BIOLOGICAL AND BEHAVIORAL STUDIES OF DALBULUS AND BALDULUS LEAFHOPPERS (MAIZE/ZEA, EGG MICROFILAMENTS, ESCAPE, OVIPOSITION, ACOUSTIC, MATING)

Behavior of leafhoppers in the related genera, Dalbulus and Baldulus (Homoptera: Cicadellidae) were compared in laboratory studies. Also studied were microfilaments produced by eggs of several leafhopper genera.;Differences in escape behavior were observed among six Dalbulus spp. and B. tripsaci. Those Dalbulus spp. that utilize Zea and Tripsacum as host plants were most responsive to a mechanical stimulus and those that are Tripsacum specialists were least responsive. D. maidis populations from areas where maize is grown seasonally, were more responsive than those from areas where maize is grown continuously. Males of most Dalbulus spp. and all D. maidis populations were more responsive than females. Escape behavior is discussed with respect to predation, trivial and migratory flights, and risks involved with escape by flight.;Egg placement by seven Dalbulus spp. on six-leaf stage maize was determined. Several oviposition patterns were apparent. A cluster analysis partitioned Dalbulus leafhoppers into three distinct groups which closely agrees with a phylogeny of the genus based on leafhopper morphology. Egg placement by Dalbulus leafhoppers is discussed in terms of their geographical distribution, habitat preference, and interspecific competition.;Waxlike microfilaments were discovered protruding from the anterior end of Dalbulus, Baldulus, Macrosteles, and Graminella eggs. The form and arrangement of the microfilaments are characteristic of monophyletic groups of Dalbulus spp. The filaments are produced by the egg 48-72 hr after oviposition at 26(DEGREES)C and can be regenerated if removed prior to eclosion. Removal of filaments does not impede egg hatch nor affect resultant nymphs. Function(s) of the microfilaments are unknown.;Male common calls (acoustic signals) of 10 Dalbulus spp. were compared and had significant variations among species but were not species specific. A cluster analysis of calls partitioned Dalbulus spp. into three groups, which with one exception, were similar to a phylogeny based on morphology. Besides common calls, Dalbulus males produce courtship, copulatory, rivalry, and distress calls. Dalbulus females produce only courtship calls. Dalbulus acoustic signals were compared to calls produced by other Auchenorrhyncha. The basic pattern of courtship and copulation for Dalbulus leafhoppers is described.