Efficacy Of Imidacloprid Research Articles

Resistance ofBemisia tabaci (Homoptera: Aleyrodidae) to insecticides in southern Spain with special reference to neonicotinoids

The tobacco whitefly, Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) which occurs in various parts of the world, has developed a high degree of resistance against several chemical classes of insecticide, including organophosphates, carbamates, pyrethroids, insect growth regulators and chlorinated hydrocarbons. The present studies were done in order to monitor the susceptibility of whitefly populations in southern Spain to insecticides commonly used there. Systemic bioassays using Spanish field populations of B tabaci collected in 1994, 1996 and 1998 indicated an increase, albeit a slow one, in resistance to imidacloprid over this period. Comparative studies of other neonicotinoids using the same bioassay revealed a high degree of cross-resistance to acetamiprid and thiamethoxam. Leaf-dip bioassays with adult females from these populations revealed a high level of resistance to cyfluthrin, endosulfan, monocrotophos, methamidophos, and pymetrozine, each at 200 mg litre−1. Buprofezin and pyriproxyfen were tested against second-instar nymphs and eggs, respectively. Buprofezin also showed a lower efficacy against ESP-98, a strain of B tabaci received from Almeria in 1998, but pyriproxyfen resistance was not obvious when tested against eggs of strain ESP-98. Field trials in 1998 revealed good efficacy of imidacloprid in one farm in the Almeria region and two greenhouses in Murcia and Sevilla, but a loss of activity by imidacloprid in another farm in the Almeria region. Cross-resistance between imidacloprid and thiamethoxam was also confirmed under field conditions. © 2000 Society of Chemical Industry

549 Imidacloprid Applications for Whitefly Control on Poinsettia Using Ebb-and-flow Systems

Ebb-and-flow systems can be used to apply systemic pesticides to greenhouse crops without worker exposure or runoff. However, there is little information on the efficacy of pesticides applied with ebb-and-flow systems. We are using silverleaf whitefly (Bemisia argentifolii) control on poinsettia (Euphorbia pulcherrima) with imidacloprid as a model system to study pesticide efficacy in ebb-and-flow systems. The objective of this study was to determine the effect of the amount of insecticide taken up by the pot on the efficacy of whitefly control. Different amounts of imidacloprid uptake were obtained by not watering the plants for 0, 1, 2, or 4 days before the imidacloprid application. The imidacloprid (132 g·L–1) was applied once when the roots of the cuttings had reached the side of the pots. These treatments were compared to an untreated control on ebb-and-flow and a standard drench application (100 mL) to hand-watered plants. Pots in the different subirrigation treatments absorbed 12 to 175 mL of imidacloprid solution. Four days after the application, leaf tissue of the hand-watered plants contained 8 to 20 times more imidacloprid than the subirrigated plants. Efficacy was determined from the percentage of surviving mature whiteflies after 2 days on the plants and by counting the number of immatures after 2 weeks. Surprisingly, imidacloprid efficacy was better in the subirrigated imidacloprid treatments than in the hand-watered treatment. Whitefly control in all subirrigated imidacloprid treatments was excellent, irrespective of the amount of imidacloprid solution taken up by the pots.

