Moist habitats are essential for adults of the Antarctic midge, Belgica antarctica (Diptera: Chironomidae), to avoid dehydration

Abstract

Abstract. Desiccation resistance of adult males and females of the midge, Belgica antarctica (Diptera: Chironomidae) was evaluated to determine how this short-lived stage maintains water balance in the dry Antarctic environment. Both sexes had slightly lower water content ( 60%) and a higher dehydration tolerance (>30% water loss) than most other insects. Water loss rates were high and increased rapidly at temperatures above 15°C, indicating that the adult midges are more hygric than many other polar terrestrial arthropods. Water gain was accomplished by free water uptake with minimal or no contribution from absorption of water vapor or metabolic water production. Parameters related to water balance did not differ among populations from different islands. Overall, the high water requirements of the adult midge appear to be a significant challenge and presumably dictate that the adult midges must emerge during the brief period when free water is readily available and seek protected microhabitats that facilitate water retention.

High resistance to oxidative damage in the Antarctic midge Belgica antarctica, and developmentally linked expression of genes encoding superoxide dismutase, catalase and heat shock proteins

“…But, unlike the heat shock response, the adults did not upregulate SOD following exposure to anoxia. Likewise, larvae are extremely droughttolerant (Hayward et al, 2007;Benoit et al, 2007b), while adults are not (Benoit et al, 2007a).…”

“…The wingless adults emerge late December to early January. They can be found in aggregations on the surfaces of rocks located near the larvae, but they never stray far from the moist habitats that are essential for their survival (Benoit et al, 2007a).…”

Multi-level analysis of reproduction in the Antarctic midge,Belgica antarctica, identifies female and male accessory gland products that are altered by larval stress and impact progeny viability

“…This hexamerin represents one of the highest expressed transcripts in developing larvae, so its accumulation during the juvenile stages is likely a critical resource for production of eggs and accessory gland components. This effect is likely even more pronounced in B. antarctica because adults do not feed or even readily drink water 136 . Along with acting as a nutritional source, the larval serum protein generated in juvenile stage of females is likely incorporated into the accessory gland gel, suggesting that a reduction in this product may directly impact gel composition.…”

Surviving in a frozen desert: environmental stress physiology of terrestrial Antarctic arthropods

“…Also, fluctuating moisture regimes are energetically costly, as larvae exposed to five dehydration/rehydration cycles burn 67% of their carbohydrate energy stores. In B. antarctica, dehydration tolerance is restricted to the larval stage; adults, which are only active for a brief period during the summer, require moist habitats and succumb to a 30% loss of body water (Benoit et al, 2007a). In addition to dehydration, Antarctic arthropods experience other forms of osmotic stress.…”