In addition, with the higher concentration, the regular DGE cycles ceased after the first 30 minutes, whereas no change was observed with the lower concentration. The loss of DGE cycles occurred because of paralysis, since no muscle activity was detected. The application of deltamethrin in the experiment of Zafeiridou and Theophilidis 75 has caused a gradual increase in the frequency of the respiratory contraction of T. Kuusik et al 74 studied the effect of topical treatment with 0. This nerve poison caused lethal neurotoxicosis, which at first was seen by abnormal coordination and hyperactivity of treated pupae.
Zheng et al 78 experimented with the effect of permethrin on the tick Amblyomma americanum L. In addition, they also studied the effect of amitraz, an acaricide and synergist, and found both permethrin and amitraz caused an increase in metabolic rate because of increasing frequency of DGE cycles or even replacement of DGE with continuous respiration.
The permethrin treatment also caused major water loss. Since amitraz is often used mixed with insecticides for better pest control, Zheng et al 78 also tested the effect of the mixture of these two pesticides. This clearly showed the synergistic effect on the CO 2 release and metabolic rate. In the case of the mixture, the authors observed two major water loss periods: the first immediately and the second 12 hours after treatment. The effects of the neonicotinoid imidacloprid on the insect respiratory system have been studied on T.
Zafeiridou and Theophilidis 75 treated T. Although both imidacloprid and deltamethrin affect the nervous system of the insect, the effects found were different. Unlike the deltamethrin, imidacloprid caused cessation of respiratory rhythms. Insecticidal plant extracts may affect insects at the same toxic level as synthetic insecticides.
Both these experiments share the result based on gravimetrical recording that the treated individuals lost more water, and in both cases the authors supposed that death came through desiccation. Harak et al 36 also worked with P. Similar to azadirachtin, pyrethrum caused lethal desiccation in parallel with muscle paralysis.
Kuusik et al 74 treated pupae of T. Simonkai, Nicotiana rustica L. All of these caused a decrease in metabolic rate and disappearance of DGE cycles, whereas with A. The lengthening of periods of muscular hyperactivity was also the cause of DGE disappearance after treatment with a natural juvenile hormone analog, extracts of Ledum palustre Marsh-Tea. Insect respirometry measurements are suitable for detection of changes caused by many different kinds of pollutants or substances. In Cry1C toxin-resistant larvae and pupae which were constantly exposed to the toxin, the metabolic rate was higher and, at the same time, body mass was lower, indicating the costs of detoxification of the toxin.
They also studied the water loss rate of pupae and observed that Cry1C toxin-exposed pupae had higher water loss rate, which indicates their increased susceptibility to desiccation. Some bioinsecticides have also been tested against the bumble bee B.
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Karise et al 48 found no changes in metabolic rate or respiratory patterns, but saw an increase in water loss rate. This study clearly demonstrates the need for testing not only active ingredients but also all the substances in pesticide formulations. The respiratory system reacts readily even to very low doses of insecticides.
Despite the many aspects affecting metabolic rate, the changes in respiratory patterns can help to ascertain the doses that are really harmful, causing reversible or irreversible injuries to insects. Using the insect respiratory system for toxicology testing has some drawbacks. First, the equipment is expensive and not readily available. However, when present, the experimental costs are minimal and a precise result can be obtained quickly.
Second, there is no current experimental protocol and, probably, the experimental conditions, measurement times, and air flow rate in the system vary with species and its specific environmental needs.
Some researchers use the mean metabolic rate over a certain time period, while others measure the basic metabolic rate. There are pros and cons for both. This review has revealed that only a few studies report all of these end points. There is a lack of standardized end points and study questions: mortality data are often not involved in the study — without this, no risk assessment can be given.
Similarly, there is a lack of dose-specific data on the concentrations of active ingredients or pesticide formulations causing or not causing any change in metabolic rate, water loss rate, or muscular activity in the context of longevity.
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The newer equipment enables measurement of several characteristics in parallel without disturbing the subject. In older publications, water loss rate was determined gravimetrically, whereas in more recent studies water loss rate is measured simultaneously allowing separation of water loss through cuticle or spiracles. Third, the respiratory patterns largely depend on metabolic rate of the insect, which in turn may be affected by several factors leading to possible misinterpretations of the results.
This review reports a variety of effects of pesticides on insect respiratory patterns, metabolic rate, or water loss rate. Although both the tested pesticides and target subjects belong to very different groups, the results of the reviewed studies indicate several common effects. Nerve poisons induce rapid or delayed disappearance of DGE rhythms due to inhibition of muscle work at different level.
Losing control over ventilatory muscle work leads to higher water loss and eventual death of the insect. Risks of large-scale use of systemic insecticides to ecosystem functioning and services. Environ Sci Pollut Res Int.
The sublethal effects of pesticides on beneficial arthropods. Annu Rev Entomol. Neural effects of insecticides in the honey bee. Kestler P. Cyclic CO 2 release as a physiological stress indicator in insects. Comp Biochem Physiol C. Insecticide poisoning: disruption of a possible autonomic function in pupae of Tenebrio molitor. Pestic Biochem Phys. Watanabe ME. Colony collapse disorder: many suspects, no smoking gun.
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Lighton JRB. Discontinuous gas exchange in insects. The role of discontinuous gas exchange in insects: the chtonic hypothesis does not hold water. J Exp Biol. Insects breathe discontinuously to avoid oxygen toxicity.
Discontinuous gas exchange in insects: a clarification of hypotheses and approaches. Physiol Biochem Zool. Buck J, Keister M. Cyclic CO 2 release in diapausing Agapema pupae. Biol Bull. Buck J. Cyclic CO 2 release in insects.
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