Associative learning of visual cues in the fruit fly parasitoid Diachasmimorpha longicaudata: temporal dynamics and potential consequences on females' fitness

NUSSENBAUM, ANA L.; DEVESCOVI FRANCISCO; BACHMANN GUILLERMO E.; PACELLI FRANCO; GARBALENA MICAELA S.; SEGURA DIEGO F.

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2024

0013-8703

Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae) is a generalistlarval-prepupal parasitoid of true fruit flies (Diptera: Tephritidae). During host-seeking,females use visual information to locate the habitat of the host (fruit of various species). Previous studies have shown that females associate the colour of the host habitatwith the availability of hosts through associative learning. In this study, we aimed tounderstand how this process is reinforced as the number of positive experiences increases and also how stable this association is, when the positive experiences cease.Additionally, under the hypothesis that associative learning has adaptive value, weevaluated the benefits of learning in two contexts: one in which host larvae are still associated with the learned colour and one where larvae are associated with a differentcolour. Repeated exposure to the unconditional stimulus for 1, 3, 5, and 7 consecutivetraining bouts influenced the preference response, as the percentage of females thatpreferred the stimulus increases with the number of training sessions. This preferenceseems to be reversible, as we found that the memory duration declines as time sincethe last training bout increased. The results obtained regarding the benefits of learning showed that females that learned a particular colour associated with the host,spent more time in that colour, made more oviposition attempts, and produced moreoffspring compared to females that learned a colour that is no longer associated withthe host. This suggests that learning should not be fixed, and females would benefitfrom adjusting their behaviour to host availability. Such colour would allow femalesto find their host more efficiently, by associating cues that lead to host finding butalso modifying their response when the cues are no longer associated with a reward,which seems a reasonable strategy for parasitoids of polyphagous hosts infestingephemeral and changing habitats, such as fruit of different species.