Influence of shelterbelt (windbreak) resources on beneficial arthropod groups

Studies have established that non-crop vegetation can increase the abundance, fecundity and activity of beneficial insects within agricultural crops, potentially enhancing the biological control of pest insect species. A common source of non-crop vegetation in agricultural areas is the establishment or conservation of rows of trees known as shelterbelts, windbreaks or hedgerows. Although research has found a positive influence of shelterbelts on beneficial arthropod groups, the specific characteristics of shelterbelts that cause this increase is less well studied.

This study was undertaken to ascertain which features of shelterbelts were most significant in influencing pest and beneficial arthropods. Sixty shelterbelts throughout the Yarra Valley wine region of south eastern Australia were analysed for differences in features and structure such as the number and diversity of trees, shrubs, grasses, bark types, as well as location within a property and other abiotic factors. These characteristics were compared to arthropod capture rates over 5 months. Results indicate that the most prominent influence on beneficial arthropods is the density of the shelterbelt, with less dense shelterbelts exhibiting a higher capture rate of potential pest control agents, including parasitoid Hymenoptera. Low density shelterbelts may reduce wind speed facilitating improved flight without the impediment of vegetation, while high density shelterbelts may interrupt flight or provide barriers to movement into adjacent crops.