MFI, BEA and FAU Zeolites scavenging role in Neonicotinoids and radical species elimination

Ecotoxicity caused by neonicotinoid pesticides is largely due to oxidative stress on non-target species. Due to the fact that reactive radical species reach the environment, materials intended for pesticide removal...

Acute and Chronic Effects of Clothianidin, Thiamethoxam and Methomyl on Chironomus dilutus

Organism tolerance thresholds for emerging contaminants are vital to the development of water quality criteria. Acute (96-h) and chronic (10-day) effects thresholds for neonicotinoid pesticides clothianidin and thiamethoxam, and the carbamate pesticide methomyl were developed for the midge Chironomus dilutus to support criteria development using the UC Davis Method. Median lethal concentrations (LC50s) were calculated for acute and chronic exposures, and the 25% inhibition concentrations (IC25) were calculated for the chronic exposures based on confirmed chemical concentrations. Clothianidin effect concentrations were 4.89 µg/L, 2.11 µg/L and 1.15 µg/L for 96-h LC50, 10-day LC50 and 10-day IC25, respectively. Similarly, thiamethoxam concentrations were 56.4 µg/L, 32.3 µg/L and 19.6 µg/L, and methomyl concentrations were 244 µg/L, 266 µg/L and 92.1 µg/L. Neonicotinoid effect concentrations compared favorably to previously published 96-h and 14-day LC50 concentrations, and methomyl effect concentrations were within the acute survival range reported for Chironomus species and other organisms.

Sub-lethal pesticide exposure erases colour vision memory and affects flower constancy in foraging honey bees

Neonicotinoid pesticide use has increased around the world despite accumulating evidence of their potential detrimental sub-lethal effects on the behaviour and physiology of bees, and its contribution to the global decline in bee health. Whilst flower colour is considered as one of the most important signals for foraging honey bees, the effects of pesticides on colour vision and memory retention remain unknown. We trained free flying foragers to an unscented artificial flower patch presenting yellow flower stimuli to investigate if sub-lethal levels of imidacloprid would disrupt the acquired association made between flower colour and food reward. We found that for concentrations higher than 4% of LD50 foraging honey bees no longer preferentially visited the yellow flowers and bees reverted back to baseline foraging preferences for blue flowers, with a complete loss of flower constancy. Higher pesticide dosages also resulted in a significant decrease in CaMKII and CREB gene expression, revealing a plausible mechanism to explain the disruption of bee foraging performance. Within important bee pollinators, colour vision is highly conserved and essential for efficient nutrition collection and survival. We thus show that to maintain efficient pollination services bees require environments free from neonicotinoid pesticides.

Physiological and metabolic alterations induced by commercial neonicotinoid formulations in Daphnia magna

Neonicotinoid insecticides are widely used agents in agriculture to control a broad range of insect pests. Although use of neonicotinoid pesticides has resulted in the widespread contamination of surface waters, sublethal toxicity data of these products in relation to non-target aquatic biota are still poor. Therefore, the objective of this study was to assess the effects of two neonicotinoid pesticides with widespread use on the basic physiological functions: the thoracic limb activity and heart rate of Daphnia magna, and to screen for their potential to affect the cytochrome P450 monooxygenase system of daphnids. The considered pesticides were the acetamiprid- and thiacloprid based products Mospilan 20 SG and Calypso 480 SC. The dose-dependent variation in the three biological endpoints considered were assessed following 24h exposures. The two neonicotinoid formulations elicited significant depression on the thoracic limb activity and heart rate of daphnids at doses close to the 48h-EC50 of the products, a response mainly attributable to the overall drop in the general health status of the organisms. The dose related variation in the ECOD activity of daphnids exposed to the selected neonicotinoid formulations followed a biphasic pattern, with starting effective doses for Mospilan 20 SG of 6.3 mg L-1 (= 1/20 of 48h-EC50 for Daphnia neonates), and for Calypso 480 SC of 0.034 mg L-1 (= 1/4000 of 48h-EC50). Maximal ECOD activity (2.2 fold increase vs. controls) was induced by Mospilan 20 SG in daphnids exposed to 114 mg L-1 product (= 48h-EC20), and by Calypso 480 SC (1.8 fold increase) at 5.2 mg L-1 dose (= 1/20 of 48h-EC50). The results outlined significant alterations in the physiological traits considered at concentrations below the immobility thresholds (48h-EC50) of the products used as benchmarks to rate their toxicity risks to aquatic biota. Therefore, we think our findings might deserve consideration in the environmental risk evaluation of these products.

Influence of pyrethroid and neonicotinoid insecticides on lizards (Reptilia, Squamata) (a review)

Pyrethroid and neonicotinoid pesticides are synthetic substances that are distributed in different economic activity spheres and until recent times were considered one of the safe types of insecticides. It is known that the use of pyrethroid and neonicotinoid insecticides have certain environmental risks for animal populations. Reptiles manifest a significant sensitivity to this family of insecticides. Lizards (Lacertilia) is a numerous group of animals, a large number of species of which is associated with biotopes located in the landscapes influenced by pesticides. Features of toxic effects of pyrethroid and neonicotinoid insecticides are investigated on a small number of Lacertilia species and mainly on small lizards. An analysis of previous studies allowed identifying certain features of the toxic effect of pyrethroids and neonicotinoids on the lizards. Affecting this group of insecticides in lizards may increase mortality and neurological deviations, whose symptoms may reduce over time. Laboratory studies indicate that these substances can lead to increased lizard lethality and to hormonal, biochemical, and neuralgic deviations. The conducted studies indicate that these insecticides have an antiandrogenic effect that may decrease the reproductive success of lizards. The metabolism of insecticides in the lizard organism causes the formation of toxic metabolites, which may be accompanied by a greater poisoning of the lizard body than detoxification. Enantiomers of the investigated insecticides, exhibit a different degree of toxicity. A number of parameters of toxic effects are proposed as biomarkers of intoxication with pyrethroid and neonicotinoid insecticides. Lizards can be used for bioindication of synthetic insecticides, but the research activities on this issue began to grow in recent decades.

Improved mitochondrial function corrects immunodeficiency and impaired respiration in neonicotinoid exposed bumblebees

Neonicotinoid pesticides undermine pollinating insects including bumblebees. However, we have previously shown that mitochondrial damage induced by neonicotinoids can be corrected by 670nm light exposure. But we do not know if this protection extends to immunity or what the minimum effective level of 670nm light exposure is necessary for protection. We use whole body bee respiration in vivo as a metric of neonicotinoid damage and assess the amount of light exposure needed to correct it. We reveal that only 1 min of 670nm exposure is sufficient to correct respiratory deficits induced by pesticide and that this also completely repairs damaged immunocompetence measured by haemocyte counts and the antibacterial action of hemolymph. Further, this single 1 min exposure remains effective for 3–6 days. Longer exposures were not more effective. Such data are key for development of protective light strategies that can be delivered by relatively small economic devices placed in hives.