The Wetting of Insect Cuticle

Pal, Rajindar

doi:10.1017/s0007485300027528

Cited by 22 publications

(17 citation statements)

References 22 publications

(11 reference statements)

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“…fresh water bugs, such as Aphelocheirus aestivus (Thorpe & Crisp 1947) or species living on the water surface, such as Podura aquatica (Noble-Nesbitt 1963a) or Paulinia acuminara (Barthlott et al 1994). Applied entomology investigates methods to enhance the wettability of the cuticle using suitable additives in order to increase the efficiency of insecticides (Pal 1950;Noble-Nesbitt 1970;Gilby 1984;Croghan & Noble-Nesbitt 1989).…”

Section: Introductionmentioning

confidence: 99%

Wettability and Contaminability of Insect Wings as a Function of Their Surface Sculptures

1996

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Wagner, T., Neinhuis, C. & Barthlott, W. 1996. Wettability and contaminability of insect wings as a function of their surface sculptures. Acta Zoologica (Stockholm) 76: 213-225.The wing surfaces of 97 insect species from virtually all relevant major groups were examined by high resolution scanning-electron-microscopy, in order to identify the relationships between the wing microstructures, their wettability with water and their behaviour under the influence of contamination.Isolated wings with contact angles between 31.6" and 155.5" were artificially contaminated with silicate dusts and subsequently fogged until drops of water ("dew") formed and rolled off. The remaining particles were counted via a digital image analysis system. Remaining particle values between 0.41% and 103% were determined in comparison with unfogged controls. Some insects with very unwettable wings show a highly significant "self-cleaning" effect under the influence of rain or dew.Detailed analysis revealed that there is a correlation between the wettability and the "SM Index" (quotient of wing surface/(body mass)06') with values ranging from 2.42 to 57.0. Furthermore, there is a correlation between the "self-cleaning" effect and the SM Index, meaning that taxa with a high SM Index, e.g. "large-winged Ephemeroptera, Odonata. Planipennia, and many Lepidoptera. have very unwettable wings and show high particle removal due to dripping water drops. The "smallwinged" insects, such as Diptera and Hymenoptera, and insects with elytra, such as Blattariae, Saltatoria, Heteroptera and Coleoptera, show completely opposite effects. This is clearly a result of the fact that species with a high SM Index are, in principle, more restricted in flight by contamination than species with a low SM Index which can also actively clean their own wings. The wings primarily serve a protection function in insects with elytra, so that the effects of contamination are probably of minor importance in these insects.

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Section: Introductionmentioning

confidence: 99%

Wettability and Contaminability of Insect Wings as a Function of Their Surface Sculptures

1996

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“…This layer causes flying insects to be considerably more water-repellent than both aquatic and terrestrial insects (16). For instance, water drops on mosquitoes have contact angles of approximately 180°on the thorax and 75-95°on the legs and wings (23). To cope with this high water-repellency, insecticides are composed of a fog of very small drops, of sizes 20 μm, which adhere to mosquitoes midflight.…”

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confidence: 99%

Mosquitoes survive raindrop collisions by virtue of their low mass

Dickerson¹,

Shankles²,

Madhavan³

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

100

101

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In the study of insect flight, adaptations to complex flight conditions such as wind and rain are poorly understood. Mosquitoes thrive in areas of high humidity and rainfall, in which raindrops can weigh more than 50 times a mosquito. In this combined experimental and theoretical study, we here show that free-flying mosquitoes can survive the high-speed impact of falling raindrops. High-speed videography of those impacts reveals a mechanism for survival: A mosquito's strong exoskeleton and low mass renders it impervious to falling drops. The mosquito's low mass causes raindrops to lose little momentum upon impact and so impart correspondingly low forces to the mosquitoes. Our findings demonstrate that small fliers are robust to in-flight perturbations.surface tension | splash | acceleration O ne of the technological feats of the 21st century is the construction of insect-sized flying robots, micro-airborne vehicles (MAVs), made possible by rapidly shrinking manufacturing and elecronics (1-7). These robots have numerous applications such as deployment in swarms for surveillance and searchand-rescue operations. In parallel with the engineering of MAVs, vigorous efforts continue to be made into understanding flight in the natural world, such as by birds and insects (8-11). Much progress has been made in understanding straight-path flight in unidirectional flow. However, much remains to be understood about the abilities of birds and insects to fly through complex conditions such as wind and rain. Such knowledge clearly has implications for ecology in terms of understanding the evolution of animals in rain forests and near waterfalls. The adaptations of these animals may also serve engineering via biological inspiration for the design of robust MAVs.Previous studies on bats have shown that rain doubles their energetic cost of flight (12). The remainder of our knowledge of the effect of precipitation is restricted to large aircraft, although they operate upon very different principles from flapping fliers. Field testing on the effects of heavy rain on aircraft (13) confirms that precipitation generally hinders locomotion. Aircraft experience greater drag (2-5%), reduced lift (7-29%), and a reduction in stall angle of 1-5°, as measured (14, 15) during a rainfall intensity of 100-1;000 mm∕h. Aircraft can reduce these losses by using wing designs that can funnel rivulets and control their diameter. These design principles may explain some of the water-repellent features common in birds' wings (16). However, they clearly do not apply for much smaller fliers such as insects which are closer in size to raindrops.Flying insects likely perceive raindrop impacts as in-flight perturbations. There have been many studies of such perturbations, although none have considered the influence of a wetting fluid such as rain. For instance, bees exposed to turbulent air resist rolling instabilities by extending their legs to increase their moment of inertia (17). Following in-flight perturbation, fruit flies actively restabilize themselv...

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“…Unsurprisingly, bees wax has a value of θ e as high as 97°, while hairless caterpillars of the moths Polia oleracea and Mamestra brassicae have values of just 18° and therefore can be considered hydrophilic. However, had they possessed hairs, θ e could have been expected to be greater and wettability reduced (Pal, 1950). Unfortunately for hairy caterpillars no value of θ e is known, but for a single body hair of an adult moth a value of 97° has been published by Pal (1950).…”

Section: Setal Structural Characteristicsmentioning

confidence: 99%

“…However, had they possessed hairs, θ e could have been expected to be greater and wettability reduced (Pal, 1950). Unfortunately for hairy caterpillars no value of θ e is known, but for a single body hair of an adult moth a value of 97° has been published by Pal (1950).…”

Section: Setal Structural Characteristicsmentioning

confidence: 99%

Depilation increases while hairiness decreases the risk of drowning: A hitherto unappreciated survival role of setae in woolly bear caterpillars of the moth Lemyra imparilis (Lepidoptera: Noctuoidea: Erebidae)

Meyer-Rochow¹

2016

Eur. J. Entomol.

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The Wetting of Insect Cuticle

Cited by 22 publications

References 22 publications

Wettability and Contaminability of Insect Wings as a Function of Their Surface Sculptures

Wettability and Contaminability of Insect Wings as a Function of Their Surface Sculptures

Mosquitoes survive raindrop collisions by virtue of their low mass

Depilation increases while hairiness decreases the risk of drowning: A hitherto unappreciated survival role of setae in woolly bear caterpillars of the moth Lemyra imparilis (Lepidoptera: Noctuoidea: Erebidae)

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