Effects of light levels and plume structure on the orientation manoeuvres of male gypsy moths flying along pheromone plumes

Abstract

Summary The upwind zigzag flights of male gypsy moths (Lymantria dispar L.; Lepidoptera: Lymantriidae) along narrow, ribbon‐like and wide, turbulent plumes of pheromone were examined in a wind tunnel at light levels of 450 and 4 lux. Under all conditions tested males flew upwind zigzag paths. In 450 lux, males flying along turbulent plumes had the highest ground speeds and the widest crosswind excursions between counterturns, compared to slow flight and a narrow zigzag of males along a ribbon plume. In a turbulent plume, males flew more slowly and had narrower zigzags in 4 than in 450 lux. Across most treatments of plume structure and light level, the rate of transverse image flow and the frequency of counterturning remained relatively constant. The effects of light levels on orientation are not readily reconcilable with a model in which moths in low light levels would head more towards crosswind, thereby enhancing the rate of transverse image flow and the perception of wind‐induced drift.

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

“…Visual modulation of odour-guided flight (flight direction relative to the wind). Using the triangles-of-velocities method (Marsh et al, 1978) as described by Cardé and Knols (Cardé and Knols, 2000), a vector representing the flight speed was calculated by taking the wind direction and speed into account ( Fig.2A). The course angle was calculated as the angle between the wind direction and flight speed vector, whereas the drift angle corresponded to the difference between track and course angle (drift angle=track angle-course angle).…”

Statistical analysis of modified complete randomized designs:applications to chemo-orientation studies

“…An insect begins at the other end of the tunnel and is challenged to track the plume to the pheromone source. The goal is to detect differences in the response of an insect to different types of plumes or treatments Linn et al, 1988a,b;Mafra-Neto and Cardé, 1998;Zanen and Cardé, 1999;Cardé and Knols, 2000;Dekker et al, 2001;Willis and Avondet, 2005). The effect of various types of formulated synthetic pheromone on different species of walking and flying insects has been studied by various researchers (Linn et al, 1988a,b;Willis and Arbas, 1991;Linn et al, 1996;Willis and Avondet, 2005).…”

“…They analysed the data using a oneway ANOVA, however, ignoring the block effects and restriction in randomization. Mafra-Neto and Cardé (1998) utilized an RCBD to test the effect of treatments; however, it is not clear from the 'Materials and methods' section whether their experimental design indeed R. S. Pilla, D. J. Kitska and C. Loader Cardé and Knols (2000) Physiol. Entomol.…”

“…From the 'Materials and methods' section of Linn et al (1996), it appears that they do not have a complete randomization protocol; however, they analysed their experimental data using an ANOVA (although not clear whether it was a one-way or two-way). The effect of light levels and plume structure on the orientation maneuvers of male Lymantria dispar (gypsy moths) flying along pheromone plumes has been studied by Cardé and Knols (2000). They used the flight tracks of 20 males per treatment (a total of six treatments), tested in a complete randomized block design.…”

“…They used the flight tracks of 20 males per treatment (a total of six treatments), tested in a complete randomized block design. The goal was to study the effects of odor plume structure on the orientation maneuvers of different species of walking and flying insects Baker, 1990;Cardé and Knols, 2000). Justus et al (2002) employed an ANOVA; however, they do not state the details of the experimental design and the statistical analysis employed such as a one-way ANOVA or an RCBD.…”