Comparative study of ovogenesis in the parasitoids of the diamondback moth, Plutella xylostella

Abstract

The Authors compared the ovarian conditions of three species, Apanteles plutellae, Diadromus collaris and Tetrastichus sokolowskii which were dominant parasitoids of P. xylostella in Miyazaki. They were reared on honey and water in the absence of the hosts, and the reproductive organs were examined. Ovaries of A. plutellae are composed of two pairs of ovarioles. Twenty to forty ripe eggs were counted in the ovaries of the wasp within 24 hours after emergence. The maximum number of the ripe eggs, 90-130, was observed in the wasps on the sixth day of adulthood. Afterwards, the conditions of the ovaries remained more or less constant. Ovaries of T. sokolowskii were usually composed of 12 or 14 ovarioles. Ten to twenty ripe eggs were observed in the wasps within 24 hours after emergence. The number of ripe eggs increased until the fourth day of adulthood, and 30 to 60 eggs were stored in the ovaries. Afterwards, the conditions remained unchanged. Ovaries of D. collaris were composed of six ovarioles. Newly emerged females had no ripe eggs in their ovaries. The maximum number of the eggs, 5-12, was observed in the wasps on the second day of the adulthood. Ovisorption began from the 6th day and continued indefinitely. No eggs were observed in the females reared for 20 days after emergence.