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Background: Parasitoids are natural enemies that can modify their behaviors as they search for hosts based on the characteristics of the sites in which they forage. Theoretical models predict that a parasitoid will stay for longer periods in high‐quality sites or patches than in those of low quality. In turn, patch quality may be linked to factors such as the number of hosts and the risk of predation. In the present study, we sought to determine if the factors of the number of hosts, risk of predation, and their interaction influence the foraging behavior of the parasitoid Eretmocerus eremicus (Hymenoptera: Aphelinidae) as theory predicts. To do this, we evaluated different parameters of parasitoid foraging behavior, such as residence time, number of oviposition events, and attacks, in sites of different patch quality. Results: Our results show that when the factors, number of hosts, and, risk of predation, were evaluated separately, E. eremicus resided for longer periods and oviposited more frequently in patches with a high number of hosts and low risk of predation than in other patches. However, when both of these factors were combined, only the number of hosts influenced some aspects of the foraging behavior of this parasitoid, such as the number of oviposition events and attacks. Conclusion: For some parasitoids like E. eremicus, theoretical predictions may be fulfilled when patch quality is linked to the number of hosts but will not be fully satisfied when patch quality is related to the risk of predation. Furthermore, at sites with different combinations of host numbers and risk of predation, host number appears to be more critical than predation risk. These results suggest that the performance of the parasitoid E. eremicus to control whiteflies will be mainly mediated by the levels of whitefly infestation and, to a small extent, by the risk of predation to which the parasitoid is subjected. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

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Population genetic structuring is common among herbivorous insects and frequently is associated with divergent host plants, such as crops and their wild relatives. Previous studies showed population genetic structuring in corn leafhopper Dalbulus maidis in Mexico, such that the species consists of two sympatric, host plant‐associated populations: an abundant and widespread "pestiferous" population on maize (Zea mays mays), and a small and localized "wild" population on perennial teosinte (Zea diploperennis), a maize wild relative with a limited distribution. This study addressed whether assortative mating and immigrant inviability mediate genetic structuring of corn leafhopper by comparing the mating and reproductive successes of pestiferous and wild females that colonize their nonassociated host plants against the successes of females colonizing their associated host plants. Assortative mating was assessed by comparing mating frequencies and premating and mating times among females of each population on each host plant; immigrant inviability was assessed by comparing, across two generations, the fecundity, survival, development time, sex ratio, and population growth rate among leafhopper populations and host plants. Our results showed that on maize, and compared to resident, pestiferous females, wild females were more likely to mate, and greater proportions of their offspring survived to adult stage and were daughters; consequently, the per‐generation population growth rate on maize was greater for immigrant, wild leafhoppers compared to resident, pestiferous leafhoppers. Our results suggested that wild leafhoppers emigrating to maize have a fitness advantage over resident, pestiferous leafhoppers, while immigrant pestiferous and resident wild leafhoppers on teosinte have similar fitnesses. [ABSTRACT FROM AUTHOR]

BACKGROUND Geocoris punctipes (Hemiptera: Lygaeidae) and Eretmocerus eremicus (Hymenoptera: Aphelinidae) are whitefly natural enemies. Previously, under laboratory conditions, we showed that G. punctipes engages in intraguild predation ( IGP), the attack of one natural enemy by another, on E. eremicus. However, it is unknown whether this IGP interaction takes place under more complex scenarios, such as semi-field conditions. Even more importantly, the effect of this interaction on the density of the prey population requires investigation. Therefore, the present study aimed to establish whether this IGP takes place under semi-field conditions and to determine whether the predation rate of G. punctipes on the whitefly decreases when IGP takes place. RESULTS Molecular analysis showed that, under semi-field conditions, G. punctipes performed IGP on E. eremicus. However, although IGP did take place, the predation rate by G. punctipes on the whitefly was nevertheless higher when both natural enemies were present together than when the predator was present alone. CONCLUSION While IGP of G. punctipes on E. eremicus does occur under semi-field conditions, it does not adversely affect whitefly control. The concomitant use of these two natural enemies seems a valid option for inundative biological control programmes of T. vaporariorum in tomato. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND Intraguild predation ( IGP), predation between species that use a common resource, can affect the populations of a pest, of the pest's natural enemy ( IG prey) and of the predator of the pest's natural enemy ( IG predator). In this study, we determined whether the parasitoid Eretmocerus eremicus (Hymenoptera: Aphelinidae) ( IG prey), modifies its foraging behaviour under the risk of IGP by Macrolophus pygmaeus (Hemiptera: Miridae) ( IG predator). Parasitoid behaviour was analysed using two bioassays (choice and no-choice) with the following treatments: (i) control, tomato leaf infested with whitefly nymphs; and (ii) PEP, tomato leaf infested with whitefly nymphs and previously exposed to the IG predator; and (iii) PP, tomato leaf infested with whitefly nymphs, with both, the IG predator and the IG prey present. RESULTS In both bioassays, we found that E. eremicus did not significantly modify the number of ovipositions, time of residence, duration of oviposition or behavioural sequence. However, in the no-choice bioassay, the number of attacks was higher and their duration shorter in the PEP treatment than in the control. CONCLUSION Our results indicate that the parasitoid may detect IGP risk to a certain extent, but it did not significantly modify its foraging behaviour, suggesting that simultaneous release of the two natural enemies can be successfully employed. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Neurotoxic pyrethroid insecticides are widely used for crop protection, and lethal and sublethal perturbations can be expected in beneficial insects. Under laboratory conditions, the lethal and sublethal effects of deltamethrin on the aphid parasitoid Diaeretiella rapae M'Intosh (Hymenoptera: Braconidae) were studied at the mummy stage and in emerging adults. Following a multistep bioassay, analyses were aimed at evaluating the effects of deltamethrin at various crucial steps in the recolonization process following a deltamethrin treatment: Parasitoid pupal development (emergence from the mummies), adult survival, and hostsearching capacity. A four-armed olfactometer was used to investigate the effect of deltamethrin on host-searching behavior (a range of concentrations causing 0.4-79.4% mortality was tested), and a Potter tower was used to test the deltamethrin effect with a realistic application method (four concentrations were tested: 0.5, 5.0, 6.25, and 50 g active ingredient [a.i.]/ha). Deltamethrin reduced the percentage of emergence from mummies, but only when exposed to the 50 g a.i./ha concentration. However, for all concentrations tested, the insecticide induced a decrease in longevity after emergence from sprayed mummies and significant adult mortality when parasitoids walked on fresh residues on leaves. Indices were defined and predicted a high mortality and, thus, reduction of recolonization capacities. However, deltamethrin had no effect on orientation behavior toward aphid-infested plants for adults that survived a residual exposure to the insecticide. The impact of deltamethrin on recolonization via pupal emergence and interest in the methodology used are discussed. [ABSTRACT FROM AUTHOR]