Non-target Predators Research Articles

The comet assay in Ceraeochrysa claveri (Neuroptera: Chrysopidae): A suitable approach for detecting somatic and germ cell genotoxicity induced by agrochemicals

Some agrochemicals are genotoxic to several organisms. Nevertheless, few protocols are currently available for measuring the toxicogenetic effects of these compounds in target and non-target field-collected species of insects important to agriculture. Herein, we used the species Ceraeochrysa claveri (Neuroptera: Chrysopidae), a non-target predator insect, to investigate the ability of an azadirachtin-based biopesticide (Azamax™) to induce DNA damage. The alkaline version of the comet assay was standardized to evaluate genetic instability caused by the toxicant in somatic (gut) and germ (nurse cells and oocytes) cells of C. claveri. For this, C. claveri larvae were distributed into three groups (10/each) and treated with Azamax™ at 0, 0.3% or 0.5% throughout the larval stage. DNA damage (tail intensity) was measured in adult insects, four days after emerged. The data showed that both doses of Azamax™ (0.3% and 0.5%) were able to significantly (p < 0.05) increase DNA damage in somatic and germ cells of C. claveri. In conclusion, C. claveri (intestinal and ovarian cells) was a sensitive bioindicator for identifying Azamax™ genotoxic potential, whereas the comet assay was a useful tool for detecting the genotoxic hazard of the pesticide in the field-collected insect species. Given that estimation of adverse effects of pollutants on ecosystems is an essential component of environmental risk assessment, the approach used can be recommended to estimate the ecotoxicity of agricultural chemicals.

Genetic Identification of Species Responsible for Depredation in Commercial and Recreational Fisheries

AbstractDepredation, the partial or complete removal of hooked fish (prey) by a nontarget predator species, is a cryptic interaction that negatively affects predators, prey, and fishing industries. However, these interactions are rarely observed, rendering positive identification of the predator nearly impossible. We therefore tested a genetic method for predator identification. Depredated remains from sharks and bony fish were sampled with buccal swabs. Genetic material was isolated from the swabs, which we hypothesized contained oral cells from the predator. A portion of the cytochrome‐c oxidase subunit I locus was amplified using prey‐specific blocking primers and sequenced in high depth using a metagenetics approach. We sequenced haplotypes from the remains of four sharks, where the predator was visually confirmed, and four bony fish, where the predator was unknown. For all interactions with known predators, our technique suggested the correct predator species. For all interactions where the predators were unknown, our technique suggested species previously confirmed as perpetrators in depredation events. Our findings provide a basis for the development of a genetic technique for predator identification, while highlighting challenges to be overcome before predator identification can be applied to large‐scale fisheries.

Abundance of Non-Target Predators in Genetically Modified Corn

Abundance of Non-Target Predators in Genetically Modified Corn

Toxicity and cytotoxicity of the insecticide imidacloprid in the midgut of the predatory bug, Podisus nigrispinus

The selectivity of insecticides on natural enemies in pest control are an important strategy for Integrated Pest Management. However, insecticides can have side effects on non-target organisms such as natural enemies. This study evaluated the histological and cytological changes mediated by the sublethal concentration of the imidacloprid insecticide on the midgut of non-target predator Podisus nigrispinus (Heteroptera: Pentatomidae), used in the biological control of pests. Imidacloprid was toxic for P. nigrispinus with LC50 = 3.75 mg L−1 and survival of 51.8%. This sublethal concentration of imidacloprid causes histological alterations in the midgut epithelium and cytotoxic features were irregular border epithelium, cytoplasmic vacuolation, and apocrine secretions in the first 6 h after exposure with the insecticide. Apoptosis in the digestive cells occurs after 12 h of exposure in the midgut. These results suggest that imidacloprid may affect the digestive physiology of P. nigrispinus and compromise the effective predation of this insect a biological control agent. The associated use of this insecticide with the predator in pest control should be carefully evaluated.

