D3293: Volatile-mediated attraction of lacewing larvae (Neuroptera: Chrysopidae) varies among sorghum cultivars

The sugarcane aphid (Melanaphis sacchari Zehntner) is an invasive pest that can cause substantial yield loss and a reduction in grain quality in sorghum. Insecticides are currently the most effective way to suppress sugarcane aphids, but this strategy is costly and likely to lead to insecticide resistance. Instead, our study focuses on herbivore-induced plant volatiles (HIPVs) as a mechanism for improving biological control provided by resident natural enemies and reducing insecticide use and the cost of aphid suppression. Our previous work has shown that a parasitoid wasp, (Aphelinus nigritus), varied in its attraction to aphid-infested sorghum varieties. Some varieties, for example, produced extremely attractive HIPVs, while other varieties were not attractive to the parasitoid. Here, we wanted to explore the response of an aphid predator, green lacewings (Chrysoperla rufilabris), in choice experiments (plants with or without aphids) with a Y-tube olfactometer. We screened two sorghum varieties for variation in attraction of natural enemies to HIPVs induced by the aphid pest. Green lacewing larvae were significantly attracted to aphid-infested DKS3707, but were repelled by aphid-infested ATx3408/RTx436. Interestingly, the parasitoid responded in the same way to both of these varieties. The results of these experiments indicate that natural enemies from different taxonomic groups are attracted to HIPVs produced by specific varieties of sorghum, but repelled by other varieties. These results also suggest that HIPVs play an important role in the attraction of natural enemies and the suppression of sugarcane aphids.