Changing Leaf Geometry Provides a Refuge from a Parasitoid for a Leaf Miner

Area of Science:

• Ecology
• Entomology
• Behavioral Ecology

Background:

• Endophagous arthropods use physical barriers for defense but leave tracks that increase predation risk.
• Leaf miners create mines on host plants, which serve as cues for their primary enemies, parasitoid wasps.
• The leaf-mining moth Acrocercops transecta exhibits distinct mine morphologies across its larval instars.

Purpose of the Study:

• To investigate how changes in mine form during larval development affect the parasitism rates of the leaf-mining moth Acrocercops transecta by the parasitoid wasp Aneurobracon philippinensis.
• To determine if the three-dimensional structure of tentiform blotch mines provides refuge against parasitoid attack.

Main Methods:

• Laboratory experiments involving controlled parasitization of A. transecta larvae in different mine types by A. philippinensis.
• Field data collection on parasitism rates across different larval instars of A. transecta.
• Comparative analysis of oviposition success rates on linear, flat blotch, and tentiform blotch mines.

Main Results:

• Successful oviposition rates by A. philippinensis were significantly lower on tentiform blotch mines compared to other mine types.
• Larvae transplanted into flat blotch mines experienced high oviposition rates, indicating age was not a deterrent.
• Field data showed a plateau in parasitism rates for fourth instar larvae, corroborating laboratory findings.

Conclusions:

• The structural complexity of leaf mines, specifically the three-dimensional tentiform blotch mines, provides an effective refuge for A. transecta larvae against parasitoid wasps.
• Different mine forms significantly influence the survival rates of endophagous larvae by altering their vulnerability to natural enemies.
• Mine morphology is a crucial factor in the evolutionary dynamics between herbivorous insects and their parasitoids.