Lethal and sublethal effects of emamectin benzoate on the rove beetle, Paederus fuscipes, a non-target predator of rice brown planthopper, Nilaparvata lugens

The use of pesticides in rice can not only manage the pest but also influence non-target organisms. The rove beetle (Paederus fuscipes), which is an important predator of the brown plant hopper (Nilaparvata lugens) in rice ecosystems, was tested to investigate acute and chronic effects of emamectin benzoate. The results from this study show that the LC50 of emamectin benzoate to adults of P. fuscipes at 72 h was 3.07 (1.84–4.54) mg a.i. L−1, whereas the LC50 of emamectin benzoate to the second instar larvae of P. fuscipes at 72 h was 2.58 (1.95–3.19) mg a.i. L−1. Tested sublethal doses (LC10 and LC30) had significant effects on the second instar developmental time of P. fuscipes compared with that of the control. The LC30 dose had a negative influence on the pre-imaginal developmental duration and the feeding potential of treated P. fuscipes larvae. Additionally, the LC30 reduced the pre-oviposition period, the fecundity and the body weight of adults emerged from treated larvae of P. fuscipes. In the sublethal experiment with adults, the fecundity and the feeding potential were significantly reduced at the LC30 dose. These results revealed that sublethal doses of emamectin benzoate negatively affected the development and biological activities of P. fuscipes, and we conclude that more attention should be paid to the use of this chemical as part of integrated pest management strategies.

The prevalence and correlates of anticoagulant rodenticide exposure in non-target predators and scavengers in Finland

The most common rodent control method worldwide is anticoagulant rodenticides (ARs), which cause death by internal bleeding. ARs can transfer to non-target predators via secondary exposure, i.e. by consuming contaminated rodents. Here we quantify the prevalence of seven AR substances in the liver tissues of altogether 17 mammalian or avian predator or scavenger species in Finland. In addition, we identify the environmental and biological factors potentially linked to secondary AR poisoning. No previous AR screenings have been conducted in the country, despite the widespread use of ARs and their potential impacts on the high levels of the ecosystem food chain. ARs were detected (≥0.3 μg/kg) in 82% of the 131 samples. The most prevalent and the AR with highest concentrations was bromadiolone (65% of samples). In 77% of the positive samples more than one (2–5) different ARs were detected. Of the environmental variables, we only found a weakly positive relationship between the coumatetralyl concentration and the livestock farm density. Conversely, overall AR concentration and number, as well as the concentration of three separate ARs (coumatetralyl, difenacoum and bromadiolone) differed among the three species groups tested, with the group “other mammals” (largely represented by red fox and raccoon dog) having higher values than the groups presented by mustelids or by birds. ARs are authorized only as biocides in Finland and a national strategy on risk management (e.g. for minimising secondary poisoning of non-target species) of ARs was adopted in 2011. Based on these results it appears that the risk mitigation measures (RMMs) either have not been followed or have not been effective in preventing wide scale secondary exposure. Continued monitoring of AR residues in non-target species is needed in order to evaluate the effectiveness of current RMMs and a need for new ones to reduce the risk of secondary poisoning.

Laboratory and semi-field evaluation of three entomopathogenic nematode species on two non-target insect predators, Coccinella septumpunctata (Coleoptera: Coccinellidae) and Chrysoperla carnea (Neuroptera: Chrysopidae)

Biocontrol potential of the entomopathogenic nematodes (EPNs) on the second-instar larvae of the non-target insect predators, Coccinella septumpunctata and Chrysoperla carnea as compared to Spodoptera littoralis (Boisd.) was evaluated. The pathogenicity of EPNs, namely, Heterorhabditis bacteriophora, Steinernema feltiae and Steinernema carpocapsae at concentrations 100, 200, 400, 800 and 1600 IJs/cup) were tested at 2, 4 and 6 days’ post-inoculation. Laboratory results showed significant differences among the mortality rates of different tested larvae, for each concentration at different time intervals. H. bacteriophora induced the highest mortality followed by S. carpocapsae treatment. However, S. feltiae was found to be more safety on predators as it causes less mortality at 6 days of treatment. The values of half lethal concentrations (LC50) were 614.06, 3797.43 and 676.47 IJs/cup for C. Carnea and 390.60, 1209.88 and 503.65 IJs/cup for C. septumpunctata treated by H. bacteriophora, S. feltiae and S. carpocapsae, respectively. In semi-field experiments, there were non-significant differences among mortality of each predator indicated at concentrations of the different EPNs after 2 days or 6 days’ post-inoculation. The study revealed a lethal pathogenic effect of EPNs against insect pests but caused low mortality on the non-target ones.

Coexistence of Bacillus thuringiensis (Bt)-transgenic and conventional rice affects insect abundance and plant fitness in fields.

