Search

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.

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.

The squash bug, Anasa tristis (De Geer) is a serious pest of cucurbit crops. The egg parasitoid, Gryon pennsylvanicum (Ashmead), is the primary parasitoid of the squash bug and has been considered ...

This study examined the ovipositional behavior of Gryon pennsylvanicum Ashmead (Hymenoptera: Scelionidae) on egg masses of two squash bug species Anasa tristis DeGeer and Anasa armigera Say (Hemiptera: Coreidae) by evaluating how parasitoid density and access to nutrition influenced percent parasitism on egg masses of different sizes in laboratory tests. When three parasitoids were exposed to A. tristis egg masses with only three to five eggs, 72.7% of parasitoids became trapped in the eggs and failed to emerge successfully. These results suggest that competition between larvae within the egg may have reduced the fitness of the surviving parasitoid. Continual access to honey water did not significantly influence parasitism rates on A. armigera egg masses and only increased parasitism on A. tristis egg masses with 20–25 eggs. Overall, parasitism rates were higher on A. armigera egg masses than on A. tristis egg masses, and parasitoids were more likely to emerge successfully from A. armigera eggs than from A. tristis eggs. Parasitoids spent the same amount of time probing eggs of the two species, but they spent significantly more time drilling into A. tristis eggs than A. armigera eggs. Measurements taken using transmission electron microscopy determined that the average combined width of the epicuticle and exocuticle of the egg chorion was significantly greater for A. tristis eggs than for A. armigera eggs. This difference may account for the lower rates of parasitism and parasitoid emergence and for the increased time spent drilling into A. tristis eggs compared with A. armigera eggs.

Many insects harbor microbial symbiotic partners that offer protection against pathogens, parasitoids, and other natural enemies. Mounting evidence suggests that these symbiotic microbes can play key roles in determining infection outcomes in insect vectors, making them important players in the quest to develop novel vector control strategies. Using the squash bug Anasa tristis, we investigated how the presence of Caballeronia symbionts affected the persistence and intensity of phytopathogenic Serratia marcescens within the insect vector. We reared insects aposymbiotically and with different Caballeronia isolates, infected them with S. marcescens, and then sampled the insects periodically to assess the intensity and persistence of pathogen infection. Squash bugs harboring Caballeronia consistently had much lower-intensity infections and cleared S. marcescens significantly faster than their aposymbiotic counterparts. These patterns held even when we reversed the timing of exposure to symbiont and pathogen. Taken together, these results indicate that Caballeronia symbionts play an essential role in S. marcescens infection outcomes in squash bugs and could be used to alter vector competence to enhance agricultural productivity in the future. IMPORTANCE Insect-microbe symbioses have repeatedly been shown to profoundly impact an insect’s ability to vector pathogens to other hosts. The use of symbiotic microbes to control insect vector populations is of growing interest in agricultural settings. Our study examines how symbiotic microbes affect the dynamics of a plant pathogen infection within the squash bug vector Anasa tristis, a well-documented pest of squash and other cucurbit plants and a vector of Serratia marcescens, the causative agent of cucurbit yellow vine disease. We provide evidence that the symbiont Caballeronia prevents successful, long-term establishment of S. marcescens in the squash bug. These findings give us insight into symbiont-pathogen dynamics within the squash bug that could ultimately determine its ability to transmit pathogens and be leveraged to interrupt disease transmission in this system.

