Role of supplemental foods and habitat structural complexity in persistence and coexistence of generalist predatory mites.

Alberto Pozzebon,Carlo Duso,Gregory M Loeb

doi:10.1038/srep14997

Abstract

Plant traits can influence the interactions between herbivore arthropods and their natural enemies. In these interactions generalist predators are often present, preying on herbivores and also on other arthropods in the same trophic guild. Variation in the strength of intraguild predation (IGP) may be related to habitat structural complexity and to additional resources outside the narrow predator-prey relationship. In this paper we study the food web interactions on grape, which involves two generalist predatory mites. We evaluated the effects of grape powdery mildew (GPM) as supplemental food, and habitat structural complexity provided by domatia. The inoculation of GPM resulted in higher predatory mite densities and reduced the negative impact of unfavorable leaf structure for one species. Access to domatia was the main factor in promoting population abundance and persistence of predatory mites. Access to domatia and GPM availability favored the coexistence of predatory mites at a low density of the intraguild prey. Our findings suggest that structural and nutritional diversity/complexity promote predatory mite abundance and can help to maintain the beneficial mites - plants association. The effect of these factors on coexistence between predators is influenced by the supplemental food quality and relative differences in body size of interacting species.

Highlights

Block that increased habitat structure created by tufts of non-glandular trichomes located at the conjunction of veins on the leaf blade mediate interactions among natural enemy arthropods, the plant and herbivores
We investigated if habitat structural complexity and a trophic supplement can affect Intraguild predation (IGP) between predatory mites, promoting coexistence of predators
The densities of T. pyri increased from 1.6 mites/leaf to 2.15 mites/leaf during the experiment on treatments with open domatia and in absence of the competitor A. andersoni (Table 2, Fig. 2)

Summary

Introduction

Block that increased habitat structure created by tufts of non-glandular trichomes located at the conjunction of veins on the leaf blade (acarodomatia or domatia) mediate interactions among natural enemy arthropods, the plant and herbivores. We used two predatory mite species that are important biocontrol agents on grapevine, Amblyseius andersoni (Chant) and Typhlodromus pyri Scheuten They can persist on grapevines with few or no mite prey potentially feeding on wind-borne pollen and plant-pathogenic fungi like Grape powdery mildew (GPM) Erysiphe necator Schw.[31,32,33,34]. Leaf traits of grapevines are often a better predictor of abundance of generalist predatory mites than the abundance of mite prey[35,36] These predators are known to engage in reciprocal intraguild predation representing an interesting case-study within this framework[37,38]. We investigated if habitat structural complexity and a trophic supplement can affect IGP between predatory mites, promoting coexistence of predators We hypothesized that these factors interact in a synergistic way thereby enhancing predatory mites persistence

Methods

Results

Conclusion