COMPARATIVE KAIROMONAL CHEMICAL ECOLOGY OF DIABROTICITE BEETLES (COLEOPTERA, CHRYSOMELIDAE, GALERUCINAE, LUPERINI, DIABROTICINA) IN A RECONSTITUTED TALLGRASS PRAIRIE ECOSYSTEM

The olfactory response to volatile semiochemicals was determined for D iabrotica undecimpunctata howardi Barber, the spotted cucumber beetle, Diabrotica virgifera virgifera LeConte, the western corn rootworm, Di abrotica barberi Smith & Lawrence, the northern corn rootworm, and Dia brotica cristata (Harris), a nonpest species in a tallgrass prairie ec osystem and adjacent corn and cucurbit agroecosystems in Illinois. The results indicate that the divergence in response to plant volatiles b y these Diabrotica species can be correlated with currently accepted p hylogenetic groupings between the virgifera and fucata groups, as well as within the virgifera group. For example, cinnamaldehyde is most at tractive to D. u. howardi (fucata group), whereas 4-methoxycinnamaldeh yde is a specific attractant for D. u. virgifera (virgifera group). Th e 2 closely related species D. barberi and D. cristata (virgifera grou p) were both attracted to eugenol, cinnamyl alcohol, and 4-methoxyphen ethanol on one or more test dates. Although D. cristata is not normall y found in cucurbit blossoms, adults were attracted to traps containin g shredded blossoms of Cucurbita maxima Duchesne ex Poir. Furthermore, all 4 Diabrotica species responded to a multicomponent synthetic lure (a cucurbit blossom mimic), suggesting a commonality of response to c ucurbit blossom aroma. A review of the literature on Diabroticite chem ical ecology suggests cucurbit volatiles acted evolutionarily as synom ones, providing a primitive means of pollination for cucurbits. For se veral Diabrotica species, the olfactory response to these volatiles al so may have facilitated the finding of noncucurbitaceous pollen source s.