Most insects maintain associations with microbes that shape their ecology and evolution. Such symbioses have important applied implications when the associated insects are pests or vectors of disease. The squash bug, Anasa tristis (Coreoidea: Coreidae), is a significant pest of human agriculture in its own right and also causes damage to crops due to its capacity to transmit a bacterial plant pathogen. Here, we demonstrate that complete understanding of these insects requires consideration of their association with bacterial symbionts in the family Burkholderiaceae. Isolation and sequencing of bacteria housed in the insects’ midgut crypts indicates that these bacteria are consistent and dominant members of the crypt-associated bacterial communities. These symbionts are closely related to Caballeronia spp. associated with other true bugs in the superfamilies Lygaeoidea and Coreoidea. Fitness assays with representative Burkholderiaceae strains indicate that the association can significantly increase survival and decrease development time, though strains do vary in the benefits that they confer to their hosts, with Caballeronia spp. providing the greatest benefit. Experiments designed to assess transmission mode indicate that, unlike many other beneficial insect symbionts, the bacteria are not acquired from parents before or after hatching but are instead acquired from the environment after molting to a later developmental stage. The bacteria do, however, have the capacity to escape adults to be transmitted to later generations, leaving the possibility for a combination of indirect vertical and horizontal transmission.

Thesquash bug, Anasa tristis (DeGeer), is an indigenous pest of squash, Cucurbita pepo L., and other cucurbits. Geocoris punctipes (Say) adults were collected from stands of mixed grasses in Spalding County, GA, held without food for 24 h, and presented A. tristis eggs, first instars, or second instars in no-choice tests. Consumption of first and second instars was significantly greater by females than by males. Egg consumption was very low with no difference between males and females (P > 0.05). Male G. punctipes consumed a range of 0 to 3 first-instar squash bugs, 0 to 6 second-instar squash bugs, and 0 eggs during the 72-h exposure. Females consumed a range of 0 to 10 first-instar squash bugs, 0 to 10 second-instar squash bugs, and a range of 0 to 1 eggs. Male G. punctipes consumed on average 1.08 ± 0.24 first-instar squash bugs, 1.68 ± 0.41 second-instar squash bugs, and 0 eggs during the 72-h exposure. Females consumed on average 4.12 ± 0.56 first-instar squash bugs, 4.28 ± 0.56 second-instar squash bugs, and 0.12 ± 0.06 eggs. Background mortality for first and second instars was similar and exceeded that for eggs in control, male, and female trials. Previous research demonstrated seasonal overlap in squash bug nymphs and G. punctipes occurrence. These data suggest that G. punctipes can contribute to the suppression of early-season squash bug populations.

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 the Tidewater 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.

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.

The fitness benefits of copulation are evident, but copulation can also incur costs to participating individuals. Many insects copulate for prolonged periods of time during which the female carries or drags the male. This behavior could result in decreased mobility, which in turn might influence the copulating pair's ability to escape from predators and to forage or thermoregulate. Here, I tested how copulation influences movement speed in the common squash bug (Anasa tristis) by measuring average movement speed of unpaired individuals and copulating pairs in an arena trial. Copulating pairs moved significantly slower but, surprisingly, the degree of size disparity between male and female did not influence movement speed. These results suggest that copulation incurs a mobility cost in this species, with potential consequences for survival, but that it is unlikely that mobility costs during copulation lead to selection for smaller male size.

The squash bug, Anasa tristis (De Geer), is a major pest of squash, pumpkin, and other cucurbits throughout North America. A. tristis is a piercingsucking feeder that causes extensive foliar wilting and fruit scarring and transmits plant pathogens. Current biological agents to control A. tristis are limited in efficacy, and newer control methods must be developed. Here we present studies of immune system transcripts as the initial step in identifying potentially vulnerable targets for control of gene expression. Following immune stimulation with bacteria, transcript levels of six components of the inducible innate system in adult female A. tristis were measured using quantitative PCR. An antibacterial peptide-encoding transcript, anacin; an enzyme central to melanization, prophenoloxidase; and three sentinel proteins, scavenger receptor, β-1,3-glucan-binding protein, and peptidoglycan-binding protein were upregulated by bacterial elicitation. Expression of a putative immunoregulatory cytokine, astakine, was identified and increased by septic puncture. We also found novel upregulation of an enzyme of central energy metabolism, arginine kinase, in response to septic puncture of A. tristis adults.

