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View related articles View Crossmark data Citing articles: 7 View citing articles Latent effect of gamma irradiation on reproductive potential and ultrastructure of males' testes of Culex pipiens (Diptera; Culicidae

a b s t r a c tThree substerilizing doses 50, 100 and 150 Gy of gamma radiation were tested against full e grown male and female pupae or against full-grown male or female pupae of Agrotis ipsilon.The results showed that fecundity of irradiated females crossed with irradiated males was decreased by increasing irradiation dose. The decrease in egg e hatchability % and increase in sterility % induced by gamma radiation were found to be positively correlated with the dose level. The parentage of larval and pupal mortality increased significantly (p 0.05) with the increase of used doses. In addition, larval and pupal durations were found to be significantly prolonged as a result of gamma-irradiation treatment. In general, the results obtained indicated that the biological action of gamma irradiation against A. ipsilon larvae was more remarkable when both crossed females and males were irradiated followed by irradiated females crossed with non-irradiated males.

Wheat flour samples were artificially infested with Corcyra cephalonica, Ephestia kuehniella, Tribolium confusum (separately) and with the three insect populations together. The effect of insects' infestation on wheat flour quantity and quality loss, fungal contamination and presence of mycotoxins was studied after two months of storage (25±2 o C and 65%RH). Wheat flour infested with insects was sieved into two portions (sieved and residual flour) after insects populations have been recorded. The results revealed radical changes in weight loss, population density of insects, nutritional composition, interaction between insects and fungal contamination in the flour samples. The maximum residual flour loss was recorded by C. ceplalonica followed by E. kuehniella while the minimum residual loss was induced by T. confusum. The flour consumption by the tested insects may be arranged in descending order as follows: three insects tested together > C. cephalonica > T. confusum > E. kuehniella. There was a significant correlation between the amount of flour consumed and insect population. Also, there was a significant increase in the total protein contents and decrease in the monosaccharaides and disaccharides in all infested sieved and residual flour samples tested. The average log total molds count in control flour samples was 1.28, while the average log of insect infested flour samples ranged from 2.36 to 4.34. Seven to ten fungal species belonging to five genera (Aspergillus, Penicillium, Cladosporium, Eurotium and Emercilla) were isolated from control and infested flour samples. Many fungal species were isolated from infested flour, but most of them belong to Aspergillus and Penicillium. Aflatoxins B1, B2 were detected in all flour samples, but at different levels. Ochratoxin A was not detected in the control samples and C. cephalonica flour samples while it was detected in flour samples infested with the other treatment.

AbstractIrradiation is a physical, environmentally friendly treatment which does not leave any residues in the product. It is increasingly used as an alternative to methyl bromide and other chemical fumigants for disinfestation of insect pest in stored grains. In this research, we try to evaluate the effect of low gamma irradiation doses in the range of 50–1200 Gy on the different stages of Callosobruchus maculatus. It was found that no adults emerged after irradiation of eggs at 450 Gy. No emerging adults (F1 generation) have been shown when larvae or pupae were exposed to 650 Gy. Also, no emerging adult has been shown from the parental C. maculatus adults irradiated with 650 Gy. When suppression of F1 generation was used for the measuring effective irradiation dose and phytosanitary efficacy, 650 Gy was required for disinfestation of cowpea seed weevils. The irradiation dose level of 650 Gy was used for the large-scale confirmatory tests applied to 27,754 adults of C. maculatus in cowpea seeds resulting in non F1 adults' production with a confidence level of 93.77%. All the physical and chemical characteristics of cowpea seeds were non-significantly (P ≤ 0.05) affected by the irradiation dose of 650 Gy. Meanwhile, this irradiation dose very slightly reduced the microbial load of cowpea seeds. We recommend the generic dose 650 Gy as the phytosanitary irradiation dose for the cowpea seed weevil.