As genetically modified (GM) crops are cultivated worldwide, concerns are emerging about the ecological consequences of the coexistence of transgenic and non-transgenic crops in fields. We first conducted field experiments using insect-resistant transgenic rice expressing Bacillus thuringiensis (Bt-transgenic rice) and its counterpart conventional rice (Oryza sativa L.) with or without insecticide spraying in 2013 and 2014. In 2015 and 2016, Bt-transgenic and conventional rice plants were employed in pure and mixed cages, with an infestation of the target insect (Chilo suppressalis) and with insecticide spraying as the control treatment to prevent target insect infestation. The presence of Bt-transgenic rice decreased the abundance of target insects but did not affect non-target insects and predators in fields. Compared with conventional rice, Bt-transgenic rice showed more empty seeds but comparable seed production in cages. The infestation of target insects significantly decreased the plant fitness of conventional rice in pure cages, but did not affect its fitness when conventional rice coexisted with Bt-transgenic rice. In mixed cages, the presence of Bt-transgenic rice decreased the abundance of target insects and the percentage of dead sheaths in conventional rice. The presence of Bt-transgenic rice benefits the growth and reproduction of non-transgenic rice in fields because of a decreased abundance of target insects. © 2018 Society of Chemical Industry.

Is Sensitivity to Anticoagulant Rodenticides Affected by Repeated Exposure in Hawks?

A seminal question in wildlife toxicology is whether exposure to an environmental contaminant, in particular a second-generation anticoagulant rodenticide, can evoke subtle long lasting effects on body condition, physiological function and survival. Many reports indicate that non-target predators often carry residues of several rodenticides, which is indicative of multiple exposures. An often-cited study in laboratory rats demonstrated that exposure to the second-generation anticoagulant rodenticide brodifacoum prolongs blood clotting time for a few days, but weeks later when rats were re-exposed to the first-generation anticoagulant rodenticide warfarin, coagulopathy was more pronounced in brodifacoum-treated rats than naïve rats exposed to warfarin. To further investigate this phenomenon, American kestrels were fed environmentally realistic doses of chlorophacinone or brodifacoum for a week, and following a week-long recovery period, birds were then challenged with a low-level dietary dose of chlorophacinone. In the present study, neither hematocrit nor clotting time (prothrombin time, Russell’s viper venom time) were differentially affected in sequentially exposed kestrels compared to naïve birds fed low-level dietary dose of chlorophacinone. While the present findings do not reveal lasting effects of anticoagulant exposure on blood clotting ability, findings in laboratory rats and other species have demonstrated such effects on blood clotting, and even other molecular pathways associated with immune function and xenobiotic metabolism. Additional studies using an environmentally realistic route of exposure and dose are underway to further test this hypothesis.

Exposure of stone marten (Martes foina) and polecat (Mustela putorius) to anticoagulant rodenticides: Effects of regulatory restrictions of rodenticide use

When anticoagulant rodenticides (ARs) are used to control rodent populations there is also a widespread secondary exposure of non-target predators to ARs. To reduce secondary exposure, regulatory restrictions in AR usage were tightened in Denmark in 2011. The restrictions included the cessation of AR use for plant protection and any use away from buildings, as well as limitations in private consumers' access to ARs. To quantify and evaluate the efficiency of the regulatory measures to reduce secondary exposure, we analysed ARs in liver tissue from 40 stone martens (Martes foina) and 40 polecats (Mustela putorius) collected before and 31 stone martens and 29 polecats collected after the restrictions were imposed.No declines in the prevalence ARs were detected following the regulatory restrictions in either stone marten (Before: 98%, After: 100%) or polecat (Before: 93%, After: 97%). The total AR concentration was higher in stone martens than in polecats in both sampling periods. Between the two sampling periods, the total AR concentrations in the mustelids increased (P<0.001). The increase was significant for stone marten (Before: 419ng/g ww, After: 1116ng/g ww, P<0.001), but not for polecat (Before: 170ng/g ww, After: 339ng/g ww). Overall, the total AR concentration was positively correlated to the urban area and the area used for Christmas tree production in which ARs were regularly used before 2011.The regulatory restrictions in AR usage did not reduce exposure of non-target stone martens and polecats. The temporal and spatial patterns of AR concentrations in predators indicate that chemical rodent control in and around buildings is the dominant source for the exposure of non-target predators in intensively human-dominated landscapes in Denmark. The results suggest that non-chemical methods for rodents control at buildings are necessary to prevent widespread secondary AR exposure of predators in human modified landscapes.

