Orientation Behaviour of Legume Pod Borer, Maruca vitrata Fabricius (Lepidoptera: Crambidae) on Different Pulses

The legume pod borer, Maruca vitrata, is recognized as serious insect pest on grain legumes and cause significant yield loss. Much research work has been carried out on management of M. vitrata with synthetic pesticides and biocides, there is paucity of knowledge on alternative non chemical methods to overcome this menace. Chemical signals from reproductive structures of host plants act as a key for lepidopteran phytophagous insects.

Effects of volatiles from flowers and pods of different pulses such as pigeonpea, greengram, blackgram, cowpea and lablab on orientation pattern of M. vitrata larvae and adult moths and attractance behaviour of male moths to their females were investigated under laboratory conditions by using multi arm olfactometer and wide spaced basins.

One day old female moths showed significantly maximum orientation towards flowers of pigeonpea (42.7%) while elder age groups had the orientation ranging from 0.0 to 34.0 per cent on blackgram flowers and control (without host) respectively. The order of host preference of M. vitrata larvae observed as cowpea (32.2%) >lablab (32.0%) >pigeonpea (18.8%) >greengram (9.0%) >blackgram (4.8%) >unsettled (3.0%). These results clearly showed the maximum preference of lablab by M. vitrata than other pulses tested. In an another experiment, one, two and three day old male moths had maximum orientation towards two day old females (31.3 to 40.0%) and this indicated more amount of sex pheromone emitted by female moths on two days after their emergence.