Effects of selected nuts on the biology of Trogoderma granarium Everts

Trogoderma granarium is a devastating pest of stored products worldwide. This species has the potential to feed, survive and reproduce in non-grain commodities, including nuts. However, biology of T. granarium has scarcely been studied on nuts. Here, we studied biology of T. granarium and constructed life tables on four nuts: peanuts, cashews, pine nuts and pecans, with wheat as a control, via the age-stage, two-sex life table method. Notable differences in the performance of several biological traits were observed when T. granarium was reared on these food commodities. Overall, wheat, peanuts and cashews favored the rapid growth and development of T. granarium over those of pine nuts and pecans. Females of T. granarium reared on peanuts and cashews laid more eggs (52.00, 47.95 eggs/female, respectively) than those reared on pecans and pine nuts (27.67, 33.06 eggs/female, respectively). Among nuts, the preadult duration of T. granarium was shortest for peanuts (59.95 d) and longest for pecans (80.00 d). The values of the net reproductive rate were significantly greater for wheat, peanuts and cashews than for pecans and pine nuts (R0 =26.18, 19.07, 15.18, 8.30 and 9.92 offspring, respectively), whereas the reverse was observed for the mean generation time (T = 62.09, 66.08, 71.92, 85.18 and 83.29d, respectively). The data revealed that peanuts and cashews favored the rapid development of T. granarium, with enhanced fecundity, high net reproductive rate and reduced generation time. While T. granarium completes its life cycle on pine nuts and pecans, it develops significantly faster on peanuts and cashews under optimal conditions. Management must therefore target these high-risk nuts in warm, dry storage to prevent rapid infestation. Authorities should also monitor international trade of non-grain commodities, as infested products can facilitate invasion into new areas.