Cucumber Beetle Research Articles

Landscape factors affect relative abundance of rootworm species and pod injury in Georgia peanuts.

The southern corn rootworm, Diabrotica undecimpunctata howardi Barber, is native to the US where it is a pest of peanut, Arachis hypogaea. The banded cucumber beetle, Diabrotica balteata LeConte, is native to the neotropics, but its range has expanded and currently includes most of the US peanut production area. The purpose of this study was to: (i) define seasonal variation in adult rootworm populations in peanut fields, and (ii) determine the effect(s) of proximity to a putative early season host (i.e., corn, Zea mays) and the presence of irrigation on rootworm infestation and pod injury in peanut. Seasonal abundance of adult rootworms in commercial peanut fields in Georgia was monitored in 2021 and 2022 using plant volatile lures attached to yellow sticky traps. Traps were located at 45, 90, and 180 m from the field edge in irrigated and nonirrigated peanut fields with and without a corn border. Two peaks in abundance were observed for both species in each year. Though peak abundance for the two species occurred nearly simultaneously, D. balteata was more abundant than D. u. howardi. Beetle abundance was highest in fields bordered by corn, but presence of irrigation was not as important for D. balteata as it was for D. u. howardi. Pod injury was greater in fields bordered by corn in both years, but there was no difference in pod injury between irrigated and nonirrigated fields. The number of beetles captured and incidence of pod injury within a field did not differ with distance from the field border.

Specialty Melons Grown under High Tunnel Conditions Yield Good to Excellent Internal Quality

Interest in local foods, especially locally grown fruit, is increasing. High tunnel vegetable growers are strategically poised to meet this demand by growing specialty melons (Cucumis melo). Although specialty melons are commonly grown in high tunnels in other parts of the world, it is an uncommon practice in the midwestern United States. The objectives of this study were to evaluate 10 specialty melon cultivars for high tunnel production and measure fruit yield and internal quality. Fruit of the cultivar Eden’s Gem yielded the greatest number of marketable fruits per plant; however, these melons are small and have a loose cavity. Fruit of the cultivars Honey Orange and Divergent yielded the largest marketable fruit per plant with tighter cavities; however, the cavities were large. All cultivars had good to excellent internal quality in terms of sugar content. The production of specialty melons in the high tunnel was successful, resulting in the production of melons with good to excellent internal quality, and several yielded three to four marketable fruit per plant. Implementing a strong pest management plan for cucumber beetle (Diabrotica undecimpunctata howardi) and powdery mildew (Erysiphe cichoracearum, Sphaerotheca fuliginea) is recommended to prevent yield loss, especially in locations such as the Midwest, where cucumber beetles often vector bacterial wilt (Erwinia tracheiphila).

Plant versus pollinator protection: balancing pest management against floral contamination for insecticide use in Midwestern US cucurbits.

Controlling crop pests while conserving pollinators is challenging, particularly when prophylactically applying broad-spectrum, systemic insecticides such as neonicotinoids. Systemic insecticides are often used in conventional agriculture in commercial settings, but the conditions that optimally balance pest management and pollination are poorly understood. We investigated how insecticide application strategies control pests and expose pollinators to insecticides with an observational study of cucurbit crops in the Midwestern United States. To define the window of protection and potential pollinator exposure resulting from alternative insecticide application strategies, we surveyed 62 farms cultivating cucumber, watermelon, or pumpkin across 2 yr. We evaluated insecticide regimes, abundance of striped and spotted cucumber beetles (Acalymma vittatum [Fabricius] and Diabrotica undecimpunctata Mannerheim), and insecticide residues in leaves, pollen, and nectar. We found that growers used neonicotinoids (thiamethoxam and imidacloprid) at planting in all cucumber and pumpkin and approximately half of watermelon farms. In cucumber, foliar thiamethoxam levels were orders of magnitude higher than the other crops, excluding nearly all beetles from fields. In watermelon and pumpkin, neonicotinoids applied at planting resulted in 4-8wk of protection before beetle populations increased. Floral insecticide concentrations correlated strongly with foliar concentrations across all crops, resulting in high potential exposure to pollinators in cucumber and low-moderate exposure in pumpkin and watermelon. Thus, the highest-input insecticide regimes maintained cucumber beetles far below economic thresholds while also exposing pollinators to the highest pollen and nectar insecticide concentrations. In cucurbits, reducing pesticide inputs will likely better balance crop protection and pollination, reduce costs, and improve yields.

