Agriculture and Agriculture et Agri-Food Canada Agroalimentaire Canada A laboratory evaluation of the toxicity of four insecticides to a predacious found in Quebec vineyards and apple orchards

Noubar J. BOSTANIAN1, Martin TRUDEAU1, and Jacques LASNIER2

1 Horticultural Research and Development Centre, Agriculture and Agri-Food Canada, 430 Gouin Blvd, St Jean-sur-Richelieu, Qc, Canada, J3B 3E6 – 2 Ag-Cord Inc R & D, 655 Delorme Street, Granby, Qc, Canada, J2J 2H4

Introduction baccarum (AB) is a cosmopolitan predator feeding on many pests found on agricultural crops grown from temperate to sub-tropical regions. In Canada. it was first reported feeding on Panonychus ulmi (Koch) on peach trees in southern Ontario.1 Around Moscow, Russia, it was the most common predacious species feeding on phytophagous on blackcurrants.2 In northern Ireland, it was reported to be feeding on rust mite.3 On grapes, in Pennsylvania, Jubb et al. 4 reported it feeding on leafhoppers. In Quebec vineyards, it is the principal predacious mite feeding on phytophagous mites and other pests such as leafhoppers (Bostanian N.J., unpublished). Little is known of the toxicity of pesticides to AB. Bushkovskaya carried out laboratory studies and reported carbaryl and dimethoate to be very toxic.5 A devastating impact on AB was also noted when multiple applications of azinphosmethyl, phosmet, chlorfenvinphos or a single application of cypermethrin was applied to kiwi trees in New Zealand.6 Field studies showed that multiple applications of mancozeb and captan/penconazole used to control scab in apples had a detrimental impact to AB.7 Mites were exposed to insecticide residues in plastic Petri dishes. In this study we report the toxicity of azinphos-methyl, carbaryl, imidacloprid, and thiamethoxam to AB A thin-layer chromatography sprayer used to collected from commercial Quebec vineyards. apply insecticides.

Table 1. Insecticide concentrations used to estimate the LC50 of one organophosphate, one carbamate, Materials & Methods and two neonicotinoïds to Anystis baccarum collected at Dunham, Qc Field collection Rate used in Specimens were collected on grapevines in an untreated vineyard in Dunham, Quebec. The collection was Insecticide orcharda Percent ® made by gently tapping a vine leaf or a fruit cluster with an Anystis into a 30 ml Solo (Urbana, Illinois designation (g. A.I. litre-1) mortality (%) Range of concentration (g. A.I. litre-1) USA) plastic cup. The cups were placed in a cooler and brought to the laboratory within an hour following Azinphos-methyll 2.000 100 0.0078 0.0039 0.0019 0.0009 0.005 the termination of the collection. Carbaryl 1.325 100 0.0026 0.0013 0.0010 0.0007 0.0006 0.0003 0.0002 Imidacloprid 1.168 0 Toxicological tests Thiamethoxam 1.178 33 Mites were exposed to a pesticide residue in plastic Petri dishes.

