|Akbar, W -|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 22, 2010
Publication Date: August 1, 2010
Citation: Akbar, W., Showler, A., White, W.H. 2010. Categorizing Sugarcane Cultivar Resistance to the Sugarcane Aphid and Yellow Sugarcane Aphid (Hemiptera: Aphidae). Journal of Economic Entomology. 103(4):1431-1437. Interpretive Summary: Aphids are a group of soft bodied insects that feed on the sap of plants. They are important pests of many agricultural crops. However, there are only two species that infest sugarcane in Louisiana: the yellow sugarcane aphid and the sugarcane aphid. Although both are capable of developing high numbers on sugarcane, it has not been determined if these aphids actually cause yield losses sufficient to justify implementing a control measure, e.g. an insecticide. One approach to answering this question is to conduct greenhouse studies designed to determine if currently grown varieties are susceptible or resistant to the insect and if they are determined to be resistant, what category of resistance is being expressed. From these studies it was determined that the variety HoCP91-555 was the most resistant variety currently being grown while L97-128 was the most susceptible. The greenhouse studies also demonstrated that the resistant varieties were categorized as resistant because they caused an adverse impact on the aphids reproductive potential. Growers in areas that consistently have high aphid infestations should plant more of the variety HoCP91-555. The study is useful to plant breeders as it shows that some varieties have resistance to the aphids therefore it would be beneficial to identify these and then use them in their breeding programs to develop additional aphid-resistant varieties.
Technical Abstract: Sugarcane in Louisiana is colonized by two aphid species, the sugarcane aphid, Melanaphis sacchari (Zehntner), and the yellow sugarcane aphid, Sipha flava (Forbes). The main problem associated with M. sacchari is transmission of sugarcane yellow leaf virus, a disease that has been added to certification standards for micropropagated sugarcane. Greenhouse pot studies were conducted to categorize commercial sugarcane cultivars for their ability to tolerate, or to express antixenotic and antibiotic effects on both aphid species. Antixenosis tests showed no preference among cultivars by either aphid species. Loss of chlorophyll content in tolerance tests also did not show differences among cultivars for both aphid species. However, antibiosis tests revealed that several life history parameters such as the reproductive period, fecundity, and longevity of both aphid species were affected on HoCP 91-555 as compared to L 97-128. Estimation of demographic statistics indicated that both aphid species exhibited a significantly lower intrinsic rate of increase, finite rate of increases, and longest generation time and doubling time on HoCP 91-555 relative to L 97-128. From these tests, cultivars in the current study can be ranked from most to the least susceptible as L 97-128> LCP 85-384> HoCP 96-540> Ho 95-988> HoCP 91-555 for M. sacchari, and L 97-128> LCP 85-384> HoCP 91-555 for S. flava. These studies suggest that antibiosis is the dominant basis of resistance in sugarcane to both aphid species, and HoCP 91-555 might be useful for developing aphid-resistant cultivars.