Simulation of early season herbivory via mechanical damage affects flower production in pumpkin (Cucurbita pepo ssp. pepo).

Damage from insect herbivores can elicit a wide range of plant responses, including reduced or compensatory growth, altered volatile profiles, or increased production of defence compounds. Specifically, herbivory can alter floral development as plants reallocate resources towards defence and regrowth functions. For pollinator-dependent species, floral quantity and quality are critical for attracting floral visitors; thus, herbivore-induced developmental effects that alter either floral abundance or attractiveness may have critical implications for plant reproductive success. Based on past work on resource trade-offs, we hypothesize that herbivore damage-induced effects are stronger in structural floral traits that require significant resource investment (e.g., flower quantity), as plants reallocate resources towards defence and regrowth, and weaker in secondary floral traits that require less structural investment (e.g., nectar rewards). In this study, we simulated early-season herbivore mechanical damage in the domesticated jack-o-lantern pumpkin Cucurbita pepo ssp. pepo and measured a diverse suite of floral traits over a 60-day greenhouse experiment. We found that mechanical damage delayed the onset of male anthesis and reduced the total quantity of flowers produced. Additionally, permutational multivariate analysis of variance (PERMANOVA) indicated that mechanical damage significantly impacts overall floral volatile profile, though not output of sesquiterpenoids, a class of compounds known to recruit specialized cucumber beetle herbivores and squash bee pollinators. In summary, we show that C. pepo spp. pepo reduces investment in male flower production following mechanical damage, and that floral volatiles do exhibit shifts in production, indicative of damage-induced trait plasticity. Such reductions in male flower production could reduce the relative attractiveness of damaged plants to foraging pollinators in this globally relevant cultivated species.

Cultivar-Specific Defense Responses in Wild and Cultivated Squash Induced by Belowground and Aboveground Herbivory

Plant domestication often alters plant traits, including chemical and physical defenses against herbivores. In squash, domestication leads to reduced levels of cucurbitacins and leaf trichomes, influencing interactions with insects. However, the impact of domestication on inducible defenses in squash remains poorly understood. Here, we investigated the chemical and physical defensive traits of wild and domesticated squash (Cucurbita argyrosperma), and compared their responses to belowground and aboveground infestation by the root-feeding larvae and the leaf-chewing adults of the banded cucumber beetle Diabrotica balteata (Coleoptera: Chrysomelidae). Wild populations contained cucurbitacins in roots and cotyledons but not in leaves, whereas domesticated varieties lacked cucurbitacins in all tissues. Belowground infestation by D. balteata larvae did not increase cucurbitacin levels in the roots but triggered the expression of cucurbitacin biosynthetic genes, irrespective of domestication status, although the response varied among different varieties. Conversely, whereas wild squash had more leaf trichomes than domesticated varieties, the induction of leaf trichomes in response to herbivory was greater in domesticated plants. Leaf herbivory varied among varieties but there was a trend of higher leaf damage on wild squash than domesticated varieties. Overall, squash plants responded to both belowground and aboveground herbivory by activating chemical defense-associated gene expression in roots and upregulating their physical defense in leaves, respectively. While domestication suppressed both chemical and physical defenses, our findings suggest that it may enhance inducible defense mechanisms by increasing trichome induction in response to herbivory.

