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.