Life Cycles of Neochetina bruchi Warner and Neochetina eichhorniae Hustache as Potential Biological Control Agents in the Semi Arid Zone of Nigeria

Abstract

Biological control is the use of living organism to suppress or control another living organisms, and it is cost-effective and environment-friendly. Water hyacinth Eichhornia crassipes infestations in Nigeria stifles economic uses of surface waters, and arthropods have been used as biological control agents to reduce water hyacinth infestations, with smooth water hyacinth weevils (Neochetina eichhorniae) and N. bruchi being the most utilized. However, these weevils are not easily available due to lack of insectaries in most ecological zones of Nigeria, which underscores the need for this study. The first step is to understand the life cycles of the weevils under the target ecological zones, so that they can be reared when the need arises. This study was conducted, with the aim of quantifying the lifecycles of Neochetina bruchi and Neochetina eichhorniae under the semi-arid Maiduguri conditions in Nigeria. The life cycles of the Neochetina species reared in the semi arid conditions show peculiar characteristics. No significant difference was observed between N. bruchi and N. eichhorniae in terms of egg duration. However, the larval stage of N. eichhorniae lasted for about 2 months, but only one in the case of month for N. bruchi. This study highlights the potentials of the two weevils (N. bruchi and N. eichhorniae) as potential biological control agents in the semi arid climate of Nigeria. The lifecycle of the weevils show that both weevils can act as biological control agents, but N. eichhorniae has greater potentials, given its longer-lasting larval stage.