A comparative study of biology and morphometrics of two different species of Earias on okra crop

Abstract

Okra shoot and fruit borers, Earias insulana and Earias vittella are the major pests of economically important crops like okra and cotton. It is important to understand pest biology and ecology before initiating control measures, however little is known about their comparative biology on okra. Therefore, we studied biometrics of E. insulana and E. vittella in laboratory conditions on okra fruits and recorded the duration of different life stages along with their morphological parameters, to differentiate both the species. Oviposition was comparable in both species, however, incubation period and oviposition period was shorter in E. vittella. Although incubation, oviposition, post-oviposition period were at par in both the species, but there was a significant difference in larval and pupa periods. Total life cycle being comparable in both species, the larval period was significantly longer in case of E. insulana (13.8 days), while its pupal period (8.5 days) was significantly shorter in comparision to E. vittella (9.9 days). Sex ratio in E. insulana and E. vittella was recorded as 1:0.72 and 1: 0.61 (male: female) respectively. Both species were slightly different in terms of their morphological parameters. This study provides basic knowledge about the biology of these pests that may be helpful while formulating IPM strategies against them in okra as well as cotton.