EFFECT OF APPLICATION METHOD, RATE, AND IRRIGATION ON IMIDACLOPRID EFFICACY AGAINST APHIDS IN SHADE TOBACCO, 1998

EFFECT OF APPLICATION METHOD, RATE, AND IRRIGATION ON IMIDACLOPRID EFFICACY AGAINST APHIDS IN SHADE TOBACCO, 1998: Admire 2F (imidacloprid) application methods, rates and the effects of irrigation were evaluated for tobacco aphid control in a cloth-covered shade tent at the CT Agricultural Expt. Station Valley Laboratory in Windsor, CT. Admire 2F was applied at 0.17 or 0.34 lb (AI)/acre (1 or 2 oz per 1000 plants based on 10,800 plants/acre) for all treatments. The soil was an Entic Haplorthod (71.8% sand, 23.0% silt, 5.2% clay, pH = 6.0 and OM = 4.0%). On 26 May, plots were fertilized with 110 lb N/acre of cottonseed meal-based 10-8-10, plots were broadcast with Lorsban 4E at 1.5 lb (AI)/acre and Ridomil 2E at 1 lb (AI)/acre and spiked to incorporate. On 3 Jun, preplant Admire 2F in 100 gpa was broadcast to appropriate plots in a 39-inch swath using a TeeJet 8004E nozzle at 18 to 20 psi and spiked. Tobacco was transplanted on 27 May to rows 39-inch apart with a 1-ft spacing within rows. There were 5 replicates of single-row plots of each treatment. Every 3rd row was an untreated border row. Plots were irrigated 27 May with 0.25 inches water. Admire 2F was applied on 29 May as a soil drench using a backpack sprayer with a TeeJet TG-3 nozzle at 15 psi to apply 20 ml/plant in 2 10-ml applications 2-cm to two sides of each plant. Plots were sidedressed with 70 lb N/acre of cottonseed meal-based 10-8-10 and cultivated on 18 Jun. Admire 2F was band applied at the last cultivation on 23 Jun in 70 gal water/acre to appropriate plots (with 83 lb N/acre) to 6 inches on either side of rows using a backpack sprayer with a TeeJet 8004-E nozzle and incorporated by mechanical cultivation and hoeing. Appropriate plots were irrigated with 0.5 in water. One leaf each from 10 plants per row was removed on 30 Jul, 4 Aug, 17 Aug, 27 Aug, and 3 Sep, and rated for apterous tobacco aphids (scale: 0 = no aphids or winged only; 1 = 1 aphid per leaf; 2 = 2-10 aphids 3 = 11-100 aphids and 4 = more than 100 aphids per leaf). Treatments were compared within dates by the nonparametric Kruskal-Wallis Test and the multiple comparison Z-Test.

Antifeedant effect, biological efficacy and high affinity binding of imidacloprid to acetylcholine receptors inMyzus persicaeandMyzus nicotianae

It is known from laboratory studies that tobacco-associated forms of Myzus persicae (Sulzer) and the closely related tobacco aphid Myzus nicotianae (Blackman) are often somewhat less susceptible to imidacloprid than non-tobacco strains of M. persicae. Choice tests (floating leaf technique) showed that tobacco aphids were also less susceptible to the antifeedant potential of imidacloprid in contact bioassays. Synergists like piperonyl butoxide or DEF did not enhance the susceptibility of tobacco-associated morphs of Myzus ssp. to imidacloprid, thus providing evidence that neither oxidative detoxication nor hydrolytic metabolization took place. However, in an attempt to study the influence of endosymbiotic bacteria on the efficacy of imidacloprid, we allowed small populations of tobacco aphids to feed on diets containing the antibiotic chlortetracycline prior to imidacloprid treatment. While the effectiveness of imidacloprid, i.e. lower LC50 values, could be improved in all strains, including the susceptible reference strain, there was no change in overall tolerance factors. In order to investigate any possible alteration of the target site, the affinity of imidacloprid and nicotine to nicotinic acetylcholine receptors in whole-aphid homogenates was measured. All strains (and clones) showed the same high-affinity binding sites and no detectable difference. Studies using the FAO dip method revealed that the lower susceptibility of M. nicotianae is not restricted to chloronicotinyls like imidacloprid or acetamiprid, because other insecticides with different modes of action such as pymetrozine and fipronil were also affected in laboratory studies. It is considered that the observed tolerance to chloronicotinyls in certain strains of Myzus ssp. is a natural variation in response, probably not coupled with any known mechanism of resistance in this species complex. © 1998 SCI

Efficacy of imidacloprid for removal and control of fleas (Ctenocephalides felis) on dogs

