Abstract
Araniella cucurbitina (Araneae: Araneidae) is a widespread orb-weaver spider commonly found in agroecosystems. Mineral particle films such as kaolin, due to their protective or anti-feeding action, can represent an alternative to pesticides, especially in organic farming systems, but little is known about its effects on A. cucurbitina. Therefore, we tested the effect of kaolin sprays on the life span of A. cucurbitina under laboratory conditions. Four treatments were tested encompassing different exposure routes. Thus, kaolin sprays were applied on (i) the surface, (ii) the prey (fly), (iii) the spider and (iv) both spider & prey. A control group was tested with water in each treatment. Results showed that sprays of kaolin significantly affected the survival of A. curcubitina when applications were done on the surface and on both spider & prey registering a reduction of 48% and 56%, respectively. Spiders in control obtained higher probability of reaching alive at the end of the assay than those treated with kaolin. Differences observed can be explained by the feeding behavior of the species and may depend on the consumption of the web by the spider and the ratio spider/fly for body size.
Highlights
Pest management strategies commonly involve the use of agrochemicals in order to maintain or improve crop yield for feeding the world population (Arias-Estevez et al, 2008)
Regarding the reduction of survival registered at the end of the experiment, kaolin caused a reduction of 56% when compared with control in the Spider & Prey treatment followed by Surface with 48%, Prey with 14% and Spider treatment with 2%
In the field, the risks of kaolin treatment to spiders may depend on their foraging mode, our study suggests that the exposure route can be relevant for spider's survival
Summary
Pest management strategies commonly involve the use of agrochemicals in order to maintain or improve crop yield for feeding the world population (Arias-Estevez et al, 2008). Kaolin is a white aluminosilicate mineral clay, chemically inert over a wide pH range that has been widely used in a variety of industrial applications, including paints, cosmetics, pharmaceuticals and agriculture (Glenn et al, 1999; Glenn and Puterka, 2005; Knight et al, 2000) The interest for this natural substance is reflected in the number of works covering different crops such as pear (Puterka et al, 2000; Daniel et al, 2005), apple (Knight et al, 2001; Friedrich et al, 2003), olive (Pascual et al, 2010), walnut and almond (Rosati et al, 2006), citrus (Hall et al, 2007), wine grape (Glenn et al, 2010), pecan (Cottrell et al, 2002), cotton (Showler, 2003; Silva and Ramalho, 2012), tomatoes (Kahn and Damicone, 2008) and cabbage (Alavo and Abagli, 2011). Those and other studies showed kaolin as an effective substance in reducing the population of
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