Pupation Substrate Type and Volume Affect Pupation, Quality Parameters and Production Costs of a Reproductive Colony of Ceratitis capitata (Diptera: Tephritidae) VIENNA 8 Genetic Sexing Strain

SIMPLE SUMMARY: The Mediterranean fruit fly, Ceratitis capitata, is a pest of fruit and vegetables in many parts of the world. The Sterile Insect Technique (SIT) is used as an environmentally friendly method for the control and/or eradication of this pest. A critical step in the production of sterile insects in biofactories is when the larvae complete their development and begin metamorphosis to become pupae. Artificial substrates are used to facilitate pupation, but little research has been devoted to this critical moment in the life cycle of the insect. We tested seven pupation substrates and five substrate volumes for a reproductive colony of C. capitata VIENNA 8 genetic sexing strain for SIT application in Mexico. One type of cellulose and sawdust at relatively low ratios of substrate:larvae enhanced pupation and were more cost-effective to produce one million pupae than other substrates including fine wheat bran currently used in a SIT mass-rearing facility in Mexico. Our study contributes to improving rearing processes involved in SIT-based pest control. ABSTRACT: Adequate pupation substrates and substrate volume are critical factors in the mass-rearing of insects for Sterile Insect Technique (SIT) applications. To identify an ideal pupation substrate for a reproductive colony of Ceratitis capitata (Wiedemann) VIENNA 8 genetic sexing strain, we first examined pupation in cellulose from recycled paper (cellulose I), sawdust, fine wheat bran, vermiculite and coconut fiber using a volume of 2.5–12.5 mL of substrate for each 5 mL volume of fly larvae. We found a positive relationship between substrate volume and pupation, with cellulose I generating the highest proportions of pupation and coconut fiber the lowest. Higher proportions of female flies (white pupae) pupated in sawdust. The proportion of female fliers increased as substrate volume rose in sawdust and coconut fiber, whereas it decreased in vermiculite and cellulose. In a second experiment, we tested three types of cellulose differing in physicochemical characteristics (celluloses I, II and III), sawdust, and fine wheat bran using a substrate:larvae ratio of 1:1. The three types of cellulose produced the highest pupation levels. The highest proportions of female fliers were observed in sawdust, and cellulose types III and II. Cellulose III and sawdust at relatively low volumes were more cost-effective to produce one million pupae than other substrates, including fine wheat bran used in a mass-rearing facility in Mexico.