Explore the vast range of titles available.

In biological control, joint releases of predators and parasitoids are standard. However, intraguild predation (IGP) can occur when a predator attacks a parasitoid, potentially affecting pest control dynamics. In addition to the focal prey (FP), Trialeurodes vaporariorum, the intraguild predator (IG-predator) Geocoris punctipes can consume the parasitoid Eretmocerus eremicus (IG-prey). In this IGP context with multiple prey, an alternative prey (AP), like the aphid Myzus persicae, may influence interactions. Theory predicts that, in simple interactions, a predator’s functional response (FR) to the FP changes with the presence of an AP. However, whether this holds in an IGP context is unknown. In this study, we empirically tested that prediction. Our results show that without IGP, G. punctipes exhibits a generalized FR with and without AP. Nevertheless, with IGP, the predator exhibited a Type II FR at low and high AP densities, increasing pressure on the FP and potentially favoring short-term biological control strategies. However, when 25 AP were offered, the predator’s response shifted, underscoring the importance of monitoring AP densities to prevent potential disruptions in FP control. In both contexts, the increase in AP produced a handling time increase and a decrease in consumption rate. These results indicate that the theoretical prediction of the effect of AP on the FR is met only under specific conditions, and the complexity of multitrophic interactions must be considered.

Background: Predatory insects exhibit variability in prey selection, influenced by prey traits such as mobility, developmental stage, and coloration. Investigating sex-specific predation preferences is essential to understanding how male and female predators utilize resources differently, avoid competition, and influence population dynamics. These insights can enhance pest control by optimizing sex ratios in inundative releases to target specific prey traits, such as mobility or stage. This study investigates the predation preferences of male and female Geocoris punctipes Say (Hemiptera: Geocoridae) on Myzus persicae (Hemiptera: Aphididae) aphids, focusing on prey mobility, stage, and coloration, using chili plants. Results: Female and male G. punctipes significantly preferred mobile prey over immobile prey. While females did not show a specific preference for any developmental stage of prey, males significantly preferred adult aphids. Females consumed substantially more light-colored prey, whereas males displayed a preference for dark-colored aphids. Conclusions: Prey mobility is a universally preferred trait for male and female G. punctipes. However, the different preferences of male and female G. punctipes for prey based on developmental stage and coloration reflect sex-specific predation strategies. Therefore, adjusting predator sex ratios during controlled releases could improve the efficacy of pest management strategies. Further research is needed to validate these sex-specific predation strategies under greenhouse conditions and assess their practical applications to improve biological control programs.

Developing a successful biological control program relies on understanding predator–prey interactions in agroecosystem field settings. Among several methods used, molecular gut content analysis (MGCA) has become a popular method to measure predator contributions to pest control services. Once MGCA is applied to diagnose predator–prey interactions, the DNA detectability half-life is often applied to adjust for differences in prey digestion time among predators. Although MGCA best practices are well established, with many primers available, further work is needed to rank among published primers for MGCA. Using a combination of laboratory feeding trials and application of diagnostic MGCA to field collected predators, we investigated Bemisia tabaci post-feeding detection times in three dominant predator functional groups (chewing, piercing/sucking, and spiders). This was based on three published B. tabaci -specific primers. These data reveal that primer choice generated significantly different B. tabaci DNA half-lives in predator gut content. The primers with longer half-life resulted in higher field predation frequency estimation. Our field data using the primer with the longest half-life suggest several abundant predators, including Hippodamia convergens , Geocoris punctipes , Orius spp., Thomisidae spider, and fire ants ( Solenopsis invicta ), are actively feeding on B. tabaci in cotton fields. Orius spp. and fire ants were the most abundant predator species in our study area and contributed the most to B. tabaci control. Our results suggest that primers can be classified based on their specific DNA half-lives and can be used to address different ecological questions such as how to study time-specific predation detection (nocturnal or diurnal).

