Involvement of the Antennal and Maxillary Palp Structures in Detection and Response to Methyl Eugenol by Male Bactrocera dorsalis (Diptera: Tephritidae)

Abstract

The oriental fruit fly, Bactrocera dorsalis (Handel) is one of the most destructive pests of fruits. The discovery of methyl eugenol (ME) as a potent male attractant for this species has led to its successful use in area-wide fruit fly control programs such as male annihilation. While the antenna is recognized as primarily responsible for male flies’ detection of attractants such as ME, little is known of the involvement of the maxillary palp. Using behavioral assays involving males with intact and ablated antennae and maxillary palp structures, we seek to ascertain the relative involvement of the maxillary palp in the ability of the male fly to detect ME. In cage bioassays (distance of ≤40 cm from the source), >97% of unmodified males will normally show a response to ME. Here, we showed that 17.6% of males with their antennae ablated were still attracted to ME versus 75.0% of males with their palps ablated. However, none of the antennae-ablated males were able to detect ME over a distance of >100 cm. Furthermore, wind tunnel bioassays showed that maxillary palp-ablated males took a significantly longer time compared to unablated males to successfully detect and eventually feed on ME. These results suggest that although the antennae are necessary for detection of ME over longer distances, at shorter distances, both antennae and maxillary palps are also involved in detecting ME. Hence, those palps may play a larger role than previously recognized in maneuvering males toward lure sources over shorter ranges.

Preference and effect of gustatory sense on sugar-feeding of fire ants

“…Pontes et al (2014) have been reported that ablation of antennae flagellum and forelegs tarsi were a suitable technique for the study of gustatory behavior in R. prolixus. Chieng, Hee & Wee (2018) explained the role of antennae and palps in detection of methyl eugenol, they removed both pairs of palps and/or antennae of male B. dorsalis via sterile fine forceps. They reported that neither the ablation of maxillary pulp nor antenna was found to affect the survival of the experimental flies compared to untreated, intact males.…”

“…Antennal sensilla of Drosophila, ants, and Heliothis armigera, e.g. basiconic and trichoid have been reported as chemoreceptors (main olfactory sense and partially gustatory sense) (Chieng, Hee & Wee, 2018;Ghaninia et al, 2018;Kumar et al, 2015;Shields et al, 2018). Antennal sensilla chaetica have potential role in olfaction and gustation, in host location of female Ectropis obliqua moths (Long et al, 2018).…”

“…In insect, ablation is the most useful technique for blocking the sensitivity of sensilla (Chieng, Hee & Wee, 2018;Kunert & Weisser, 2005;Pontes et al, 2014;Potting, Perry & Powell, 2005). The pairs of palps and/or antennae of male B. dorsalis was removed via sterile fine forceps to study the response in detection of methyl eugenol (Chieng, Hee & Wee, 2018). In honey bees, to block the sensitivity of antennae, two-silicon compounds were used to cover the antennae (Letzkus et al, 2006).…”

Antennal and palpal sensilla of three predatory Lispe species (Diptera: Muscidae): an ultrastructural investigation

“…Maxillary palps mainly acted as gustatory sensory organ 37 that react to molecules with low or zero vapor pressure, involved in contact or short-distance chemosensory functions 38 , compared to that of antennae, which typically perceive more volatile olfactory signals or chemical cues 39 . Shiraiwa 40 pointed out that maxillary palps of fruit flies can improve their sensitivity to food odours, others suggested that maxillary palps perceive olfactory signals at shorter distance, and can be integrated with the signals perceived in antennae to allow better manoeuvring when approaching lures 41 . Larger maxillary palps of L .…”

Recent Advancements in Studies on Chemosensory Mechanisms Underlying Detection of Semiochemicals in Dacini Fruit Flies of Economic Importance (Diptera: Tephritidae)

“…Identifying the organ involved in the detection of male attractants is of much interest. Notably, recent studies have demonstrated that male attractants are detected not only by the antennae, but also by the maxillary palps, entailing different effects among fruit fly species [52][53][54]. For ME-sensitive B. dorsalis, ablation of male antennae remarkably reduced responsiveness to ME at a short range [52].…”