Potential investment tradeoff between offspring production and functional recovery promoted by larval cannibalism in Coccinella septempunctata (Coleoptera: coccinellidae).

Background: Since larval cannibalism is frequently observed in intensive rearing systems, the regeneration of lost legs is common for the beneficial species Coccinella septempunctata (Coccinella: Coccinellidae) to adapt to the competitive environment, but whether functional recovery occurs in the leg-regenerated coccinellids remains unknown. To evaluate the functional recovery of regenerated right foreleg after being damaged, the behaviors of leg-regenerated ladybugs containing predation, attachment, intraspecific competition, prey preference and fecundity were studied in the laboratory.

Results: The prey consumption and searching rate of leg-regenerated ladybugs decreased, and their handling time extended. A significantly reduced attachment coefficient was detected in leg-regenerated coccinellids. Because of the competitive inferiority, leg-regenerated ladybugs were greatly hampered in competition with normal opponents, and this inferiority led to a switch of prey preference from big-sized adults to small-sized first-second instar nymphs of Paratrioza sinica. However, although reduced functional abilities were examined, the leg-regenerated paternity had a higher reproductive output compared to the normal paternity.

Conclusion: Leg-regenerated ladybugs caused by cannibalism may make an investment tradeoff between egg fecundity and functional recovery. Thus, larval cannibalism potentially improves the offspring production of the biological control agent in complex environments. © 2018 Society of Chemical Industry.