Ovipositors of female leafminers were examined
microscopically to locate and describe types of sensory receptors present. Two basic types were found: trichoid sensilla and basiconic sensilla. These receptors are believed to function as mechano- and chemoreceptors to
evaluate the suitability of a host plant for feeding, oviposition, and subsequent larval development.
Two greenhouse experiments were conducted to evaluate
the effects of photoperiod and application of plant growth
regulators on two factors: 1) feeding and oviposition site
selection and 2) spatial distribution of feeding and
oviposition sites on individual chrysanthemum plants. In
the photoperiod experiment, leafminers fed and oviposited
more intensely on chrysanthemums grown under short days (SD)
than on plants grown under long days (LD). Densities of
feeding punctures and larval mines on chrysanthemums grown
under SD was positively related to leaf height on the plant,
and negatively related to leaf trichome density. Spatial
distribution of feeding and oviposition sites within plants
under LD was variable, and no specific pattern of preference
was discerned. An experiment to determine the effect of
plant growth regulators on site selection by female
leafminers revealed no significant differences (P > 0.05) in feeding and oviposition densities on chrysanthemums treated
with plant growth regulators napthalene napthaleneacetic acid,
gibberellic acid, and daminozide.
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