Paraserianthes falcataria (Lin.) Fosberg, native to the Indonesian archipelago is a fast growing tree species recently introduced to India. Its wood is light and is used for a variety of purposes for making fisherman's float, packing cases, plywood, pulpwood, matchwood etc.
Over 25 species of insects have been reported to attack this tree in Kerala, of which at least 2 species cause serious damage in plantations. This include a bagworm defoliator Pteroma plagiophleps Hamp.(Lepidoptera, Psychidae) and the tree borer Indarbela quadrinotata (Lepidoptera, Metarbelidae). The former species has been reported from plantations in central Kerala and the latter from the south.
I. quadrinotata is a polyphagous insect attacking a variety of trees like Casuarina equisetifolia, Prunus domestica, Acacia spp. and Anacardium occidentale. The larvae tunnel into the wood through the axils of side shoots and come out to feed on the bark through a sleeve made of frass and excreta webbed together extending from the tunnel mouth. Larval life lasts for about 8 months. Several larvae may attack the same tree at different locations in heavy infestations and this may result in serious injury to the bark. Apart from this, the holes left on the trunk lead to infestation by pathogenic organisms and the trees suffer from die-back. Affected trees also break at the points of attack. Data generated from plantations affected by I. quadrinotata indicate considerable reduction in the yield. The annual yield of timber from affected plantations was only 4.38 cum per hectare while yield ranging from 1040 cum/ha/annum has been recorded from healthy plantations. The impact of the borer I. quadrinotata on tree survival and timber yield in P. falcataria plantations will be discussed.
Key words: Paraserianthes falcataria, Indarbela quadrinotata, impact, Kerala, India.
Correspondence: George Mathew, Division of Entomology, Kerala Forest Research Institute, Peechi 680 653, Kerala, India
Telefax: 91-0487-782249