Navigation of Lutzomyia longipalpis (Diptera: Psychodidae) under dusk or starlight conditions

Abstract

The responses of male and female Lutzomyia longipalpis (Lutz & Neiva) to different wavelengths of light was tested by presenting the sandflies with two light sources simultaneously, a series of test wavelengths between 350-670 nm and a 400 nm control. To test whether L. longipalpis could discriminate between the test and control, three sets of experiments were carried out in which the test wavelengths were presented at higher, equivalent or lower intensity than the control. In all three experiments, ultra-violet (350 nm) and blue-green-yellow (490-546 nm) light was more attractive to L. longipalpis than the control wavelength. However, at low intensity, UV was less attractive, than equivalent or higher intensity UV light. At intensities equivalent to or higher than the control wavelength, ultra-violet light was more attractive than blue-green. Furthermore, at low intensity, green-yellow (546 nm) light was more attractive to males whereas blue-green (490 nm) was more attractive to females. Blue-violet (400 nm) and orange-red (600-670 nm) light were least attractive in all three sets of experiments. Response function experiments indicated that the responses were dependent on both intensity and wavelength and that therefore more than one photoreceptor must be involved in the response. The results indicated that L. longipalpis can discriminate between different wavelengths at different intensities and thus have true colour vision. It also suggests that L. longipalpis may be able to navigate at dusk or under moonlight or starlight conditions using light in the blue-green-yellow part of the spectrum. The difference in response of males and females to light in this region is interesting and may indicate the different ecology of the sexes at night. Overall, these results may have important implications for sandfly trap design.

Lutzomyiaspp. (Diptera: Psychodidae) Response to Olfactory Attractant- and Light Emitting Diode-Modified Mosquito Magnet X (MM-X) Traps

“…It is interesting that color is the only factor that inßuences whiteßy landings on plant and nonplant surfaces van Lantern 1976, van Lantern andWoets 1977). In a study conducted by Mellor and Hamilton (2003), a greater percentage of Lu. longipalpis was attracted toward 490 Ð546-nm than 400-nm wavelength light at lower, equivalent, and higher light intensities.…”

“…longipalpis respond maximally to light in the UV region and blue-green-yellow region (Mellor et al 1996). Mellor and Hamilton (2003) provided evidence that Lu. longipalpis is more attracted to UV, blue, green, and yellow wavelengths and were able to discriminate between wavelengths independent of intensity.…”

Moonlight and blood-feeding behaviour of Lutzomyia intermedia and Lutzomyia whitmani (Diptera:Psychodidae:Phlebotominae), vectors of American cutaneous leishmaniasis in Brazil

“…However, the effect of the darkness on the blood feeding frequency is more difficult to explain. The most likely explanation is that the moonlight helps sand flies to navigate and to find its host (Mellor & Hamilton 2003). Further studies under more controlled conditions are needed to understand the effects of moonlight intensity observed in this and other studies.…”

“…They are mostly nocturnal and in the light of existing knowledge one might expect these vectors to be affected by the lunar cycle (Chaniotis et al 1971, Mellor & Hamilton 2003.…”

Light-Emitting Diode Technology Improves Insect Trapping

“…Whereas incandescent bulbs produce a broad spectrum of light to attract insects, LEDs can be selected to emit a narrow bandwidth or specific color. Previous studies have found that mosquitoes (Wilton andFay 1972, Burkett andButler 2005), phlebotomine sand flies (Mellor and Hamilton 2003), and Culicoide flies (Bishop et al 2004) are attracted preferentially to specific wavelengths of light. Finally, LED bulbs are advantageous in that they can be changed quickly in the field to configure the trap to the particular needs of a trapping environment.…”