الفهرس | Only 14 pages are availabe for public view |
Abstract SUMMA-BY The onion bulb fly Eumerus amoenu~ Loew. is one of the main insects which infesting onion crop in Egypt either in field or in storage. The stored onion bulbs are destroyed by larvae, and loss in stored crop depends upon population density. Using of gamma radiation in controlling insects appears to have some advantages over other control methods. The objective of this study was to investigate gamma irradiation effects on E. amoenus which is considered one of the most important insects in Egypt. A.Effect of gamma radiation on different developmental stages: a- Egg stage: 1- Percentage hatchability of irradiated one and two-dayold eggs decreased by increasing dose. 2- Percent hatchability of 1 and 2-d-old eggs dropped to zero at a dose of 10 and 30 Gy. respectively. 3- Increasing of egg irradiation dose decreased percent pupation and emergence of 1 and 2-d-01d eggs. 4- As a resu1t of egg irradiation, egg-larvae and pupal duration of 1 and 2-4-01d eggs increased by increasing doses. 5- Females seemed to be more successful in emergence than males, when 1 and 2-d-old eggs were irradiated by different doses. b- Larval stage: 1- Bgg-larvae duration increased by increasing dose. 2- There was a gradual decrease in percent pupation by increasing dose. 3- The dose 50 Gy prevented adult emergence of 2-d-old larvae, while the dose 60 Gy was required to produce the same effect to fully grown larvae. 4- Females seemed to be more successful in emergence than males with all radiation doses used. c- Pupal stage: 1- Gamma radiation reduced fecundity and fertility of all matings for 1 and 7-d-old pupae. 2- The dose 4.0 and 90 G.r caused complete sterility for females and males of fu1ly grown pupae. respectively. 3- i’he dose 50 Gy prevented adult emergence of both sexes of l-d-old pupae, while the dose 90 Gy did not affect the adult emgergence of 7-d-old pupae. 4- Pupal irradiation caused a slight effect on pupal duration of I-d-old pupae. and did not affect the older ones. 5- Percent malformed adults of both sexes of I-d-old pupae increased at the dose was increased until it reaches to 100~ at the dose of 20 Gy, while the tested doses for the older ones gave normal adults. 6- Adult longevity of l-d-old pupae was reduced by increasing the dose while adult longevity of fully grown pupae was increased by’increaisng dose. d- Adult stage: 1- Fecundity and fertility of l-d-old adult reduced by increasing dose. 2- !he dose 60,150 and 50 Gy caused complete sterility for females, males and both sexes, respectively. B. Effect of gamma radiation on mating competitiveness: l 1- Irradiated males (1) mated with unirradiated males an females at ratio or 1 : 1 : 1 caused 24.4~egg hatch. 2- Increasing the ratio to 5 : 1 : 1 and 10 : 1 I 1 caused 11.7 and 2.2 percent hatch, respectively. 3- !be calculated competitiveness values for 3 ratios were 1.04, 0.6, and 2.2 respectively. 4- Males and females botll treated with a sterilizing dose ratio caused 68.8% infertility in the resulting eggs. 5- When the ratio of sterile males and females was increased to 5 : 5 : 1 : 1, 10 : 10 : 1 : 1 and 15 : 15 : 1 : 1 (I ! :I ~ : U t : u ~), the percentage infertility was 80.9, 92.7 and 100, respectively. 6- The competitiveness values for these flooding ratios were 0.88, 0.83, 0.93 and 1.00, respectively. |