Mechanisms of Olfaction in Insects - ResearchSpace@Auckland ...

General Introduction 27
Figure 1.7: Scanning electronmicrograph of adult male (left) and female (right)
antennaes of E.postvittana. The pheromone sensitive long sensilla trichodea are
present in higher numbers on the male antennae than the female (shown with yellow
arrow) suggesting a role in sex pheromone reception of male moths (Jordon, 2006).
Scale bars = 0.1mm.
Pheromone and plant volatile recognition experiments in E. postvittana have been
done using EAG response recordings of antennae and ORNs (Rumbo, 1981; Karg et
al., 1992; Suckling et al., 1996). The long sensilla trichodea localised in two radial
rows on each male antennal segments are sensitive to pheromone components
(Rumbo, 1981). This sensilla type is not present in the female antennae, as shown by
scanning electron microscopy (Figure 1.7). Experiments showed that each sensilla
(including the pheromone sensitive sensilla) had three ORN cells associated with it,
however, only two of these three were shown to be active in the pheromone specific
sensillum (Rumbo, 1983). To determine what specific plant odorants the male and
female moths respond to, EAG experiments and oviposition assays were carried out
(Suckling et al., 1996). The odorants were chosen based on their presence in fruit and
host plants of the moth (Table 1.2). These experiments revealed that eugenol, geraniol
and citral acted as oviposition deterrents while hexanal, linalool, nonanol, and octanol
were attractants for the moth.