Predation risk and mating behavior: the responses of moths to bat-like ultrasound

SUMMARY All animals have to cope with sensory conflicts arising from simultaneous input of incongruent data to different sensory modalities. Nocturnal activity in moths includes mate-finding behaviour by odour detection and bat predator avoidance by acoustic detection. We studied male moths that were simultaneously exposed to female sex pheromones indicating the presence of a potential mate, and artificial bat cries simulating a predation risk. We show that stimulation of one sensory modality can modulate the response to information from another, suggesting that behavioural thresholds are dynamic and depend on the behavioural context. The tendency to respond to bat sounds decreased as the quality and/or the amount of sex pheromone increased. The behavioural threshold for artificial bat cries increased by up to 40 dB when male moths where simultaneously exposed to female sex pheromones. As a consequence, a male moth that has detected the pheromone plume from a female will not try to evade an approaching bat until the bat gets close, hence incurring increased predation risk. Our results suggest that male moths'reaction to sensory conflicts is a trade-off depending on the relative intensity of the input to CNS from the two sensory modalities.

Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 88%

See 1 more Smart Citation

Her odours make him deaf: crossmodal modulation of olfaction and hearing in a male moth

Skals

Anderson

Kanneworff

et al. 2005

“…the sound emitted by predating bats in a trade-off situation between finding a mate and being caught by a predator (Skals et al, 2005;Svensson et al, 2004) than moths flying without pheromone or sitting still, responding to the pheromone without being able to mate successfully would be disadvantageaous. Indeed, two species of moths, Pseudaletia unipuncta and Ostrinia nubilalis, reduce their mate-seeking behaviour under high levels of predation risk (Acharya and McNeil, 1998).…”

Section: Discussionmentioning

confidence: 99%

Switching attraction to inhibition: mating-induced reversed role of sex pheromone in an insect

Barrozo¹,

Gadenne²,

Anton³

2010

SUMMARYIn the moth, Agrotis ipsilon, newly mated males cease to be attracted to the female-produced sex pheromone, preventing them from re-mating until the next night, by which time they would have refilled their reproductive glands for a potential new ejaculate. The behavioural plasticity is accompanied by a decrease in neuron sensitivity within the primary olfactory centre, the antennal lobe (AL). However, it was not clear whether the lack of the sexually guided behaviour results from the absence of sex pheromone detection in the ALs, or if they ignore it in spite of detection, or if the sex pheromone itself inhibits attraction behaviour after mating. To test these hypotheses, we performed behavioural tests and intracellular recordings of AL neurons to non-pheromonal odours (flower volatiles), different doses of sex pheromone and their mixtures in virgin and newly mated males. Our results show that, although the behavioural and AL neuron responses to flower volatiles alone were similar between virgin and mated males, the behavioural response of mated males to flower odours was inhibited by adding pheromone doses above the detection threshold of central neurons. Moreover, we show that the sex pheromone becomes inhibitory by differential central processing: below a specific threshold, it is not detected within the AL; above this threshold, it becomes inhibitory, preventing newly mated males from responding even to plant odours. Mated male moths have thus evolved a strategy based on transient odour-selective central processing, which allows them to avoid the risk-taking, energy-consuming search for females and delay re-mating until the next night for a potential new ejaculate.

“…This tradeoff, where one stimulus is ignored so as to attend the other has been referred to as limited attention (Dukas, 2002) and is thought to be the result of the limited amount of information a nervous system can process in a given time. Studies with tympanate moths where males were simultaneously exposed to female pheromones and artificial bat cries, suggests these moths make a behavioural tradeoff depending on the relative intensity from the two sensory modalities (Acharya and McNeil, 1998;Skals et al, 2005;Svensson et al, 2004).…”

Section: Object-motionmentioning

confidence: 99%

Visual stimuli induced by self-motion and object-motion modify odour-guided flight of male moths (Manduca sexta L.)

Verspui

Gray

2009

SUMMARY Animals rely on multimodal sensory integration for proper orientation within their environment. For example, odour-guided behaviours often require appropriate integration of concurrent visual cues. To gain a further understanding of mechanisms underlying sensory integration in odour-guided behaviour, our study examined the effects of visual stimuli induced by self-motion and object-motion on odour-guided flight in male M. sexta. By placing stationary objects (pillars) on either side of a female pheromone plume, moths produced self-induced visual motion during odour-guided flight. These flights showed a reduction in both ground and flight speeds and inter-turn interval when compared with flight tracks without stationary objects. Presentation of an approaching 20 cm disc, to simulate object-motion,resulted in interrupted odour-guided flight and changes in flight direction away from the pheromone source. Modifications of odour-guided flight behaviour in the presence of stationary objects suggest that visual information, in conjunction with olfactory cues, can be used to control the rate of counter-turning. We suggest that the behavioural responses to visual stimuli induced by object-motion indicate the presence of a neural circuit that relays visual information to initiate escape responses. These behavioural responses also suggest the presence of a sensory conflict requiring a trade-off between olfactory and visually driven behaviours. The mechanisms underlying olfactory and visual integration are discussed in the context of these behavioural responses.