Research Geneticist, Crop Genetics and Breeding Research Unit USDA-ARS Tifton, Georgia, United States
The sugarcane aphid, Melanaphis sacchari (Hemiptera: Aphididae), is a widely distributed insect that attacks grasses in different genera including Saccharum and Sorghum. The invasive aphid superclone was first discovered in the US attacking grain sorghum in Texas in 2013 . Since then it has been found in at least 25 states including Georgia. Aphids feed on plant sap and can grow to such large numbers that the plants fail to produce a panicle and often die. Further, the aphid produces honeydew that encourages growth of sooty mold that not only reduce plant photosynthesis but the stickiness of the honeydew also disrupts grain harvest. In 2017, an epizootic in sugarcane aphid population on sorghum was observed in Tifton, GA. Since then epizootics were observed in the following years, with cyclical patterns of aphid population build ups followed by crashes, beginning in June to early September. To identify fungal pathogens causing these epizootics, we monitored aphid populations over a 3-yr period in three farms in Tifton, GA. Infected aphids were collected and set up for fungal isolation and identification. Using a combination of morphological features and multilocus sequencing data we identified different species of entomopathogenic fungi in the orders Entomophthorales and Hypocreales. Aphids with resting spores (Entomophthorales) have also been collected and will be processed in vivo for fungal identification.
