Life history parameters of the parasitoid wasp, Anisopteromalus calandrae (Hymenoptera: Pteromalidae) parasitizing cowpea beetle, Callosobruchus maculatus on six legumes species

Abstract

Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae) is recognized as a highly efficient biological control agent for several stored-product pests, targeting the late-instar larvae or pupae of various beetle species. Host plant metabolites may significantly affect species at the third trophic level. The life history traits of A. calandrae parasitizing Callosobruchus maculatus, which were reared on seeds from six legume species (broad bean, cowpea, lentil, green gram, chickpea, and soybean), were evaluated under controlled conditions of 27 ± 2 °C, 60 ± 5 % relative humidity, and a photoperiod of 10:14 (L:D) h. The longest development duration was recorded for soybean (28.56 days), while the shortest was noted for cowpea (12.41 days) and green gram (13.24 days). The parasitoid had the maximum female adult longevity (19.80 days) and fecundity (86.78 eggs) when reared on cowpea, whereas it demonstrated the lowest longevity (5.08 days) and fecundity (13.51 eggs) on soybean. The elevated values of net reproductive rate (R₀), intrinsic rate (r), and finite rate (λ) of A. calandrae were documented for the cohort raised on cowpea, while diminished values were seen on soybean. The life cycle parameters of A. calandrae were associated with the biochemical properties of the examined legume species. The energy stores of fourth instar C. maculatus larvae reared on various legume grains influenced the parasitoid's life history features. The potential correlation between the host plant metabolites and fourth instar larvae's energy reserves of C. maculatus with the life history traits of A. calandrae is explored. The findings could have implications for C. maculatus biological control.