Comparative Efficacy of Organic Mulching and Organic Neem Oil in the Control of spotted and striped cucumber beetles affecting the growth and yield of Cucumber in Uyo, Akwa Ibom State

A research work was undertaken in the University of Uyo Teaching and Research Farm, Main Campus, Uyo, from March to May during the 2023 cropping season to assess the effect of Organic Mulching and Neem Oil in the Control of Cucumber Beetles (spotted “Diabrotica undecimpunctata” and striped “Acalymma vitatum”) affecting the growth and yield of Cucumber (Cucumis sativum, Saira F1 variety). The experiment was laid out in Randomized Complete Block Design (RCBD). The experimental plot consisted of three (3) replicates with 2 treatments: organic mulch, organic Neem oil application and control. An early maturing variety of cucumber “Saira F1” was used as planting material sown in March which lasted till May. Data on insect pest population count, growth and yield parameters were studied and the data obtained were analyzed and subjected to analysis of variance using Fisher`s Least Significant Difference (LSD) at 5% probability level. The results from insect population count parameters revealed that Neem oil at 100ml application rate which recorded 10.50 and 6.00 was significantly effective in managing spotted and striped cucumber beetles respectively compared to organic mulch (3kg) which recorded 47.00 and 14.00 for spotted and striped cucumber beetles and control unit which had 61.00 and 42.00 for spotted and striped cucumber beetles respectively. Neem oil at 100ml application rate was also more effective in improving the growth and yield of cucumber plant compared to organic mulch. Hence, Farmers in Uyo, Akwa Ibom State should employ Neem oil in managing spotted and striped cucumber beetles in cucumber production as this is a promising botanical insecticide to check the activities of field cucumber beetles thereby bringing their destructive activities to a minimum and also improves yield.

Row covers limit pests and disease and increase profit in organic acorn squash

Organic cucurbit growers face many challenges to production including insect pests, insect-vectored diseases, and non-vectored diseases. While Organic Material Review Institute (OMRI) -listed pesticides underperform at suppressing pests and diseases, some alternative pest management strategies hold promise, but little research exists on their cost-effectiveness. We compared the efficacy of mesotunnel systems (nylon-mesh netting row covers deployed over bent metal hoops) and OMRI-listed pesticides (fungicides and insecticides) on acorn squash across 2 years. During the early part of the season, before row covers were removed for pollination, we found 1.7 (2020) and 0.3 (2021) times more cucumber beetles in the uncovered plots compared to the mesotunnels. Powdery mildew incidence was 36 and 25% lower under the mesotunnels compared to the uncovered plots in 2020 and 2021, respectively. Marketable yield of acorn squash was 46–54% higher in the mesotunnels compared to the uncovered treatments. OMRI-listed pesticide treatments reduced powdery mildew incidence compared to untreated control treatments. However, for pest presence, OMRI-listed pesticide treatments did not differ from untreated control treatments in either year, nor did it differ in marketable yield in 2020. Finally, the mesotunnel-only system was 47% more profitable compared to the OMRI-listed pesticide treatment and 47% more profitable compared to the uncovered plots. These results highlight mesotunnels as an economically viable pest management strategy for organic cucurbit growers in the U.S.

Evaluating Pollination and Weed Control Strategies under Mesotunnel Systems for Organic Muskmelon Production in Iowa

