Effects of Grape Berry Moth Management Practices and Landscape on Arthropod Diversity in Grape Vineyards in the Southern United States

Abstract

Agricultural monocultures with intensive pest management practices reduce diversity and create instability in agricultural ecosystems, thereby increasing reliance upon pesticides. This study compares the influence of three insect pest management programs in vineyards on arthropod diversity as well as parasitism and control of grape berry moth (Endopiza viteana), the key pest of grapes (Vitis labrusca) in eastern North America. Vineyards in Bald Knob, Hindsville, Judsonia, Lowell, and Searcy, Ark., were managed with a range of intensity of insecticide use, a reduced insecticide program with Exosex-GBM dispensers for mating disruption, or no pesticide use in abandoned vineyards. Arthropod diversity and carabid (Carabidae) density in each vineyard was sampled with pitfall traps. Grape berry moth flight was monitored by pheromone traps. Grape berry moth–infested grapes were collected from the field and reared in the lab until parasites or moths emerged. There were significant differences in arthropod diversity between vineyard sites, with Shannon diversity index values generally higher in woods and managed vineyards with conventional sprays and/or mating disruption than in abandoned sites. Shannon index values for arthropod diversity were significantly lower at the vineyard edge in Searcy (recently abandoned), vineyard center and edge in Bald Knob (abandoned), and the vineyard edge in Hindsville (conventional sprays). In 2003, carabid density was significantly highest in the edge and center of the Hindsville vineyard (high insecticide usage) and the abandoned Bald Knob vineyard had significantly lowest carabid density. Apparently, insecticide sprays resulted in more food on the vineyard floor for carabids. The vineyard floor management was too variable among vineyards to deduce its effect on carabid density. With some exceptions, low-spray and no-spray vineyards generally showed greater diversity and parasitism of grape berry moth than high-spray vineyards. Parasitism was higher in some high-spray vineyards than in low-spray with mating disruption vineyards. Grape berry moth flight and berry damage were more dependent on spray timing than intensity. This study demonstrates that insect pest management programs impact arthropod diversity and parasitism. Further testing is needed to determine why parasitism of grape berry moth decreased in the vineyards using the mating disruption tactic.