|Legaspi, Jesusa - Susie|
Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2002
Publication Date: 12/1/2002
Citation: Setamou, M., Bernal, J., Legaspi, J.C., Mirkov, T.E. 2002. Parasitism and location of sugarcane borer (lepidoptera: pyralidae) by cotesia flavipes (Hymenoptera: Braconidae) on transgenic and conventional sugarcane. Environmental Entomology. 31(6):1219-1225.
Interpretive Summary: Sugarcane borer, Diatraea saccharalis, is successfully controlled by a parasite, Cotesia flavipes, in sugarcane in south Texas. However, a major pest, the Mexican rice borer, Eoreuma loftini, causes losses in sugarcane estimated to be about $10-20 million a year. The use of genetically- engineered sugarcane is one method being tested to control the Mexican rice eborer. A transgenic or genetically engineered sugarcane is a variety of sugarcane that was transformed to incorporate a gene called GNA (Galanthus nivalis agglutinin) from the snowdrop lily. GNA is known to have insecticidal properties against insects. However, effects of transgenic sugarcane on non-target insects such as the parasites will need to be studied. Thus, the objective of our research is to determine the effectiveness of parasites and parasitism rates of Cotesia flavipes attacking the sugarcane borer, D. saccharalis,in transgenic and conventional sugarcane. Under choice and no-choice types of experiments an using an olfactometer, we found that the parasites spent more time in odor zones that had more plant damage by the sugarcane borer compared to the blank (control) odor zones. Results of laboratory and field cage experiments indicated no differences in parasitism of sugarcane borer in transgenic and conventional sugarcane. The results of this study suggest that transgenic sugarcane expressing GNA would not significantly affect parasitism of the sugarcane borer in the field.
Technical Abstract: Location and parasitism of Diatraea saccharalis (F.) hosts by Cotesia flavipes (Cameron) were compared between hosts fed either conventional or transgenic sugarcane expressing Galanthus nivalis agglutinin (GNA) under choice and no-choice conditions. In olfactometer experiments, females of C. flavipes randomly visited the different odor zones available but spent significantly more time in odor zones corresponding to plants damaged by D saccharalis versus blank (control) odor zones. However, they spent similar amounts of time in odor zones corresponding to damaged-transgenic and conventional sugarcane. Laboratory and field-cage experiments showed that C. flavipes equally parasitized D. saccharalis feeding on transgenic and conventional sugarcane plants. Moreover, sex ratio and brood size of C. flavipes were similar on hosts fed transgenic or conventional sugarcane. The results of this study suggested that transgenic sugarcane expressing GNA would not significantly affect host location and parasitism of D. saccharalis by C. flavipes in the field.