Living on the edge: Detecting spatial associations between immigrating L. maculicollis adults, larvae and preferred host plants on golf course fairways

The annual bluegrass weevil (Listronotus maculicollis) (ABW) is a destructive pest of close cut golf course turfgrass in the Northeastern United States. ABW is controlled primarily with preventive insecticide applications targeting the adults as they migrate onto fairways from nearby overwintering sites in spring. Our goal was to develop sampling plans to predict larval infestations requiring control measures. We monitored ABW adult spatial distribution from emergence through oviposition. The spatial distributions of adults, larvae and their preferred hosts (Poa annua) in spatially referenced grids were analyzed by Spatial Analysis by Distance IndicEs (SADIE). Adults appeared to be randomly dispersed upon arrival on fairways, becoming increasingly more aggregated at peak densities. Significant aggregations of cumulative adult captures and larvae were found on edges of fairways when the entire width of fairways was sampled. Despite this, adult distribution rarely coincided with the following week’s spatial pattern, suggesting that adults actively disperse across fairways throughout the oviposition period. Significant spatial association was detected between cumulative adult counts and larvae, but rarely between either stage and P. annua. Sampling the edges of the fairways resulted in a more uniform distribution and significant spatial associations of both weevil stages during peak weeks, indicating potential for savings in sampling costs compared to sampling the entire width of fairways. Our results suggest that future research should address the potential for targeting controls to edges of fairways.