Defining ecologically relevant scales for spatial protection with long-term data on an endangered seabird and local prey availability.

Human activities are important drivers of marine ecosystem functioning. However, separating the synergistic effects of fishing and environmental variability on the prey base of nontarget predators is difficult, often because prey availability estimates on appropriate scales are lacking. Understanding how prey abundance at different spatial scales links to population change can help integrate the needs of nontarget predators into fisheries management by defining ecologically relevant areas for spatial protection. We investigated the local population response (number of breeders) of the Bank Cormorant (Phalacrocorax neglectus), a range-restricted endangered seabird, to the availability of its prey, the heavily fished west coast rock lobster (Jasus lalandii). Using Bayesian state-space modeled cormorant counts at 3 colonies, 22 years of fisheries-independent data on local lobster abundance, and generalized additive modeling, we determined the spatial scale pertinent to these relationships in areas with different lobster availability. Cormorant numbers responded positively to lobster availability in the regions with intermediate and high abundance but not where regime shifts and fishing pressure had depleted lobster stocks. The relationships were strongest when lobsters 20-30 km offshore of the colony were considered, a distance greater than the Bank Cormorant's foraging range when breeding, and may have been influenced by prey availability for nonbreeding birds, prey switching, or prey ecology. Our results highlight the importance of considering the scale of ecological relationships in marine spatial planning and suggest that designing spatial protection around focal species can benefit marine predators across their full life cycle. We propose the precautionary implementation of small-scale marine protected areas, followed by robust assessment and adaptive-management, to confirm population-level benefits for the cormorants, their prey, and the wider ecosystem, without negative impacts on local fisheries.

Insecticidal effects of aqueous extracts of wild pomegranate peel and seed (Punica granatum L.) against rose aphids, Macrosiphum rosaeformis

Efficacy of wild pomegranate (Punica granatum Linn.) fruit peel and seeds aqueous extract was evaluated for the control of common insect pests aphids (Macrosiphum rosaeformis) and for its influence on useful non-target predators viz., Coccinella septempunctata. Lethal doses of daru peel and seed suggested these became more toxic to aphids after 24 hr of exposure. A significant difference was obtained in percentage aphids reached to untreated leaves over peel extract treated leaves (23:57 and 23:77) and seed extract treated leaves (7:80 and 17:80) at 90 and 180 min time intervals in food choice assays. No significant effect was observed against Coccinella. LC50 values of daru peel and seed extracts along with mixture of three flavonoids (Kaempferol, Quercetin and Myricetin) were assessed at 48 hr values were 34.9, 4.7 and 0.6 mg/ml and at 72 hr these were 16.1, 0.000001 and 0.00001 mg/ml, respectively. In both the cases field bioassays showed affectivity till 7 DAT. Field data indicated that only X1(1 mg/ml) and X2 (0.1 mg/ml) concentrations of mixture were effective till 11 days after treatment. These are the first reports of the toxic effect of wild pomegranate (daru) fruit peel aqueous extract against M. rosaeformis, hence the study suggests possible usage of Punica granatum peel for the control of rose aphids.

Aphicidal effects of terpenoids present in Citrus limon on Macrosiphum roseiformis and two generalist insect predators

The current study is the first report that revealed insecticidal effects of lemon (Citrus limon) peel aqueous extract (LFPAE) against common insect pest of rose, aphids (Macrosiphum roseiformis) and for its influence on useful non-target predators viz., Coccinella septempunctata and Orius laevigatus on rose plants. Effects of LFPAE seemed promising concerning pest and predators of Rosa spp. The LC ESI Q-TOF MS/MS analysis of extract revealed the presence of (l-pipecolic acid, scopoletin, pulegone, γ-terpinene, carvone, menthone, myrcene, limonene, (−)-trans-isopiperitenol, geranial and linalool as active components that may be ascribed to observed effects. Also, some major terpenoids α-pinene, β-pinene, γ-terpinene, menthone, linalool, limonene which are known to be present in lemon were tested for their efficacy. LFPAE did not show any toxicity towards C. septempunctata. However, it was moderately toxic to O. laevigatus. Food choice assays and odor choice assay revealed that there was no significant difference obtained between the percentage of pests/predators that reached a particular choice (LFPAE treated, or untreated rose leaves). According to LC50 values of LFPAE for aphids, the highest toxicity and least value (6.68mg/ml), was obtained at 72h which was almost similar to the lowest concentration tested (×6=6.25mg/ml). Besides at 24 and 48h LC50 values were somewhere around ×2 (100mg/ml) and ×3 (50mg/ml) concentrations. Among all the terpenoids tested at 24–72h, γ-terpinene was most toxic with LC50 value ranging from 0.18 to 0.004mg/ml followed by menthone (0.8–0.008), β-pinene (5.8–0.004), limonene (5.8–0.009), mixture (8.5–0.003), linalool (12.3–0.13) and α-pinene (17.8–0.02), respectively. Field data showed that LFPAE at ×1 (200mg/ml), ×2 and ×3 concentration was effective until nine days after treatment (DAT) and lowest concentration ×4 did not show affectivity beyond seven days. However, terpenoids mixture at ×1 (10mg/ml each) showed affectivity till 11DAT and lower two concentrations (×2 and ×3) caused significant mortality up to 7DAT.

