Occurrence of Neogregarine-Like Protozoan <i>Farinocystis</i> sp. in an Artificial Diet Mass-Rearing System in the West Indian Sweet Potato Weevil, <i>Euscepes postfasciatus</i>（Coleoptera: Curculionidae）

Abstract

Abstract:In the process of the mass rearing of West Indian sweet potato weevils Euscepes postfasciatus Fairmaire on an artificial diet, the eggs of the weevil are washed and disinfected before inoculation to remove the risk of infection by the neogregarine protozoan Farinocystis sp. However, protozoan infection was recently detected in this mass-rearing system. To identify the infection route, we conducted a detailed investigation of the occurrence of the Farinocystis sp. infecting the weevils in larval rearing and egg collection containers. In the larval rearing containers, the infection rates at 8 weeks after egg inoculation were 56.1% for larvae, 14.7% for pupae, and 1.5% for adults. Investigations of 130 rearing containers detected only 5 containers with absolutely no infection. In the egg collection container, the infection rate increased with the number of days elapsed in both sexes but the rate of increase was significantly higher for males. These findings suggested that the treatment was not sufficient to completely eliminate or deactivate the Farinocystis sp. in the larval rearing containers, causing contamination of infected weevils in the egg collecting containers and, possibly, subsequent horizontal infection.