Expression of early and late-emerging phenotypes in both diapausing and non-diapausing Delia radicum L. pupae

Feeding preferences of nymphs of a predatory stink bug, Eocanthecona furcellata, to Spodoptera litura larvae fed with various food items were examined. Bugs preferred larvae fed with spinach leaves to those feeding on bean sprouts. Solvent extracts of S. litura larvae given spinach or lettuce leaves contained a large amount of (E)-phytol which was found to elicit the proboscis-protruding behavior of this bug. (E)-Phytol was not detected in similar extracts of larvae fed with bean sprouts containing no (E)-phytol. When S. litura larvae fed with artificial diets containing various amounts of chlorophyll, the (E)-phytol contents in those larvae and their feces increased in proportion to the dietary chlorophyll contents, indicating that (E)-phytol was derived from the chlorophyll ingested through hydrolysis. Bugs showed the proboscis-protruding behavior in response to extracts of larvae fed with spinach and lettuce leaves or a kidney-bean artificial diet, and their response depended on (E)-phytol contents. On the other hand, extracts of larvae fed with bean sprouts were not effective. When a larva fed with bean sprouts was treated with (E)-phytol and presented together with a larva fed with spinach leaves, bugs failed to distinguish between the two. These results indicate that (E)-phytol originating from chlorophyll in the prey diet serves as an important cue in the prey-locating behavior of E. furcellata.