Evaluation of bacillus thuringiensis berliner for the management of rice leaf folders

Abstract

The study was conducted with the objective of survey and identification of the natural enemies of leaffolder and other lepidopterous pests of rice and to evaluate the efficacy of B. t. formulations against the leaffolders of rice. The survey was conducted at the Agricultural Research Station, Mannuthy and the Kerala State Agricultural Department Seed Farm, Mannuthy. The field trials to evaluate the efficacy of rice leaffolders were conducted at the Agricultural Research Station, Mannuthy during Kharif 1995 and Kharif 1996 . .. The present study revealed the occurrence of five viroses, two bacterioses and a nematode infection in the

various lepidopterous pests of rice.

Four Braconids, three

Ichneumonids one Eulophid, one Chalcid and a Bethylid parasite were also recorded from various lepidopterous pests of rice. The B.t. formulations tested were found to be effective against the leaf folders on rice. The percentage of leaf damage during Kharif 1995 showed the B.t. formulations Biotox, BTT, Biolep to be the best treatments. With respect ~to the grain yield, BTT was the best treatment followed by

Dipel, Biolep and Biotox. During Kharif 1996, Dipel followed by Biotox and monocrotophos were found to be the best in terms of percentage of leaf damage. Based on the yield during 1996, BTT was found to be the superior one followed by monocrotophos.

B. t formulations were found to be safe to predatory spiders, other predators and paras i toids of folders.

the leaf

The combination of BTT and C.m. GV was able t.o reduce the leaf damage and data on larval mortality showed the leaf folder larvae to be susceptible to the combination of BTT and C.m. GV. The GV of C. medinalis was found to be highly host specific.