Colored shading nets impede insect invasion and decrease the incidences of insect‐transmitted viral diseases in vegetable crops

Abstract

Abstract Black shading nets are commonly used to protect agricultural crops from excessive solar radiation and wind, and for water saving. Recent studies have demonstrated that when black nets were replaced by either red, yellow, or pearl nets ( C hromati N ets ™ ) of equivalent shading capacity, it increased the fruit yield and improved the quality of bell peppers ( C apsicum annuum L .) and tomatoes ( S olanum lycopersicum L .) (both S olanaceae). We studied the effects of these colored shading nets on the infestation by aphids [ M yzus persicae ( S ulzer) and A phis gossypii Glover (both H emiptera: A phididae)] and whiteflies [ B emisia tabaci ( G ennadius) ( H emiptera: A leyrodidae)], and the incidence of the viral diseases transmitted by these insects, for five consecutive years (2006–2010). These studies were conducted in the semi‐arid B esor region in southern Israel. The plants were grown in ‘walk‐in’ tunnels that were covered by several nets of 35% shading capacity in the range of photosynthetically active radiation. Although the shading nets permit free passage of these pests, the infestation levels of aphids and whiteflies in tunnels covered by either the yellow or pearl nets were consistently 2–3× lower than in tunnels covered by the black or red nets. In accordance with the pest results, when the incidences of C ucumber mosaic virus in pepper grown under the black or red nets ranged between 35 and 89%, they were 2–10× lower under the yellow or pearl nets. Similarly, when the incidences of necrotic P otato virus Y in tomato grown under black or red nets ranged between 42 and 50%, they were 2–3× lower under the yellow or pearl nets. Also, when the incidences of T omato yellow leaf curl virus in tomato grown under the black or red nets ranged between 15 and 50%, but they were 2–4× lower under the yellow or pearl nets. Putative mechanisms of crop protection achieved by the yellow and pearl nets are discussed.