In this study, the effect of strip intercropping green bean (GB), Phaseolus vulgaris L., with garlic (G), Allium sativum L., in three row ratios (3GB:5G, 3GB:8G and 3GB:11G) was assessed on two-spotted spider mite (TSSM), Tetranychus urticae Koch, compared with green bean sole crop over two growing seasons, in 2017 and 2018. The results indicated that intercrops reduced the densities of T. urticae eggs and mobile forms on the vegetative growth, the flowering, and the bean expansion stages of green bean plants compared with sole crop. In this study, seven predators of T. urticae including Stethorus gilvifrons (Mulsant), Orius niger (Wolff), Neoseiulus zwoelferi (Dosse), Chrysoperla carnea (Stephens), Geocoris punctipes (Say), Scolothrips sexmaculatus Pergande, and Nabis pseudoferus (Remane) were collected on TSSM-infested green bean plants during the two growing seasons. Among them, S. gilvifrons and O. niger were the main predators of TSSM on green bean plants in the two growing seasons. Furthermore, the densities of O. niger were significantly higher in intercrops on the vegetative growth and the flowering stages of green bean compared with sole crop, whereas no significant difference was observed in the densities of S. gilvifrons between intercrops and sole crop in 2017 and 2018. Moreover, the values of the Shannon diversity index (H′) and Pielou’s evenness index (J′) for the composition of TSSM predators were greater in the three intercrops compared with sole crop for the entire growing seasons 2017/2018. On the other hand, the land equivalent ratio (LER), which is used to assess the yield benefit in intercrops, was greater than one in intercrops, especially in the 3GB:5G ratio (1.29 in 2017 and 1.40 in 2018). These results indicated that strip intercropping green bean with garlic could be effective in the control of T. urticae in green bean fields.

Generalist insect predators play an essential role in regulating the populations of Bemisia tabaci and other pests in agricultural systems, but may be affected negatively by insecticides applied for pest management. Evaluation of insecticide compatibility with specific predator species can provide a basis for making treatment decisions with the aim of conserving natural enemies. Eleven insecticides representing six modes of action groups were evaluated for toxicity against four predator species and at different developmental stages. Full-concentration series bioassays were conducted on laboratory-reared or insectary-supplied predators using Petri dish and systemic uptake bioassay techniques. Highest toxicities were observed with imidacloprid and clothianidin against first and second instar nymphs of Geocoris punctipes (Say) (Hemiptera: Geocoridae). Later instar nymphs were less susceptible to neonicotinoid treatments based on higher LC50s observed with imidacloprid, thiamethoxam, and dinotefuran against third or fourth instar nymphs.The pyrethroid insecticide bifenthrin was highly toxic against adults of G. punctipes and Orius insidiosus (Say) (Hemiptera: Anthocoridae). Standard concentration/mortality evaluation of nonacute toxicity insecticides, including buprofezin, pyriproxyfen, spirotetramat, and spiromesifen, was inconclusive in terms of generating probit statistics. However, low mortality levels of insects exposed for up to 120 h suggested minimal lethality with the exception of pyriproxyfen that was mildly toxic to Chrysoperla rufilabris (Burmeister) (Neuroptera: Chrysopidae).

Intraguild predation (IGP) takes place when natural enemies that use similar resources attack each other. The impact of IGP on biological control can be significant if the survival of natural enemy species is disrupted. In the present study, we assessed whether Geocoris punctipes (Hemiptera: Lygaeidae) engages in IGP on Eretmocerus eremicus (Hymenoptera: Aphelinidae) while developing on whitefly nymphs of Trialeurodes vaporariorum (Hemiptera: Aleyrodidae). In choice and non-choice tests, we exposed G. punctipes to parasitized and non-parasitized whitefly nymphs. We found that G. punctipes does practice IGP on E. eremicus. However, choice tests assessing G. punctipes consumption revealed a significant preference for non-parasitized T. vaporariorum nymphs. Subsequently, we investigated whether E. eremicus females modify their foraging behavior when exposed to conditions involving IGP risk. To assess this, we analyzed wasp foraging behavior under the following treatments: i) whitefly nymphs only (control = C), ii) whitefly nymphs previously exposed to a predator ( = PEP) and, iii) whitefly nymphs and presence of a predator ( = PP). In non-choice tests we found that E. eremicus did not significantly modify its number of attacks, attack duration, oviposition duration, or behavior sequences. However, E. eremicus oviposited significantly more eggs in the PEP treatment. In the PP treatment, G. punctipes also preyed upon adult E. eremicus wasps, significantly reducing their number of ovipositions and residence time. When the wasps were studied under choice tests, in which they were exposed simultaneously to all three treatments, the number of attacks and frequency of selection were similar under all treatments. These results indicate that under IGP risk, E. eremicus maintains several behavioral traits, but can also increase its number of ovipositions in the presence of IG-predator cues. We discuss these findings in the context of population dynamics and biological control.

