This paper presents the first acute toxicity data of the natural insecticide spinosad in amphibians. The sensitivity of two neotropical sympatric anuran species, Boana pulchella and Rhinella arenarum, to spinosad-based formulation Tracer™ was evaluated. Lethal effects are reported in tadpoles of B. pulchella stage 25 between 2.81 and 35.44 mg spinosad/L, while for the same concentration range no lethal effects were detected in tadpoles of R. arenarum of the same stage. In addition, Tracer™ produced sublethal effects at the individual level on the swimming activity, morphology (growth and presence of abnormalities), and development of B. pulchella from 2.81 to 5.78 mg spinosad/L, while in R. arenarum effects were only detected in the swimming activity and growth from 2.78 and 6.22 mg/L, respectively. At the biochemical level, Tracer™ produced inhibition of different enzymatic activities, among them, catalase activity at 2.81 mg spinosad/L, glutathione S- transferase activity from 2.81 to 2.98 mg spinosad/L, and acetylcholinesterase activity at 2.81 mg spinosad/L. These findings allow us to conclude that B. pulchella is more sensitive than R. arenarum to spinosad-based formulation Tracer™. The effects demonstrated here are not consistent with those expected since spinosad is supposed to be an environmental healthy alternative. This paper provides useful and necessary information to implement regulations on the use of new compounds entering the market and its associated risks. | Instituto de Recursos Biológicos | Fil: Bahl, María Florencia. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Química. Centro de Investigaciones del Medio Ambiente; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. | Fil: Brodeur, Celine Marie Julie. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Bilológicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. | Fil: Salgado Costa, Carolina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Química. Centro de Investigaciones del Medio Ambiente; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. | Fil: D'Andrea, María Florencia. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Recursos Bilológicos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. | Fil: Sansiñena, Jesica Alejandra. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Química. Centro de Investigaciones del Medio Ambiente; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. | Fil: Marino, Damián José. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Química. Centro de Investigaciones del Medio Ambiente; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. | Fil: Natale, Guillermo S. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Departamento de Química. Centro de Investigaciones del Medio Ambiente; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina.

The present study was undertaken to assess the impact of a candidate mosquito larvicide, spinosad (8, 17 and 33 μg L−1) on a field population of Daphnia magna under natural variations of water temperature and salinity, using Bti (0.16 and 0.50 μL L-1) as the reference larvicide. Microcosms (125 L) were placed in a shallow temporary marsh where D. magna was naturally present. The peak of salinity observed during the 21-day observation period may have been partly responsible for the decrease of daphnid population density in all the microcosms. It is also probably responsible for the absence of recovery in the microcosms treated with spinosad which caused a sharp decrease of D. magna abundance within the first two days following treatment whereas Bti had no effect. These results suggest that it may be difficult for a field population of daphnids to cope simultaneously with natural (water salinity and temperature) and anthropogenic (larvicides) stressors.

The use of insecticides based on metabolites found in live organisms, such as the insecticide spinosad, has been an option for the control of agricultural pests because of the allegedly low toxicological risk for nontarget arthropods, such as stingless bees. In the current study, we evaluate the effects of chronic oral exposure to spinosad during the larval phase on survival, developmental time, body mass, midgut epithelial remodeling, and the peritrophic matrix (PM) of Partamona helleri stingless bee workers. Worker larvae that were raised in the laboratory were orally exposed to different concentrations (0, 6.53, 13.06, 32.64, and 3,264 ng. a.i. bee⁻¹) of spinosad (formulation), and the resulting survival, developmental time, and body mass were studied. The concentration of spinosad recommended for use in the field (3,264 ng. a.i. bee⁻¹) reduced the survival of workers during development. Also, sublethal concentrations of spinosad delayed the development and caused morphological changes in the midgut epithelium. Finally, the chronic exposure of larvae to 32.64 ng. a.i. bee⁻¹ spinosad also altered the remodeling of the midgut during metamorphosis and affected the organization of the PM of larvae, pupae, and adults. Our data suggest possible environmental risks for using spinosad in cultures that are naturally pollinated by stingless bees.

