Choosing Organic Pesticides over Synthetic Pesticides May Not Effectively Mitigate Environmental Risk in Soybeans

Background: Selection of pesticides with small ecological footprints is a key factor in developing sustainable agricultural systems. Policy guiding the selection of pesticides often emphasizes natural products and organic-certified pesticides to increase sustainability, because of the prevailing public opinion that natural products are uniformly safer, and thus more environmentally friendly, than synthetic chemicals. Methodology/Principal Findings: We report the results of a study examining the environmental impact of several new synthetic and certified organic insecticides under consideration as reduced-risk insecticides for soybean aphid (Aphis glycines) control, using established and novel methodologies to directly quantify pesticide impact in terms of biocontrol services. We found that in addition to reduced efficacy against aphids compared to novel synthetic insecticides, organic approved insecticides had a similar or even greater negative impact on several natural enemy species in lab studies, were more detrimental to biological control organisms in field experiments, and had higher Environmental Impact Quotients at field use rates. Conclusions/Significance: These data bring into caution the widely held assumption that organic pesticides are more environmentally benign than synthetic ones. All pesticides must be evaluated using an empirically-based risk assessment

Effects of an nC24 agricultural mineral oil on tritrophic interactions between French bean (Phaseolus vulgaris L.), two-spotted mite (Tetranychus urticae Koch) and its predator, Phytoseiulus persimilis Athias-Henriot.

A comprehensive evaluation of the effects of an nC24 agricultural mineral oil (AMO) on tritrophic interactions between French bean Phaseolus vulgaris cv. Redlands Pioneer [Fabales : Fabaceae ], two spotted mite (TSM) Tetranychus urticea Koch [Acari: Tetranychidea] and the predatory mite Phytoseiulus persimilus Atheus-Henriot [Acari: Phytoseiidae] was conducted under laboratory conditions

Impact of nC24 horticultural mineral oil deposits on oviposition by greenhouse whitefly Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae)

The impact of nC24 horticultural mineral oil deposits on oviposition by greenhouse whitefly on tomato leaves was determined in laboratory choice and no-choice tests. The deposits significantly suppressed oviposition. No eggs were laid on leaves treated with aqueous emulsions of 20 mL of oil/L of water in the choice test and on the leaves treated with 10 and 20 mL of oil/L in tbe no-choice test. The relationships between oviposition and oil concentration (0, 2.5, 5, 10 and 20 mL of oiI/L) in sprays in the choice test suggested that deposits of sprays containing > I0 mL of oil/100 L of water would completely suppress oviposition for 2 d after the application of spray. In the no-choice test, deposits of sprays containing 5 mL of oil/L reduced oviposition by 97% over 2 d

Impact of nC24 horticultural mineral oil deposits on the behaviour of Frankliniella schultzei (Trybom) (Thysanoptera: Thripidae)

The impact of nC24 horticultural mineral oil deposits on oviposition by tomato thrips (Frankliniella schultzei) on French bean pods and tomato seedlings was determined in four laboratory experiments. The results showed that deposits on dipped bean pods repelled adult tomato thrips and significantly reduced oviposition. The impact of the deposits was similar for aqueous emulsions with oil concentrations ranging from 2.5 to 15 mL of oil/L of water. The effect of deposits did not decline significantly as the oil deposits aged over the 5 day period. On tomato seedlings, sprays containing 10 mL of oil/L of water significantly reduced oviposition but 5 mL/L sprays had no significant effect. The results for 15 and 20 mL/L sprays were affected by unexpected oil induced phytotoxicity

Impact of nC24 agricultural mineral oil deposits on the searching efficiency and predation rate of the predatory mite Phytoseiulus persimilis Athias-Henriot (Acari : Phytoseiidae)

Walking activity, walking straightness, walking speed and searching efficiency of the predatory mite Phytoseiulus persimilis Athias-Henriot were measured on French bean leaf discs that were sprayed with either distilled water, or one of 0.25%, 0.50% and 1.00% w/w aqueous emulsions of an nC24 agricultural mineral oil (AMO). There was no significant difference in percentage of time that mites spent walking in the control (water-sprayed) conditions and in any of the oil treatments. Walking paths were significantly straighter in the oil treatments than in the control, but differences among the oil treatments did not differ significantly. Walking speeds in the oil treatments were significantly slower than in the control and decreased with increasing oil concentration. Deposits of oil at all concentrations significantly suppressed searching efficiency in comparison with control, and searching efficiency in the 1.00% oil treatment was significantly lower than in the 0.25% oil treatment. First predation of P. persimilis on AMO-contaminated eggs of two-spotted mite (Tetranychus urticae Koch) on unsprayed leaf discs was significantly delayed in all oil treatments in comparison with the control. However there was no significant effect on the overall predation rate. In the tests of P. Persimilis predation on AMO-contaminated T. urticae eggs on sprayed leaf discs, the number of first predation occurrences in the first hour was significantly lower in 0.50% and 1.00% oil treatments than in the control. Overall predation rates were significantly reduced by oil but they did not differ significantly among the oil treatments

