Reproduction, Development, Longevity, and Host Mortality of Sympiesis marylandensis (Hymenoptera: Eulophidae), a Parasitoid of Spotted Tentiform Leafminer (Lepidoptera: Gracillariidae), in the Laboratory

Abstract

Sympiesis marylandensis Girault was reared on the spotted tentiform leafminer, Phyllonorycter blancardella (F.), in the laboratory. At 23°C, a photoperiod of 16:8 (L:D), and with abundant hosts, 19 S. marylandensis adult females lived 59 ± 5 (x̄ ± SEM) d and parasitized 495 ± 26 hosts. Females killed an additional 279 ± 11 larvae by host-feeding and paralysis, for a total of 774 ± 35 larvae killed per female per lifetime. The overall sex ratio of offspring was 2.29:1 (male/female). Fourth-instar leafminer hosts yielded 99.3% male parasitoid offspring, whereas the sex ratio was nearly 1:1 on host fifth instars and pupae. The net reproductive rate (Ro) of S. marylandensis was 144.3 females per female per generation under these conditions. Mean generation time was 11 d. Adult parasitoids fed 10% sucrose or honeydew from apple aphids, Aphis pomi De Geer, lived significantly longer than adults given crab apple fruit or water only. Development time from egg to adult at five different constant temperatures was determined; the developmental threshold was 9.1°C for males and 8.3°C for females. Parasitoid fecundity, longevity, generation time, carbohydrate requirement, polyphagy, and restricted use of fourth instars may affect biological control of spotted tentiform leafminer.