Electrophysiological and behavioural responses of chestnut moths, Cydia fagiglandana and C. splendana (Lep., Tortricidae), to sex attractants and odours of host plants

Abstract

EAG recordings were made from both males and females of Cydia fagiglandana (Zell.) and C. splendana (Hb.) on stimulation with the tortricid sex attractants (E,E)‐8,10‐dodecadien‐l‐yl acetate (E8E10‐12:Ac), (E,E)‐8,10‐dodecadien‐l‐ol (E8E10‐12:OH) and (Z)‐8‐dodecen‐l‐yl acetate (Z8‐12:Ac). The dose‐response curves of the various attractants were almost identical for males of both species. The order of increasing EAG sensitivity was E8E10‐12:OH < Z8‐12:Ac < E8E10‐12:Ac. In females, EAGs increased in the order E8E10‐12OH < E8E10‐12:Ac < Z8‐12:Ac. They were much less sensitive to the sex attractants; the EAG amplitudes to E8E10‐12:Ac were 20–50 times smaller than those of males. The antennae of C. fagiglandana females were about twice more responsive to the sex attractants than those of females of C. splendana. Recordings from single antennal olfactory cells of C. fagiglandana males showed responses of 1 or 2 cells on stimulation with the sex attractants and with volatiles from chestnut leaves. The diel spontaneous locomotor activities of both species as measured in actographs ran almost concurrently. Most moths were active during the first 4–6 h and the last 2.5 h of the night. During the day the moths were inactive, except females of C. splendana which already showed some activity at the end of the afternoon. A correlation appeared to exist between the locomotor activities and behavioural responsiveness to attractive odours. Behavioural responses of males and females were studied in a wind‐tube in the presence and the absence of an airstream. Female calling behaviour was observed. Results suggested that E8E10‐12:Ac is a main component of the female sex pheromone of both Cydia species. A stream of air, whether or not loaded with attractants, always induced antennal elevation and grooming of the antennae and palps in both males and females. Responses to upwind attractants only occurred after switching off the airstream. It is proposed that either (1) attractive odours in combination with an airstream may evoke an ‘internal excitatory state’ that finds active expression in standing air or that (2) intermittent stimulation with odours, which may occur in the unsteady air shortly after switching off the airflow, is indispensable for inducing upwind displacement. Branches of chestnut attracted both sexes and functioned as arrestants. Contrary to what was found in several other moth species, signals from the host plant did not appear to induce pheromone production. Males as well as females were attracted to E8E10‐12:Ac, to calling conspecific females and to the smear of abdomen tips cut off from calling conspecific females. With a paper loaded with E8E10‐12:Ac and three conspecific females present in the tube, the females lined up about 20 cm from each other and started to call. These results suggested that sensitivity of the females to their own sex attractants may permit them to detect the presence of other calling females, leading to settling and synchronization of pheromone production, and avoidance of pher...

Coding and interaction of sex pheromone and plant volatile signals in the antennal lobe of the codling moth Cydia pomonella

“…Den Otter et al, 1996;Hansson et al, 1989;Schneider et al, 1998), including C. pomonella (Ansebo et al, 2004), and the central processing of sex pheromone information in females has previously been studied in S. littoralis (Anton and Hansson, 1995;Ochieng et al, 1995;Sadek et al, 2002) and H. virescens (Hillier et al, 2006). In codling moth females, pheromone components elicited a response in PNs innervating a group of OGs in the lateral region of the AL, close to the entrance of the AN; these PNs also responded to a number of plant volatiles (Table2, Fig.3D, Fig.4B).…”

On the use of microwave radar devices in chronobiology studies: An application withPeriplaneta americana

“…These actometers have been shown to be sensitive enough to record flight and locomotor activity of individual insects such as tsetse flies (Van der Goes van Naters, Den Otter, & Maes, 1998), moths (Den Otter, De Cristofaro, Voskamp, & Rotundo, 1996;Renou, Berthier, Desbarats, Van der Pers, & Guerrero, 1999), Anopheles mosquitos ( Van de Broek, Den Otter, & Van der Pers, 1999), and fruit flies (Knoppien, Van der Pers, & Van Delden, 2000). In the present study, we describe a homemade microwave radar device for monitoring locomotor activity in insects and small mammals.…”

Comparative behavioral and EAG responses of female obliquebanded and redbanded leafroller moths (Lepidoptera: Tortricidae) to their sex pheromone components

“…Specifically, exposure to pheromone advances and/or increases the level of female calling in some species, which is thought to increase the probability of attracting a mate (Palanaswamy & Seabrook, 1985;Stelinski et al, 2006). It has also been suggested that autodetection may provide a mechanism by which females maximally distribute themselves among limited host-plant resources (den Otter et al, 1996). Others have speculated that female capability for detecting their pheromone may result in aggregations of females increasing local probability of attracting males (Birch, 1977) or that it may serve as a mechanism for lek formation (Schneider et al, 1998).…”