Bacterial wilt of cucurbits, caused by Erwinia tracheiphila, is spread by spotted (Diabrotica undeimpunctata howardi) and striped (Acalymma vittatum) cucumber beetles and results in major losses for US cucurbit (Cucurbitaceae spp.) growers. Organic growers of muskmelon (Cucumis melo) lack reliable control measures against bacterial wilt. During previous field trials in Iowa, USA, a system called mesotunnels, which are 3.5-ft-tall barriers covered with a nylon mesh insect netting, resulted in a higher marketable yield of organic ‘Athena’ muskmelon than low tunnels or noncovered plots. However, satisfactory pollination and weed control are challenging in mesotunnels because the netting covers the crop for most or all of the growing season, and economic feasibility of these systems has not been determined. Consequently, two field trials conducted in Iowa from 2020 to 2022 evaluated strategies to ensure pollination under mesotunnels in commercial-scale plots, assess effectiveness of teff (Eragrostis tef) as a living mulch for weed control in mesotunnel systems, and compare the profitability of the treatment options for organic ‘Athena’ muskmelon. The treatments used during the pollination trial were as follows: full season, in which mesotunnels remained sealed all season and bumble bees (Bombus impatiens) were added at the start of bloom for pollination; open ends, wherein both ends of the tunnels were opened at the start of bloom then reclosed 2 weeks later; and on-off-on, in which nets were removed at the start of bloom and then reinstalled 2 weeks later. The full-season treatment had significantly higher marketable yield than the other treatments in two of three trial years. Plants with the full season and open ends treatments had a bacterial wilt incidence <2.5% across all three years and similar numbers of cucumber beetles, whereas plants with the on-off-on treatment had an average bacterial wilt incidence of 11.0% and significantly more cucumber beetles. The open ends treatment had fewer bee visits to ‘Athena’ muskmelon flowers than the other treatments. In the 2-year (2021–22) weed management trial, treatments applied to the furrow between plastic-mulched rows were as follows: landscape fabric; teff seeded at 4 lb/acre and mowed 3 weeks after seeding; teff seeded at 4 lb/acre and not mowed; a control with bare ground where weeds were mowed 3 weeks after transplanting; and a bare ground control with no mowing. The landscape fabric and mowed teff treatments had statistically similar marketable yield, and mowing appeared to minimize yield losses compared with nonmowed treatments. The landscape fabric had no weeds, followed by mowed teff, mowed bare ground, and nonmowed teff. Nonmowed bare ground had the highest weed biomass. The partial budget and cost-efficiency ratio analysis indicated that the full-season treatment was the most cost-efficient pollination option for mesotunnel systems. An economic analysis of the weed management strategies showed that using teff as a living mulch in the furrows between organic ‘Athena’ muskmelon rows, coupled with timely mowing to suppress its growth, can generate revenue comparable to that of landscape fabric. Our findings suggest that organic ‘Athena’ muskmelon growers in Iowa may gain the greatest yield and soil quality benefits when mesotunnels are kept closed for the entire season, bumble bees are used for pollination, and teff (mowed 3 weeks after seeding) is used to control weeds in the furrows. Further trials integrating these pollination and weed management strategies would help validate a comprehensive approach to organic ‘Athena’ muskmelon production under mesotunnels.

Belowground insect herbivory induces systemic volatile emissions that strengthen neighbouring plant resistance aboveground.

Plants transmit ecologically relevant messages to neighbouring plants through chemical cues. For instance, insect herbivory triggers the production of herbivore-induced plant volatiles (HIPVs), which can enhance neighbouring plant defences. HIPVs are emitted from directly damaged plant tissues and from systemic, nondamaged tissues. Although volatile-mediated interplant interactions have been observed both above- and belowground, it remains unknown whether belowground herbivory induces systemic HIPVs aboveground that influence neighbouring plants. To explore how belowground herbivory affects interplant interactions aboveground, we characterised systemic HIPVs from squash induced by belowground striped cucumber beetle (Acalymma vittatum) larval herbivory. We exposed squash 'receiver plants' to systemic HIPVs or volatiles from nondamaged plants. We then measured herbivore resistance by challenging 'receiver plants' with aboveground-feeding herbivores: adult beetles (A. vittatum) or squash bugs (Anasa tristis). We discovered belowground-damaged plants emitted more (E)-β-ocimene, a key volatile from the systemic HIPV blend, than nondamaged controls, and that exposure to systemic HIPVs enhanced neighbouring plant resistance to aboveground squash bugs, but not adult beetles. Further investigations into the mechanism of interplant interaction revealed β-ocimene alone can elicit plant resistance against squash bugs. Overall, our findings reveal a novel form of volatile-mediated interactions between plants spanning across aboveground-belowground plant systems.

Effect of dose and trap type on captures of striped and spotted cucumber beetles using synthetic vittatalactone.

