Studies On The Biology And Ecology Of Tetrastichus Hagenowii (Hymenoptera: Eulophidae)

Tetrastichus hagenowii is a primary egg parasitoid of cockroaches. The color of the adult body is dark and they have strong taxis to light. The egg of T. hagenowii is elongate oval and slightly arched in the middle and its cephalic end only slightly narrow, the egg stage lasts 48-54 hours. The newly hatched larvae is smooth and translucent. Its head bears a pair of chitinised mandibles. There are pairs of spiracles on the both sides meso?and metathoracic segments and the first seven abdominal segments. The larval stage lasts 11 -26 days. The larvae void the meconium in the ootheca. The pupae stage lasts 20?2 days with the round thorax.Under 27±1℃, RH70±5%, L: D=14: 10 circumstances, the developmental period (from the egg stage to pupae) of T. hagenowii was 50.27 days. A female T. hagenowii could parasitize P. americana oothecae with the maxmium of 4 and the average of 2. 4 grains. The mean individuals of offsprings was 56. 7. After emerged from the oothecae, the parasitoids could immediately copulate. The male adults had evidently copulation competition. T. hagenowii takes sexual and parthenogenesis mode with the parasitism of 56.67±7.32 and 53.35±8.45 respectively. There was no different between its two reproduction modes. T. hagenowii hadn' t evidently preoviposition period. The highest egg parasited was at the first day after emergence.The effect of nutrient on adult life span was significantly. The longevity of the adults with 10% honey water was 30 days and water 20 days and 13 days with nothing respectively.Parasitism was much different in the age of Parasitoid. The relationship between parasitism (Y) and the age (X) of the parasitoid assumed Y = -10. 333X + 92. 165 (R2=0. 9508) when adults were supplied with 10% honey water, and Y = -9.699X + 92.529 (R2=0. 9207) when supplied nothing respectively. There was no difference in parasitism whether nutrition offered. The number of offsprings and the rate of emergence of F1 generation tended to decrease when the adult age of parasitoid rised.The female progeny was not affected by nutrient. Time of illumination didn' t affect the parasitism and sex rate as well. The effect of hostal egg age (X) on the parasitism (Y) was significant with the following equation: Y = -0. 6943X + 34.158 (R2=0. 9206) . Development period of the parasitoids was shortened when hostal egg age rised.There was a good relationship between the density of oothecae significantly and it's parasitism. It could be described with Holling II model: Na= 0.0125 TrN0 /(1+0. 0125ThN0). The effect of age (X) of T. hagenowii on the parasitism (Y) was significant. It could be simulated with the following equation a = 0. 1192P-0.01093.The parasitism of the oothecae was descending when they was handled in the temperature of -18 . The rate sex declined as well. When the oothecae was handled exceeded 4 hours, the numbers of parasitoids each oothecae emerged acutly dropping. The oothecae beinghandled exceeded 3 hours, the number of cockroach each oothecae emerged was 0. There were no difference in parasitism and emergence rate of their descendants.It could postpone the emergency of parasitoid adults for 20?110 days when parasitized oothecae ( pupe stage of the parasitoid) were stored at temperature of 8 and their decendant' s parasitism weren' t affected. While stored egg and larve stage of parasitoid the decendant' s parasitism were whereas.The parasitism was increased when the density of the parasite ids increased. It could be described with the following formula Y = 24. 05 ln X + 51.961. The proportion of females was statistical difference in each process. The emergence of oothecae if not parasited was simulated with following formula Y = 164. 77e-0.969X.Releasing of these parasitoids showed T. hagenowii had higher searching ability. Percentage of parasitism in four rooms of 20 square eter were 16. 55%, 23.5%, 66.54%, 70. 20% respectivly.