Cucurbit yellow vine disease (CYVD), caused by the squash bug (Anasa tristis)-transmitted bacterium Serratia marcescens, was first identified in Oklahoma and Texas in 1988 and in Georgia in 2012. S. marcescens is a highly diverse species found in many ecological niches. In previous studies, CYVD strains of S. marcescens formed a closely related group separate from non-CYVD strains based on biological and molecular characterization techniques. Multilocus sequence analysis (MLSA) of six housekeeping genes and repetitive elements-based polymerase chain reaction (rep-PCR) using the BOX and ERIC primers were used to assess the genetic diversity of CYVD strains of S. marcescens collected in Georgia together with a strain from Texas and seven non-CYVD strains of S. marcescens. rep-PCR results revealed genetic diversity among CYVD strains while MLSA results showed a 100% similarity across the six loci for all but one of the CYVD strains, which differed at the icd locus by five polymorphisms. For both methods, CYVD strains clustered separately from nonplant-pathogenic S. marcescens strains and were most similar to a rice endophyte strain. One CYVD strain isolated from a squash bug shared genetic similarities with non-CYVD strains, and may be the result of a recombination event between CYVD and non-CYVD strains.

A two-year study evaluated the effect of a flowering border of buckwheat Fagopyrum esculentum Moench on rates of egg parasitism, egg predation and adult parasitism on two squash bug species, Anasa tristis (DeGeer) and Anasa armigera Say, by comparing rates in squash fields with and without a flowering border. Furthermore, we evaluated whether there was an edge effect by comparing parasitism and predation rates in plots located in the corner of a squash field with plots located in the center of a squash field for fields with and without a flowering border. The egg parasitism rates were not affected by either treatment (flowering border or control) or plot location (edge or center). Anasa armigera egg masses only accounted for 4.3% of the total egg masses collected. The egg parasitism rates increased gradually throughout the season, peaking in the last week of August in 2017 at 45% for A. tristis egg masses. The most common egg parasitoid recovered was Gryon pennsylvanicum (Ashmead) followed by Ooencyrtus anasae (Ashmead). Adult parasitism was not affected by treatment, but A. tristis adult parasitism rates were higher in plots located on the edge of squash fields compared with plots located in the center of squash fields in 2016. Since adult parasitoid, Trichopoda pennipes (Fabricius) flies were observed visiting buckwheat flowers, future studies could explore the possibility that the flowering buckwheat may have a more impact on adult parasitism if there was a greater distance between fields with and without a flowering border.

Polycultures, or multicrops, are groupings of plants that grow more prolifically when planted together as compared to when planted alone as monocultures. One of the best known and widely utilized polycultures is the milpa cropping system - the cultivation of maize, beans, and squash together as “the three sisters.” Milpa has been utilized by the indigenous population of Central America for millennia due to its consistent abundant harvests; today it remains a cornerstone of the region’s tradition, diet, and economic growth. Likely contributing to this legacy is the known association of polycultures and heightened resistance to disease, yet the mechanism underlying this relationship in milpa has largely been unexplored. To assess the health of farm soil exposed to milpa monocrops, bicrops, and multicrops, we measured the growth of two bacterial strains: a Burkholderia strain symbiotic of Anasa tristis (the squash bug, an agricultural pest) and a plant pathogenic Serratia strain that is the primary causal agent of cucurbit yellow vine disease (CYVD). We found that after one week in both the polyculture (corn, bean, and squash) soil and the corn monoculture soil, the growth of Burkholderia was significantly inhibited. However, in both corn & bean and bean & squash biculture soils, the growth of the strain was significantly enhanced. The growth of the Serratia strain did not yield any significant increase or decrease after one week in any milpa soil. We conclude that the cultivation of milpa in its polyculture configuration demonstrates antibiotic activity towards the Burkholderia strain SQ4A. Our investigation supports findings that certain multicrop systems are less susceptible to disease than monocultures possibly due to their greater microbial biomass; thus we can infer a higher amount of root exudates present in the soil, of which a substantial amount may be anti-microbials.

