Abstract:ABSTRACT. The spontaneous locomotor activity of the larvae of Culiseta incidens was monitored with acoustic actographs. Individuals, in water resting on the cones of the speakers, displayed an activity rhythm in LD 12:12 with peak activity in the light phase. A similar rhythm occurred in DD following rearing in either LD 12:12 or LL, with free‐running periods of 23.5–24 h. No evidence was found of any consistent differences between the periods of the larvae and pupae. The amplitude of the pupal rhythm gradual… Show more
“…We found no effects of circadian timing on larval movement speed ( p = 0.40), time spent moving ( p = 0.41), or time spent next to the arena walls ( p = 0.55). These observations support previous findings that mosquito larvae, unlike adults, exhibit little behavioural variation during the day [21,22]. Figure 1.Quantifying the chemosensory environment in naturalistic larval habitat sizes.…”
Mosquitoes are prolific disease vectors that affect public health around the world. Although many studies have investigated search strategies used by host-seeking adult mosquitoes, little is known about larval search behaviour. Larval behaviour affects adult body size and fecundity, and thus the capacity of individual mosquitoes to find hosts and transmit disease. Understanding vector survival at all life stages is crucial for improving disease control. In this study, we use experimental and computational methods to investigate the chemical ecology and search behaviour of Aedes aegypti mosquito larvae. We first show that larvae do not respond to several olfactory cues used by adult Ae. aegypti to assess larval habitat quality, but perceive microbial RNA as a potent foraging attractant. Second, we demonstrate that Ae. aegypti larvae use chemokinesis, an unusual search strategy, to navigate chemical gradients. Finally, we use computational modelling to demonstrate that larvae respond to starvation pressure by optimizing exploration behaviour—possibly critical for exploiting limited larval habitat types. Our results identify key characteristics of foraging behaviour in an important disease vector mosquito. In addition to implications for better understanding and control of disease vectors, this work establishes mosquito larvae as a tractable model for chemosensory behaviour and navigation.
“…We found no effects of circadian timing on larval movement speed ( p = 0.40), time spent moving ( p = 0.41), or time spent next to the arena walls ( p = 0.55). These observations support previous findings that mosquito larvae, unlike adults, exhibit little behavioural variation during the day [21,22]. Figure 1.Quantifying the chemosensory environment in naturalistic larval habitat sizes.…”
Mosquitoes are prolific disease vectors that affect public health around the world. Although many studies have investigated search strategies used by host-seeking adult mosquitoes, little is known about larval search behaviour. Larval behaviour affects adult body size and fecundity, and thus the capacity of individual mosquitoes to find hosts and transmit disease. Understanding vector survival at all life stages is crucial for improving disease control. In this study, we use experimental and computational methods to investigate the chemical ecology and search behaviour of Aedes aegypti mosquito larvae. We first show that larvae do not respond to several olfactory cues used by adult Ae. aegypti to assess larval habitat quality, but perceive microbial RNA as a potent foraging attractant. Second, we demonstrate that Ae. aegypti larvae use chemokinesis, an unusual search strategy, to navigate chemical gradients. Finally, we use computational modelling to demonstrate that larvae respond to starvation pressure by optimizing exploration behaviour—possibly critical for exploiting limited larval habitat types. Our results identify key characteristics of foraging behaviour in an important disease vector mosquito. In addition to implications for better understanding and control of disease vectors, this work establishes mosquito larvae as a tractable model for chemosensory behaviour and navigation.
“…There are in fact few papers that deal with the developmental changes in the manifestation of the circadian clock (e.g. Rensing, 1965;Pittendrigh & Minis, 1971;Jones & Reiter, 1975;Clopton, 1979).…”
Three eclosion rhythms of Diatraea grandiosella Dyar (Lepidoptera, Pyralidae) showed different phase relationships to the LD cycle, different degrees of synchronization and different sensitivity to a brief light perturbation. Egg hatching occurred mainly at dawn, whereas pupation and adult emergence occurred mainly at dusk. The egg hatching was the most synchronized rhythm of the three, pupation the least. The egg hatching rhythm was more sensitive to a brief light perturbation than was the adult emergence rhythm. A light pulse in the middle of the night caused greater disturbance in the egg hatching rhythm than did a pulse placed in the early night. The three rhythms persisted in both DD and LL. LL free-running rhythm gradually became desynchronized and broke down at the third cycle. The phase relationships reveal difficulties in applying the 'external coincidence model' to this species' photoperiodic response.A vast literature has been accumulated on the circadian control of various rhythmic phenomena in animals and plants (Bunning, 1973). These rhythms are most frequently entrained by light and temperature cycles, environmental cues which organisms also use for photoperiodic responses (Withrow, 1959). On the basis of this similarity, Biinning (1936) proposed that both daily and seasonal timing phenomena are controlled by a common endogenous mechanism, viz a circadian oscillation.Since then, numerous photoperiodic models based on circadian oscillations have been pro-
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