Factors affecting reproductive success and life history parameters of Bracon hebetor Say (Hymenoptera: Braconidae) from three host-associated populations

Authors: SAADAT, DORNA - Shahid Chamran University Of Ahvaz; SERAJ, ALI ASGHAR - Shahid Chamran University Of Ahvaz; GOLDANSAZ, SEVED HOSSEIN - University Of Tehran; Williams, Livy

Submitted to: Entomological Society of America Annual Meeting
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/10/2016
Publication Date: 2/16/2016
Citation: Saadat, D., Seraj, A., Goldansaz, S., Williams Iii, L.H. 2016. Factors affecting reproductive success and life history parameters of Bracon hebetor Say (Hymenoptera: Braconidae) from three host-associated populations . Entomological Society of America Annual Meeting. 96: 86-92.

Interpretive Summary: Augmentative releases of native beneficial insects are viable strategies for suppression of crop pests. Appropriate rearing and release strategies rely on a thorough understanding of the reproductive biology of the beneficial insect. In the present study, we evaluated the effects of the source of the beneficial insect, fruit condition (i.e., ease of host access for beneficial insect), impact of using an intermediate host insect for rearing, and winter-simulated cold storage of hosts on the reproductive performance of the beneficial insect, Bracon hebetor. We measured life history parameters, including attack rate and offspring sex ratio. Bracon hebetor originating from a pomegranate orchard host insect habitat generally had greater reproductive performance than those sourced from stored dry fruit or tomato field habitats. Hosts infesting intact pomegranate fruit suffered greater levels of attack (e.g., paralysis, parasitism, and oviposition) than did more accessible hosts infesting damaged fruit. However, offspring sex ratio of B. hebetor was generally more female-biased in the damaged fruit treatments. The developmental period of B. hebetor was shorter on hosts that had been subjected to a 2-month cold storage period (winter simulation) than newly-emerged hosts not subjected to cold storage. Sex ratio of offspring did not differ significantly between the treatments. Our studies demonstrated differential effects of beneficial insect population source, and other biological factors, on the reproduction of B. hebetor, and suggested that rearing conditions can be manipulated to control development and sex ratio of this beneficial insect. Development of optimal release strategies is a topic for future studies.

Technical Abstract: Augmentative releases of native natural enemies are viable strategies for suppression of crop pests. Appropriate mass rearing and release strategies rely on a thorough understanding of the reproductive biology of the natural enemy. In the present study, we evaluated the effects of parasitoid source (host habitat origin), fruit condition (i.e., ease of host access for parasitoid), impact of using a factitious intermediate host for rearing, and winter-simulated cold storage of hosts on the reproductive performance of Bracon hebetor. Several life history parameters, including attack behavior, proportion of paralyzed hosts, parasitism, oviposition, offspring sex ratio, and life table parameters were measured. Wasps originating from a pomegranate orchard-Ectomyelois ceratoniae host habitat generally had greater reproductive performance than those sourced from stored dry fruit-Plodia interpunctella or tomato field-Helicoverpa armigera habitats. Hosts infesting intact pomegranate fruit suffered greater levels of attack (e.g., paralysis, parasitism, and oviposition) than did more accessible hosts infesting damaged fruit. However, offspring sex ratio was generally more female-biased in the damaged fruit treatments. The developmental period of B. hebetor larvae and pupae was shorter (mean generation time) on Ephestia kuehniella hosts that had been subjected to a 2-month cold storage period (winter simulation) than newly-emerged hosts not subjected to cold storage. Sex ratio of offspring did not differ significantly between the treatments. Our studies demonstrated differential effects of wasp population source, and other biotic factors, on the reproductive biology of B. hebetor. Development of optimal release strategies is a topic for future studies.