Abstract

The bark caterpillar Indarbela quadrinotata is a polyphagous wood boring insect, attacking a variety of tree species in India. Although generally considered as a pest of minor importance in forestry, this insect is a serious pest in horticultural plantations of guava, apple, pomegranate, jujube, etc., in several parts of India. 1. quadrinotata is widely distributed in Kerala attacking a variety of tree species like Peltophorum pterocarpum, Delonix regia, Terminalia catappa, Casuarina equisetifolia, Swietenia macrophylla, Macaranga peltata, Anacardium occidentale and Ceiba pentandra. Recently, large-scale build up of this insect was noticed in some plantations of Paraserianthes falcataria in the southern Forest Circle, mainly at Punalur. Studies were made on the factors leading to the build up of this insect in plantations and its possible control. Among the factors favouring establishment of this insect, availability of appropriate alternative host plants which will enable survival of a residual pest population was found to be important. Age of the plants was also found to have direct relation with borer attack as saplings were found to be more susceptiable. At Punalur, the avenue trees of P. pterocarpum, S. macrophylla and D. regia were found tobe the major host plants of this insect. In plantations, infestation generally starts with the onset of premonsoon rains in late May. The signs of infestation become apparent from July onwards when the sleeve-like structure made of frass and excreta extending from the borer holes are seen on the trunk of affected trees. The rate of feeding was found to be faster during the summer months. Larval stage lasts for about 8 months. Pupation occurs within the tunnel, with the cephalic end of the pupa slightly protruding from the tunnel mouth. In the field, pupation was noticed to commence from late February onwards. Pupal period lasts for about 9 days. Control trials have indicated that plantations of P. falcataria can be protected from this insect by spot application of insecticides. Of the various insecticides screened against this insect, monocrotophos (0.1), quinalphos (0.1) and fenvalerate (0.08) gave best results