The sugarcane aphid is a severe pest of sweet sorghum that can lead to complete crop failure. $16-25 million of sweet sorghum is grown annually in Kentucky US. Current management practices are limited and more need to be developed to improve the sustainability of sweet sorghum. Growers who practice organic agriculture must rely on insecticidal soap for chemical control, which provides inconsistent control of aphids. We propose the integration of parasitic wasp releases with insecticidal soap spray applications for sugarcane aphid management. Parasitoid releases will give organic growers another option to manage the sugarcane aphid, buffering against the inconsistency of insecticidal soap. Parasitoids deposit their eggs inside aphids, which hatch and kill the aphid as they develop. The parasitoid species Aphidius colemani has been found attacking sugarcane aphids in Mexico, can suppress sugarcane aphid populations in the lab and can be easily purchased by growers in large quantities for releases in their crops.
- Assess if mass releases of Aphidius colemani can suppress sugarcane aphid populations and reduce insecticidal sprays needed
- Improve sweet sorghum grower’s knowledge of effective sugarcane aphid management tactics
Sweet sorghum fields were selected in south central Kentucky, US in 2019. Fields were cultivated and managed by Amish growers for commercial production. Eight fields (0.4 -1.2 ha) were paired and randomly designated as either a control or a parasitoid release field. Fields were surveyed weekly for sugarcane aphids. At the first detection of sugarcane aphids in a parasitoid release field, parasitoids were ordered from the insectary and released 48 hours after delivery along the middle of the field. Parasitoids were released at a rate of 14,800 individuals per hectare. Fields were searched eight days after release for evidence of parasitoid attacks on aphids in the form of parasitoid pupae, called mummies. Insecticidal soap sprays were performed by growers once the sugarcane aphid had crossed the recommended action threshold of 10/40 plants checked having >50 sugarcane aphids on a leaf. Fields were sprayed regardless of treatment to protect grower’s crop. Effectiveness of parasitoids was assessed by reduction in sugarcane aphids and number of insecticidal sprays needed.