Bitrophic and Tritrophic Effects of Transgenic cry1Ab/cry2Aj Maize on the Beneficial, Nontarget Harmonia axyridis (Coleoptera: Coccinellidae).

Harmonia axyridis (Pallas) is a common and abundant predator in China and may be exposed to Cry toxins that are produced in Bt crops either by feeding on plant parts or by feeding on target or nontarget herbivorous insects. A new Bt maize line, expressing the Cry1Ab/Cry2Aj fused protein, has been developed and should be rigorously assessed for the ecological risks on the natural enemy. Laboratory experiments were carried out to study the effects of this Bt maize on nontarget predator H. axyridis via bitrophic interaction of adult H. axyridis feeding on Bt maize pollen and tritrophic interaction of H. axyridis consuming the lepidopteran prey. Spodoptera exigua (Hübner) neonate larvae were used to transfer Bt protein because they could survive after ingesting transgenic cry1Ab/cry2Aj maize kernels in the previous study. ELISA bioassays confirmed that the Bt protein could be transferred, but diluted through Bt maize-prey-predator. Life history parameters such as survival, development, weight, fecundity, and egg hatching rate were not significantly different when H. axyridis consumed prey that had been reared on Bt maize compared with prey reared on a nontransformed parental control. Furthermore, feeding directly on Bt maize pollen also had no detrimental effects on fitness, survival, and weight of female and male adults. In conclusion, our results indicate that transgenic cry1Ab/cry2Aj maize poses no ecological risks on the nontarget predator H. axyridis.

Development of an eco-friendly mosquitocidal agent from Alangium salvifolium against the dengue vector Aedes aegypti and its biosafety on the aquatic predator.

Plant extracts with their enriched chemical constituents have established potential alternative mosquito control agents. In this research, we developed an eco-friendly mosquitocidal agent from Alangium salvifolium leaves against the dengue and Zika virus vector Aedes aegypti and we investigated its biosafety on the mosquito aquatic predator Toxorhynchites splendens. Results showed that the methanolic extract of A. salvifolium leaves was composed by eight main compounds, with major peak area for hexadecenoic acid (21.74%). LC50 and LC90 values calculated on Ae. aegypti fourth instar larvae were 104.80 and 269.15ppm respectively. The methanolic extract tested at 100ppm decreased the α-β carboxylesterase and SOD ratio significantly and upregulated the GST and CYP450 level. The A. salvifolium methanolic extract displayed significant repellent and adulticidal activity at 100 and 400ppm respectively. The treatment with 100ppm of the methanolic extract led to 210min of protection from Ae. aegypti bites. Four hundred parts per million of the extract showed 98% adult mortality within 30min from the treatment. Lastly, biosafety assays on the mosquito aquatic predator Tx. splendens showed that the toxicity of the A. salvifolium extract was significantly lower if compared to the cypermethrin-based treatments. The methanolic extract of A. salvifolium showed a maximum of 47.3% mortality rate at the concentration of 1000ppm, while 0.7ppm of cypermethrin achieved 91.3% mortality rate on Tx. splendens. Overall, our study enhances basic knowledge on how to improve natural larvicidal agents against dengue and Zika virus mosquito vector with harmless responses on non-target aquatic predators.

Fabrication of highly effective mosquito nanolarvicides using an Asian plant of ethno-pharmacological interest, Priyangu (Aglaia elaeagnoidea): toxicity on non-target mosquito natural enemies.