Striped cucumber beetle, Acalymma vittatum (F.) and spotted cucumber beetle (Diabrotica undecimpunctata howardi Barber) are key pests of cucurbits. Pesticide applications directed against cucumber beetles can jeopardize bee pollination which is essential to crop yield. Alternative selective tactics, including behavioral control for managing cucumber beetles, are needed in order to improve pest management. The striped cucumber beetle pheromone vittatalactone is attractive to both male and female adults, and also to spotted cucumber beetles. We tested the response of both species to different doses of synthetic vittatalactone, and to different trap types, in field trapping experiments in Maryland. Both species showed strong dose-response in May-June and October 2020. Among 12 trap types tested during a 2-wk experiment in June, using 1 mg mixed vittatalactone, sticky panel traps caught the most of each species, with vittatalactone-baited traps exceeding unbaited traps by >8 fold for striped and >2 fold for spotted, and with significant response to yellow versus clear color absent in striped, but strong in spotted. Among nonsticky traps, those with yellow or yellow-green exceeded those without these colors for both beetle species, and a ground-placed boll weevil trap captured the most striped cucumber beetles. Bucket-style traps caught excessive nontarget bumblebees (Bombus spp.) if yellow, and a few beetles, if all green. Results allow field monitoring with a choice of sticky or nonsticky traps and suggested lure loading of 1 mg mixed vittatalactone, containing ~90 μg active isomer. These findings contribute to the development of multispecies behavioral monitoring and control as a component of cucurbit IPM.

Living mulches reduce natural enemies when combined with frequent pesticide applications

Agricultural intensification with frequent pesticide applications often diminishes biological control services delivered by beneficial insects. However, re-integrating diverse and structurally complex non-crop habitat may mitigate negative effects by providing refugia to natural enemies, enabling rapid recolonization of pesticide-treated crops. This study examines the compatibility of chemical control with non-crop habitat management by manipulating pesticide treatments and living mulches between rows of zucchini crops in four replicated experiments across the Southeastern United States. The hypothesis was that living mulches and pesticide applications would each negatively impact pests and have interactive effects on predatory insects, with negative pesticide effects being attenuated in plots with untreated living mulches serving as refugia for predators between crop rows. Instead, combining living mulches with pesticide applications reduced natural enemy densities, relative to bare plots. Pesticide applications had no effect on spotted and striped cucumber beetle pests, while living mulches directly reduced them by 25%. Conversely, pesticide applications reduced squash bug pressure by 50%, while living mulches had no effect. Although crops were grown in plastic mulch to protect them from competition, living mulches reduced zucchini yields by 54% at sites where living mulches were less-managed. Alternatively, living mulches had more neutral effects on yields at sites where mulches were mowed monthly, suggesting that living mulches require management to minimize competition with crops. These results suggest that the grass-dominated living mulches tested in this study did little to harmonize chemical and biological control. While non-crop plant diversity has clear benefits for natural pest suppression in many systems, these benefits cannot be generalized across all plant and insect taxa. Future efforts to fine-tune management of non-crop habitat within fields will be strengthened by consideration of traits of key pests and their specific responses to both pesticide applications and plant diversity.

Vittatalactone is the Male-Produced Aggregation Pheromone of the Western Striped Cucumber Beetle, Acalymma trivittatum.

We found that vittatalactone, specifically (3R,4R)-3-methyl-4-[(1S,3S,5S)-1,3,5,7-tetramethyloctyl]oxetan-2-one, is the male-produced aggregation pheromone of the western striped cucumber beetle, Acalymma trivittatum (Mannerheim), as was previously shown for the striped cucumber beetle, Acalymma vittatum (F.) (Coleoptera: Chrysomelidae). A synthetic mixture containing 9% of the authentic natural pheromone, is attractive to both sexes of both species in the field, as demonstrated by trapping using baited and unbaited sticky panels in California and earlier in Maryland. Females of both species do not produce detectable vittatalactone. This finding expands the usefulness of the synthetic vittatalactone mixture for pest management throughout the range of both A. vittatum and A. trivittatum. Development of vittatalactone time-release formulations combined with cucurbitacin feeding stimulants offer the potential for selective and environmentally-friendly cucurbit pest management tactics.

