Detecting Change in a Sorghum Field Infested by Sugarcane Aphid

The sugarcane aphid, Melanaphis sacchari (Zehntner), is a destructive insect pest of sorghum, Sorghum bicolor (L.) Moench. Outbreaks of sugarcane aphids were reported in commercial sorghum fields in Kansas, Louisiana, Mississippi, Oklahoma, and Texas. Infestations of sugarcane aphids in sorghum fields are initiated when winged aphids land on plants in the field and produce nymphs. Infestations in a field are not uniform and can increase rapidly in size and intensity. The study used airborne multispectral remote sensing to assess change over time in infestations by sugarcane aphids in sorghum fields. Differencing of bi-temporal normalized differenced vegetation index images followed by analysis of change depicted numerically in the image was effective for assessing the extent of temporal change in infestation by sugarcane aphids in a commercial sorghum field. Classification of normalized differenced vegetation index imagery from two dates into land-cover categories including one for sorghum infested with sugarcane aphid, followed by comparison of change in area and distribution of categories was also a useful method for assessing temporal change in infestations by sugarcane aphids in sorghum. Results indicated it was possible to detect and assess change in sorghum fields infested by sugarcane aphids, with 65% increase in area in a field severely infested by sugarcane aphids in only 1 week.