SQUASH BEETLE TRENCHING BEHAVIOR - AVOIDANCE OF CUCURBITACIN INDUCTION OR MUCILAGINOUS PLANT SAP

1. Foraging patterns of the squash beetle, Epilachna borealis Fabriciu s (Coleoptera: Coccinellidae), in field cages are not consistent with the hypothesis that this beetle avoids leaves in which its feeding dam age has caused the induction of cucurbitacins. 2. E. borealis feeding does not induce accumulation of cucurbitacins inside or outside of fee ding trenches. 3. Cucurbitacins do not reduce the survival or growth r ate of E. borealis larvae. 4. High concentrations of cucurbitacins fai l to deter E.borealis feeding; rather, cucurbitacins are feeding stimu lants for squash beetles. 5. Trenching behaviour in E.borealis is facu ltative and correlates with leaf turgor and the degree to which sticky phloem sap oozes from damaged leaves. 6. Mucilaginous phloem sap in m any curcurbit species inhibits feeding by E. borealis when it is appli ed to beetle mouthparts.