Morphological variation and sex-biased frequency of wing dimorphism in the pygmy grasshopper Tetrix subulata (Orthoptera: Tetrigidae)

Abstract

Abstract. Dimorphism in wing length is well known in many insect species. It is generally believed that a trade-off between dispersal and reproduction exists, with the long-winged (LW) morph being a better disperser due to its superior flight capability. The short-winged (SW) morph is less mobile and it is hypothesised that females of this morph invest more of their energy reserves in producing offspring. We determined the variation in body and wing size in the pygmy grasshopper Tetrix subulata (Orthoptera: Tetrigidae). The results of the morphological study support the occurrence of two clearly distinct wing morphs in both sexes. SW individuals, especially males, were smaller and in accord with proposed developmental instability showed greater variability in body size than LW individuals. Using data for 700 wild-caught individuals from 10 populations, we demonstrate a variable frequency in the percentage of LW individuals, ranging from all-LW to all-SW populations, even if the LW morph is by far the most common morph in an area. The male-biased percentage of LW individuals recorded in intermediate populations supports a difference in the dispersal reproduction trade-off between the sexes.

On the role of sex differences for evolution in heterogeneous and changing fitness landscapes: insights from pygmy grasshoppers

“…Re-analysis of data collected more recently from another population [16] confirms that wing morphs do not differ in body size in our study areas (ANOVA, effect of sex: F 1,194 = 852.70, p < 0.0001; effect of wing morph: F 1,194 = 0.27, p = 0.60), but see Steenman et al [98]. There is also no correlation between maternal body size and the incidence of long-winged phenotypes among captive-reared offspring [95], arguing against a genetic correlation between wing morph and body size.…”

Energy balance of food in a detrito-bryophagous groundhopper (Orthoptera: Tetrigidae)

“…Tetrix subulata is one of the most widespread groundhopper species in Europe (Holst, 1986). The body length of adults ranges from 10 to 14 mm, and females are usually larger than males (Steenman, Lehmann & Lehmann, 2013;Steenman, Lehmann & Lehmann, 2015;Lehmann et al, 2018). This species is active from March to the end of October in Central Europe (Holst, 1986, Kočárek, Holuša & Vidlička, 2005, when nymphs hatch in summer (August), molt to adulthood in autumn, hibernate and reproduce in spring.…”

“…This species is active from March to the end of October in Central Europe (Holst, 1986, Kočárek, Holuša & Vidlička, 2005, when nymphs hatch in summer (August), molt to adulthood in autumn, hibernate and reproduce in spring. The adult season is split into the autumn dispersal-related cohort (Lehmann et al, 2018) and the reproducing spring cohort (Steenman, Lehmann & Lehmann, 2015). The groundhopper usually prefers damp places, and it is often found near rivers in moist habitats (Baur, Baur & Roesti, 2006).…”

Testing for trade-offs between flight and reproduction in the mountain pine beetle (Coleoptera: Curculionidae) on two pine (Pinaceae) hosts

“…This is particularly important for taxa that rely heavily on energy acquired as a juvenile to fuel adult flight (Thomas 1988). Energy use during insect flight decreases subsequent reproductive output through a reduction in the size or number of eggs in many species (Isaacs and Byrne 1998;Fox and Czesak 2000;Elkin and Reid 2005;Gu et al 2006;Zhang et al 2009;Gibbs and Dyck 2010;Guerra 2011;Elliott and Evenden 2012;Steenman et al 2013;Duthie et al 2014). However, compensation of energy used in flight can also occur by postdispersal feeding (Niitepõld and Boggs 2015).…”