Parasitism behavior of the braconid wasps, Coccygidium luteum and Cotesia icipe and the interaction between the two parasitoids species and their host, Spodoptera frugiperda
The research focuses on studying the interaction (Synergy/competition) and reproductive capacities of two Spodoptera frugiperda larval parasitoids (Coccygidium luteum and Cotesia icipe) in Ghana. The research also studies the life span and larval instar preference of the parasitoids. Findings from the study will enhance knowledge on the tri-trophic interactions in the ecosystems of parasitoids and the fall armyworm. This will help understand the likelihood of successful population establishment of these larval parasitoids. Several parasitoids where obtained from fall armyworm larvae sampled in West Africa. The most promising ones where the Telenomus remus, Coccygidium luteum and Cotesia icipe. Before the introduction of Coccygiduim luteum and Cotesia icipe as a biological control agent option, one must critically study their bio- ecology to understand how effective they are in reducing the population of the fall armyworm pest population beyond economic injury level.
CABI in collaboration with IITA and the NARS of different countries identified ten parasitoid species of FAW in West Africa including Ghana between 2018 and 2019. These parasitoid species include two egg parasitoids, one egg-larval, five larval, and two larval-pupal parasitoids. Of particular interest, are two braconid larval parasitoid species, Coccygidum luteum (Brullé) and Cotesia icipe Fernandez-Triana & Fiaboe.which were identified in West Africa. In Ghana, C. luteum was one of the most abundant parasitoids, causing up to 19% parasitism to FAW, while C. icipe was very rear and caused less than 1% parasitism. By contrast in Kenya and Tanzania, the microgasterid C. icipe has become the most abundant larval parasitoid of S. frugiperda following its recent description from specimens obtained from Spodoptera exigua (Hübner) and Spodoptera littoralis (Boisduval). In addition, in the two East African countries, C. luteum was less abundant and has caused less than 10% parasitism to FAW. This situation calls for our curiosity to understand the reason for the sporadic occurrence of C. icipe on S. frugiperda in Ghana, compared to C. luteum, as an important step for developing a biological control programme in the country, based on the braconid larval parasitoid species.
The major purpose of this study is to provide enough scientific information on the behaviour and interaction of C. luteum and C. icipe, as well as their potential to control FAW larvae, as a base line to inform the necessity to consider one or both of the two parasitoids in an augmentative biological control programme in Ghana.