Population Dynamics of Insect Pests and Beneficials on Different Snap Bean Cultivars

Snap bean is an important crop in the United States. Insecticides are commonly used against pests on snap bean, but many pests have developed resistance to the insecticides and beneficials are threatened by the insecticides. Therefore, host plant resistance is a sustainable alternative. Population dynamics of insect pests and beneficials were assessed on 24 snap bean cultivars every week for six weeks. The lowest number of sweetpotato whitefly (Bemisia tabaci) eggs was observed on cultivar 'Jade', and the fewest nymphs were found on cultivars 'Gold Mine', 'Golden Rod', 'Long Tendergreen', and 'Royal Burgundy'. The numbers of potato leafhopper (Empoasca fabae) and tarnished plant bug (Lygus lineolaris) adults were the lowest on cultivars 'Greencrop' and 'PV-857'. The highest numbers of adults were found in Week 1 (25 days following plant emergence) for B. tabaci and Mexican bean beetle (Epilachna varivestis); Week 3 for cucumber beetle, kudzu bug (Megacopta cribraria), and E. fabae; Weeks 3 and 4 for thrips; Week 4 for L. lineolaris; and Weeks 5 and 6 for bees. Temperature and relative humidity correlated with B. tabaci, E. varivestis, bee, and predator ladybird beetle populations. These results provide valuable information on the integrated pest management of snap beans.

Comparison of Row Cover Systems for Pest Management in Organic Muskmelon in Iowa

Organic growers of cucurbit (Cucurbitaceae) crops in the midwestern United States have difficulty managing bacterial wilt—a fatal disease with a pathogen (Erwinia tracheiphila) that is transmitted by striped and spotted cucumber beetles (Acalymma vittatum and Diabrotica undecimpunctata howardi, respectively). Registered organic insecticides lack effectiveness, and host plant resistance is rare in commercial cultivars of many cucurbit crops. Row covers are widely used as barriers to minimize pest access, but the spunbonded polypropylene fabric covering traditional low tunnels must be removed at bloom to prevent overheating and facilitate pollination, thereby exposing the crop for the rest of the season. “Mesotunnels”—nylon mesh fabric covering 3.5-ft-high hoops—provide more space than low tunnels and mitigate overheating. In field experiments at Iowa State University (Ames, IA, USA) during 2016–18, two variations of mesotunnels—full-season tunnels [with purchased bumble bees (Bombus impatiens) added for pollination] and part-season tunnels (with covers removed for 2 weeks during bloom to provide pollinator access)—were compared with low tunnels and a noncovered treatment for organic ‘Athena’ muskmelon (Cucumis melo) production. Based on scouting results, full-season mesotunnels required no insecticides and part-season mesotunnels averaged 0.6 spray per season compared with 1.0 and 5.0 sprays per season for the low-tunnel and noncovered treatments, respectively. Incidence of pest and disease damage was zero for the full-season mesotunnels, 5% to 22% for the part-season mesotunnels, and 37% to 70% for both of the other treatments. Marketable yield for the full-season mesotunnel treatment exceeded the noncovered treatment significantly each year, and mean marketable yields were greater numerically than for the other treatments. Both mesotunnel treatments had a marketable yield that averaged more than twice that of the noncovered treatment in each year. Economic analysis (partial budget and cost-efficiency ratio) indicated that mesotunnels were likely to be more profitable in Iowa, USA, than either the low-tunnel or noncovered systems, but also that the year-to-year differential among treatments in profitability could be substantial. Additional experiments are needed to evaluate the efficacy of these integrated pest management practices and their profitability at spatial scales representative of commercial farms.

Spotted cucumber beetle (Diabrotica undecimpunctata howardi) is attracted to vittatalactone, the pheromone of striped cucumber beetle (Acalymma vittatum)

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.