Abstract Objective To evaluate efficacy of a 9.1% (w/w) imidacloprid solution, applied topically, to remove fleas from dogs and the duration of residual flea control when dogs were exposed to continuing flea infestation. Animals 32 adult mixed-breed dogs. Procedure Dogs were allocated to 4 groups of 8 dogs each; dogs of 3 groups received a single dose of imidacloprid, and those of the fourth group received excipient. Each dog was infested with 100 adult fleas on study days -3, -1, 6, 13, 20, 27, and 33. Treatments were applied on day 0. Each dog was examined for live fleas on days -2, 1, 7, 14, 21, 28, and 34. Posttreatment efficacy was determined by comparing the mean number of live fleas remaining on the treated dogs with the mean number of live fleas remaining on the control dogs. Results All 3 imidacloprid dosages provided flea control ≥ 96.9% one day after treatment. Maximal efficacy of all 3 dosages (99.1 to 100%) was observed at 7 days after treatment. Flea control with 3.75 mg of imidacloprid/kg of body weight ranged from 94.4 to 96.9% for days 14 to 28 and decreased to 91.6% by 34 days after treatment. Flea control with 7.5 and 10.0 mg of imidacloprid/kg was 97.8 to 100% through day 28. At day 34, dosages of 7.5 and 10.0 mg of imidacloprid/kg were 97.6 and 96.9% efficacious, respectively. Conclusion 7.5 or 10.0 mg of imidacloprid/kg are equivalent and superior to 3.75 mg/kg for flea control over the course of a 34 day posttreatment period. Clinical Relevance Monthly imidacloprid application of 7.5 to 10 mg/kg will rapidly kill existing and reinfesting flea infestations on dogs and break the flea life cycle by killing adult fleas before egg production begins. (Am J Vet Res 1997;58:848–850)

Evaluating insecticides for the control of narcissus flies under field conditions in Israel

In Israel, narcissus bulb flies (Diptera: Syrphidae) are serious pests of cultivated flower bulbs of the families Liliaceae and Amaryllidaceae. The large narcissus fly(Merodon eques) is the major pest, whereas the small narcissus fly (a new species in the genusEumerus, yet to be described) is only a secondary pest. The large narcissus fly is also considered a quarantine pest by the U.S.A. authorities. Narcissus bulbs,Narcissus tazetta (var. ‘Ziva’), were planted in an experimental field at Bizzaron during November 1995 and harvested during June 1996. Currently aldicarb (Temik) is recommended for the control of narcissus fly larvae. We compared the control efficacy of imidacloprid (Confidor) and isazofos (Miral) with that of aldicarb. These latter insecticides were applied to the soil in February, in April, or on both dates. The mean level of damaged bulbs in the untreated plots was 32%. Two applications of aldicarb, one in February and one in April, reduced the damage to the lowest level of 0.5%. A single application of aldicarb in February, and two applications of imidacloprid—one in February and one in April—reduced the damage to 5-10%. Treatments with imidacloprid in February or in April, reduced the damage to 12-13%. Neither one application of aldicarb in April, nor any of the treatments with isazofos, was effective. In all treatments, larvae of the large narcissus fly were found in only approximately one-third of the damaged bulbs. The level of infestation with the small narcissus fly in the untreated bulbs was only approximately 2%. The effects of the insecticide treatments on the small narcissus fly were similar to those recorded for the large narcissus fly .

Control of Aphids on Potted Chrysanthemum, Ft. Collins, Co 1993

Abstract A mixed aphid population (green peach aphid, black chrysanthemum aphid) present on greenhouse grown chrysanthemums was used to determine speed of uptake by plants and efficacy of imidacloprid (Bay NTN 33893). Plants were arranged in a RCB design with 6 replications. Granules were surface applied on either 29 Sep, 3 Nov, or 8 Nov and watered into the potting mix. Evaluations were made 11 Nov and 18 Nov by counting all aphids on one randomly selected terminal per plant in each of the four plants per pot.

Comparison of imidacloprid and furathiocarb seed dressing insecticides for the control of the black maize beetle, Heteronychus arator Fabricius (Coleoptera: Scarabaeidae), in maize

The efficacy of imidacloprid (a nitromethylene) and furathiocarb (a carbamate) as seed dressing insecticides for control of the black maize beetle adults, Heteronychus arator, in maize was compared in laboratory and greenhouse trials. The numbers of damaged plants, extent of plant damage and numbers of dead adults were recorded. Results indicated that both chemicals had a systemically translocated insecticidal action. Imidacloprid also had a systemically translocated antifeedant action in the stems of plants. The apparent absence of an antifeedant action in the furathiocarb treatment rendered it inferior to the imidacloprid treatment. The necessity for measuring plant damage in future trials was demonstrated.

Monitoring Susceptibility of Whiteflies to Imidacloprid and Resistance Management for Nicotinoid Insecticides

The purpose of the investigation discussed in this article was to assess and monitor the susceptibility of field populations to imidacloprid and to compare estimates of susceptibility with in-field efficacy of imidacloprid. This document is ENY681, a publication of the Entomology and Nematology Sciences Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Publication Date: September 2003.