Instar-specific defense ofColeomegilla maculata lengi (Col.: Coccinellidae): Influence on attack success of the intraguild predatorChrysoperla rufilabris (Neur.: Chrysopidae)

We conducted a laboratory study of the behavioural interactions between larval stages of the lady beetleColeomegilla maculata lengi Timberlake and an intraguild predator, the lacewingChrysoperla rufilabris Burmeister. Ladybird susceptibility to predation by third instarC. rufilabris is age-specific and influenced by larval defensive strategies. First and second instars ofC. maculata were captured more consistently by chrysopid larvae than third and fourth instars. Young coccinellids generally exhibit escape reactions (dropping, fleeing, retreating) but, do not survive after being caught by lacewings. In addition to escape reactions, older larvae may actively defend themselves by wriggling or biting, even after being pierced. The proportion of physical interactions that resulted in coccinellid death was significantly lower for older instars (<2%) than for first (35%) and second (19%) instars. Capture efficiency byC. rufilabris was related to the coccinellid-chrysopid size ratio. Dropping off the leaves, the most common defensive behaviour displayed by coccinellid larvae, contributed to reduce overall mortality of first instars to a level similar to the one observed for older stages. However, lacewings were able to prevent coccinellid dropping by impaling and holding their prey in the air, or by falling with the ladybirds to the ground where they continued their attack.