Development of Meteorus pulchricornis and regulation of its noctuid host, Pseudaletia separata

AbstractAlthough apomixis is the most common form of parthenogenesis in diplodiploid arthropods, it is uncommon in the haplodiploid insect order Hymenoptera. We found a new type of spontaneous apomixis in the Hymenoptera, completely lacking meiosis and the expulsion of polar bodies in egg maturation division, on the thelytokous strain of a parasitoid waspMeteorus pulchricornis(Wesmael) (Braconidae, Euphorinae) on pest lepidopteran larvaeSpodoptera litura(Fabricius) (Noctuidae). The absence of the meiotic process was consistent with a non-segregation pattern in the offspring of heterozygous females, and no positive evidence was obtained for the induction of thelytoky by any bacterial symbionts. We discuss the conditions that enable the occurrence of such rare cases of apomictic thelytoky in the Hymenoptera, suggesting the significance of fixed heterosis caused by hybridization or polyploidization, symbiosis with bacterial agents, and occasional sex. Our finding will encourage further genetic studies on parasitoid wasps to use asexual lines more wisely for biological control.

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Sublethal effects of organophosphorus insecticide phoxim on patch time allocation and oviposition behavior in a parasitoid wasp Meteorus pulchricornis

Bulletin of Entomological Research ◽

10.1017/s0007485321000614 ◽

2021 ◽

pp. 1-10

Author(s):

Sheng Sheng ◽

Yan Song ◽

Sheraz Ahmad ◽

Jiao Wang ◽

Ying Shao ◽

...

Keyword(s):

Time Allocation ◽

Sublethal Effects ◽

Insect Pests ◽

Oviposition Behavior ◽

Host Density ◽

Parasitoid Wasp ◽

Patch Time Allocation ◽

Meteorus Pulchricornis ◽

Allocation Decisions ◽

Patch Residence Time

Abstract Parasitoid wasps are key agents for controlling insect pests in integrated pest management programs. Although many studies have revealed that the behavior of parasitic wasps can be influenced by insecticides, the strategies of patch time allocation and oviposition have received less attention. In the present study, we forced the endoparasitoid Meteorus pulchricornis to phoxim exposure at the LC30 and tested the foraging behavior within patches with different densities of the host, the larvae of the tobacco cutworm Spodoptera litura. The results showed that phoxim treatment can significantly increase the patch-leaving tendency of female wasps, while host density had no impact. The number of oviposition and the number of previous patch visits also significantly influenced the patch time allocation decisions. The occurrence of oviposition behavior was negatively affected by phoxim exposure; however, progeny production was similar among patches with different host densities. Phoxim exposure shaped the offspring fitness correlates, including longer durations from cocoon to adult wasps, smaller body size, and shorter longevity. The findings of the present study highlight the sublethal effects that reduce the patch residence time and the fitness of parasitoid offspring, suggesting that the application of phoxim in association with M. pulchricornis should be carefully schemed in agroecosystems.

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