Comparative life table analysis of Trichogramma bournieri Pintureau and Babault and Trichogramma sp. nr. mwanzai Schulten and Feijen (Hym., Trichogrammatidae) from Kenya

Abstract: Egg parasitoids of the genus Trichogramma (Hym., Chalcidoidea: Trichogrammatidae) have been successfully utilized for biocontrol of several lepidopteran pests world‐wide. Trichogramma bournieri Pintureau and Babault and Trichogramma sp. nr. mwanzai Schulten and Feijen, which are native to Kenya and recovered from Chilo partellus eggs, were compared with the aim of evaluating them for field releases in Kenya for the control of lepidopteran pests, particularly Helicoverpa armigera and Plutella xylostella in tomato and kale, respectively. Age‐specific life tables were constructed at the Institute for Biological Control (BBA), Darmstadt, Germany in 1999 using a cohort of 60 mated females each at 26 ± 1°C, 70 ± 10% relative humidity and 16 h light : 8 h dark photoperiod. The adult female performance and population growth statistics with associated standard errors were computed. There was no significant difference in adult longevity between selected strains of the two species. Trichogramma sp. nr. mwanzai showed significantly higher cumulative as well as daily mean fertility (75.97 and 18.11, respectively) compared with T. bournieri (47.83 and 13.24, respectively), and the respective proportion of female progenies were 52 and 72%. The intrinsic rate of natural increase was 0.309 and 0.306, while the net reproductive rate was 35.16 and 31.22 for T. sp. nr. mwanzai and T.bournieri strains, respectively. The study has also shown that there is no significant difference in the intrinsic rate of natural increase and the net reproductive rate between the two native species. In summary, there is difference between the two strains in their parasitization potential but not in population growth potential. Consequently, no preference can be given to one species when selecting for mass rearing purposes. Adult female performance is superior in T. sp. nr. mwanzai than in T. bournieri. Hence, the former strain should receive particular attention in future studies.