Diel Variation in the Abundance and Composition of the Predator Assemblages Feeding on Soybean Aphid, Aphis glycine (Hemiptera: Aphididae)

Abstract

The soybean aphid, Aphis glycines, has recently emerged as the most.harmful pest of soybean crops in the north central United States. Previous studies ·have shown potential for conservation biocontrol of this pest as a more economically and environmentally sustainable alternative to chemical pesticides. Research conducted so far on the diurnal natural enemy assemblage of soybean aphid points to large generalist arthropod predators, with coccinellid beetles being most efficient in controlling this pest. This study sought to describe the previously unstudied nocturnal predator community and assess its potential contribution to aphid suppression. This was accomplished by using surveillance video cameras to continuously monitor individual soybean plants infested with soybean aphid throughout the growing season at Kellogg Biological Station in Hickory Comers, MI. Predators observed on video were identified as specifically as possible and the abundance and time spent on soybean plants by each taxa was recorded. !he total abundance of each taxon was quantified to portray differences between day and nighttime communities. The results showed a significant difference in the generalist predator community between day and night. The major taxa observed in the diurnal community were Coccinellidae (lady beetles) and Anthocoridae (pirate bugs), correlating with previous studies. The nocturnal community appeared to be dominated by two groups of arachnids, the Opiliones (harvestmen) and Araneae (spiders). Overall nighttime predator abundance was less than daytime, but small sample size didn't allow for this to be confirmed yet. Future research is needed to clarify the significance of arachnid predators and other nocturnal· generalists to soybean aphid mortality and determine whether they have potential to offer biocontrol services to the management of this agricultural pest.