A faunistic survey of the Hispaniolan bugs of the family Coreidae is presented based on the study of over 1000 specimens deposited in several entomological collections. The new species Zicca gloriosa sp. nov. is described from the Dominican Republic. Another 12 species are new records for the island, 11 of them being new records for the Dominican Republic: Althos obscurator (Fabricius, 1803), Anasa acutangula Stål, 1870, Anasa tristis (De Geer, 1773), Eubule spartocerana Brailovsky, 1992, Leptoglossus confusus Alayo & Grillo, 1977, Mamurius cubanus Barber & Bruner, 1947, Merocoris distinctus Dallas, 1852, Merocoris typhaeus (Fabricius, 1798), Phthia rubropicta (Westwood, 1842), Sethenira ferruginea Stål, 1870, and Zicca rubricator rubricator (Fabricius, 1803). New records for Haiti are Anasa scorbutica (Fabricius, 1798), Catorhintha selector Stål, 1859, Chariesterus gracilicornis Stål, 1870, Rhytidophthia splendida (Valdes, 1910) and Zicca taeniola (Dallas, 1852). The literature citations presented in Perez-Gelabert (2008) of Leptoglossus cinctus (Herrich-Schäffer, 1836) and Leptoglossus stigma (Herbst, 1784) are probably based on erroneous identifications and not counted as part of the Hispaniolan fauna. The total number of species presently known from Hispaniola is raised to 28. Key to subfamilies, tribes, genera and species are included, as well as color dorsal habitus.

Autotomy, induced limb loss, is a trait that is effectively used throughout the animal kingdom to avoid predation and entrapment, and has independently evolved multiple times. Within the insect clade, species have been observed autotomizing legs, antennae, cerci, and caudal filaments. However, our knowledge of which species autotomize and the frequency of limb loss in natural populations is quite limited. Understanding autotomy’s diversity can provide key insights into how this extreme trait has evolved and is a first step in understanding the costs and benefits of this behavior. Here, we quantify the frequency of leg loss and investigate the ability to autotomize in nine coreid (Insecta: Hemiptera: Coreidae) species ( Euthochtha galeator F., Anasa andresii Guerin-Meneville, Anasa tristis DeGeer, Narnia femorata Stal, Chelinidea vittiger McAtee, Leptoglossus phyllopus L., Acanthocephala declivis Say, Acanthocephala terminalis Dallas, and Acanthocephala femorata F.), across five tribes. In wild populations of these species, limb absence ranged from 7.9 to 21.5%. In the lab, all nine species investigated were able to autotomize. These discoveries are particularly interesting because some coreids use their hind legs in intrasexual competitions for access to females; therefore, autotomy in coreids can mean permanently losing a sexually selected weapon. These observations provide a more complete understanding of autotomy’s diversity while also developing new hypotheses regarding the interaction between autotomy, sexual selection, and natural selection.

Seasonal changes in egg parasitism and predation rates on sentinel (laboratory-reared) and wild (naturally occurring) egg masses of the squash bug, Anasa tristis (De Geer), were evaluated in squash fields in Maryland from June through September in 2013 and 2014. Rates of egg parasitism were significantly higher on wild egg masses than on sentinel egg masses. Squash bug nymphal emergence was significantly higher on sentinel egg masses than on wild egg masses. Between the first week of July and the first week of September of both survey years, squash bug nymphs emerged from 24.2% of wild eggs compared with 46.2% of sentinel eggs and parasitoids emerged from 55.7% of wild eggs compared with only 21.8% of sentinel eggs. Sentinel egg masses significantly underestimated the rate of natural egg parasitism. The egg parasitoid, Gryon pennsylvanicum (Ashmead), was responsible for over 99% of parasitism of squash bug eggs. There was a significant negative correlation between parasitoid emergence and nymphal emergence, suggesting that parasitoids were able to suppress squash bug populations. The average rate of parasitoid emergence peaked on wild egg masses on the fifth week of July at 72.8%, whereas the average rate of nymphal emergence from wild egg masses was

