Stage-Specific Life Table Studies of Legume Pod Borer, Maruca vitrata Fabricius (Lepidoptera: Crambidae) on Different Pulses

The legume pod borer, Marca vitrata Fabricius, is one of the major stress factors
affecting the production of many grain legumes. Their webbing nature of flowers and pods
can cause severe infestation, leading to significant yield loss. Identifying the vulnerable stage
in the life cycle of an insect pest is critical for sustainable pest management. Hence, stage-
specific life table studies of this pest was conducted in response to feeding on pulses viz.,
pigeon pea (cv. CO-RG-6), green gram (cv. CO-GG-7), black gram (cv. CO-BG-6), cowpea
(cv. CO-7), and lablab (cv. Rohini) under laboratory conditions (27.9 ± 2.2 °C, 76.6 ± 9.1%
RH). The results revealed the highest egg mortality of M. vitrata (14.0%) on black gram and the lowest (6.0%) in lablab. Among five larval instars, maximum larval mortality was
recorded at the first instar stage of black gram (13.95%), followed by green gram (7.61%) as
against 3.13% on lablab. The highest survival rate of 1.00 was recorded in the third and fifth
instar larvae on pigeon peas and the third instar larvae on black gram. The maximum trend
index of 0.91 on pigeon peas showed the highest larval survival, and the highest generation
survival on lablab (0.44) and pigeon pea (0.43) indicating the emergence of a higher number
of female moths. In perusal of different parameters, lablab was found to be a comparatively
more suitable host for the ideal growth and development of M. vitrata.