant death. To date, the relationship between squash bug presence and plasticulture has not been adequately investigated. This 2-yr study evaluated the effects of white, black, and reflective plastic mulch colors on the occurrence of all squash bug life stages and marketable zucchini yield in Virginia. In both years, A. tristis adults and egg masses were more numerous on zucchini plants grown in white and reflective plastic mulch compared to bare ground plants. Greater nymphal densities and marketable fruit yield were observed in certain plastic mulch treatments versus the bare ground treatment, yet these differences were not consistent in both years. Contrary to the repellency effects reflective mulches have on other cucurbit insect pests, our research suggests that reflective and other plastic mulch colors can negatively impact squash bug management, especially in regions with high A. tristis pressure. Our study offers new insights for cucurbit growers to use when considering whether they should implement plasticulture in their growing systems.

Co-occurring herbivorous pests may have shared or divergent responses to plant- and insect- derived cues, creating challenges for effective pest management in agroecosystems. We examined how behaviors of two endemic specialist herbivores of Cucurbitaceae crops, squash bugs ( Anasa tristis , Hemiptera: Coreidae) and striped cucumber beetles ( Acalymma vittatum , Coleoptera: Chrysomelidae) are affected by cues in the Cucurbita pepo agroecosystem. We evaluated plant resistance to squash bugs and beetles using cultivars that typify the two domesticated subspecies C. p. pepo (e.g., zucchini) and C. p. ovifera (e.g., straightneck summer squash), and tested how squash bugs respond to beetle aggregation and feeding. Across several field experiments, we demonstrated that squash bugs prefer to oviposit on C. p. ovifera over C. p. pepo , while beetles had the opposing preference. Nonetheless, there was no link between preference and squash bug nymphal survival or development. While squash bugs and beetles diverge in preference, we found that squash bugs positively respond to beetle-derived cues. More squash bug oviposition was observed on plants with greater beetle damage and, using both actively feeding beetles and synthetic lures, we demonstrate that bugs eavesdrop on and respond to vittatalactone, the male-produced beetle aggregation pheromone. Thus, squash bugs appear to exploit the cue of a co-occurring specialist beetle for host choice and this has implications for management: while there are trade-offs in varietal preference, synergistic trapping of both pests may be possible. By evaluating the behavior of co-occurring pests, management strategies with multi-species efficacy can be identified and applied in agroecologically-based pest management.

Summary Viruses are widespread in both natural and agricultural plant communities and can significantly alter diverse traits of their host plants that mediate key interactions with other organisms. Yet, the impacts of plant viruses on broader community dynamics remain little studied. Here, we explore the effects of Cucumber mosaic virus, a common non‐persistently transmitted plant virus, on short‐ and long‐term interactions of herbivorous and predatory insects with squash (Cucurbita pepo) plants in a weedy field setting, as well as virus‐induced changes in plant phenotypes that mediate these interactions. Cucumber mosaic virus has previously been shown to have numerous effects on host plants that likely influence interactions with arthropods, including reduced plant size, increased volatile emissions, and diminished plant quality and palatability for aphid vectors. Infection reduced the likelihood of many herbivorous insects arresting and feeding on plants, as well as the apparency of plants to herbivores that base in‐flight foraging on visual cues. In particular, infection drastically reduced numbers of a specialist squash herbivore (Anasa tristis) on plants in the field – a pattern likely driven by a reduction of phagostimulatory sugar levels in leaf tissue and concurrent increase in amino acid levels, as nymphal development was not obviously impacted by infection status. Relative to effects on herbivores, virus infection had little impact on the ability of predatory insects to locate aphid prey, although an experiment examining plant visitation in the absence of aphids revealed reduced numbers of foraging Syrphidae (Diptera) and Coccinellidae (Coleoptera) on infected plants but increased visitation and oviposition by Chrysopidae (Neuroptera). CMV infection may reduce overall herbivore pressure on infected plants through effects on palatability and apparency, yet predators appear to locate herbivorous prey that do occur on infected plants as efficiently as those on healthy plants. Virus infection can significantly influence plant interactions with the insect community (including non‐vector as well as vector insects) with potential implications both for disease spread and for broader community dynamics. Lay Summary

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.

This study investigated the abundance and richness of insect pests and beneficial insects on 20 squash cultivars across three seasons in middle Georgia, U.S. Insects were sampled using yellow sticky cards, pan traps and sweep nets. Bemisia tabaci Gennadius (sweet potato whitefly) was prevalent in all seasons, while other key pests showed distinct seasonal peaks. Diaphania hyalinata Linnaeus (melonworm) peaked mid-July in summer 2021 (21 June–1 August), while Thysanoptera species, Acalymma vittatum Fabricius (striped cucumber beetle), and Diabrotica balteata LeConte (banded cucumber beetle) peaked late July-early August. In fall 2021 (4 October–14 November), Epilachna borealis (squash beetle), D. hyalinata, and D. nitidalis Stoll (pickleworm) were more active in early to mid-October, whereas D. undecimpunctata howardi Barber (spotted cucumber beetle) peaked in late November. In fall 2022 (17 October–20 November), D. balteata and D. undecimpunctata howardi peaked mid October to early November, while Anasa tristis DeGeer (squash bug) peaked in mid–late November. Orius insidiosus Say (minute pirate bug) peaked in late summer 2021 and remained stable in fall 2021. Pollinators were most active in mid-fall. Cultivars influenced insect abundance. ‘Saffron’ and ‘Amberpic 8455’ harbored the most O. insidiosus and fewer D. balteata and Thysanoptera species. ‘Golden Goose Hybrid’ had the highest moth numbers. These patterns suggest that cultivar traits influenced pest susceptibility and beneficial arthropods’ activity. Temperature and relative humidity were positively correlated with A. vittatum and E. borealis numbers, but rainfall negatively affected bees. These findings underscore the importance of cultivar selection and weather condition considerations in integrated pest management.