Development of a Diet Production System for Conopomorpha cramerella (Lepidoptera: Gracillariidae), a Major Cocoa Production Pest in Southeast Asia and the Pacific Islands

Abstract

The development of artificial diets for the cocoa pod borer Conopomorpha cramerella, a major pest of cocoa plants, has undergone significant advancements. In this study, we present the success rates of two diet formulations, MM1 and MM4, which have been progressively improved. Nutritional composition analysis revealed that the MM1 diet differed from the natural host, cocoa pods, in several aspects, including protein, carbohydrate, and vitamin C content. To address these differences, modifications were made to the diet compositions, leading to the MM4 diet version. These modifications resulted in improved diet quality and reduced contamination, leading to enhanced success rates in all stages of C. cramerella development. Larval development, pupation success rates, and adult emergence rates were significantly higher in the MM4 diet compared with the MM1 diet. Moreover, the duration of larval development and pupal stage decreased, while adult longevity increased with the MM4 diet. The overall development success of diet-reared insects from egg to adult was comparable with that of insects reared on cocoa pods. However, the cocoon formation, body length and fresh weight of the adults reared on the artificial diets were lower than those reared on cocoa pods. This diet formulation provides a promising approach for laboratory rearing of C. cramerella and opens avenues for further research and mass-rearing initiatives to mitigate the impact of this pest on cocoa production.