Age-related reproductive biology of Trichogrammatoidea lutea on eggs of the African bollworm Helicoverpa armigera

Abstract

Trichogrammatoidea lutea Girault (Hymenoptera Trichogrammatidae) is an egg parasitoid of the African bollworm Helicoverpa armigera (Hubner) (Lepidoptera Noctuidae) in southern Africa. To determine the potential of T. lutea as a biological control agent of H. armigera, longevity, daily parasitism, fecundity, number of progeny per egg and sex ratio with regard to maternal age were examined under laboratory. The maximum longevity of T. lutea male and female adults was 14 and 16 days, respectively. Reproduction by T. lutea commenced on the day of eclosion and lasted for 14 days. The mean realized fecundity of T. lutea was 52 offspring per female. Daily fecundity and sex allocation depended on maternal age. Daily percentage parasitism and fecundity were highest on the day of eclosion and decreased with female age until no egg was parasitized from day 15. The sex ratio was femalebiased during the first three days, and thereafter became male-biased from day 4 until day 14. The number of progeny per host egg was also highest at 2.2 on the day of eclosion, then decreased to 0.9 on day 8 and thereafter increased to 2.0 on day 13. The overall sex ratio of T. lutea was approximately 1:1. The net replacement rate (R0), mean generation time (T) and intrinsic rate of population increase (rm) of T. lutea were determined at 25.5, 9.8 and 0.3, respectively. Findings from this study show great potential of T. lutea as a biological control agent of H. armigera.

African bollworm Helicoverpa armigera