Morphology and Morphometry of the Reproductive Tract of the Cotton Boll Weevil after Prolonged Feeding on Alternative Diets

SIMPLE SUMMARY: The cotton boll weevil is the main cotton pest in the Americas. Alternative diets induce reproductive dormancy and/or diapause in this weevil. This fact has led researchers to postulate that these boll weevils in reproductive diapause can survive during the off-season, colonizing the subsequent cotton crop. However, there are no data on whether these weevils fed for prolonged periods on alternative food sources can reverse the atrophy of their reproductive organs after being given a diet that favors reproduction, or if their advanced age may impair viable egg production and, consequently, their progeny. The results obtained confirm our hypothesis that feeding for prolonged periods with alternative diets (inappropriate for reproduction) affects the reproductive tract of male and female boll weevils differently, and females and old males may not reverse the atrophy of their reproductive organs even after accessing cotton squares. ABSTRACT: Anthonomus grandis Boheman (Coleoptera: Curculionidae) survives on alternative diets; however, this induces reproductive diapause. The objective was to evaluate the morphology and morphometry of the reproductive tract of this weevil after feeding on alternative diets. The experimental design was completely randomized with 160 replications and treatments arranged in a factorial design 3 × 3, represented by A. grandis adults fed on 3 food types (fragments of banana (T1) or orange (T2) endocarp, or with cotton squares of cultivar BRS 286 (T3, control)) and three evaluation periods (30, 60, and 90 days) and after each of these periods they were fed with cotton squares for 10 days. The reproductive tract of 100% of A. grandis females fed banana endocarp, orange endocarp, and cotton squares for 30 and 60 days and then cotton squares were morphologically adequate for reproduction, and after 90 days, only 50% of those fed cotton squares were in this condition. The length of the ovarioles and the width of the mature oocyte were greater for A. grandis fed on cotton squares and smaller in those with banana and orange endocarps. Histological sections reveal that male testes even with strong degenerative signals are already producing spermatozoa. On the other hand, females displayed ovaries with nurse cells in the tropharium and some maturing oocytes in the vitellarium. The body length was longer and the testis area and diameter smaller in males fed on cotton squares than in those with banana and orange endocarp. Anthonomus grandis females fed for ≥90 days with alternative food sources do not recover the functionality of their reproductive tract, even after consuming, for 10 days, a diet that favors reproduction. On the other hand, the males remain with their reproductive organs functional with this condition.