Stink bugs (Hemiptera: Pentatomidae) are economic pests of cotton and soybean. This study was conducted to examine predation on stink bugs by arthropod predators in cotton and adjoining soybean habitats. Gut-content analysis based on polymerase chain reaction (PCR) was used to detect stink bug deoxyribonucleic acid (DNA) in predators collected from both crops over a 5 wk period. Nezara viridula (L.), Euschistus servus (Say), Chinavia hilaris (Say), and Euschistus quadrator Rolston were detected on soybean and cotton. Piezodorus guildinii (Westwood) and Thyanta custator custator (F.) were detected only on soybean whereas Euschistus tristigmus (Say) was detected only on cotton. Over both crops, 13 predators screened positive for a variety of stink bug species DNA by PCR analysis: Geocoris punctipes (Say) and Geocoris uliginosus (Say) (Hemiptera: Geocoridae), Orius insidiosus (Say) (Hemiptera: Anthocoridae), Hippodamia convergens Guérin-Méneville, Harmonia axyridis (Pallas) (cotton), and Scymnus sp. (cotton) (Coleoptera: Coccinellidae), Oxyopes salticus Hentz and Peucetia viridans (Hentz) (cotton) (Araneae: Oxyopidae), Solenopsis invicta Buren (Hymenoptera: Formicidae), Podisus maculiventris (Say) (Hemiptera: Pentatomidae), Mecaphesa asperata (Hentz) (Araneae: Thomisidae), Zelus renardii Kolenati (Hemiptera: Reduviidae), and Notoxus monodon (F.) (cotton) (Coleoptera: Anthicidae). In soybean, the percentage of G. punctipes and G. uliginosus screening positive for N. viridula was high, 87.3%, whereas the percentage screening positive for E. servus was moderately high, 60.3%. In cotton, the percentage of N. viridula DNA in gut-contents of O. insidiosus was high, 91.6%. Detection of P. guildinii and/or T. c. custator DNA in predators in cotton and of E. tristigmus DNA in predators in soybean demonstrated predator dispersal between soybean and cotton. In soybean, the percentage of P. guildinii DNA in gut contents of G. punctipes, G. uliginosus, and O. insidiosus, including those individuals in cotton that dispersed from soybean, was high. We conclude that a complex of arthropod predators prey on a complex of stink bugs in both cotton and adjoining soybean while foraging in and between these crops.

The kudzu bug, Megacopta cribraria (F.) (Hemiptera: Plataspidae), is a newly invasive exotic insect found primarily on kudzu, but also on soybean, in the southeastern United States. We used molecular gut-content analysis to document predation on this pest by insects and spiders in soybean, and to detect remains of crop-specific alternative prey in predators' guts as markers of predator migration between soybean and adjacent cotton. M. cribraria was found exclusively on soybean. Eight native generalist predators over both crops screened positive by specific PCR for DNA of the pest: Geocoris punctipes (Say), Geocoris uliginosus (Say), Orius insidiosus (Say), Podisus maculiventris (Say), Hippodamia convergens Guérin-Méneville, Zelus renardii (Kolenati), Oxyopes salticus Hentz, and Peucetia viridans (Hentz) ; a ninth predator, the exotic Solenopsis invicta Buren, also screened positive for M. cribraria DNA. P. viridans was the only arthropod that tested positive for DNA of this invasive pest in only one crop, cotton. Two plant-feeding pentatomid species, Piezodorus guildinii (Westwood) and Thyanta custator (F.), were found exclusively on soybean, and another, Euschistus tristigmus (Say), was specific to cotton in the context of this study. Detection of predation on a combination of M. cribraria and P. guildinii and T. custator in cotton and M. cribraria and E. tristigmus in soybean demonstrated that these predators dispersed between crops. These results strongly support the use of soybean habitats adjacent to cotton as part of a conservation biological control strategy against M. cribraria. This is the first report documenting predation on this exotic pest in the field via molecular gut-content analysis.

