Physiological and Evolutionary Changes in a Biological Control Agent During Prey Shifts Over Several Generations

Area of Science:

• Ecology
• Evolutionary Biology
• Entomology

Background:

• Biological control agents often face prey scarcity post-release, leading to dietary shifts.
• Predators adapting to alternative prey can undergo significant physiological and evolutionary changes.
• Understanding these adaptations is crucial for assessing the environmental risks of biological control.

Purpose of the Study:

• To investigate the effects of experimental prey shifts on the life history traits, gene expression, and genotype frequencies of the ladybird beetle, *Cryptolaemus montrouzieri*.
• To explore short-term experimental evolution in a specialist predator under novel prey conditions.

Main Methods:

• Subjected *C. montrouzieri* to continuous feeding on aphids (*Megoura japonica*) or alternating between aphids and mealybugs (*Planococcus citri*) for four generations.
• Monitored life history traits (development, fecundity, survival, weight).
• Analyzed gene expression patterns and genotype frequencies, focusing on the *vitellogenin* gene.

Main Results:

• Aphid consumption led to reduced performance and significant physiological adjustments, including altered development and fecundity, and widespread gene expression changes.
• Performance traits like development time, adult weight, and survival showed partial recovery in aphid-fed lines over generations, suggesting adaptive evolution.
• A shift back to mealybugs accelerated fecundity recovery, correlating with a shift towards a specific *vitellogenin* gene genotype.

Conclusions:

• The specialist predator *C. montrouzieri* exhibits rapid adaptive evolution in response to prey shifts.
• Dietary changes induce significant physiological and genetic modifications, impacting fitness and evolutionary trajectories.
• The potential for rapid adaptation to novel prey by biological control agents necessitates careful consideration of environmental risks, particularly non-target effects.