The benefits of intraguild predation for a top predator spider

Abstract

1. Intraguild predation (IGP) among generalist predators significantly affects the food web dynamics but the benefits of IGP for top predators are still unclear. 2. We offered diets consisting of aphids, of spiders, and their sequential mix (i.e. polytypic diet) to the spider Philodromus cespitum and measured its survival, weight, development, and fecundity. To avoid a species-specific effect, the aphid and spider prey consisted of several similarly sized species. 3. The spider diet prolonged survival in comparison to starvation while the aphid and polytypic diets enabled the highest survival of juveniles. The spider diet resulted in low weight gain and slow development in juveniles at the population level. However, the weight change was highly variable among individuals, and a substantial portion of the individuals engaging in IGP gained the most weight compared to other diets. The aphid and polytypic diets resulted in the largest weight increase and fastest development in juveniles at the population level, and there was little variability in the amount of weight gained among individuals. Diet did not affect survival of adult females, but females on the spider and polytypic diets had higher fecundity than those on the aphid diet. 4. While both the aphids and the spiders had energetic and nutritional value for Philodromus cespitum, a polytypic diet consisting of a mix of them improved overall fitness. IGP therefore seems to be an adaptive strategy of Philodromus cespitum, and IGP on small spiders may increase its performance in ecosystems where aphids are highly dominant pests.

Field investigation‐ and dietary metabarcoding‐based screening of arthropods that prey on primary tea pests

“…We hypothesize that C. blandum probably prey on the juveniles of these prey. However, the life stage of prey cannot be identified by the present method because the primers were not specific to any life stage (Yang, Liu, Yuan, Zhang, Peng, et al, 2017) spiders address energy limitations caused by scarce prey (Haghani et al, 2019;Michalko et al, 2021;Wise, 1995). Among the prey species, most included tea pests, and the three main tea pest species were found in the prey spectrum of C. blandum (Table S6).…”

“…Similar to the results of Yang et al (2021), a few spider species ( Neoleptoneta sp., Pardosa sp., and Theridion sp. ; Table ) were included in the prey spectrum of C. blandum , thus indicating intraguild predation (Michalko et al, 2021). Intraguild predation is a common phenomenon observed in diet analyses of spiders (Saqib et al, 2021; Yang et al, 2021), and it is likely an adaptive strategy that helps spiders address energy limitations caused by scarce prey (Haghani et al, 2019; Michalko et al, 2021; Wise, 1995).…”

“…; Table ) were included in the prey spectrum of C. blandum , thus indicating intraguild predation (Michalko et al, 2021). Intraguild predation is a common phenomenon observed in diet analyses of spiders (Saqib et al, 2021; Yang et al, 2021), and it is likely an adaptive strategy that helps spiders address energy limitations caused by scarce prey (Haghani et al, 2019; Michalko et al, 2021; Wise, 1995). Among the prey species, most included tea pests, and the three main tea pest species were found in the prey spectrum of C. blandum (Table ).…”

Density‐independent prey choice, taxonomy, life history, and web characteristics determine the diet and biocontrol potential of spiders (Linyphiidae and Lycosidae) in cereal crops

“…Spiders often preferentially forage for pests such as aphids, which have been recorded in the diet of up to 63% of spiders under field conditions (Sunderland et al, 1986; Welch et al, 2016). Some pest species can elicit a toxic effect on spiders (Bilde & Toft, 2001), but may be regularly predated regardless given the nutritional benefit they confer upon the spider, especially when diluted by other prey (Michalko et al, 2021; Toft, 1995). Spider foraging is thought to reactively redress nutritional deficiencies (Mayntz et al, 2005) and optimal nutritional intake can be achieved either by ingestion of high‐quality prey or nutritionally complementary alternative prey (Michalko et al, 2020; Toft, 2013).…”

“…Some pest species can elicit a toxic effect on spiders (Bilde & Toft, 2001), but may be regularly predated regardless given the nutritional benefit they confer upon the spider, especially when diluted by other prey (Michalko et al, 2021; Toft, 1995). Spider foraging is thought to reactively redress nutritional deficiencies (Mayntz et al, 2005) and optimal nutritional intake can be achieved either by ingestion of high‐quality prey or nutritionally complementary alternative prey (Michalko et al, 2020; Toft, 2013). Although alternative prey is thought to positively affect spider‐mediated biocontrol efficacy by enhancing predator fitness (Ostman, 2004; Roubinet et al, 2017), this is taxon‐specific and may increase intraguild predation, reducing the overall benefit of spider‐mediated biocontrol (von Berg et al, 2012; Davey et al, 2013; Moreno‐Ripoll et al, 2014; Traugott & Symondson, 2008).…”