Spider Fauna of Semiarid Eastern Colorado Agroecosystems: Diversity, Abundance, and Effects of Crop Intensification

Abstract

Spiders are critical predators in agroecosystems. Crop management practices can influence predator density and diversity, which, in turn, can influence pest management strategies. Crop intensification is a sustainable agricultural technique that can enhance crop production although optimizing soil moisture. To date, there is no information on how crop intensification affects natural enemy populations, particularly spiders. This study had two objectives: to characterize the abundance and diversity of spiders in eastern Colorado agroecosystems, and to test the hypothesis that spider diversity and density would be higher in wheat (Triticum aestivum L.) in crop-intensified rotations compared with wheat in conventional rotations. We collected spiders through pitfall, vacuum, and lookdown sampling from 2002 to 2007 to test these objectives. Over 11,000 spiders in 19 families from 119 species were captured from all sampling techniques. Interestingly, the hunting spider guild represented 89% of the spider fauna captured from all sites with the families Gnaphosidae and Lycosidae representing 75% of these spiders. Compared with European agroecosystems, these agroecosystems had greater diversity, which can be beneficial for the biological control of pests. Overall, spider densities were low in these semiarid cropping systems, and crop intensification effects on spider densities were not evident at this scale.

Species composition, seasonal abundance and population dynamics of predatory spiders from cotton field plots of irrigated and semi-arid regions of Punjab, Pakistan

“…Sherawat (2012) observed 47 spider species from wheat crop fields of the district Sheikhupura, Punjab, Pakistan, while Naseem (2016) collected 54 spider species from citrus orchards in Pakistan. Bao et al (2018) also collected 61 spider species from rice fields, and Kerzicnik et al (2013) recovered 119 spider species from the wheat agroecosystems. Avalos et al (2013) captured 200 spider species from citrus cultures.…”

Increased grazing intensity in pastures reduces the abundance and richness of ground spiders in an integrated crop-livestock system

“…Furthermore, during a soybean cycle, there are at least eight pesticide applications, which represent a considerable quantity of chemicals that are harmful to invertebrate fauna (Řezáč et al 2010;Prieto-Benítez and Méndez 2011). Soybean harvesting also affects the spider community due to machinery traffic and particularly due to changes in vegetation structure (Kerzicnik et al 2013). There is no pesticide application or machinery traffic during the grazing cycle, but intensified grazing can affect the arthropod communities through environmental disturbance, changes in plant diversity and vegetation structure, and a reduction in total resource abundance.…”