Direct and indirect effects of development temperature on adult water balance traits of Eldana saccharina (Lepidoptera: Pyralidae)

Elsje Kleynhans; Des E Conlong; John S Terblanche

doi:10.1016/j.jinsphys.2014.06.018

Direct and indirect effects of development temperature on adult water balance traits of Eldana saccharina (Lepidoptera: Pyralidae)

J Insect Physiol. 2014 Sep:68:69-75. doi: 10.1016/j.jinsphys.2014.06.018. Epub 2014 Jul 4.

Authors

Elsje Kleynhans¹, Des E Conlong², John S Terblanche³

Affiliations

¹ Centre for Invasion Biology, Department of Conservation Ecology and Entomology, Faculty of AgriSciences, Stellenbosch University, Stellenbosch, South Africa. Electronic address: elsje.subtrop@gmail.com.
² Centre for Invasion Biology, Department of Conservation Ecology and Entomology, Faculty of AgriSciences, Stellenbosch University, Stellenbosch, South Africa; Crop Biology Resource Centre, South African Sugarcane Research Institute, 170 Flanders Drive, Mount Edgecombe, Durban 4300, South Africa.
³ Centre for Invasion Biology, Department of Conservation Ecology and Entomology, Faculty of AgriSciences, Stellenbosch University, Stellenbosch, South Africa.

PMID: 25008194
DOI: 10.1016/j.jinsphys.2014.06.018

Abstract

For water balance physiology, prior thermal history may pre-condition individuals to be more sparing in their water consumption at a given temperature upon subsequent exposure, or alternatively, may relax constraints on water economy leading to more frivolous use of water at a later stage. Here we test these two major alternative hypotheses on the adult life stage of Eldana saccharina Walker (Lepidoptera: Pyralidae) by exposing them to different rearing temperatures (acclimation treatments) during immature stage development and comparing adult physiological performance (water loss rates, time to death) and water-balance related traits (body size, water content). Developmental acclimation at 20°C, 25°C or 30°C throughout the larval and pupal stage resulted in significant effects on water balance traits of two-day old adult male and female E. saccharina. In summary, lower developmental acclimation resulted in a 61% increase in water loss rate (range: 0.78mg/h) and a 26% reduction in survival time (6.8h). Initial body water content and initial body mass generally remained similar across male acclimation groups while higher developmental acclimation reduced female body mass significantly. High developmental acclimation resulted in significantly higher (∼23%) body water content at death possibly indicating a better overall ability to withstand desiccating conditions, although there was no difference in time to death compared to the intermediate group. The relationship between time to death and body mass was altered from negative at 25°C and 30°C acclimation, to positive at 20°C acclimation. These results show pervasive effects of rearing temperature on adult physiological performance, with low temperature relaxing what appear to be substantial constraints on water economy at higher temperatures for E. saccharina. Furthermore, they are significant for understanding the recent range expansion of E. saccharina into cooler environments in southern Africa and for management of the species.

Keywords: Critical body water content; Desiccation; Developmental temperature; Phenotypic plasticity; Stem borer; Stress resistance.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Acclimatization / physiology*
Animals
Body Water*
Body Weight
Female
Male
Moths / growth & development
Moths / physiology*
Sex Factors
Temperature*
Water-Electrolyte Balance / physiology*