Effect of Selection for Pyrethroid Resistance on Abiotic Stress Tolerance in from Merida, Yucatan, Mexico.

The study of fitness costs of insecticide resistance mutations in has generally been focused on life history parameters such as fecundity, mortality, and energy reserves. In this study we sought to investigate whether trade-offs might also exist between insecticide resistance and other abiotic stress resistance parameters. We evaluated the effects of the selection for permethrin resistance specifically on larval salinity and thermal tolerance.

Aerobic function in mitochondria persists beyond death by heat stress in insects.

The critical thermal maximum (CT) of insects can be determined using flow-through thermolimit respirometry. It has been demonstrated that respiratory patterns cease and insects do not recover once the CT temperature has been reached. However, if high temperatures are maintained following the CT, researchers have observed a curious phenomenon whereby the insect body releases a large burst of carbon dioxide at a rate and magnitude that often exceed that of the live insect.

Thermal acclimation in a complex life cycle: the effects of larval and adult thermal conditions on metabolic rate and heat resistance in Culex pipiens (Diptera: Culicidae).

It has now been well established that insects can respond to variation in their environment via acclimation, yet the extent of the response varies among populations and environmental characteristics. One under-investigated theme which may contribute to this variation concerns acclimation effects across the life cycle. The present study explores how acclimation in the larval stage of Culex pipiens affects thermal relations in the adult stage.

Thermal resistance and performance correlate with climate in populations of a widespread mosquito.

The abundance and success of widely distributed species across variable environments make them suitable models for exploring which traits will be important for resilience to climate change. Using a widespread mosquito species, Culex tarsalis, we have investigated population-level variation in the critical thermal maximum (CT(max)) and the metabolic response to temperature (MR-T). Adult female C.

Inversion 2La is associated with enhanced desiccation resistance in Anopheles gambiae.

Background: Anopheles gambiae, the principal vector of malignant malaria in Africa, occupies a wide range of habitats. Environmental flexibility may be conferred by a number of chromosomal inversions non-randomly associated with aridity, including 2La. The purpose of this study was to determine the physiological mechanisms associated with the 2La inversion that may result in the preferential survival of its carriers in hygrically-stressful environments.

2La chromosomal inversion enhances thermal tolerance of Anopheles gambiae larvae.

Background: The mosquito Anopheles gambiae is broadly distributed throughout sub-Saharan Africa and this contributes to making it the most efficient vector of malaria on the continent. The pervasiveness of this species is hypothesized to originate in local adaptations facilitated by inversion polymorphisms. One inversion, named 2La, is strongly associated with aridity clines in West and Central Africa: while 2La is fixed in arid savannas, the 2L+a arrangement is predominantly found in the rainforest.

Bias, precision and accuracy in the estimation of cuticular and respiratory water loss: a case study from a highly variable cockroach, Perisphaeria sp.

We compared the precision, bias and accuracy of two techniques that were recently proposed to estimate the contributions of cuticular and respiratory water loss to total water loss in insects. We performed measurements of VCO2 and VH2O in normoxia, hyperoxia and anoxia using flow through respirometry on single individuals of the highly variable cockroach Perisphaeria sp. to compare estimates of cuticular and respiratory water loss (CWL and RWL) obtained by the VH2O-VCO2 y-intercept method with those obtained by the hyperoxic switch method.

Evidence from mosquitoes suggests that cyclic gas exchange and discontinuous gas exchange are two manifestations of a single respiratory pattern.

In this paper we demonstrate that the apparent pattern of gas exchange in insects, as observed using flow-through respirometry, is strongly affected by the rate of flow of air through the system. This is true not only because of the time constant of the respiratory chamber in which the insect resides, but also due to the effect of flow rate on the residence time of air as it passes through the detection chamber in the gas analyzer. It is demonstrated that insects respiring with a discontinuous gas exchange pattern can appear to be using a cyclic respiratory pattern.

Physiology of desiccation resistance in Anopheles gambiae and Anopheles arabiensis.

Desiccation resistance and water balance were studied in the adult female mosquitoes Anopheles arabiensis and Anopheles gambiae sensu stricto. When the two species were reared from egg to adult under identical conditions, An. arabiensis had significantly higher desiccation resistance than did An.

Metabolic rate in female Culex tarsalis (Diptera: Culicidae): age, size, activity, and feeding effects.

We used flow-through respirometry on female mosquitoes to observe individual ventilatory pattern and to measure metabolic rate at rest, during activity and after a blood-meal. At rest, young adult females of the species Culex tarsalis ventilated cyclically with an average VCO2 of 6.5 nl/min and frequency of 45 mHz.