Studies On The Reproductive Biology Of Tetrastichus Hagenowii (Ratzeburg) (Hymenoptera: Eulophidae)

Tetrastichus hagenowii (Ratzeburg) is a small eulophid parasitoid of cockroach egg capsules with a worldwide distribution. It is an important natural enemy to many kinds of cockroaches and plays a role on controling cockroaches population. The Periplaneta americana oothecae was selected as the host of T. hagenowii in the cultural room. In this paper the effect several factors on the reproduction of T. hagenowii, the effect of freezing cockroach oothecae on reproduction of T. hagenowii, the effect of feedstuff on development and reproduction of P. Americana, the applying of T. hagenowii by artificial rearing were studied respectively. The results were as follows:1 The effect several factors on reproduction of T. hagenowiiThe parasitic character of T. hagenowii is in parthenogenesis and sexual mode with 0% and 46.02% female descendant respectively. The most reproductive capacity of the females occurred in the first 5 days of their lifetime with a peak at the second day, eggs declined six days in emergence. The oviposition duration ranged from 1 to 11 with the mean oviposition duration of 3.63 days. A female wasp was capable of parasitizing 1 to 5 oothecae with the mean oothecae number of 1. The proportion of female was more than 60%.Female T. hagenowii has a pair of ovaries. Each ovary consists 8 to 12 of ovarioles. The number of ovarioles in both ovaries is identical the individual. One ovariole has eggs 1 to 6. The average of total eggs in ovary of 1-d-old female and 2-day-old female was 45.2 and 80.1 respectively. The mean total eggs in ovary of 4- to 7-d-old female from 62.5 to 70.4 and there were no significant differences between these age female.The effect of five constant temperatures (20, 25, 27, 30 and 33 degreesC) on the rate of development, the number of wasp emergence per oothecae, sex ratio and longevity of T. hagenowii were evaluated in laboratory. Developmental rate was directly correlated with temperature. Developmental rate was shorter at higher temperatures. The effective accumulated temperature and threshold temperature for development of T. hagenowii from egg to adult were 459.13 degree-day and 15.46 degreesC respectively. Neither the mean number of wasps emerging from each oothecae nor the sex ratio of T. hagenowii was affected by temperatures. The average of individual number of offsprings emerged from per oothecae (59.58 adults/oothecae) and percentage of female (78.81 %) produced were highest at 27 degreesC. Females lived significantly longer than males in all temperatures. The results indicated that the most favorable temperature range was 25-30 degreesC and a moderate temperature of 27 degreesC was optimal for T.