Effects of host size and laboratory rearing on offspring development and sex ratio in the solitary parasitoid Agrothereutes lanceolatus (Hymenoptera: Ichneumonidae)

• Published in: European journal of entomology Vol. 112; no. 2; pp. 281 - 287
• Main Author: Ueno, Takatoshi
• Format: Journal Article
• Language: English
• Published: Ceske Budejovice Institute of Entomology 02.04.2015; Institute of Entomology, Biology Centre, Czech Academy of Science
• Subjects: agrothereutes lanceolatus; Animal reproduction; Biology; cryptinae; Females; host quality; host selection; Hymenoptera; Ichneumonidae; idiobiont; Laboratories; laboratory rearing; Males; sex allocation; Sexes; Sperm; Studies; Tortricidae
• ISSN: 1210-5759; 1802-8829
• DOI: 10.14411/eje.2015.048

Agrothereutes lanceolatus is a solitary ectoparasitoid attacking mature larvae, prepupae and pupae of tortricid and pyralid moths, including Homona magnanima, which is an important pest of tea. Here, the effects of host size on offspring survival, size and sex ratio in A. lanceolatus were investigated. Wild-caught and laboratory-reared parasitoids were used to identify the effects of laboratory rearing on the above three biological parameters. Offspring survival was lower in laboratory-reared generations than the F1 generation. Large parasitoids emerged from large hosts. The offspring sex ratio was positively correlated with host size. The sex ratio at the egg stage inferred from maternal fertilization act also changed in response to host size, although there was imperfect control of female egg deposition. A striking difference was detected in the offspring sex ratio in the different generations. Offspring sex ratio was more male-biased in laboratory reared generations. These results suggest that inbreeding depression caused a reduction in offspring survival and the male-biased sex ratio in the laboratory.