Mosquitoes threaten the lives of humans, livestock, pets and wildlife around the globe, due to their ability to vector devastating diseases. Aglaia elaeagnoidea, commonly known as Priyangu, is widely employed in Asian traditional medicine and pest control. Medicinal activities include anti-inflammatory, analgesic, anticancer, and anesthetic actions. Flavaglines, six cyclopenta[b]benzofurans, a cyclopenta[bc]benzopyran, a benzo[b]oxepine, and an aromatic butyrolactone showed antifungal properties, and aglaroxin A and rocaglamide were effective to control moth pests. Here, we determined the larvicidal action of A. elaeagnoidea leaf aqueous extract. Furthermore, we focused on Priyangu-mediated synthesis of Ag nanoparticles toxic to Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi. The plant extract and the nanolarvicide were tested on three mosquito vectors, following the WHO protocol, as well as on three non-target mosquito predators. Priyangu-synthesized Ag nanoparticles were characterized by spectroscopic (UV, FTIR, XRD, and EDX) and microscopic (AFM, SEM, and TEM) analyses. Priyangu extract toxicity was moderate on Cx. quinquefasciatus (LC50 246.43; LC90 462.09μg/mL), Ae. aegypti (LC50 229.79; LC90 442.71μg/mL), and An. stephensi (LC50 207.06; LC90 408.46μg/mL), respectively, while Priyangu-synthesized Ag nanoparticles were highly toxic to Cx. quinquefasciatus (LC50 24.91; LC90 45.96μg/mL), Ae. aegypti (LC50 22.80; LC90 43.23μg/mL), and An. stephensi (LC50 20.66; LC90 39.94μg/mL), respectively. Priyangu extract and Ag nanoparticles were found safer to non-target larvivorous fishes, backswimmers, and waterbugs, with LC50 ranging from 1247 to 37,254.45μg/mL, if compared to target pests. Overall, the current research represents a modern approach integrating traditional botanical pesticides and nanotechnology to the control of larval populations of mosquito vectors, with negligible toxicity against non-target including larvivorous fishes, backswimmers, and waterbugs.

Curzerene, trans-β-elemenone, and γ-elemene as effective larvicides against Anopheles subpictus, Aedes albopictus, and Culex tritaeniorhynchus: toxicity on non-target aquatic predators.

A wide number of studies dealing with mosquito control focus on toxicity screenings of whole plant essential oils, while limited efforts shed light on main molecules responsible of toxicity, as well as their mechanisms of action on non-target organisms. In this study, GC-MS shed light on main essential oil components extracted from leaves of the Suriname cherry Eugenia uniflora, i.e., curzerene (35.7%), trans-β-elemenone (11.5%), and γ-elemene (13.6%), testing them on Anopheles subpictus, Aedes albopictus, and Culex tritaeniorhynchus larvae. Non-target toxicity experiments were carried out on four species of aquatic larvivorous organisms, including fishes, backswimmers, and waterbugs. The essential oil from E. uniflora leaves tested on An. subpictus, Ae. Albopictus, and Cx. tritaeniorhynchus showed LC50 of 31.08, 33.50, and 36.35μg/ml, respectively. Curzerene, trans-β-elemenone, and γ-elemene were extremely toxic to An. subpictus (LC50=4.14, 6.13, and 10.53μg/ml), Ae. albopictus (LC50=4.57, 6.74, and 11.29μg/ml), and Cx. tritaeniorhynchus (LC50=5.01, 7.32, and 12.18μg/ml). The essential oil from E. uniflora leaves, curzerene, trans-β-elemenone, and γ-elemene showed low toxicity to larvivorous fishes, backswimmers, and waterbugs, with LC50 ranging from 303.77 to 6765.56μg/ml. Predator safety factor (PSF) ranged from 55.72 to 273.45. Overall, we believe that curzerene isolated from the essential oil from E. uniflora leaves can represent an ideal molecule to formulate novel mosquito larvicides, due to its extremely low LC50 on all tested mosquito vectors (4.14-5.01μg/ml), which far encompasses most of the botanical pesticides tested till now. Notably, the above-mentioned LC50 did not damage the four aquatic predators tested in this study.

Nano-formulation enhances insecticidal activity of natural pyrethrins against Aphis gossypii (Hemiptera: Aphididae) and retains their harmless effect to non-target predators.

