INSTAR-SPECIFIC DEFENSE OF COLEOMEGILLA-MACULATA LENGI (COL., COCCINELLIDAE) - INFLUENCE ON ATTACK SUCCESS OF THE INTRAGUILD PREDATOR CHRYSOPERLA-RUFILABRIS (NEUR., CHRYSOPIDAE)

We conducted a laboratory study of the behavioural interactions betwee n larval stages of the lady beetle Coleomegilla maculata lengi Timberl ake and an intraguild predator, the lacewing Chrysoperla rufilabris Bu rmeister. Ladybird susceptibility to predation by third instar C. rufi labris is age-specific and influenced by larval defensive strategies. First and second instars of C. maculata were captured more consistentl y by chrysopid larvae than third and fourth instars. Young coccinellid s generally exhibit escape reactions (dropping, fleeing, retreating) b ut, do not survive after being caught by lacewings. In addition to esc ape reactions, older larvae may actively defend themselves by wrigglin g or biting, even after being pierced. The proportion of physical inte ractions that resulted in coccinellid death was significantly lower fo r older instars (< 2%) than for first (35%) and second (19%) instars. Capture efficiency by C. rufilabris is was related to the coccinellid- chrysopid size ratio. Dropping off the leaves, the most common defensi ve behaviour displayed by coccinellid larvae, contributed to reduce ov erall mortality of first instars to a level similar to the one observe d for older stages. However, lacewings were able to prevent coccinelli d dropping by impaling and holding their prey in the air, or by fallin g with the ladybirds to the ground where they continued their attack.