The kudzu bug, Megacopta cribraria (F.) (Hemiptera: Plataspidae), is a newly invasive exotic insect found primarily on kudzu, but also on soybean, in the southeastern United States. We used molecular gut-content analysis to document predation on this pest by insects and spiders in soybean, and to detect remains of crop-specific alternative prey in predators' guts as markers of predator migration between soybean and adjacent cotton. M. cribraria was found exclusively on soybean. Eight native generalist predators over both crops screened positive by specific PCR for DNA of the pest: Geocoris punctipes (Say), Geocoris uliginosus (Say), Orius insidiosus (Say), Podisus maculiventris (Say), Hippodamia convergens Guerin-Meneville, Zelus renardii (Kolenati), Oxyopes salticus Hentz, and Peucetia viridans (Hentz) ; a ninth predator, the exotic Solenopsis invicta Buren, also screened positive for M. cribraria DNA. P. viridans was the only arthropod that tested positive for DNA of this invasive pest in only one crop, cotton. Two plant-feeding pentatomid species, Piezodorus guildinii (Westwood) and Thyanta custator (F.), were found exclusively on soybean, and another, Euschistus tristigmus (Say), was specific to cotton in the context of this study. Detection of predation on a combination of M. cribraria and P. guildinii and T. custator in cotton and M. cribraria and E. tristigmus in soybean demonstrated that these predators dispersed between crops. These results strongly support the use of soybean habitats adjacent to cotton as part of a conservation biological control strategy against M. cribraria. This is the first report documenting predation on this exotic pest in the field via molecular gut-content analysis.

A number of cotton varieties have been genetically transformed with genes from Bacillus thuringiensis (Bt) to continuously produce Bt endotoxins, offering whole plant and season-long protection against many lepidopteran larvae. Constant whole-plant toxin expression creates a significant opportunity for non-target herbivores to acquire and bio-accumulate the toxin for higher trophic levels. In the present study we investigated movement of Cry1Ac toxin from the transgenic cotton plant through specific predator-prey pairings, using omnivorous predators with common cotton pests as prey: (1) the beet armyworm, Spodoptera exigua (Lepidoptera: Noctuidae), with the predator Podisus maculiventris (Heteroptera: Pentatomidae); (2) the two-spotted spider mite, Tetranychus urticae (Acarina: Tetranychidae), with the predatory big-eyed bug Geocoris punctipes (Heteroptera: Geocoridae) and (3) with the predatory damsel bug Nabis roseipennis (Heteropera: Nabidae); and (4) the thrips Frankliniella occidentalis (Thysanoptera: Thripidae) with the predatory pirate bug Orius insidiosus (Heteroptera: Anthocoridae). We quantified Cry1Ac toxin in the cotton plants, and in the pests and predators, and the effects of continuous feeding on S. exigua larvae fed either Bt or non-Bt cotton on life history traits of P. maculiventris. All three herbivores were able to convey Cry1Ac toxin to their respective predators. Among the herbivores, T. urticae exhibited 16.8 times more toxin in their bodies than that expressed in Bt-cotton plant, followed by S. exigua (1.05 times), and F. occidentalis immatures and adults (0.63 and 0.73 times, respectively). Of the toxin in the respective herbivorous prey, 4, 40, 17 and 14% of that amount was measured in the predators G. punctipes, P. maculiventris, O. insidiosus, and N. roseipennis, respectively. The predator P. maculiventris exhibited similar life history characteristics (developmental time, survival, longevity, and fecundity) regardless of the prey's food source. Thus, Cry1Ac toxin is conveyed through non-target herbivores to natural enemies at different levels depending on the herbivore species, but continuous lifetime contact with the toxin by the predator P. maculiventris through its prey had no effect on the predator's life history. The results found here, supplemented with others already published, suggest that feeding on Cry1Ac contaminated non-target herbivores does not harm predatory heteropterans and, therefore, cultivation of Bt cotton may provide an opportunity for conservation of these predators in cotton ecosystems by reducing insecticide use.