Ant-lepidopteran associations along African forest edges

Area of Science:

• Ecology
• Zoology
• Entomology

Background:

• Forest edges in tropical Africa host complex interactions between caterpillars and territorially dominant arboreal ants (TDAAs).
• Understanding caterpillar coexistence strategies with ants is crucial for comprehending insect community dynamics.

Purpose of the Study:

• To investigate the diverse mechanisms by which caterpillars coexist with TDAAs in tropical African forests.
• To document the range of interactions, from avoidance to exploitation, between 22 lepidopteran species and 5 TDAA species.

Main Methods:

• Field observations of caterpillars and TDAAs in their natural habitat.
• Recording of interactions, including feeding habits, defensive behaviors, and ant-attendance.
• Transfer bioassays using last-instar caterpillars to assess acceptance by alien ant colonies.

Main Results:

• Caterpillars utilize silk for protection (Pyralidae, Nymphalidae) or possess physical defenses like bristles (Poritiinae).
• Some species engage in direct ant interactions, offering secretions (Theclinae) or obtaining trophallaxis (Polyommatinae, Miletinae, Lachnocnema, Eublemma).
• Caterpillars within ant nests exhibit specialized behaviors, including predation on ant brood (Euliphyra, Eberidae) and obtaining trophic resources (Eublemma).

Conclusions:

• Caterpillars exhibit remarkable adaptations for coexistence with ants, ranging from passive defense to active exploitation.
• Chemical cues, such as appeasing odors, play a role in acceptance by ants, but colony-specific cues can lead to rejection.
• Co-evolutionary processes between ants and caterpillars (both Heterocera and Rhopalocera) are evident in these tropical forest edge ecosystems.