Seasonal Life Cycle ofZatypota albicoxa(Hymenoptera: Ichneumonidae), an Ectoparasitoid ofParasteatoda tepidariorum(Araneae: Theridiidae), in Southwestern Japan

Abstract

The seasonal life cycle of Zatypota albicoxa, an ectoparasitoid of the house spider, Parasteatoda tepidariorum, was examined in Tōon, in warmtemperate southwestern Japan. The larvae were found all year round, but eggs, pupal cocoons, and adults were found only from March to November. In winter, only the medium second-instar larvae were found, suggesting that they are in diapause state. Seasonal occurrence of each developmental stage in the field indicated that this parasitoid produces more than four generations per year. The life cycle in Tōon is substantially similar to that in Hirosaki, in cool-temperate northern Japan, but some of the traits differed geographically. Occurrence of newly formed pupal cocoons was 2 months earlier and length of the season for growth and reproduction was 4 months longer in Tōon than in Hirosaki. Appearance of the pupal cocoon is more or less coincident with the period when monthly mean temperatures reach around 10°C. The observed geographical difference in the seasonal life cycle may be due to the difference in local climatic conditions, but not to a difference in seasonal host availability.