Flight capability and flight motor pattern in a sedentary South African grasshopper,Phymateus morbillosus– a comparison with migratory species

Abstract

Abstract. Among the Acridoidea, not all species are strong fliers. We have examined the possible causes for loss of flight in a species with a reduced flight system, the South African grasshopper, Phymateus morbillosus (L.). This is a sedentary species that, in the field, displays only marginal flight (in males) or no flight (in females). In a wind tunnel, however, this species can be stimulated to perform flight movements for a short time. In the present study, several morphometric parameters and aspects of the flight motor output have been examined. The data are compared with those of the migratory locust species (Locusta migratoria L. and Schistocerca gregaria Forsk.). Phymateus morbillosus can exhibit the typical flight motor pattern for short periods of up to 1 min. Morphometric data and wing-beat frequency in P. morbillosus are similar to that of other members of this insect group. However, female specimens of P. morbillosus are too heavy to lift themselves for active flight. We assume that females of this species invest in the augmentation of reproduction rather than investing in the flight system.

Sexual dimorphism in the pyrgomorphid grasshopper Phymateus morbillosus: from wing morphometry and flight behaviour to flight physiology and endocrinology

“…This could mean that neuronal inputs and/or outputs to and from the flight muscles are impaired, and, second, a high wing loading can be compensated for by an increase in the frequency of the beating of the wings and/or an increase in the amplitude of the wing stroke. Experiments were undertaken in parallel, but independently to the present study, to investigate these problems and others (see Kutsch et al ., 2002).…”

Optimal resource allocation, maternal investment, and body size in a solitary bee, Osmia bicornis

“…Wing area, wing length, and thorax mass (M T ) were measured in relation to fresh body mass (M FB , an indirect measure of body size) to analyse the intraspecific correlations between several indices of flight performance and body size (Dudley, 2000;Kutsch et al, 2002;Dillon & Dudley, 2004;Roberts et al, 2004;Buchwald & Dudley, 2010). Emerging bees were killed by freezing, weighed freshly to 0.1 mg, and cut into tagmata.…”

Biased dispersal ofMetrioptera bicolor, a wing dimorphic bush‐cricket

“…Hence, only the hind wings were photographed on a microscope slide with millimeter scaling (Eschenbach, Nürnberg, Germany, scale accuracy 0.01 mm) with a Nikon Coolpix 4500 (Chiyoda, Tokio, Japan). Using ImageJ 1.36b (Abramoff et al, 2004), the wing length and wing area were determined, and the aspect ratio was calculated as wing length squared, divided by the wing area (Marden, 1987;Kutsch et al, 2002). High aspect ratio values indicate narrow wings, whereas low values indicate short, stubby wings.…”

“…The long-winged morph of insect species is generally assumed to serve as dispersal unit, which maintains the gene flow between populations (Vickery, 1965;Peterson & Denno, 1997;Simmons & Thomas, 2004). However, long wings do not necessarily imply that such individuals do disperse or are good flyers (Roff, 1986;Ritchie et al, 1987;Roff & Fairbairn, 1991;Gäde, 2002;Kutsch et al, 2002;Socha & Zemek, 2003).…”