The insecticidal activity of a new nano-formulated natural pyrethrin was examined on the cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae), and the predators Coccinella septempunctata L. (Coleoptera: Coccinellidae) and Macrolophus pygmaeus Rambur (Hemiptera: Miridae), in respect with the nano-scale potential to create more effective and environmentally responsible pesticides. Pyrethrin was nano-formulated in two water-in-oil micro-emulsions based on safe biocompatible materials, i.e., lemon oil terpenes as dispersant, polysorbates as stabilizers, and mixtures of water with glycerol as the dispersed aqueous phase. Laboratory bioassays showed a superior insecticidal effect of the pyrethrin micro-emulsions compared to two commercial suspension concentrates of natural pyrethrins against the aphid. The nano-formulated pyrethrins were harmless, in terms of caused mortality and survival time, to L3 larvae and four-instar nymphs of the predators C. septempunctata and M. pygmaeus, respectively. We expect that these results can contribute to the application of nano-technology in optimization of pesticide formulation, with further opportunities in the development of effective plant protection products compatible with integrated pest management practices.

Modeling Exposure of Mammalian Predators to Anticoagulant Rodenticides

Anticoagulant rodenticides (AR) are a widespread and effective method of rodent control but there is concern about the impact these may have on non-target organisms, in particular secondary poisoning of rodent predators. Incidence and concentration of AR in free-living predators in Denmark is very high. We postulate that this is caused by widespread exposure due to widespread use of AR in Denmark in and around buildings. To investigate this theory a spatio-temporal model of AR use and mammalian predator distribution was created. This model was supported by data from an experimental study of mice as vectors of AR, and was used to evaluate likely impacts of restrictions imposed on AR use in Denmark banning the use of rodenticides for plant protection in woodlands and tree-crops. The model uses input based on frequencies and timings of baiting for rodent control for urban, rural and woodland locations and creates an exposure map based on spatio-temporal modelling of movement of mice-vectored AR (based on Apodemus flavicollis). Simulated predator territories are super-imposed over this exposure map to create an exposure index. Predictions from the model concur with field studies of AR prevalence both before and after the change in AR use. In most cases incidence of exposure to AR is predicted to be greater than 90%, although cessation of use in woodlots and Christmas tree plantations should reduce mean exposure concentrations. Model results suggest that the driver of high AR incidence in non-target small mammal predators is likely to be the pattern of use and not the distance AR is vectored. Reducing baiting frequency by 75% had different effects depending on the landscape simulated, but having a maximum of 12% reduction in exposure incidence, and in one landscape a maximum reduction of <2%. We discuss sources of uncertainty in the model and directions for future development of predictive models for environmental impact assessment of rodenticides. The majority of model assumptions and uncertainties err on the side of reducing the exposure index, hence we believe the predictions to be robust and to indicate that the scale of the problem may be large.

Nanofabrication of Graphene Quantum Dots with High Toxicity Against Malaria Mosquitoes, Plasmodium falciparum and MCF-7 Cancer Cells: Impact on Predation of Non-target Tadpoles, Odonate Nymphs and Mosquito Fishes

Recently, it has been highlighted an overlooked connection between the biting activity of Anopheles mosquitoes and the spread of cancer. The excellent physico-chemical properties of graphene quantum dots (GQDs) make them a suitable candidate for biomedical applications. We focused on the toxicity of GQDs against Plasmodium falciparum and its vector Anopheles stephensi, and their impact on predation of non-target mosquito predators. Biophysical methods, including UV–vis, photoluminescence, FTIR and Raman spectroscopy, XRD analysis and TEM, confirmed the effective GQD nanosynthesis. LC50 against A. stephensi ranged from 0.157 (larva I) to 6.323 ppm (pupa). The antiplasmodial activity of GQDs was evaluated against CQ-resistant (CQ-r) and CQ-sensitive (CQ-s) strains of P. falciparum. IC50 were 82.43 (CQ-s) and 85.17 μg/ml (CQ-r). In vivo experiments conducted on Plasmodium berghei infecting albino mice showed moderate activity of GQDs if compared to chloroquine. Concerning non-target effects, the predation efficiency of Gambusia affinis, Anax immaculifrons and Hoplobatrachus tigerinus post-treatment with GQDs was enhanced. Lastly, GQDs were toxic against MCF-7 breast cancer cell lines with an IC50 = 24.81 μg/ml, triggering apoptosis in treated cells. Overall, we highlighted the multipurpose potential of GQDs for the development of newer drugs in the fight against Anopheles vectors, Plasmodium parasites and breast cancer cells.