Ecological Costs and Benefits of Teak Defoliator (Hyblaea puera Cramer) Outbreaks in a Mangrove Ecosystem

The Teak defoliator moth (Hyblaea puera) is a well-known pest causing significant economic losses on timber production from teak plantations during their seasonal outbreaks. Apart from Teak, it also attacks an alternative host plant, Avicennia marina, a prominent mangrove tree species abundant along the west coast of India, causing severe and extensive defoliation of Mangroves. However, the ecological role of this pest species in the mangrove ecosystem appears to be complex and is much less understood. Here we report the lesser known ecological aspects of Hyblaea infestation from the Mangrove ecosystem of Thane creek area of Mumbai, Maharashtra, India, based on our field observations. Beyond the apparent feeding damage and defoliation caused by the Hyblaea caterpillars, there are quite a few positive ecological services that these pests are rendering to the mangrove system, especially in the context of mangroves of Mumbai. These include promotion of mangrove diversity, nutrient enrichment and boosting of fishery yield. A possibility of genetic divergence between the Hyblaea populations feeding on Teak and Avicennia is also indicated based on obvious differences in behavioural and life history traits between the populations of this pest in Teak plantations and Mangroves. The paper throws up an apparent conservational dilemma of whether Hyblaea puera in the context of Mangrove ecosystem is a ‘pest to be controlled or a species to be conserved’ ?.