Biology, Morphometric Characteristics and Life Table Parameters of the Okra Shoot and Fruit Borer, Earias vittella (Fabricius) (Lepidoptera: Noctuidae) under Laboratory Conditions

Abstract

Background: In a controlled laboratory environment, the morphometric characters, developmental biology, fecundity, sex ratio and life table of the okra shoot and fruit borer, Earias vittella (Fabricius), were studied. The insect exhibited four larval instars showing geometric growth in accordance with Dyar’s law. Methods: A cohort of 100 freshly deposited eggs was used to conduct life table analysis under laboratory conditions at 25±2oC and 70 ± 10% RH. Age-specific and stage-specific life table parameters were computed. Morphometric characters of all life stages were recorded using a Leica stereomicroscope. Fecundity, sex ratio, developmental durations and survivorship were also recorded. Results: The incubation period ranged from 1 to 5 days (3.30±1.26 days), while the total larval duration ranged from 4 to 14 days (8.63±1.89 days). The pupal period lasted 7 to 9 days (7.82±0.79 days). Adult longevity varied from 7 to 16 days in females and 6 to 14 days in males. Fecundity ranged from 146 to 181 eggs per female (161.5±24.91) and egg hatchability was 73.45±4.35%. The sex ratio (male: female) was 1:1.04. Life table analysis revealed higher mortality during egg and early larval stages. K-value analysis confirmed that early developmental stages contributed the most to generation mortality. These findings are providing essential baseline data for better integrated pest management of Earias vittella (F.) on okra.