Cucurbit crops are attacked by a pest complex that threatens production via direct feeding and disease transmission. The goals of this study were to quantify the amount of biocontrol service supplied to pumpkin fields and determine if this was affected by local habitat management or the surrounding landscape. Using sentinel eggs, we measured predation of squash bug, Anasa tristis , and spotted cucumber beetle, Diabrotica undecimpunctata howardi , by generalist predators. We found that predators significantly removed D. undecimpunctata howardi but not A. tristis eggs. The guild of predators found to attack D. undecimpunctata howardi included Araneae, Carabidae, Cricetidae, Entomobryidae, Formicidae, Gryllidae and Opiliones. A smaller, but overlapping guild of predators was found to attack A. tristis , which included Araneae, Cricetidae, Formicidae and Gryllidae. Formicidae was consistently the dominate predator of both pest species. We examined how the addition of either a non-native annual plant insectary of sweet alyssum, Lobularia maritima , or a diverse insectary planted with native perennial forbs and grasses influenced predator abundance, composition, or biocontrol services relative to a grass control. We found no difference in either the predator community feeding on pest eggs or the proportion of eggs that they removed from adjacent pumpkin fields. Larger-scale landscape composition did influence the amount of egg predation occurring in pumpkin agroecosystems, however, these relationships varied among pests and across years of the study. Biological control is commonly predicted to increase with landscape diversity and the amount of non-crop habitat present surrounding focal fields, yet we found that when landscape did influence egg predation it was agricultural landscapes supporting the highest egg removal. This study illustrates that patterns relating landscape and localized habitat management to crop pest predation are not constants, they can vary among years within a crop as well as among agricultural cropping systems.

Within promiscuous mating systems, copulation often functions as more than a means of fertilization, and copulation durations can vary widely. Copulating for prolonged durations can enhance both female and male reproductive success, but can also result in costs: females of some insect species experience increased fecundity and fertility through male-provided nutrition during prolonged copulations, but also decreased longevity due to male-driven mechanisms. Here, for a common, promiscuous insect species (the squash bug, Anasa tristis), we first describe the range of copulation duration, which spans from 2 min to over 23 h. To investigate whether female A. tristis benefit from prolonged copulation, we next manipulated copulation duration and female diet, and we documented the resulting fecundity, fertility, and longevity of each female. We found no evidence that prolonged copulation durations affect female reproductive success. Females produced fertile eggs after a single 30 min copulation, and they subsequently produced fertile eggs for an additional 4 weeks. Our findings suggest that females do not benefit from prolonged copulations, that sperm transfer occurs very early during copulations, and that females can store sperm for long durations. Consequently, we suggest that female harassment avoidance and male mate-guarding may explain prolonged copulations in this species.

Individuals of different species sometimes mate in nature, and such behavior often carries costs, such as wasted gametes and inviable offspring. One context in which interspecific mating commonly occurs is when closely related species come into secondary contact. Here, we tested whether reproductive isolation is greater in an area of recent secondary contact than in allopatry for two closely related insect species, and we examined whether mating between individuals of these two species constitutes reproductive interference. In Florida, two species of squash bugs (Hemiptera: Coreidae: Anasa tristis DeGeer and Anasa andresii Guérin-Méneville) have been secondarily sympatric for ≥80 generations, and male A. andresii copulate with female A. tristis. Because hybridization is often costly for females, we predicted that secondarily sympatric females would be less likely to mate with heterospecifics than would allopatric females. We found no evidence of recent selection on reproductive isolation: females from both populations were equally likely to mate with heterospecifics, and heterospecific males did not make more mating attempts than conspecifics to achieve copulations. However, female A. tristis paired with heterospecifics produced many fewer eggs and offspring than females paired with conspecifics, and this did not differ according to whether females were from allopatric or sympatric populations. Our findings show that reproductive barriers between these species existed before secondary contact. We suggest that habitat use may limit encounter frequency, and that female choice, multiple mating, and postcopulatory processes may reduce costs for females. Consequently, we suggest that mating systems and ecological factors mediate the effects of reproductive interference.

