Growth, Development, and Nutritional Physiology of Grasshoppers from Subarctic and Temperate Regions

Abstract

Despite the importance of developmental rate, growth rate, and size at maturity in the life history of poikliotherms, the trade-offs among these traits and selection pressures involved in the evolution of these traits are not well understood. This study compared these traits in a grasshopper, Melanoplus sanguinipes F. (Orthoptera: Acrididae), from two contrasting geographical regions, subarctic Alaska and temperate Idaho. The growing season in the interior of Alaska is about 80 d shorter than at low-elevation sites in Idaho. We hypothesized that the Alaskan grasshoppers would show more rapid growth and development than grasshoppers from Idaho, at the cost of greater sensitivity to food quality. On a diet of lettuce and wheat bran, grasshoppers from Alaska developed from egg hatch to adult more rapidly than those from Idaho at each of three different temperature regimes. Averaged over all temperature treatments, the weight of the Alaskan grasshoppers was about 5% less than that of the Idaho grasshoppers at the adult molt. Feeding and digestive efficiencies were determined for the final two instars using two meridic diets: one with a high concentration of nutrients and the other with the same formulation but diluted with cellulose. Alaskan grasshoppers again developed more rapidly, weighed less, and had faster growth rates than those from Idaho. Alaskan grasshoppers supported their more rapid growth by increasing postingestive efficiencies; that is, they had higher conversion rates of digested matter to biomass on the high-quality diet, greater assimilation of food on the low-quality diet, and greater efficiency of nitrogen assimilation or retention on both diets. There was no evidence that performance of Alaskan grasshoppers suffered any more than that of the Idaho grasshoppers on the low-quality diet.

Ecotypic differentiation between urban and rural populations of the grasshopper Chorthippus brunneus relative to climate and habitat fragmentation

“…Grasshopper body size is of great biological significance as female body mass is typically related to several fecundity traits: number of eggs per egg pod, total number of egg pods, and female lifespan (Richards and Waloff 1954;. Selection of higher female body mass in populations from warmer environments has been observed in many Acrididae species and along different climatic gradients (Telfer and Hassall 1999;Tregenza et al 2000;Berner and Blanckenhorn 2006;Fielding and Defoliart 2007). Grasshoppers are well-known exceptions to Bergmann's rule .…”

“…Females are heavier in warmer regions (Tregenza et al 2000;Berner and Blanckenhorn 2006;Fielding and Defoliart 2007) or in regions with mild winters (Telfer and Hassall 1999). Heavier weight is often associated with longer development time that is sometimes compounded by lower growth rate (Hatle et al 2002;Berner and Blanckenhorn 2006;Fielding and Defoliart 2007).…”

Effects of Soil Depths on Nymphal Eclosion of Melanoplus sanguinipes (Fabricius)

“…No recent reports on the use of plowing to manage grasshopper could be found. In North Dakota, tillage to a depth of 11.4 cm provided up to 83% M. bivvitatus control [12]. No published reports on the use of cultural methods for grasshoppers control under Alaska cold soils conditions are available.…”

“…Considerable research has been conducted on grasshopper biology, ecology, competition, food quality, predators, pathogens, and population regulation of Alaska grasshoppers [6][7][8][9][10][11][12] but little work has been conducted on cultural practices (tillage, plowing) to manage grasshoppers in Interior Alaska. There is a lack of understanding of how cultural practices can affect egg mortality and nymphal emergence.…”

“…Dag Hammarskjöld 3241, Vitacura, Santiago, Chile, Room 319, USA; Tel: 56-2-923-2295; Fax: 56-2-923-2101; E-mail: alberto.pantoja@fao.org Alaska since it is expected that insect, diseases, and weed populations will increase with climate change [14]. Additionally, adaptation to northern environments has been demonstrated for high-latitude populations of grasshoppers [6][7][8][9][10][11][12]. The ability to control grasshoppers with cultural practices and the development of integrated pest management (IPM) tactics will be a major step toward controlling grasshoppers in Alaska.…”