THE SYNCHRONIZATION OF THE LIFE CYCLES BETWEEN CALLOSOBRUCHUS CHINENSIS (L) AND ITS PARASITE ANISOPTEROMALUS CARANDRAE (HOWARD)

Abstract

Using the azuki bean weevil, Callosobruchus chinensis (L) and its parasitic wasp, Anisopteromalus carandrae (Howard) the developmental stage of the host attacked, the percentage of parasitism and the developmental duration of the parasitic wasp were examined in relation to the stages of host development under controlled condition of temperature (30℃) and relative humidity (70%), Discussion was done on the synchronization of the life cycles between the host and the parasite. It was ascertained that the host is parasitized at the 3rd to 4th larval instars or the pupal stage of its development. The 4th larval instars of the host were parasitized by all the wasps released, while the parasitization on the 3rd larval instars and pupae of the host were attained by a few of the released wasps. The percentages of parasitism changed with the progress of the development of the host larva as shown in Fig. 1. When the parasite attacked the host at the developmental stage of 11 to 17 days after being oviposited, the mean developmental duration of the parasite was about 14 days. In the host at the stage of 7 to 10 days after being oviposited, the parasites bred were divided into two groups, rapid and slow, concerning the duration of their development. The mean developmental duration in the rapid group was about 15 days. Individuals of the slow group grew depending upon the development of the hosts on which they parasitized, and their emergence took place about 8 days later than that of their host. When the parasites of this group emerged the 3rd instar larvae of the host in the next generation were available for parasite attacking. Therefore, the delay in the emergence of the parasite which was provided a host at the younger stage may be effective for the synchronization between the life cycles of the host and the parasite.