Utilizzo di tecniche elettrofisiologiche e comportamentali indirizzate al controllo eco-compatibile di popolazioni di insetti di interesse ambientale, sanitario e agronomico

The Mediterranean fruit fly, Ceratitis capitata Wied., is a worldwide pest for horticulture because of its high biological potential, the difficulty of control and the broad polyphagy, mainly addressed, in Southern Europe, to pomaceous (apples and pears) and citrus (oranges) cultures. Information in the literature on the olfactory sensitivity in the medfly is still incomplete and only a few data are reported on the responses to alcohols, aldehydes, esters and acids, but with no reference to the physiological state (Light et al., 1988). Aim of the present work was to obtain further knowledge on the typology and topology of olfactory chemosensilla on both - medial and lateral - antennal surfaces in males and females. In addition, their electrophysiological activity has been evaluated in response to extracts of fruits and foliage from various host-plants and their primary compounds in two different -wild and lab reared- medfly populations, also in relation to the sex and to the physiological (virgin vs. mated) state of the insects. HRSEM morphological analysis has highlighted the presence of 4 different olfactory chemosillum types on both the medial and lateral antennal surface which may be classified as basiconic, clavate, trichoid and grooved sensilla. No difference in number and distribution has been observed between sexes, except for the female lateral surface, where a statistically higher number of clavate sensilla was detected. The EAG responses show that 1) the male olfactory sensitivity of lab reared medflies to headspace collected from fruits of lemon, orange, clementine, prickly pear, apple and their relative foliage was higher than that of females, while an opposite situation was found for wild insects; 2) same results were obtained when virgin and mated insects were considered; 3) virgin males and females displayed a higher sensitivity than the mated ones in the wild and lab populations, respectively; 4) within each population, the olfactory sensitivity was higher in mated males than mated females in lab population, while the opposite was found for wild insects. The olfactory sensitivity of the medfly to host-plant fruits and foliage in relation to physiological state and rearing conditions is discussed.