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摘要
The purpose of this research was to determine the efficacy of ionizing irradiation as a phytosanitary treatment against the pink hibiscus mealybug, Maconellicoccus hirsutus Green (Hemiptera: Pseudococcidae), a species having major pest status in the Indian subcontinent and elsewhere. Various ontogenetic stages of M. hirsutus were exposed to gamma radiation at different doses to assess the metamorphic disruptions leading to lethality and/or adult sterility. Effective treatment doses (ED99.9) ranged from 28 to 371 Gy where induced lethality due to metamorphic arrest and prevention of adult formation were used as the measure of efficacy against the various irradiated pre-imaginal stages. Further, ED99.9 doses ranging from 30 Gy for the radio-sensitive egg stage to 88 Gy for the N-3-female-the most resistant pre-imaginal stage-were sufficient to induce sexual sterility in the parent generation (P) adults due to a carry-over effect of sub-lethal doses administered to the pre-imaginal stages. The ED99.9 values to induce sterility in adult females ranged from 112 to 235 Gy depending on the age of the irradiated adult females. Further, the effect of sub-sterilizing irradiation doses given to P generation adults was ascertained on the viability of their F-1 progeny. ED99.9 doses in the range of 37-79 Gy administered to P adult females belonging to various age groups were sufficient to induce the complete prevention of F-1 female adult formation. A gamma radiation ED99.9 dose in the range of 30-52 Gy administered to P adults-depending on which of the various age groups was irradiated-induced complete F-1 sterility. In addition, this study also examined sensory characteristics like color and weight loss, and physico-chemical features like total soluble solids, titratable acidity, pH, vitamin C and beta-carotene contents of irradiated table grapes, Vitis vinifera L.(Vitales: Vitaceae)-a major host of Maconellicoccus hirsutus-that were found to be unaffected by phytosanitary irradiation at the highest dose tested, 400 Gy. The results indicated that at least 371 Gy would be required to cause metamorphic inhibition in the most radio-resistant pre-imaginal N3 female stage and similar to 240 Gy to completely sterilize the most radioresistant adult gravid female stage. However, the phytosanitary dose could be further reduced to less than 200 Gy if the criterion of efficacy would be the prevention of the formation of F-1 N-2 nymphs. This criterion warrants pilot testing to validate the final gamma irradiation dose to be employed for phytosanitary irradiation. This range of quarantine doses would also ensure no damage to the nutritional quality of irradiated foods.
- 出版日期2016-10
