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A secondary sexual character for sex determination of Cydia pomonella (L.) (Lepidoptera : Tortricidae) adults, trapped with kairomone lure

Auteurs : Fernández (Dario Eduardo), Cichon (Liliana), Avilla (Jesús) et Bosch (Dolors)

Année de publication : 2007
Publication : Bulletin de l'Organisation Internationale et Intégrée contre les Animaux et les Plantes nuisibles, Section régionale ouest-paléarctique (OILB/SROP)
Volume : 30
Fascicule : 4
Pagination : 273-278

Résumé :

Since the introduction of the pear ester, ethyl (E,Z)-2,4-decadienoate, in order to monitor adult Cydia pomonella (L.) (Lepidoptera: Tortricidae) populations, a fast, reliable and easy way to discriminate between sexes is imperative. Up to now, the main character used is the structure of the tip of the abdomen. The presence of a rectangular "black spot" in the centre of the under-side of the forewing of males has also been reported. Our objectives were to prove the occurrence of the secondary sexual character named as the "black spot" on the underside forewing of male codling moth, and to detect possible differences in the wing scales present in males and females inside and outside the "black spot" area. Adults from 9 lab and field codling moth populations from Spain, Argentina, Italy and France were collected. All the adults were checked for both characters: the tip of the abdomen and the forewing spot and they were classified as "positive" when the concurrence was confirmed and "negative" when there was not coincidence. The wings were observed under the Scanning Electro Microscope (SEM). More than 1,500 adults were observed. The "black spot" was visible with the naked eye in all but 3 males, but in these cases, it was observed under the stereoscopic microscope. Any female showed the "black spot". The scales present inside the "black spot" had more rounded edges at the tip compared to those on other areas of the same wing. On the other hand, female scales in different parts of the under-side of the forewing were comparable to those of the male outside the "black spot" area. However, female scales have more acute spikes at the tip. We conclude that the "black spot" in the under-side of the forewing of codling moth males is a reliable character to be used to distinguish between male and females of the species