Developmental response of tropical warehouse moth, Ephestia cautella (Walker) (Lepidoptera: Pyralidae)s larvae to stored cocoa beans fermented at varied degrees

Abstract

Developing larvae of major insect pests like Ephestia cautella rapidly degrade stored cocoa beans through feeding and other biological activities on the beans. Completion of developmental stages of insects may be influenced by a number of biochemical factors triggered by the primary post-harvest processing of cocoa beans prior to storage. Hence, this study assessed the development of E. cautella from first instar larval stage to adult stage on cocoa beans fermented at varied degrees. Fresh ripening pods of Amelonado variety (N38) were harvested and fermented variedly at 0 -7 days, and sun-dried to about 5-6% moisture content. The variedly fermented cocoa beans (300 g/treatment) were infested with newly hatched first instar larvae of E. cautella (N=10) in a completely randomized design with four replications at 28±2°C and 70±5% relative humidity (RH). Days to adult emergence of the larvae of E. cautella on the cocoa beans varied significantly (P>0.05) between 0 day and 76.50 days in 4 days and 7 days-fermented beans, respectively. Significant variations occurred (P>0.05) in the total adult emergents of E. cautella, ranging between 0 and 8.25 in 4 days and 1 day fermented beans, respectively. This study reveals that the fermentation period of cocoa beans prior to drying and storage influenced adult emergence of E. cautella on stored cocoa beans, with 0 -3 days fermented beans highly susceptible to E. cautella's development to adult stage. Cocoa beans need to be fermented adequately for 4 to 7 days before drying to prevent insects' damage. Notably, 4-days fermented cocoa beans did not support E. cautella development to adult stage at 90 days post larvae-introduction. The 4-days fermented cocoa beans require further investigations for its nutritional suitability and importance in human diets.

Geomorphologic and allometric variations in the populations of adult cocoa moth, Ephestia cautella (Lepidoptera: Pyralidae) from Southwestern Nigeria

“…In each state, four locations were randomly selected based on available production data of high, medium and marginal production (Table 1) and were reared on cocoa bean samples from each location in the laboratory at ambient tropical conditions to obtain a stock culture per location. To obtain homogenous culture the method described by Oyedokun and Omoloye (2015) was adapted, in which adults (male and female) from each location were paired singly in mating and oviposition cages (18.5 cm top x 13.5 cm base x 19.5 cm height) diameter lined with black filter paper prior to introducing the adults to provide the contrast needed to collect the milky-white laid eggs. The eggs laid after 24 h were collected and placed in 90 mm diameter Petri dishes lined with black filter paper for eclosion.…”