The taxonomy of Diadegma parasitoids of Plutella xylostella was recently worked out and Diadegma mollipla, a species of very variable morphology is considered the major parasitoid of P. xylostella in sub-Saharan Africa. After field surveys showed that parasitism rates of P. xylostella by D. mollipla in South Africa were much higher than those in Kenya molecular and morphological studies were initiated. Although morphological studies have not yet yielded any consistent differences preliminary PCR-RFLP results have shown that the two D. mollipla strains from South Africa and Kenya are different. However no differences were detected between two Kenyan strains of D. mollipla from P. xylostella and from the potato tuber moth, Phthorimaea operculella.
A Kenyan strain of Diadegma mollipla was reared in the laboratory on Plutella xylostella larvae. Laboratory experiments where conducted to determine some of the biological attributes of this parasitoid. Within a temperature range of 21-27°C the parasitoid's mean developmental period of 16.23 days was not significantly different from that of the host of 16.6 days. The sex ratio of the parasitoid progeny was 1:1.5 in favor of the females. Observations on mating behavior showed that newly emerged adults mated for 6-17 minutes (mean 7.61 minutes). Of the four treatments used to examine the influence of food on longevity, honey and sugar solutions significantly increased longevity for both males and females. On the honey and sugar solutions the females and males lived for up to 44 and 38 , and 34 and 28 days respectively. The parasitoids survived for an average of two days when not fed or given water only. The results are discussed in relation to those of other Diadegma species attacking the Diamondback moth in other parts of the world.
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA