Influence of Senegalia macrostachya seed availability on Caryedon furcatus (Anton & Delobel) oviposition behaviour and its larvae survival

Abstract

Senegalia macrostachya is a wild legume whose seeds are highly prized by the Burkinabe population. Unfortunately, they are severely depreciated during storage by the main pest Caryedon furcatus. However, very few studies have looked at the impact of the amount of S. macrostachya seeds on major biological parameters such as egg laying and development of C. furcatus. These data could contribute to better control of this pest. The aim of the study was to evaluate the impact of the quantity of S. macrostachya seeds on the egg laying behaviour of C. furcatus and on the ability of the larvae to weave their cocoons. Pairs of C. furcatus up to 24 hours old were placed separately with Petri dishes containing 5, 10, 20, 50, 100 and 200 seeds of S. macrostachya in four replicates per treatment. The seeds were renewed daily until the females died. After egg laying, the seeds were incubated until adult emergence. Our results showed that the rate of egg-bearing seeds increased significantly from 77.60% when the female had 5 seeds to 100% when she had 100 seeds. Similarly, the rate of larvae that were able to weave their cocoons increased significantly with the number of seeds. The variation in the amount of seeds and the number of pairs of C. furcatus has a strong impact on the behaviour and development of C. furcatus. The results suggest the need to control C. furcatus on S. macrostachya especially in case of mass storage for the benefit of the consumers.