Spatial Organization of Antennal Olfactory Sensory Neurons in the Female Spodoptera littoralis Moth: Differences in Sensitivity and Temporal Characteristics

Abstract

Single-cell recordings from olfactory sensory neurons (OSNs), housed in sensilla located at the base and at the tip of the antenna, showed selective responses to plant odors and female sex pheromone in this polyphagous moth. A spatial variation existed in sensitivity: OSNs present on the more proximal segment (P) were more sensitive than those on the more distal segment (D). OSNs of the 2 locations also differed in temporal characteristics: OSNs on P had shorter latency and displayed more phasic responses, whereas those on D had more tonic responses, especially at low stimulus concentrations. The 196 OSNs responding to our 35 monomolecular stimuli in the screening were housed in 32 functional sensillum types: 27 in basiconic, 3 in long-trichoid, 2 in coeloconic, and 3 in auricillic sensilla. The OSNs in basiconic, coeloconic, and auricillic sensilla responded to plant-associated odorants, whereas OSNs in long-trichoid sensilla responded to female-produced sex pheromone components. Short-trichoid sensilla showed spontaneous activity, but no responses to any odorant tested. OSN specificity to plant stimuli ranged from highly specific to broadly tuned, but it did not differ clearly from females in more specialized moths. OSN response diversity is discussed in terms of olfactory coding, behavior, and ecological specialization.

Evolution of two receptors detecting the same pheromone compound in crop pest moths of the genus Spodoptera

“…We thus propose that SlitOR6 is expressed in the LT2A OSNs and that SlitOR13 is expressed in the newly described LT3 OSNs. The identification of a new type of pheromone-sensitive sensilla in S. littoralis, even after decades of electrophysiological studies (Muñoz et al, 2008;Binyameen et al, 2012), emphasizes the benefits of studying in detail both response spectra and expression patterns of ORs. Albeit difficult to perform, precise single-sensillum recordings at the distal part of the antennae deserve future attention and may lead to the identification of new functional types of sensilla.…”

“…In H. armigera, the relative abundance of sugar-detecting neurons in the distal region of the antenna has been linked with an ecological need to probe the nectar of the flowers (Jørgensen et al, 2007). In female S. littoralis, it has been hypothesized that the lowered response sensitivity of distal OSNs to several, but not all, odorants could participate in close range orientation to high concentration odor flux (Binyameen et al, 2012). Similarly, one can speculate that the distal localization of SlitOR13-expressing OSNs may play a role in a shorter range assessment of the pheromone blend composition, during the mating process.…”

Feeding and oviposition deterrent activities of microencapsulated cardamom oleoresin and eucalyptol against Cydia pomonella

“…MEC-E treatments were unable to keep codling moth populations below suggested trap thresholds of 5-10 codling moths per trap per week (Tables 4 and 5). This diversity of dramatically different responses to 1,8-cineole between codling moths and bark beetles could be due to moth's highly specialized pheromone detection system (Binyameen et al, 2012). On the other hand, the proportion of mated female moths still remained below 50% in MEC-E treated blocks (Table 6).…”

Concurrent modulation of neuronal and behavioural olfactory responses to sex and host plant cues in a male moth

“…Single sensillum recordings were performed from the antennal long trichoid sensilla known to respond to pheromone components [16].…”

“…Its behaviour in response to pheromone and plant odours, and the physiology and morphology of the olfactory apparatus, have been extensively studied (e.g. [2,[12][13][14][15][16][17]). We have investigated whether mating-induced olfactory and behavioural modulation to floral and green cues observed in female moths [2] is sex specific, and whether the response to female sex pheromone is modulated in males after mating.…”