EFFECTS OF TEMPERATURE ON AND SOME COMPETITIVE CHARACTERISTICS OF METEORUS LEVIVENTRIS (WESMAEL) AND MICROPLITIS KEWLEYI MUESEBECK (HYMENOPTERA: BRACONIDAE), PARASITOIDS OF BLACK CUTWORM LARVAE, AGROTIS IPSILON (HUFNAGEL) (LEPIDOPTERA: NOCTUIDAE) (COEXISTENCE, HOST DISCRIMINATION, SUPERPARASITISM, MULTIPLE PARASITISM)
Abstract
Females of Meteorus leviventris (Wesmael) and Microplitis kewleyi Muesebeck (Hymenoptera: Braconidae) more frequently oviposited in older black cutworm (BCW) larvae than in younger larvae. More progeny per parasitoid female and more progeny per host were produced when parasitizing older instars. Host instar did not affect sex ratio of progeny produced by female parasitoids. M. leviventris completed development at all four temperatures (15, 20, 25, and 30 C), but M. kewleyi did not complete development at 15 C. Higher percentage of M. leviventris than M. kewleyi immature stages survived at each temperature. Rates of development of both species increased with temperature, but development times of M. leviventris were shorter than those of M. kewleyi from 20 to 30 C. Longevities of M. kewleyi and M. leviventris decreased as temperature increased, but M. kewleyi females lived longer than M. leviventris females from 20 to 30 C. Rates of parasitism and progeny production by M. kewleyi and M. leviventris also increased with temperature. Temperature affected sex ratio of M. kewleyi progeny but not of M. leviventris. Female progeny production by M. kewleyi and M. leviventris was highest during the first few days of adult life and subsequently declined with female age. Net reproductive rate, and intrinsic and finite rates of increase of M. leviventris were higher, and generation time and cohort generation times were shorter than those of M. kewleyi at 20 to 30 C. M. leviventris females could not discriminate between healthy hosts and previously parasitized hosts. However, M. kewleyi females could discriminate hosts that were previously parasitized by its own species at 1 and 4 days after initial ovipositions. Superparasitism did not affect progeny survival and sex ratio of M. kewleyi but did affect progeny sex ratio of M. leviventris. Multiply parasitized hosts always produced the parasitoid species that initially oviposited. Multiple parasitism by M. leviventris did not affect progeny survival or progeny sex ratio of M. kewleyi. However, multiple parasitism by M. kewleyi did affect progeny survival and sex ratio of M. leviventris.
Degree
Ph.D.
Subject Area
Entomology
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