Phenotypic transformation affects associative learning in the desert locust.

Area of Science:

• Animal behavior
• Neuroscience
• Ecology

Background:

• Desert locusts undergo phase polyphenism, shifting from solitary to gregarious forms with population density.
• Phase change influences locust behavior, including feeding and social interactions.

Purpose of the Study:

• To investigate phase-dependent differences in associative learning in desert locusts.
• To understand the neuroecological mechanisms underlying adaptive feeding strategies during locust phase change.

Main Methods:

• Associative learning tasks involving odor-food pairings were conducted with solitarious and gregarious locusts.
• Locusts were subjected to crowding to induce the transiens phase, and their learning capabilities were re-evaluated.
• Specific learning paradigms assessed aversive and appetitive associative learning.

Main Results:

• Solitarious locusts acquired aversions faster than gregarious locusts.
• Acutely crowded solitarious (transiens) locusts showed a complete blockade of new aversive learning, while appetitive learning remained unaffected.
• Transiens locusts could override prior aversions with new appetitive associations, particularly with hyoscyamine-odor pairings.

Conclusions:

• Phase-specific aversive learning supports distinct feeding strategies in desert locusts.
• Crowding-induced suppression of aversive learning in transiens locusts is a critical mechanism for adapting to food-scarce environments.
• This neuroecological adaptation allows locusts to overcome learned avoidance and exploit available resources during population outbreaks.