A parasitoid wasp induces overwintering behaviour in its spider host

Area of Science:

• Behavioral Ecology
• Parasitology
• Evolutionary Biology

Background:

• Parasites and parasitoids often manipulate host behavior.
• The evolutionary origins and specificity of such host manipulation are poorly understood.
• Polysphinctine wasps are known to alter spider web-spinning for pupation.

Purpose of the Study:

• Investigate the origin of behavior evoked by the parasitic wasp Zatypota percontatoria.
• Determine if host manipulation by Z. percontatoria is universal or host-specific.
• Understand the functional similarity of manipulated behaviors in different spider hosts.

Main Methods:

• Observed species-specific web manipulation by Z. percontatoria larvae in Neottiura bimaculata and Theridion varians.
• Examined natural web-building behaviors of unparasitized spiders.
• Induced similar behaviors in unparasitized spiders by altering environmental conditions.

Main Results:

• Parasitized N. bimaculata built dense webs; parasitized T. varians constructed cupola-like structures.
• Unparasitized N. bimaculata naturally build dense webs for egg sacs and overwintering.
• Unparasitized T. varians naturally build cupolas for overwintering.
• Induced behaviors in unparasitized hosts mimicked those evoked by the parasite.
• The evoked behaviors were functionally protective and occurred naturally in hosts during specific life stages.

Conclusions:

• The parasitic wasp larva evokes behaviors that are part of the host's natural repertoire.
• Manipulation is species-specific in its expression but functionally conserved, exploiting existing defensive strategies.
• This study reveals the origin of evoked behaviors as repurposed natural host behaviors.