Activity patterns in different developmental stages and sexes of Larinioides sclopetarius (Clerck) (Araneae, Araneidae)

The foraging behaviour in web building spiders involves: (1) placing the web in the habitat, (2) constructing the web, (3) attacking prey entangled in the web, and (4) ingesting prey (Leborgne et al., 1991). Foraging theory suggests that organisms should exhibit foraging behaviour that optimizes the relationship between benefits and costs (Schoener, 1971; Pyke et al., 1977). The two major benefits of foraging are a decreased risk of starvation and an increased ability to reproduce or grow (Abrams, 1991). While the material invested in each web may represent a majority of the spider’s daily energetic cost (Peakall & Witt, 1976; Prestwich, 1977), further potential costs of foraging are the risk of predation, stress from adverse physical conditions, and reduced time available for other fitness-enhancing activities (Abrams, 1982). Furthermore, the relative costs and benefits of foraging may vary according to the development and the sex of the individual (Higgins, 1995), and therefore one might expect different foraging strategies to be employed by individuals of different ages and sexes. Various studies have found differences in activity patterns of spiders in regard to sex (e.g. Alderweireldt, 1994) or stage of development (Hayes & Lockley, 1990; Bayram, 1996), but they do not provide an explanation for these differences. Similarly, studies have also pointed out relationships between prey availability and the seasonal activity patterns of spiders (e.g. Bradley, 1993). However, the optimization of the time spent foraging, which may vary with prey density, has rarely been studied in terms of optimal foraging theory (but see Caraco, 1980; Abrams, 1982). Our study aimed to address these issues by describing activity patterns with regard to the developmental stage, sex, and prey abundance in the nocturnal orb-web weaving spider Larinioides sclopetarius (Clerck). The spiders can occur in populations with very high densities consisting of individuals of various developmental stages and sexes. They live in permanent, functional independent aggregations in habitats Activity patterns in different developmental stages and sexes of Larinioides sclopetarius (Clerck) (Araneae, Araneidae)