The influence of sublethal deposits of agricultural mineral oil on the functional and numerical responses of Phytoseiulus persimilis (Acari : Phytoseiidae) to its prey, Tetranychus urticae (Acari : Tetranychidae)

Occasional pesticide application in integrated pest management to at least part of a crop requires that any biological control agents must re-invade previously sprayed areas in order that resurgent pests can be constrained. The ability of the phytoseiid predatory mite Phytoseiulus persimilis to feed on adult two-spotted spider mite (TSSM) Tetranychus urticae on excised leaf discs in both control conditions and in a treatment with a sub lethal residue of agricultural mineral oil (AMO) was assessed. The predator exhibited a Type II functional response with the asymptote significantly higher in the AMO conditions due to the fact that the prey grew slower and reached a smaller size in this treatment. In terms of prey volume eaten, the satiation level of the predator was unchanged by the AMO deposits. The numbers of eggs produced by adult P. persimilis females at densities of 4, 8 and 16 TSSM adult females/disc in the control were significantly higher than those in the AMO treatment, but were similar for the higher density levels, 32 and 64 prey per disc. Thus the functional response in terms of volume of prey eaten explained the numerical response in terms of predator eggs produced. The presence of AMO deposits when the prey were at high density had no effect on predator efficiency (volume eaten) but resulted in a lower intake than that in control conditions when there was a greater distance between prey

Relative toxicity of nC24 agricultural mineral oil to Tetranychus urticae Koch (Acari: Tetranychidae) and Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) and its possible relationship to egg ultrastructure

The relative toxicity (LC₅₀ values based on mg oil/cm2) is evaluated of aqueous nC24 agricultural mineral oil (AMO) emulsions to the egg, six-legged nymph (larva), eight-legged protonymph and adult stages of two-spotted mite (Tetranychus urticae) and its predator, Phytoseiulus persimilis, on French bean leaf discs, using a Potter spray tower to apply of the oil. The egg of P. persimilis was the least susceptible stage (LC₅₀ 444.84) and its LC₅₀ was significantly higher than all other stages tested of either P. persimilis or T. urticae. The LC₅₀ for adult female T. urticae (LC50 63.89) was significantly lower than the larva (LC₅₀ 93.86); however, there was no significant difference in response between the protonymph (LC₅₀ 70.44) and the larva, which were both higher than T. urticae eggs (LC₅₀ 17.55). LC₅₀s for P. persimilis larva (LC₅₀ 43.87), protonymph (LC₅₀ 41.55) and adult female (LC₅₀ 53.34) were similar. Scanning electron microscopy showed that the egg surface of T. urticae is usually well covered with fine silk that may trap more oil and increase AMO efficacy. Other possible differences in AMO efficacy between T. urticae and P. persimilis may be due to differences in egg size, egg incubation period, egg surface structure and the presence of vulnerable respiratory cones in T. urticae eggs. Dose of 0.2–0.3% (w/w) is considered to be the most appropriate for nC24 AMOs use against T. urticae in combination with P. persimilis in integrated pest management programs

LC-ESI (+)-MS/MS MRM chromatograms of a soil sample spiked with 0.04 ng/g of clothianidin and thiamethoxam and 1 ng/g clothianidin-d3 and thiamethoxam-d3 internal standards.

<p>LC-ESI (+)-MS/MS MRM chromatograms of a soil sample spiked with 0.04 ng/g of clothianidin and thiamethoxam and 1 ng/g clothianidin-d3 and thiamethoxam-d3 internal standards.</p

Determination of 7 neonicotinoids and 3 herbicide residues (ng/g; dry weight) using QuEChERS sample preparation and LC-ESI(+)-MS/MS analysis of two soil samples collected from a conservation forest of old growth Carolinian species.

<p>Clear Creek Conservation Area, Chatham-Kent, ON 2013.</p><p>* mean recovery of 3 spiked levels prepared in triplicate (0.10, 1.00 and 10.00 ng/g)</p><p>Determination of 7 neonicotinoids and 3 herbicide residues (ng/g; dry weight) using QuEChERS sample preparation and LC-ESI(+)-MS/MS analysis of two soil samples collected from a conservation forest of old growth Carolinian species.</p

Scatter distribution and notched boxplot of water samples collected from the puddles within/around commercial maize fields, ON, 2013.

<p>(¹Total of clothianidin and thiamethoxam).</p