Spotted cucumber beetle/southern corn rootworm: profile of a polyphagous native pest

Abstract Spotted cucumber beetle, Diabrotica undecimpunctata (Coleoptera: Chrysomelidae), a North American native leaf beetle species also known as southern corn rootworm (SCRW), is a polyphagous pest of various crops including cucurbits (Cucurbitaceae), corn (Zea mays), soybeans (Glycine max), snap beans (Phaseolus vulgaris), peanut (Arachis hypogaea), and sweetpotato (Ipomoea batatas). Larvae are below-ground pests of corn, sorghum (Sorghum spp.), peanut, and sweetpotato. Adult damage impacts cucurbits by damage to seedlings and fruit and transmission of bacterial wilt (causal agent Erwinia tracheiphila) by eastern populations. Adult feeding also damages fresh market beans and occasionally leafy and fruiting vegetables. Damage on many other crops such as field soybeans, dry beans, and sorghum, is often cosmetic and/or inconsequential. Adults overwinter in mild climates and spread seasonally northward, with multiple generations and populations increasing into the late summer. Diverse natural enemies attack all stages, but their ecology and impact are poorly known, particularly below ground. A female-produced sex pheromone and floral volatiles are known attractants, and cucurbitacins (bitter phytochemicals) are feeding stimulants, offering potential selective behavioral control. Management practices are directed against pest complexes, including other below- and above-ground pests, depending on the crop. Chemical controls are soil-applied for protection from root-feeding larvae, systemic seed treatments for early-state crop feeding, and broadcast application in fruiting cucurbits and beans. Action thresholds and monitoring are not well developed. Cultural controls include field and cultivar choice, row covers in high-value crops, and available crop resistance. The wide host range, abundance, and mobility of adults make prediction and monitoring challenging.

Undercover operation: Belowground insect herbivory modifies systemic plant defense and repels aboveground foraging insect herbivores

Plants attacked by insects may induce defenses locally in attacked plant tissues and/or systemically in non-attacked tissues, such as aboveground herbivory affecting belowground roots or belowground herbivory modifying aboveground tissues (i.e., cross-compartment systemic defense). Through induced systemic plant defenses, above-and belowground insect herbivores indirectly interact when feeding on a shared host plant. However, determining the systemic effects of herbivory on cross-compartment plant tissues and cascading consequences for herbivore communities remains underexplored. The goal of this study was to determine how belowground striped cucumber beetle (Acalymma vittatum) larval herbivory alters aboveground zucchini squash (Cucurbita pepo subsp. pepo) defenses and interactions with herbivores, including adult cucumber beetles and squash bugs (Anasa tristis). To explore this question, field and laboratory experiments were conducted to compare responses of aboveground herbivores to belowground larvae-damaged plants and non-damaged control plants. We also characterized changes in defensive chemicals and nutritional content of aboveground plant structures following belowground herbivory. We discovered belowground herbivory enhanced aboveground plant resistance and deterred aboveground foraging herbivores. We also found that larvae-damaged plants emitted higher amounts of a key volatile compound, (E)-β-ocimene, compared to non-damaged controls. Further investigation suggests that other mechanisms, such as plant nutrient content, may additionally contribute to aboveground herbivore foraging decisions. Collectively, our findings underscore connections between above-and belowground herbivore communities as mediated through induced systemic defenses of a shared host plant. Specifically, these findings indicate that belowground larval herbivory systemically enhances plant defenses and deters a suite of aboveground herbivores, suggesting larvae may manipulate aboveground plant defenses for their own benefit, while plants may benefit from enhanced systemic defenses against multi-herbivore attack.

Understanding Psammophory in <i>Raphanus sativus</i> and <i>Lagenaria siceraria</i>: An Approach to Reduce Herbivory

Sand entrapment on plant surfaces, termed psammophory is a widely known trait of the plants having significance in reducing herbivory and regarded as one of the potential plants defense phenomena. Trichomes protruding from the surface of leaves and stems defend plants from many herbivores. These trichomes of plants often entrap sand on their surfaces or release some exudates on which sand can get adhered, this phenomenon of carrying sand on their surfaces is called psammophory. Sand and soil are naturally nonnutritive and most of the herbivores find them difficult to process. The presence of these substances (soil, sand) increases the plant defense and reduce herbivory. There is lack of studies for investigating the impact of psammophory on economic plants including vegetables. The current study attempts to understand the benefit of the psammophoric properties of soil and sand in reducing the attacks of herbivores on radish ( Raphanus sativus ) and bottle gourd ( Lagenaria siceraria ). Both of these species suffer a heavy loss in their yield due to cabbage borer (Hellula undalis Fabr.) and western striped cucumber beetle ( Acalymma vittata ), respectively. The current study examined whether presence of sand on these plant surfaces physically protected them from herbivores.