This study evaluated how the size of the egg mass and the parasitoids prior exposure to eggs influenced parasitism rates by Gryon pennsylvanicum Ashmead (Hymenoptera: Scelionidae) on egg masses of two squash bug species, Anasa tristis DeGeer and Anasa armigera Say (Hemiptera: Coreidae). G. pennsylvanicum is the primary egg parasitoid of A. tristis. There were no published reports available on egg parasitism of A. armigera. In choice tests, there was no difference in host acceptance by G. pennsylvanicum of egg masses of the two squash bug species. In no-choice tests, overall parasitism rates were significantly higher on A. armigera egg masses than on A. tristis egg masses. Naive parasitoids had significantly higher parasitism rates than experienced parasitoids on egg masses of both squash bug species. In a comparison of parasitism rates of field-collected and laboratory-tested A. tristis egg masses of different sizes, parasitism rates were similar in the field and in the laboratory, with the exception of egg masses with > 25 eggs. Only 17.9% of eggs were parasitized in the laboratory, compared with 36.4% in the field. Results of this study indicate that transient egg limitation prevents G. pennsylvanicum from ovipositing in every available host egg in large squash bug egg masses. The low parasitism rate of G. pennsylvanicum on large egg masses may limit its effectiveness as a biological control agent of squash bugs.

The ovipositional preferences of two squash bug species, Anasa tristis (DeGeer) (Heteroptera: Coreidae) and Anasa armigera Say (Heteroptera: Coreidae), were evaluated in paired choice tests of different species and cultivars of plants in the family Cucurbitaceae. Females of A. tristis preferred to oviposit on the cultivar from which they were reared over three other cultivars of the same species. However, females did not show any ovipositional preference for different cultivars when they had no previous exposure to either cultivar. Females of A. tristis were equally likely to oviposit on Cucurbita pepo, Cucurbita maxima, and Cucurbita moschata but were significantly more likely to oviposit on C. pepo than on cucumber and watermelon. Females of A. armigera were equally likely to oviposit on C. pepo or cucumber, regardless of the species they were reared on. When A. armigera was reared on C. pepo, females were more likely to oviposit on C. maxima than on cucumber and less likely to oviposit on C. moschata than on cucumber.

Mating between species is common, but seldom adaptive. Mate preferences and receptivity to mating attempts may both contribute to such matings, also called reproductive interference. Here, we tested the hypothesis that both male mate preference for female body size and female receptivity contribute to reproductive interference between two secondarily sympatric insect species. In north-central Florida, the squash bug Anasa tristis co-occurs with a recently introduced, smaller congener, Anasa andresii. Male A. andresii are frequently found copulating with larger female A. tristis in the field. We found that male A. andresii prefer larger heterospecific females over conspecific females, that female A. tristis accept some mating attempts by heterospecific males, and that female A. tristis are more promiscuous with conspecifics than are female A. andresii. Our findings suggest that both male mate choice and female receptivity contribute to mating between these species.

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.

A broad range of environmental conditions likely regulate predator-prey population dynamics and impact the structure of these communities. Central to understanding the interplay between predator and prey populations and their importance is characterizing the corresponding trophic interactions. Here, we use a well-documented molecular approach to examine the structure of the community of natural enemies preying upon the squash bug, Anasa tristis, a herbivorous cucurbit pest that severely hinders organic squash and pumpkin production in the United States. Primer pairs were designed to examine the effects of organic management practices on the strength of these trophic connections and link this metric to measures of the arthropod predator complex density and diversity within an experimental open-field context. Replicated plots of butternut squash were randomly assigned to three treatments and were sampled throughout a growing season. Row-cover treatments had significant negative effects on squash bug and predator communities. In total, 640 predators were tested for squash bug molecular gut-content, of which 11% were found to have preyed on squash bugs, but predation varied over the season between predator groups (coccinellids, geocorids, nabids, web-building spiders and hunting spiders). Through the linking of molecular gut-content analysis to changes in diversity and abundance, these data delineate the complexity of interaction pathways on a pest that limits the profitability of organic squash production.

