Modulation of whitefly take‐off and flight orientation by wind speed and visual cues

Abstract

The effect of different wind speeds on take‐off and flight orientation of the sweetpotato whitefly, Bemisia tabaci Gennadius (Homoptera: Aleyrodidae), was studied in the presence of a green visual stimulus which reflected 550 ± 10 nm light, or a white stimulus of the same intensity. When the white light was present, take‐off was negatively correlated with wind speed. Analysis of the flight tracks of whiteflies in 0, 15 and 30 cm/s wind with the white light present showed that flight was not directed toward the stimulus in zero wind, and that insects were carried downwind as the wind increased. Net displacement downwind was significantly slower than the wind speed, indicating that B. tabaci can control its rate of displacement relative to its surroundings, and is not always passively transported by the wind. In the presence of the green visual stimulus, take‐off and flight behaviour of B. tabaci was markedly different to that observed in the presence of the white light. Taking off was more likely and whiteflies made upwind orientated flights, landing on the illuminated section of the screen when it reflected green light. At all wind speeds tested, the mean ground speeds of B. tabaci were approximately 20 cm/s whether the insects were flying upwind or downwind. This uniformity of ground speed regardless of the changing effects of wind‐induced drift in different directions strongly suggests that whiteflies actively control their ground speed using visual flow fields in a manner similar to all other flying insects examined thus far.

Prevention of Whitefly Entry from a Greenhouse Entrance by Furnishing an Airflow-Oriented Pre-Entrance Room Guarded with Electric Field Screens

“…Unfortunately, the conventional method of using air curtaining or air projecting (Carlson et al, 2006) to blow insects off workers may be ineffective at removing whiteflies that typically cling to clothing. Isaacs et al (1999) reported that whiteflies can sense wind velocity and terminate take-off as the wind speed increases. Our alternative approach was to remove clothing in the pre-entrance room, close the door quickly (within 5 s) and, most importantly, refrain from touching infested plants before entering the greenhouse.…”

Whiteflies stabilize their take-off with closed wings

“…Whiteflies (Hemiptera: Aleyrodidae) are notorious agricultural pests, and their biology and flight behavior have been studied extensively (Blackmer and Byrne, 1993;Byrne, 1991;Isaacs et al, 1999). However, with the exception of one qualitative description (Weber, 1931, see Discussion), very little work has been done on their flight initiation mechanism.…”

Related but not alike: not all Hemiptera are attracted to yellow

“…Studies of flight behavior have shown that aphids and whiteflies use vision to control their groundspeed but can't sustain upwind flights in airflows exceeding 1 m.s −1 (Kennedy and Stroyan, 1959;Kennedy and Thomas, 1974;Isaacs et al, 1999). Thus, their flight abilities are restricted in terms of distance (i.e., a few meters) and altitude.…”

“…Most studies have shown that aphids (Kennedy et al, 1961;Moericke, 1969;Prokopy and Owens, 1983;Hardie, 1989;Döring, 2014) and whiteflies (Vaishampayan et al, 1975a,b;Coombe, 1982;Isaacs et al, 1999) orient preferentially toward green and yellow surfaces. Insect color perception is dependent upon the sensitivity of their photoreceptors.…”