The dishes were treated before the introduction of the mites. A thin a Based on spray volume of 540 litres ha -1. coat of the test insecticides were applied to the interior of the Petri dishes, the side walls and the covers. A thin-layer chromatography sprayer set at 10.34 kPa was used to apply the insecticides. At that Table 2. Relative toxicity of two anticholinsterases to Anystis baccarum collected at Dunham, Qc pressure the amount of insecticide residue on the Petri dish was 2.00 mg/cm2. The cages were stored in growth chambers set at a 2 Slope (±SE) LC50 (CI 95%) df χ g 25°C and 70% RH for a period of two hours for drying. Only one Insecticide (g. A.I. litre-1) specimen was introduced into the treated cages from the Solo cups desigantion to eliminate cannibalism among the treated specimens. The cages Azinphos-methyll 3.723 (0.471) 0.0016 (0.0014 - 0.0019) 3 2.334 0.062 with the treated AB were stored in a growth chamber set at 25°C, Collection made by gently tapping a fruit cluster. Carbaryl 6.226 (1.012) 0.0117 (0.0010 - 0.0014) 5 5.894 0.206 70% relative humidity and 16:8 light:dark photoperiod. The control a Number of test individuals is 216 when df is equal to 3 and 288 when df is equal to 5. were treated with tap water and mortality counts were made 24 hours after treatment. Whenever required percent mortality was calculated according to Abbott.8 Specimens were considered dead References when they were unable to move a distance equivalent to their own width when the cage was shaken. The following insecticides were 1. Putman WL and Herne DHC, Relations between Typhlodromus caudiglans Schuster (Acarina: phytoseiidae) and evaluated: azinphosmethyl (Guthion® 50WP), carbaryl (Sevin® phytophagous mites in Ontario peach orchards. Can Entomol 98:808-820 (1966). XLR), imidacloprid (Admire® 240FS), and thiamethoxam (Actara® 2. Lange AB, Drozdovskii EM and Bushkovskaya LM, The effectiveness of Anystis baccarum in the control of small 25WG). All four insecticides were provided by courtesy of Bayer predatory phytophages. Zasch Rast 1:26-28 (1974). (in Russian) 3. Cuthbertson AG, Bell AC and Murchie AK, Impact of the predatory mite Anystis baccarum (: Anystidae) on Agricultural Division, Toronto Canada. The LC50 value was 9 apple rust mite Aculus schlechtendali (Prostigmata: Eriophyidae) populations in northern Ireland `Bramley` orchards. Ann estimated by probit analyses with PoloPC. The rates are based on Appl Biol 142:107-114 (2002). -1 the application of 540 litres ha of sprayable material. Anystis baccarum (L.) (: Anystidae) 4. Jubb GL Jr, Masteller EC and Lehman RD, Survey of in vineyards of Erie County, Pennsylvania; Acari Int J Acarol 11:201-207 (1985) 5. Bushkovskaya LM, The effect of chemicals (insecticides, fungicides) on the mite Anystis baccarum (predator of plant Results & Discussions pests). Zasch Rast 10:53 (1974). (in Russian) 6. Ferguson AM, Stratton AE and Hartley MJ, Insect control on kiwifruit, in Proceedings of the 31st New Zealand Weed and Azinphos-methyl and carbaryl, were extremely toxic to AB (Table 1). In contrast, imidacloprid and Pest Control Conference, part I, ed by Ferguson AM, Stratton AE and Hartley MJ, August 8-10 1978, New Plymouth, New thiamethoxam are virtually non-toxic to AB according to IOBC standards.10 Generally speaking mites are Zealand, pp 135-139 (1978). notorious for developing resistance to pesticides very quickly. Yet AB was extremely susceptible to the two 7. Cuthbertson AGS and Murchie AK, The impact of fungicides to control apple scab (Venturia inaequalis) on the predatory acetylcholine esterase inhibitors. Even though these two acetylcholine esterase inhibitors have been mite Anystis baccarum and its prey Aculus schlechtendali (apple rust mite) in northern Ireland `Bramley` orchards. Crop Prot 22:1125-1130 (2003). around for at least forty years, the recommended field rate of azinphos-methyl was 1250 fold the LC50 8. Abbott WS, A method of computing the effectiveness of an insecticide, J Econ Entomol 18:265-267 (1925). value of this insecticide to AB and it was 113 fold the LC50 value of carbaryl to AB (Table 2). In contrast, 9. LeOra Software, POLO-PC Probit and Logit Analyses, Berkley, Ca (1987). the two neonicotinoids are non-toxic to slightly toxic in these laboratory evaluations of residual toxicity. The 10. Hassan, SA, Guidelines for testing the effects of pesticides on beneficial organisms: Description of test methods. pronounced toxicity of the two acetylcholinesterase inhibitors to AB in these tests precludes semi-field and Pesticides and Beneficial Organisms, IOBC/wrpr Bulletin 15(3): 1-3 (1992). field toxicological studies. On the other hand, imidacloprid and thiamethoxam, were virtually non-toxic. 11. James DG, Pesticide susceptibility of two coccinellids (Stethorus punctatum picipes and Harmonia axyridis) important in biological control of mites and aphids in Washington hops. Biocontrol Sci Tech 13: 253-259 (2003). 12. James DG, Toxicity of imidacloprid to Galendromus occidentalis, Neoseiulus fallacis and Amblyseius andersoni (Acari: Elsewhere, a contact toxicity study indicated imidacloprid to cause 100% mortality of Stethorus punctum Phytoseiidae) from hops in Washington State, USA. Exp Appl Acarol 31:275-281 (2003). 11 picipes (Casey) and 80.0% mortality of Harmonia axyridis Pallas. Whereas thiamethoxam caused 100% 13. James DG, Biological control of Tetranychus urticae Koch (Acarina:Tetranychidae) in southern New South Wales mortality of S. punctum picipes and only 33.3% mortality of H. axyridis.11 Among predacious mites, peach orchards: the role of Amblyseius victoriensis. Aust J Zool 38:415-422 (1990). James12 reported 100% mortality of Galendromus occidentalis Nesbitt, Neoseiulus fallacis Garman and 14. James DG, Imidacloprid increase egg production in Amblyseius victotiensis (Acari: Phytoseiidae). Exp Appl Acarol only 35.6% mortality of Amblyseius andersoni (Chant). Earlier James had reported the different attributes 21:75-82. of imidacloprid to Euseuis (Amblyseius) victoriensis (Womersley) and the inclusion of this insecticide in 15.Mizell RF and Sconyers MC, Toxicity of imidacloprid to selected arthropods in the laboratory. Fla Ent 75:277-280 (1992). Australian IPM programs for stone fruit.13,14 In that study he also reported the repellent properties of imidacloprid to E. victoriensis. Since 1992 imidacloprid has been shown not to be toxic to several species of mites (Neoseilus collegae (De Leon), Phytoseiulus macropilis (Banks), and Proprioseiopsis mexacanus Acknowledgements (Garman)).15 The authors thank Bayer Crop Science and Syngenta Crop Protection for kindly providing the insecticides. In synopsis, the results of this laboratory study show that azinphosmethyl and carbaryl are very toxic to AB Gaétan Racette and the team of 12 students are also thanked for their efforts to collect timely hundreds of whereas the two neonicotinoids imidacloprid and thiamethoxam are relatively innocuous. Field studies specimens and participating in the bio-essays. should be initiated to elucidate if neonicotinoids have the same repellent attributes to anystids as they have to phytoseiids.

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