بررسی مقایسه‌ای ‌تاریخچه‌ی زیستی زنبورهای پارازیتویید تخم سن گندم Ooencyrtus telenomicida و Ooencyrtus fecundus

Two species of egg parasitoids of sunn-pest (SP), Eurygaster integriceps Puton (Hem., Scutelleridae), are Ooencyrtus telenomicida and Ooencyrtus fecundus (Hym., Encyrtidae), that have similar ecological range, and overlapping time of seasonal activity. Their fecundity-life tables has not studied together. On the other hand, high variation in parameter estimates is observed even on a single species in different studies. As a result, an intact comparison between species is impossible. Therefore, in this study a comparative study of the two species was carried out. A cohort including 25 females were coupled individually by the same number of males. All events were recorded from birth to death for all individuals. The emerged progeny was sexed to determine age-specific sex ratio. It was known that fecundus was a thelytokous population, that just produce female progeny without insemination. The telenomicida however was a arrhenotokous population with a 1:1 sex ratio, that decreased by a rate of 1% per day from an initial rate of 65% (S=0.648x-0.0116, R2=0.6975, F=76.10, df=1, 33, P<0.0001). Developmental time of telenomicida was slightly shorter (21.35±0.84 and 22.23±0.90 d respectively) and no protandry or protogyny was observed. Post-oviposition period of both species was very long and up to 74 d was recorded among the cohort. A few females lived up to 110th day. Longevity was shorter for males in telenomicida (52.0±6.5 and 74.6±5.32 for male and female respectively). All life table parameters except generation time and death rate was significantly different between the two species (P<0.01). Intrinsic rate of increase, net replacement rate and generation time was 0.1645±0.0042, and 0.1475±0.0024 d-1, 127.6±15.7 and 79.6±5.8 per generation, and 29.4±0.35 and 29.7±0.37 d for telenomicida and fecundus respectively. This data suggests a 60% advantage of arrhenotokous telenomicida over telytokous fecundus per generation, providing that unlimited resources be available.