Abstract: Citrus leaf miner (Phyllocnistis citrella Stainton) is native to Asia and one of the most serious pests of Iran’s citrus nursery stocks. In the present study, the possibility of insect mass rearing on four various citrus hosts and the effects of gamma irradiation on the pupal mortality and reproduction of this pest were studied. Trifoliate orange and grapefruit showed less infection, while the number of pupae in Valencia oranges and sweet lemons cages was so high. There was not any significant difference between weight of male and female pupae among different citrus hosts, but generally the weight of male pupae was less than females. Use of Valencia orange or sweet lemons seedlings in especial dark emergence and oviposition cages could be recommended for mass rearing of this pest. In this study, the effects of gamma radiation at doses 100 to 450 Gy on biological and reproductive parameters of the pest has been determined. The results show that mean percent of pupal mortality increased with increasing doses and reached to 28.67% at 450 Gy for male pupae and 38.367% for female pupae. Also, the mean values of this parameter were higher for irradiated female, which indicated the higher sensitivity of this sex. The gamma ray irradiation from 200 and 300 Gy caused decrease in male and female adult moth longevity, respectively. The eggs were laid by emerged females, and their hatchability was decreased by increasing gamma doses. The fecundity of females in both combinations of crosses (irradiated male × normal female and irradiated female × normal male) did not differ, but fertility of laid eggs by irradiated female × normal male affected seriously and the mean values of this parameter reached to zero at 300 Gy. The hatchability percentage of produced eggs by normal female × irradiated male at 300 Gy was 23.29% and reached to less than 2 % at 450 Gy as the highest tested dose. The results of this test show that females have more radio-sensitivity in comparison to males.
Abstract: Scolothrips longicornis Priesner is one of the
important predators of tetranychid mites with a wide distribution
throughout Iran. Life table and population growth parameters of S.
longicornis feeding on two-spotted spider mite, Tetranychus
turkestani Ugarov & Nikolski were investigated under laboratory
condition (26±1ºC, 65±5% R.H. and 16L: 8D). To carry of these
experiments, S. longicornis collections reared on cowpea infested
with T. turkestani were prepared. The eggs with less than 24 hours
old were selected and reared. The emerged larvae feeding directly on
cowpea leaf discs which were infested with T. turkestani. Thirty
females of S. longicornis with 24 hours age were selected and
released on infested leaf discs. They replaced daily to a new leaf disc
and the laying eggs have counted. The experiment continued till the
last thrips had died. The result showed that the mean age mortality of
the adult female thrips were between 21-25 days which is nearly
equal life expectancy (ex) at the time of adult eclosion. Parameters
related to reproductive table including gross reproductive rate, net
reproductive rate, intrinsic rate of natural increase and finite rate of
increase were 48.91, 37.63, 0.26 and 2.3, respectively. Mean age per
female/day, mean fertile egg per female/day, gross hatch rate, mean
net age fertility, mean net age fecundity, net fertility rate and net
fecundity rate were 2.23, 1.76, 0.87, 13.87, 14.26, 69.1 and 78.5,
respectively. Sex ratio of offspring also recorded daily. The highest
sex ratio for females was 0.88 in first day of oviposition. The sex
ratio decreased gradually and reached under 0.46 after the day 26 and
the oviposition rate declined. Then it seems that maintenance of
rearing culture of predatory thrips for mass rearing later than 26 days
after egg-laying commence is not profitable.