The egg parasitoid Telenomus remus production and efficacy against the fall armyworm, Spodoptera frugiperda in Ghana: preliminary lessons
Since 2016, Africa has experienced the outbreak of the fall armyworm, Spodoptera frugiperda, that originated from the Americas. In less than 4 years, the new invasive species has invaded almost all African countries and spread into Asia, causing significant crop losses, especially for maize. The immediate solutions promoted by different countries were based on chemical use and in most of the countries, farmers have also applied unregistered products which may lead to serious adverse effects on both human and environmental health.
Fortunately, more than 12 parasitoids have already been identified, playing fortuitous biological control of FAW in Africa, opening the way for the development of conservation and/or augmentative biological control on the continent. Among the parasitoids identified, Telenomus remus Nixon (Hymenoptera: Scelionidae) was reported parasitizing the FAW egg masses in West, East and South African regions. It was reported in Ghana in 2019 in the southern part of the country and have been reared and maintained in the lab.
There have been some challenges in the mass rearing of T. remus on factitious hosts such as storage moths’ eggs. Our efforts to mass rear T. remus on two stored grain pest eggs, Cadra cautella (Walker) (Lepidoptera: Pyralidae) and Corcyra cephalonica (Stainton) (Lepidoptera Pyralidae) have not been successful so far. While T. remus could be reared successfully on FAW eggs, the cannibalistic behaviour in FAW larvae remains a huge constraint to obtaining enough adults to produce egg masses. Recent field trials on releasing T. remus to control FAW in maize initiated by CABI are providing promising results.
The way forward is to find suitable alternative host for the mass rearing of T. remus or improving the rearing of FAW to make it cost-effective.