Project No. 2337

PRIORITY PROJECT

Primary Supervisor

Dr Lena Grinsted – University of Portsmouth

Co-Supervisor(s)

Prof Alan Stewart – University of Sussex

Dr Yann Bourgeous – University of Portsmouth

Prof Matt Guille – University of Portsmouth

Summary

Biological pest control is key to sustainable solutions for intensive agriculture.

Spiders can provide effective pest control in the right circumstances, but their effectiveness is usually limited because most species are generalist predators that will engage in intra-guild predation, including cannibalism, when present at high densities.

We hypothesise that group living spiders are uniquely suited for pest control because of their unusually high tolerance of conspecifics and avoidance of cannibalism, allowing high predator densities.

The group living spider, Cyrtophora citricola, occurs in tropical and subtropical areas around the world, as well as southern parts of Europe. In southern Spain it associates with cacti that surround agricultural fields. It covers the cacti in dense webbing that functions as a substrate for other predatory and klepto-parasitic spiders (Argyrodes argyrodes; Holocnemus pluchei). The large webbing intercepts, and may help to control, a variety of flying insects such as the moth Tuta absoluta that has become a devastating pest of tomato crops worldwide. However, webs may also capture important crop pollinators.

The global occurrence of C. citricola and its group living tendencies makes it an ideal candidate for use in integrated pest management. However, the trophic and behavioural interactions within its community of predators and parasites must be understood to assess its ability to provide pest control, and to elucidate the optimal species composition within colonies for providing this ecosystem service.

The project aims to:
1) Determine the behavioural interactions amongst predators and parasites in a series of controlled lab-based experiments, while evaluating the effectiveness of spider communities to control T. absoluta.
2) Explore the trophic interactions amongst predators, parasites, pests and pollinators by manipulating species compositions in field settings and using meta-barcoding to analyse spider gut content (eDNA).
3) Construct advice for management of optimal spider-group community structure for providing pest control.

Candidates must have a strong interest in behavioural ecology. A good understanding of experimental design, experience conducting field work, and familiarity with the software R and with meta-barcoding are desirable, but not essential.