An insectary mixture of flowering annuals suitable for use in the high desert irrigated agriculture of New Mexico was developed over 3 years using pumpkins, Cucurbita moschata L., as a model cropping system. Plant establishment, survival, and flowering phenology were assessed in both clay and sandy soils by using weekly quadrat samples. Abundance of beneficial insects and spotted cucumber beetle, Diabrotica undecimpunctata howardi Barber, were monitored with yellow sticky cards (Trece Inc., Adair, OK). Abundance of squash bug, Anasa tristis (DeGeer), was monitored weekly by sampling eggs and nymphs. Establishment of the flowering mixture was significantly better in clay than sandy soils in each of the 3 years. Of the fifteen plant species tested, California bluebell (Phacelia campanularia A. Gray), buckwheat (Fagopyrum esculentum Moench), dill (Anethum graveolens L.), Plains coreopsis (Coreopsis tinctoria Nuttall), garden cosmos (Cosmos bipinnatus Cavanilles), and sweet alyssum (Lobularia maritim...

The squash bug, Anasa tristis, is a pest of cucurbits that exerts direct damage on crops and is a vector of plant pathogens. We established cell lines from this insect to serve as tools for basic biology, including virology and immunology, as well as applied studies, such as insecticide development programs. We initiated 15 cell cultures, using nine media or combinations of media. The media yielding the best results were a modification of Kimura's medium and a combination of two commercially available cell culture media (EX-CELL 420 and L15). We designated the two cell lines as BCIRL-AtE-CLG11 and BCIRL-AtE-CLG15. From the AtE-CLG15 line, we isolated two sub-lines, A and B. Of these, the most consistently replicating line was AtE-CLG15A. We determined the doubling time of this line (190 h) and its mean cell diameter (14.5 ± 0.7 μm). We characterized the AtE-CLG15A line using DAF-PCR. The BCIRL-AtE-CLG15A cell line is now available for researchers world-wide.

The squash bug, Anasa tristis (DeGeer) (Hemiptera: Coreidae), is an indigenous pest of squash and other cucurbits. Pesticides can control squash bug populations although many small-scale growers in the Southeast seek alternative methods of management. Cultural control methods, including varying the planting date and farmscaping, are not well understood under southeastern conditions. The goal of farmscaping is to increase natural ecosystem functions to aid in the control of pest populations. In the summers of 2014 and 2015, field plots of squash, separated by a minimum of 150 m were organized in a split-split plot design, with floral resources at the whole-plot level and varied planting date at the subplot level. Data were collected on squash bug abundance and fruit yield (kg), and abundance of potential natural enemies of A. tristis. Plots with added floral resources had fewer squash bug adults than plots without added floral resources in four of eight possible year × site × planting date combinations. Furthermore, the site in 2014 which had a reduction in squash bug adult abundance also had an increase in the abundance of potential enemies, including spiders, ground beetles, and predaceous Hemiptera. There were additional instances when potential natural enemy abundance was greater in resource-enhanced plots, but they were not associated with sites that had a reduction in yield loss or squash bug abundance. The use of floral resources to attract natural enemies and beneficial insects merits further investigation.