Does IPPM bear fruit? Evaluating reduced‐risk insecticide programmes on pests, pollinators and marketable yield

Abstract Integrated pest and pollinator management (IPPM) has been touted as a novel approach to control pests while mitigating negative effects of insecticides on pollinators. In addition to non‐chemical approaches, IPPM programmes focus on insecticide treatments with low bee toxicity, threshold‐based applications and restricted timings to avoid sprays during pollinator foraging. However, the singular and combined effect of this approach on pollination services and pest management is understudied and generally lacks field validation. In two field studies, we evaluated the effect of IPPM insecticide programmes on striped cucumber beetle (Acalymma vittatum) management, pollination and watermelon yield. The first trial (2020) featured insecticide treatments representing a factorial combination of (1) products varying in bee toxicity (bifenthrin, cyclaniliprole and acetamiprid), (2) application frequencies (weekly vs. threshold‐based) and (3) application timings (AM vs. PM), as well as an untreated control. These data were then used to inform a second trial (2021) that applied two insecticide treatments (IPPM based or grower standard) to commercial‐scale (20–30 acres) fields in collaboration with regional watermelon farms. Weekly beetle densities, pollinator visitation and yield data were collected to determine programme efficacy. Overall, beetle infestations were successfully managed with all insecticide treatments, none of which compromised marketable yield. In 2020, threshold‐based insecticide programmes offered statistically similar levels of pest control but required 20%–80% fewer applications compared to a weekly programme. Furthermore, pollinator visitation was increased in threshold‐based programmes by ~42% across all products. The on‐farm validation trial in 2021 upheld these findings; IPPM fields had effective beetle control but with 1–7 fewer insecticide applications compared to grower standard fields. IPPM fields also had 62% greater pollinator visitation and 49% more melons during harvest compared to grower standard fields. Synthesis and applications. Our study demonstrates the capacity of IPPM programmes to manage pests while mitigating negative effects on pollinators. In particular, administering insecticide applications by pest thresholds led to the greatest enhancement in pollinator function. These findings also suggest that growers can benefit from this approach with reduced insecticide costs while encouraging pollination in pollinator‐dependent crops.

Sequestration of cucurbitacins from cucumber plants by Diabrotica balteata larvae provides little protection against biological control agents

Cucurbitaceae plants produce cucurbitacins, bitter triterpenoids, to protect themselves against various insects and pathogens. Adult banded cucumber beetles (Diabrotica balteata), a common pest of maize and cucurbits, sequester cucurbitacins, presumably as a defensive mechanism against their natural enemies, which might reduce the efficacy of biological control agents. Whether the larvae also sequester and are protected by cucurbitacins is unclear. We profiled cucurbitacin levels in four varieties of cucumber, Cucumis sativus, and in larvae fed on these varieties. Then, we evaluated larval growth and resistance against common biocontrol organisms including insect predators, entomopathogenic nematodes, fungi and bacteria. We found considerable qualitative and quantitative differences in the cucurbitacin levels of the four cucumber varieties. While two varieties were fully impaired in their production, the other two accumulated high levels of cucurbitacins. We also observed that D. balteata larvae sequester and metabolize cucurbitacins, and although the larvae fed extensively on both belowground and aboveground tissues, the sequestered cucurbitacins were mainly derived from belowground tissues. Cucurbitacins had no detrimental effects on larval performance and, surprisingly, did not provide protection against any of the natural enemies evaluated. Our results show that D. balteata larvae can indeed sequester and transform cucurbitacins, but sequestered cucurbitacins do not impact the biocontrol potential of common natural enemies used in biocontrol. Hence, this plant trait should be conserved in plant breeding programs, as it has been demonstrated in previous studies that it can provide protection against plant pathogens and generalist insects.