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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #181433
Title: DEVELOPING THE STERILE INSECT TECHNIQUE FOR FALSE CODLING MOTH: INFLUENCE OF RADIATION DOSE AND RELEASE RATIO ON FRUIT DAMAGE AND POPULATION GROWTH IN FIELD CAGES

Author
item HOFMEYR, J - CRI/CITRUSDAL,S. AFRICA
item Carpenter, James
item BLOEM, STEPHANIE - IAEA, RALEIGH, NC

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2005
Publication Date: 12/1/2005
Citation: Hofmeyr, J.H., Carpenter, J.E., Bloem, S. 2005. Developing the sterile insect technique for Cryptophlebia leucotreta (Lepidoptera: Tortricidae): Influence of radiation dose and release ratio on fruit damage and population growth in field cages. Journal of Economic Entomology. 98(6):1924-1929.

Interpretive Summary: The false codling moth (FCM) is the most serious pest of citrus in South Africa, and it also is a pest of corn, cotton and many other crops. Many U.S. Federal and State Agencies have expressed concern that this pest could soon be introduced into the U.S. as a direct result of increased international trade and tourism between the U.S. and many African countries. USDA-APHIS Port Interception Network records indicate that these concerns are well founded. In this study we examine the influence of radiation dose and release ratio on FCM fruit damage and population growth in field cages. The number of damaged fruit per cage, the number of larval entries, and the number of FCM offspring per cage decreased as the overflooding ratio of sterile to fertile FCM increased. A significant reduction in egg hatch was observed in the progeny of crosses between F1 females or F1 males originating from the treatment cages when compared to crosses of F1 moths originating from the control cages. The lowest mean number of fertile F1 adult females and males was obtained from the 150 Gy and 10T:1U ratio treatment. This treatment also showed the lowest per generation rate of increase (<1 from the P1 to the F1 generation), suggesting that growth in the fertile population would have been prevented if releases of treated moths at this dose and ratio were maintained in the field. In countries where FCM does not occur (e.g., the United States), the technologies and methodologies developed for a sterile insect technique (SIT) program to control FCM in South Africa could be available for use in an eradication campaign should FCM become established as an exotic invasive pest. The results from this study serve to advance the development of these SIT strategies.

Technical Abstract: The effect of radiation dose and different release ratios of treated (T) to untreated (U) false codling moth, Cryptophlebia leucotreta (Meyrick), on the incidence of fruit damage, the competitiveness of the treated males, and population growth was examined inside field-cages. Navel orange trees were individually enclosed in large nylon mesh cages. Newly emerged adult moths treated with either 150 or 200 Gy of gamma radiation were released into the cages at ratios of 5T:1U or 10T:1U. The fruit was collected after four weeks and the number of damaged fruit and larval entries per cage were recorded for each treatment. Infested fruit was maintained in the laboratory until all emerging F1 progeny were collected and out-crossed to untreated moths of the opposite gender. Treatment had a significant effect on the mean number of larval entries and on the number of undamaged fruit per cage. The number of larval entries as well as the number of F1 progeny per cage decreased as the overflooding ratio increased. A significant reduction in egg hatch was observed in the progeny of crosses between F1 females or F1 males originating from the treatment cages when compared to crosses of F1 moths originating from the control cages. The lowest mean number of fertile F1 adult females and males was obtained from the 150 Gy and 10T:1U ratio treatment. This treatment also showed the lowest per generation rate of increase (<1 from the P1 to the F1 generation), suggesting that growth in the fertile population would have been prevented if releases of treated moths at this dose and ratio were maintained in the field.