Effects of x-ray irradiation on male navel orangeworm (Lepidoptera: Pyralidae) on mating, fecundity, fertility, and inherited sterility

Authors: Light, Douglas; Ovchinnikova, Inna; Jackson, Eric; Haff, Ronald - Ron

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/19/2015
Publication Date: 7/12/2015
Publication URL: http://handle.nal.usda.gov/10113/61674
Citation: Light, D.M., Ovchinnikova, I., Jackson, E.S., Haff, R.P. 2015. Effects of x-ray irradiation on male navel orangeworm (Lepidoptera: Pyralidae) on mating, fecundity, fertility, and inherited sterility. Journal of Economic Entomology. 8(5):2200-2212. doi: 10.1093/JEE/TOV201.

Interpretive Summary: Male navel orangeworm moths, Amyelois transitella, were irradiated using a laboratory x-ray emitter to determine the dose needed to achieve complete egg sterility of mated female moths and inherited egg sterility of the following generation. Adult males were irradiated in a series of two experiments at 100-300 Gy and at 50-175 Gy. The number of eggs laid and rate of egg hatch for females mated with irradiated males was compared with the mating of normal unirradiated moths. The production of fertilized eggs was affected by exposure of males to dose levels of >50 Gy compared to unirradiated controls. Development of eggs to the pre-hatch larval stage was significantly reduced at exposure doses >100 Gy, with none developing at >125 Gy doses. Hatching of eggs was significantly decreased at exposure doses 50 to 100 Gy, while no eggs hatched at >125 Gy doses. The number of times females mated was affected at male treatment doses of >150 Gy, with the percentage of females found unmated increasing, while total mating and multiple-mated females decreased. Emergence of second generation adults was low and occurred only for progeny of parental males exposed to doses <100 Gy, with no adult emergence at >125 Gy. Though numbers of unfertilized eggs appeared similar for control and irradiated females, no second generation eggs hatched for the test exposures of 50 – 100 Gy. Based on our results, a dose of >125 Gy had efficacy in inducing both primary parental sterility in treated male moths and inherited sterility in the second generation of male and female moths. Thus, the navel orangeworm might be considered a candidate for the sterile insect technique (SIT) using adults irradiated at these moderate x-ray exposure doses. Being able to use a lower irradiation rate might allow for increased mating fitness and perhaps better SIT efficacy, especially when integrated with mating disruption suppression programs.

Technical Abstract: Male adult navel orangeworm, Amyelois transitella, were irradiated using a laboratory x-ray emitter to determine the dose needed to achieve complete egg sterility of mated female moths and inherited egg sterility of F1 generation. Adult male A. transitella were irradiated in a series of two experiments at 100-300 Gy and at 50-175 Gy. The fecundity and fertility of normal females crossed with irradiated test males was compared with the mating of nonirradiated moths. Female fertility in production of fertilized eggs was affected by exposure of males to dose levels of >50 Gy compared to unirradiated controls. Development of eggs to the pre-hatch larval stage was significantly reduced at exposure doses >100 Gy, with none developing at >125 Gy doses. Eclosion of eggs was significantly decreased at exposure doses 50 to 100 Gy, while no eggs hatched at >125 Gy doses. Mating frequency was affected at male treatment doses of >150 Gy, with the percentage of females found unmated increasing, while total mating and multiple-mated females decreased. Emergence of F1 adults was low and occurred only for progeny of parental males exposed to doses <100 Gy, with no adult emergence at >125 Gy. Though fecundity in numbers of unfertilized eggs appeared similar for control and irradiated females, no F2 eggs hatched for the test exposures of 50 – 100 Gy. Based on our results, a dose of >125 Gy had efficacy in inducing both primary parental sterility in treated male moths and inherited sterility in F1 male and female moths. Thus, A. transitella might be considered a candidate for the sterile insect technique (SIT) using adults irradiated at these moderate x-ray exposure doses. Being able to use a lower irradiation rate might allow for increased mating fitness and perhaps better SIT efficacy, especially when integrated with mating disruption suppression programs.