BACKGROUND The squash bug, Anasa tristis (De Geer), is a major insect pest of cucurbits. Control of squash bugs with insecticidal chemicals is difficult to achieve. We investigated the potential of companion planting with white yarrow (Achillea millefolium L.) or feverfew [Tanacetum parthenium (L.) Sch. Bip.] for squash bug management in field plantings of summer squash (Cucurbita pepo L.). RESULTS Companion planting with white yarrow had few effects. Companion planting with feverfew tended to reduce squash bug populations, but results often were not statistically significant (P ≥ 0.05). Early-season ventilated row covers (without herbs) neither reduced squash bug populations nor increased squash yields. Herbs reduced marketable squash yields compared with the control only once out of seven experiments. CONCLUSION The tested companion planting strategies inconsistently affected squash bug populations on summer squash. Therefore, these strategies are not recommended to commercial producers. © 2016 Society of Chemical Industry

Plant chemicals mediating interactions with insect herbivores seem a likely target for manipulation by insectvectored plant pathogens. Yet, little is currently known about the chemical ecology of insect-vectored diseases or their effects on the ecology of vector and nonvector insects. We recently reported that a widespread plant pathogen, Cucumber mosaic virus (CMV), greatly reduces the quality of host-plants (squash) for aphid vectors, but that aphids are nevertheless attracted to the odors of infected plants—which exhibit elevated emissions of a volatile blend otherwise similar to the odor of healthy plants. This finding suggests that exaggerating existing host-location cues can be a viable vector attraction strategy for pathogens that otherwise reduce host quality for vectors. Here we report additional data regarding the effects of CMV infection on plant interactions with a common nonvector herbivore, the squash bug, Anasa tristis, which is a pest in this system. We found that adult A. tristis females preferred to oviposit on healthy plants in the field, and that healthy plants supported higher populations of nymphs. Collectively, our recent findings suggest that CMV-induced changes in host plant chemistry influence the behavior of both vector and non-vector herbivores, with significant implications both for disease spread and for broader community-level interactions.

The squash bug, Anasa tristis (De Geer), is a major indigenous pest of Cucurbita species across the United States and a vector of cucurbit yellow vine disease. The seasonal phenology of the squash bug in central Kentucky and its natural enemies were studied using summer squash planted sequentially throughout the 2005 and 2006 growing seasons. The squash bug was first detected on 5 June 2005 and 3 June 2006. In both years, peak numbers of all squash bug stages occurred in July and August. Our field data, substantiated by published degree-day models for squash bug development, suggest one complete and a partial second generation of squash bugs in 2005 and one complete generation of squash bugs in 2006. The most abundant ground-active predators in squash fields included Araneae, Carabidae, Staphylinidae, and Geocoridae. Coleomegilla maculata (De Geer) and Geocoris punctipes (Say) were the most abundant foliage-inhabiting predators. Direct field observations of predators feeding on squash bugs or their eggs included G. punctipes, Pagasa fusca (Stein), and Nabis sp. The parasitoids Trichopoda pennipes (Fabricius) and Gyron pennsylvanicum (Ashmead) were found also. Squash bug egg masses were monitored to determine predation and parasitism rates in the field. In four studies during 2005 and 2006, predation rates were low (7% or less), and parasitism ranged from 0 to 31%. Overall, squash bug egg mortality increased as the season progressed.

Retention or loss of transmissibility after molting was tested for adult and nymphal squash bug, Anasa tristis (De Geer), a natural vector of the plant pathogen Serratia marcescens Bizio, the causal agent of cucurbit yellow vine disease. Squash bug adults and nymphs fed from bacteria-infiltrated squash cubes were caged on squash test plants and transferred weekly to new plants for eight consecutive weeks. Twelve percent of the bugs that acquired as adults transmitted the bacterium to at least one of the test plants; 75% of these transmitters inoculated more than one plant. Transmission to plants occurred as late as 3 to 8 weeks postacquisition. Ten percent of squash bugs that fed on S. marcescens as fifth instars inoculated plants after molting to the adult stage; 77% of these transmitters inoculated more than one plant. Two insects that fed on S. marcescens as third instars inoculated squash plants. When examined by scanning electron microscopy, the foregut cibaria of transmitting insects were free of bacteria-like structures. The ability of A. tristis to transmit S. marcescens after molting to the adult stage suggests that the hemocoel acts as the site of retention of transmissible bacteria.