The house fly, Musca domestica L., is a cosmopolitan insect pest of public and animal health importance that serves as a mechanical vector of pathogens. Aimed at prospective resistance management to reduce environmental pollution, we characterized the inheritance pattern, realized heritability, fitness cost, cross resistance, stability and mechanism of clothianidin resistance in M. domestica that were collected from the poultry farm. By continuous selection with clothianidin for 11 generations, the clothianidin selected M. domestica strain (Clotha-SEL) developed a 3827-fold resistance compared to a susceptible strain. However, resistance to clothianidin was proved to be unstable when selection with clothianidin was removed for five generations (G₇ to G₁₂). Inheritance pattern analysis at G₈ of Clotha-SEL (RR = 897) revealed that resistance to clothianidin was polygenic, autosomal and incompletely dominant. Realized heritability (h²) for resistance value was 0.38 (at G₁₁) in the tested strain. Synergist bioassays showed that microsomal oxidases and esterases might not contribute significantly in resistance evolution. Fitness costs of clothianidin resistance were present, for example, reduction in growth potential of the Clotha-SEL strain in comparison to the untreated counterpart strain (UNSEL) was observed. No cross resistance to bifenthrin and fipronil and a very low cross-resistance to spinosad were observed. These insecticides could be alternated with clothianidin as an insecticide resistance management tool to sustain its efficacy for a longer time period. These results shall be utilized to devise a proactive resistance management strategy for use of clothianidin against M. domestica that will be helpful to alleviate the allied threats to environmental and human health.

The adaptive fitness of insect species can be shaped by how males and females respond, both physiologically and behaviorally, to environmental challenges, such as pesticide exposure. In parasitoid wasps, most toxicological investigations focus only on female responses (e.g., survival and especially parasitism abilities), leaving the male contributions to adaptive fitness (survival, locomotion, mate search) poorly investigated. Here, we evaluated the toxicity of the spinosyn insecticide spinosad against the South American fruit fly, Anastrepha fraterculus, and we used the parasitoid wasp Diachasmimorpha longicaudata (Ashmead) to evaluate whether sex-linked locomotory and physiological responses would influence the susceptibility of these organisms to spinosad. Our results revealed that D. longicaudata males were significantly more susceptible (median lethal time (LT₅₀) = 24 h) to spinosad than D. longicaudata females (LT₅₀ = 120 h), which may reflect the differences in their locomotory and physiological (e.g., respiratory) responses to mitigate insecticide exposure. Compared to D. longicaudata females, male wasps were lighter (P < 0.001), walked for longer distances (P < 0.001) and periods (P < 0.001), and exhibited higher sensilla densities in their tarsi (P = 0.008), which may facilitate their intoxication with the insecticide. These findings indicate that male parasitoids should not be exempt from insecticide selectivity tests, as these organisms can be significantly more affected by such environmental challenges than their female conspecifics.

Many species of devastating insect pests have acquired a high degree of resistance to insecticides in the field during the last few decades. Spodoptera exigua, for example, is the most damaging pests of economic crops with a worldwide spread. In a present study, the comparative growth, reproduction, and detoxification enzyme activity were evaluated along with exposure to three insecticides at low lethal doses of lufenuron, indoxacarb, and spinosad as compared to the control. Results indicate that the larval developmental time was significantly extended on lufenuron (21.5 ± 29 days) followed by indoxacarb (20.28 ± 0.24 days) and spinosad (19.74 ± 0.23 days) as compared to that on the control (18.13 ± 0.13 days). Similarly, the lowest number of eggs of S. exigua females were recorded on lufenuron (328.75 ± 50.81 eggs) followed by spinosad (367 ± 36.4 eggs) and indoxacarb (411.58 ± 42.38 eggs) as compared to that on the control (560.2 ± 13.47). Interestingly, the lowest intrinsic rate of increase (r) (0.121 ± 0.009) and highest mean generation time (T) (36.2 ± 0.35 days) were observed when larvae were treated to a low lethal concentration (LC₂₀) of lufenuron as compared to that of indoxacarb, spinosad, and control. In addition, considerably lower activity of all detoxification enzymes in larvae was recorded on lufenuron after control as compared to that on indoxacarb and spinosad. Our study serves as a reference and basis for the toxicity and low lethal evaluation of lufenuron, indoxacarb, and spinosad on life table parameters and enzymatic properties in S. exigua, which may contribute to identifying targets for effective control of S. exigua.

This paper presents the first acute toxicity data of the natural insecticide spinosad in amphibians. The sensitivity of two neotropical sympatric anuran species, Boana pulchella and Rhinella arenarum, to spinosad-based formulation Tracer™ was evaluated. Lethal effects are reported in tadpoles of B. pulchella stage 25 between 2.81 and 35.44 mg spinosad/L, while for the same concentration range no lethal effects were detected in tadpoles of R. arenarum of the same stage. In addition, Tracer™ produced sublethal effects at the individual level on the swimming activity, morphology (growth and presence of abnormalities), and development of B. pulchella from 2.81 to 5.78 mg spinosad/L, while in R. arenarum effects were only detected in the swimming activity and growth from 2.78 and 6.22 mg/L, respectively. At the biochemical level, Tracer™ produced inhibition of different enzymatic activities, among them, catalase activity at 2.81 mg spinosad/L, glutathione S- transferase activity from 2.81 to 2.98 mg spinosad/L, and acetylcholinesterase activity at 2.81 mg spinosad/L. These findings allow us to conclude that B. pulchella is more sensitive than R. arenarum to spinosad-based formulation Tracer™. The effects demonstrated here are not consistent with those expected since spinosad is supposed to be an environmental healthy alternative. This paper provides useful and necessary information to implement regulations on the use of new compounds entering the market and its associated risks.

