FINE MORPHOLOGY OF THE ANTENNAE OF DIASPIS ECHINOCACTI (BOUCHÉ) 1833 (HEMIPTERA: DIASPIDIDAE)

Abstract

FINE MORPHOLOGY OF THE ANTENNAE OF DIASPIS ECHINOCACTI (BOUCHÉ) 1833 (HEMIPTERA: DIASPIDIDAE).

The antennae in the Diaspididae are reduced to minute appendages composed of one antennomere called the “antennal tubercle”. Few or no setae can be found on the antennal tubercle, although some small pegs in cuticular invaginations can be seen. In Diaspis echinocacti, the single antennal seta arises from two fused sensilla at its base. The chemoreceptive (olfactory) function of these multiporous sensilla was demonstrated using crystal violet and Transmission Electron Microscopy (TEM), while further information was obtained using light microscopy (LM), confocal laser scanning microscopy (CLSM) and Scanning Electron Microscopy (SEM). Some hypotheses on the possible function of these sensilla are discussed: (a) a feedback system to regulate the production of the female pheromone; (b) for detecting a male pheromone (postulated), or (c) for detecting a pheromone (postulated) produced by the crawlers. The possible evolutionary reduction in the number of antennal sensilla by fusion is evaluated. The lowest number of setae is accepted as the derived status for the character.

Key words: host-plant kairomones; mass-rearing; Opuntia ficus-indica, prickly pear, morphology.