ants and Dehydration

Temperature increases associated with global climate change are likely to be accompanied by additional environmental stressors such as desiccation and food limitation, which may alter how temperature impacts organismal performance. To investigate how interactions between stressors influence thermal tolerance in the common forest ant, Aphaenogaster picea, we compared the thermal resistance of workers to heat shock with and without pre-exposure to desiccation or starvation stress. Knockdown (KD) time at 40.5 °C of desiccated ants was reduced 6% compared to controls, although longer exposure to desiccation did not further reduce thermal tolerance. Starvation, in contrast, had an increasingly severe effect on thermal tolerance: at 21 days, average KD time of starved ants was reduced by 65% compared to controls. To test whether reduction in thermal tolerance results from impairment of the heat-shock response, we measured basal gene expression and transcriptional induction of two heat-shock proteins (hsp70 and hsp40) in treated and control ants. We found no evidence that either stressor impaired the Hsp response: both desiccation and starvation slightly increased basal Hsp expression under severe stress conditions and did not affect the magnitude of induction under heat shock. These results suggest that the co-occurrence of multiple environmental stressors predicted by climate change models may make populations more vulnerable to future warming than is suggested by the results of single-factor heating experiments.

Topics: Animals; Ants; Climate Change; Dehydration; Forests; Heat-Shock Response; Hot Temperature; HSP40 Heat-Shock Proteins; HSP70 Heat-Shock Proteins; Insect Proteins; Starvation; Thermotolerance

Abiotic environmental variables strongly affect the outcomes of species interactions. For example, mutualistic interactions between species are often stronger when resources are limited. The effect might be indirect: water stress on plants can lead to carbon stress, which could alter carbon-mediated plant mutualisms. In mutualistic ant-plant symbioses, plants host ant colonies that defend them against herbivores. Here we show that the partners' investments in a widespread ant-plant symbiosis increase with water stress across 26 sites along a Mesoamerican precipitation gradient. At lower precipitation levels, Cordia alliodora trees invest more carbon in Azteca ants via phloem-feeding scale insects that provide the ants with sugars, and the ants provide better defense of the carbon-producing leaves. Under water stress, the trees have smaller carbon pools. A model of the carbon trade-offs for the mutualistic partners shows that the observed strategies can arise from the carbon costs of rare but extreme events of herbivory in the rainy season. Thus, water limitation, together with the risk of herbivory, increases the strength of a carbon-based mutualism.

Topics: Animals; Ants; Carbohydrate Metabolism; Cordia; Costa Rica; Dehydration; Hemiptera; Herbivory; Host-Parasite Interactions; Mexico; Models, Biological; Nicaragua; Rain; Symbiosis

Topics: Animals; Ants; Cordia; Dehydration; Hemiptera

Since some years lindane has been replaced by tartar emetic in a sweet tasting liquid against ants, of which a three year old girl drank nearly 50 ml containing 2.3 g tartar emetic. This is a multiple of the lethal dose for children. But this child survived. The course of the intoxication and its therapy are described. The levels of antimony were controlled in blood and urine.

Topics: Antimony; Antimony Potassium Tartrate; Ants; Child, Preschool; Combined Modality Therapy; Dehydration; Female; Gastroenteritis; Humans; Insecticides; Metabolic Clearance Rate