ABSTRACT
Diachasmimorpha longicaudata (Ashmead, 1905) (Hymenoptera: Braconidae) is one of the most used parasitoids in biological control programs of tephritids worldwide. Nevertheless, the knowledge about search strategies related to its learning and memory ability for finding its host Anastrepha fraterculus (Wiedemann, 1830) (Diptera: Tephritidae) is still limited. We observed residence time (RT) and parasitism of D. longicaudata females from A. fraterculus larvae reared on artificial diet, guava or mango and later exposed to these fruits odors. We registered the learning behavior of female parasitoids conditioned with vanilla essential oil (VEO) and orange essential oil (OEO) and evaluated with the same volatiles in chemotaxis’ bioassays. We also recorded the memory of this parasitoid exposed to VEO. Insects were kept under controlled chambers (25 ± 2 °C, 70 ± 10% RH) with 14 h photophase (adults) or in the scotophase (immature). The chemotactic responses were recorded with a "Y" olfactometer and the parasitism (immature stage conditioning), in larvae kept in fractions with guava pulp, mango or without pulp (control). Parasitoids females reared on larvae maintained on artificial diet were exposed to VEO or OEO for 4 h and learning and memory (VEO) evaluated in olfactometer, every 24 until 72 h. Inexperienced females of D. longicaudata were more attracted to volatiles of mango and guava when contrasted with control. Nevertheless, the experienced ones presented higher RT to the odors from fruits that they developed. However, when the odors of these fruits were offered simultaneously, the RT was higher for mango volatiles. The percentage of parasitism of inexperienced wasps was higher on the presence of pulps and, to experienced, in the larvae with odors which it had been conditioned. RT of inexperienced females was significantly higher for acetone than for odors of oils. Female with previous contact with VEO responded more to this odor than to control, however, no differences were found in chemotactic responses of females pre-exposed to OEO. VEO odor memory was maintained at least 48 h. We conclude that experienced females recognized odors to which they developed and the oils to which they have been given experience, resulting in preference as to residence time, resulting in preference to them as to the residence time. However, recognizing interference factors in host-parasitoid communication may allow greater adequacy and reliability to use D. longicaudata in biological control programs.
KEYWORDS
Chemotaxy; parasitism; fruit fly; memory
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