Differences in characteristics of egg sacs of Metepeirasp. in two environments of the Monte Desert, Mendoza, Argentina

JULIETA LEDDA; FLORENCIA FERNÁNDEZ CAMPÓN; COPPERI, SOFÍA; DANIELA SADOVSKY

Simposio; 2020 AAS Virtual Summer Symposium; 2020

American Arachnological Society

The guild of weaver spiders uses vegetation as an anchor for their webs. Therefore, an environment that has vegetation with greater structural complexity provides a greater number of anchor points, greater protection against predators (Stanska et al. 2018), a greater number of sites available for oviposition (Denis et al. 1998). The coloration of the eggsacs in some species varies as camouflage (Craig 2003). Other spiders camouflage the eggsacs with detritus (Barrantes 2007) or wrap eggsacs in a leaf (Moya et al., 2010) to protect the eggs against parasites and predators. I will compare eggsac characteristics and oviposition sites of Metepeira sp (Araneidae). at two different habitat types, creosote bush scrubs and Prosopis sp. forest patches in the Ñacuñán Biosphere Reserve located in the Monte Desert of Mendoza, Argentina. One of the objectives is to analyze whether the characteristics of the egg sacs and oviposition site differ between habitat types. Two pairs of sites corresponding to creosote Bush scrub and Prosopis forest were selected. In each site, egg sacs were collected by hand between November to April. I found a total of 27 eggsacs (scrub n=13; forest n=14). At the scrub site, there was a greater number of eggsac anchored to the vegetation, (62%) while in forests sites most of them were suspended by web threads (79%). Characteristics of eggsac recorded were: presence of detritus covering the sac (most common in scrub sites) and color of the ourlayer of the sac (brown/dark brown). There was an association between the presence of detritus and the oviposition site. Most of the egg sacs anchored to the vegetation contained detritus, while the egg sacs that were suspended from the web had no detritus. These data support the idea that the structure of the vegetation affects the microenvironment where the egg sacs are deposited and their external characteristics. These characteristics associated with the environment could be defense strategies against predators and parasitoids.