Abstract

A study was made of insect pest problems in plantations of Albizia falcataria and Gmelina arborea in Kerala. Twenty-five species of insects were found associated with A. falcataria, of which all except 4 were recorded on this tree for the first time in India. The insect complex included leaf-feeders, sap-suckers and live tree borers, but most were minor pests. The bagworm, Pteroma plagiophleps Hamp. (Lepidoptera, Psychidae) formerly known as an occasional minor pest of the tamarind tree, is recognized as a serious pest of A. falcataria. Outbreaks of this insect occurred in some plantations which resulted in total defoliation in patches leading to large-scale tree mortality and growth retardation. The biology of this little-known species, its seasonal incidence, host range and distribution in Kerala are reported. It has now spread to Delonix regia planted as avenue trees throughout Kerala. For emergency control, several insecticides were tested and the most effective ones determined. Caterpillars of the plerid butterfly Eurema blanda silhetana caused occasional localised defoliation in young stands and the scolytid heetle, Xyleborus fornicatus bored into the stem of live saplings. Thirty-four species of insects were found associated with Gmelina arborea, of which all except 5 were recorded on this tree for the first time in India. The most serious was the tingitid bug, Tingis beesonal which erupted into outbreaks in young plantations and caused defoliation, leading to die-back of terminal shoot. Young plantations were also affected by the scolytid borer, X. fornicatus, as in the case of A. falcataria. The leaf and shoot webbing caterpillar, Epiplema fulvilinea caused moderately high defoliation on some occasions. The defoliating beetle, Calopepla leyana, recognized as a major pest elsewhere in India was present in small numbers but outbreaks were not noticed. The above 4 species are recognized as potentially serious pests; but their full impact can be judged only when more extensive plantationsare raised