Imidacloprid - Induced Pathophysiological Damage in the Midgut of Locusta Migratoria (Orthoptera: Acrididae) in the Field

Neonicotinoids are modern insecticides widely used in agriculture worldwide. Their impact on target (nervous system) and non-target (midgut) tissues has been well studied in beneficial insects including honeybees. However, their effects on pest insects on the field are comparably rarely described. Here, we have studied the effects of the neonicotinoid imidacloprid on the midgut of the pest insect Locusta migratoria caught in the field. We found that in the midgut of imidacloprid-exposed locusts the activity of enzymes involved in reactive oxygen metabolism was perturbed. By contrast, the activity of P450 enzymes that have been shown to be activated in a detoxification response and that were also reported to produce reactive oxygen species was elevated. Probably as a consequence, markers of oxidative stress including protein carbonylation and lipid peroxidation accumulated in midgut samples of these locusts. Histological analyses revealed that their midgut epithelium is disorganized and that the brush border of the epithelial cells is markedly reduced. Indeed, microvilli are significantly shorter, misshapen and possibly non-functional in imidacloprid-treated locusts. We hypothesize that imidacloprid induces oxidative stress in the locust midgut, thereby changing the shape of midgut epithelial cells and probably in turn compromising their physiological function. Presumably, these effects reduce the survival rate of imidacloprid-treated locusts and the damage they cause in the field.

Beneficial Insects for Biological Pest Control in Greenhouse Cannabis Production

A greenhouse cannabis cultivation took place in Agriculture university of Athens in order to quantify the efficiency of beneficial insects as a main method of pest management. Cannabis plants grown in two greenhouses and beneficial insects were released only in one greenhouse as a means to investigate the efficacy against pests by the comparison with the control greenhouse. Measurements included the visual estimation of infestation, the recording of pest species and populations, and the comparison of infestations and yields amongst greenhouses. Our results indicate that beneficial insects could control pest populations up to 100%. Even though the environmental conditions were not optimal and consecutive pest infestations were observed throughout the duration of our study, the beneficial insects successfully managed the pest populations. In conclusion, biological control with beneficial insects is a very effective method for pest management in greenhouse cannabis production.

Investigation of the Effects of Probiotics on Sub-Chronic Neonicotinoid Toxicity in Rats

Probiotics have been shown to have positive effects when it comes to combating various health issues when consumed, preventing even the absorption of environmental toxins. One of the main environmental toxins encountered today is pesticide residues. Neonicotinoids, widely applied today in countries that have approved of them, are a known class of insecticides with an excellent and effective potency. Neonicotinoids have been shown to cause various toxic effects, either acutely or chronically, on human health and on beneficial insects when exposed. To clarify the assumption that probiotics could counteract these toxic effects, especially on vital organs, the probiotic yeast “Saccharomyces boulardii” (S. boulardii) was tested against the neonicotinoids, acetamiprid (ACE) and imidacloprid (IMI), as it has outstanding physiological and metabolic properties. The results obtained from the studies indicated that although ACE and IMI induced liver, kidney, brain and bowel damage, there was a considerable level of protection by the dietary supplementation of S. boulardii, as it reduced the absorption of these insecticides.

The Role of Cytochrome P450s in Insect Toxicology and Resistance

Insect cytochrome P450 monooxygenases (P450s) perform a variety of important physiological functions, but it is their role in the detoxification of xenobiotics, such as natural and synthetic insecticides, that is the topic of this review. Recent advances in insect genomics and postgenomic functional approaches have provided an unprecedented opportunity to understand the evolution of insect P450s and their role in insect toxicology. These approaches have also been harnessed to provide new insights into the genomic alterations that lead to insecticide resistance, the mechanisms by which P450s are regulated, and the functional determinants of P450-mediated insecticide resistance. In parallel, an emerging body of work on the role of P450s in defining the sensitivity of beneficial insects to insecticides has been developed. The knowledge gained from these studies has applications for the management of P450-mediated resistance in insect pests and can be leveraged to safeguard the health of important beneficial insects. Expected final online publication date for the Annual Review of Entomology, Volume 67 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Novel inhibitors of the renal inward rectifier potassium (Kir) channel of the mosquito vector Aedes aegypti

The mosquito continues to be the most lethal animal to humans due to the devastating diseases that it carries and transmits. Controlling mosquito-borne diseases relies heavily on vector management using neurotoxic insecticides with limited modes of action. This has led to the emergence of resistance to pyrethroids and other neurotoxic insecticides in mosquitoes, which has reduced the efficacy of chemical control agents. Moreover, many neurotoxic insecticides are not selective for mosquitoes and negatively impact beneficial insects such as honeybees. Developing new mosquitocides with novel mechanisms of action is a clear unmet medical need; this review covers the efforts made toward this end by targeting the renal inward rectifier potassium channel (Kir) of the mosquito.