Effect of fungicide sprays on spiders in vineyards

Abstract

Spiders are the most abundant naturally occurring predators in vineyards and play a crucial role in natural pest control. However, vineyards are frequently sprayed with fungicides, which can harm spider communities. Fungus-resistant grape varieties can drastically reduce this fungicide input. The spiders on grape vines that were sprayed with a variable number of fungicide applications in 32 vineyards in different landscapes in Southwestern Germany were recorded. Vineyards received between 0 and 14 fungicidal sprays of varying toxicity (cumulated hazard quotients for honeybee up to 6). The majority of spiders benefited from a reduction in the number fungicide sprays, particularly Dictynidae, Philodromidae, Theridiidae and Thomisidae. Overall, space web weavers, orb web weavers and ambush hunters were most strongly affected by the frequency and toxicity of fungicide applications. The response of spiders to the landscape were highly variable and included both positive and negative effects of the percentage cover of woodland. In conclusion, reducing the cumulative hazard of fungicides by reducing the number of fungicide applications is a key element in fostering spiders in vineyards.