Honeybee (Apis mellifera L.) provides not only bee products of immense value but also render invaluable free service as cross-pollination and propagation of several cultivated and wild species, thereby, maintaining biological diversity. Bee larvae and adults might be killed or suffer various sublethal effects when placed in contact with pollen and nectar contaminated with insecticides. The present work was conducted to investigate the toxicity of seven insecticides on laboratory using oral toxicity test and their side effects on A. mellifera in cotton fields. Results indicated that lambda-cyhalothrin was the most toxic-tested pesticide, recording the lowest LC₅₀ and LC₉₀ values at all tested periods and the lowest LT₅₀ and LT₉₀ at all tested concentrations, followed by abamectin, spinosad, chlorpyrifos, and emamectin benzoate. On the other side, dipel and pyridalyl recording the highest LC₅₀ and LC₉₀ at all tested periods and the highest LT₅₀ and LT₉₀ at all tested concentrations. As for the application of pesticides in cotton fields, the tested pesticides significantly increased the number of dead workers in comparison with control. The tested pesticides significantly decreased bee foraging activities, i.e., number of foraging workers, number of worker collecting nectar, number of worker gathering pollen grains, area of broad workers, and honey bee yields. Dipel and pyridalyl were the most safety pesticides on honey bee workers in laboratory and field, so it could be introduced as a component in IPM programs of cotton pests.

Fourteen pesticides were screened and determined through quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction process combined with GC-MS/MS in arid agriculture soil. The aims of the current investigation were to account the occurrence of organochlorine (OCP) and organophosphates (OPP) pesticide residues as well as other groups of pyrethroids (PYRs), carbamates, and biopesticides using a combined of QuEChERS and GC-MS/MS techniques in agriculture soils at Al-Kharj region, Saudi Arabia, and to investigate correlation between pesticide losses in soils and some physicochemical characteristics of pesticides including an octanol-water coefficient partition (Kₒw) and the vapor pressure (Vp). Prediction of pesticide fate by considering both pesticide and soil physio-chemical properties will facilitate the management of pesticide application and minimize the hazards of environmental pollution. The fate of pesticide residue in soils is generally controlled by soil/air exchange, water interaction, and biodegradation. The results indicated that 14 pesticide residues were measured in collected samples of various soils, spinosad, chlorpyrifos methyl, dimethoate, chlorpyrifos, lindane (γ-HCH), permethrin, and methomyl which were the most abundant sources of contamination in the studied region. p,p-DDT, o,p-DDT, bifenthion, β-cyfluthrin, and methidathion were less commonly detected. Single parameter least squares regression equations (sp-LSRE) for Vp and Kₒw against the loss of each pesticide residue showed a significant change in concentration levels (p < 0.05) between the two seasons. The results showed that vapor pressure and octanol-water partition coefficient data are not enough to model pesticide residue losses in arid low organic carbon soil. More soil-related data is needed to describe the dissipation mechanisms of these pesticide residues in the region.

Field and lab trials took place in Crete (July to September 2016), concerning the residual degradation and toxicity of seven active ingredients applied as bait sprays against the olive fruit fly. Highest residues were recorded in olive leaves for dimethoate and phosmet (~ 60 mg/kg) immediately after application (day 1+), while a threefold and fivefold reduction was observed 1 week later, respectively. Residues of pyrethroids were determined at lower levels (< 10 mg/kg) but remained almost stable for a longer period of time. Finally, thiacloprid and spinosad residues were determined at 5.81 and 0.19 mg/kg respectively (day 1+), and rapidly decreased below the LOQ. Highest toxicity against the olive fruit fly was observed just right after the application of dimethoate (100%), a-cypermethrin (80%), and L-cyhalothrin (72.92%). Although the toxicity of dimethoate was significantly reduced 1 week after the application (80%) and then minimized, toxicity of pyrethroids remained almost stable (> 60%) for the first 2 weeks and then decreased to 30–40%, which remained stable up to the end of the study (8 weeks). Concerning phosmet, its toxicity ranged from 35 to 56% for 3 weeks with no significant reduction, while spinosad presented a lower toxicity profile (50% only for 1 week). The benefits of these results in the knowledge of insecticide residues and their toxicity against olive fruit fly can be used for improving olive fruit fly control.