Abamectin Concentrations Research Articles

Prevention of Pine Wilt of Scots Pine (Pinus sylvestris) with Systemic Abamectin Injections

We examined the efficacy of the insecticide/nematicide abamectin to prevent pine wilt disease caused by the pinewood nematode (Bursaphelenchus xylophilus) in Scots pine (Pinus sylvestris). Pinewood nematode movement was inhibited (>80% death or paralysis) following a 48 hr exposure to abamectin concentrations as low as 0.1 μL a.i. per L (100 ppb). A commercial formulation of abamectin (Avid™) was injected into Scots pine using a pressurized systemic trunk injection tube (STIT) technique. Fifteen to 30 mL (0.45 to 0.90 fl oz) of Avid per STIT could be injected into the trees in less than 1 hr. Trees were successfully injected throughout February, March, and April at temperatures above 4.4°C (40°F). Survival after 1 year of 10 cm diameter (4 in) at breast height (dbh) Scots pines injected with Avid and subsequently inoculated with pinewood nematode was higher (75%) than in pines injected with water (42%). Similarly, survival after 3 years of large Scots pines (30 to 60 cm [12 to 24 in] dbh)] injected with Avid and exposed to a natural epidemic of pine wilt was higher (96%) than in noninjected pines (33%) or those injected with water (71%). These results indicate that preventive injections of Scots pine with Avid are effective in protecting against pine wilt disease.

Abamectin effects on rainbow trout (Oncorhynchus mykiss)

The effect of abamectin (ABM) on rainbow trout (Oncorhynchus mykiss) was studied. The acute toxicity of ABM on rainbow trout was established, following the target 58-h water bath exposure of ABM concentrations from 0.6 to 4.5 microg/l, on the basis of which LD75 (4.0 microg/l) was calculated. The histological changes in organs showed a direct toxicity of ABM for rainbow trout since degenerative changes in brain and kidney and--to a minor extent--in liver were established. The values of the ABM residues in fish muscle tissue with skin were proportional to the exposed concentrations of ABM.

Time profile of abamectin and doramectin excretion and degradation in sheep faeces

We studied abamectin and doramectin excretion and their degradation in sheep faeces under field conditions on pasture after a single subcutaneous dose (0.2mg/kg body weight). In the excretion experiment, maximal abamectin concentration (1277ng/g dry faeces) was detected on day 3, while doramectin concentration showed two peaks (2186 and 1780ng/g dry faeces on days 2 and 5, respectively). Both avermectins were excreted at approximately the same rate (k=0.23day−1 for abamectin and 0.19day−1 for doramectin). In the field, a rapid loss of abamectin and doramectin from sheep faeces was seen during the first 32days after which concentrations remained constant at approximately 77ng/g and 300ng/g, respectively. The half life values (DT50) for abamectin and doramectin dissipation from sheep faeces were 23 and 22days, respectively, during the first 32days. Dissipation of both avermectins was strongly correlated with moisture content of the faeces.

Determinación de residuos de abamectina-triclabendazol en tejidos bovinos

SUMMARY Abamectin (ABM) and Triclabendazole (TCBZ) are two potent antiparasitic drugs that differ in their chemical structure and spectrum of action. In this study, a sensitive HPLC-method was developed and validated to determine ABM and TCBZ residues in bovine edible tissues, and the pattern of tissue depletion of an oral formulation containing the association abamectin (ABM) - triclabendazole (TCBZ) was characterized. Sixteen parasitefree heifers (232 ± 37.5 kg body weight) were treated with the oral formulation at a dose rate of 0.2 mg of ABM/kg and 10mg of TCBZ/kg of live weight. Treated animals were slaughtered weekly in randomly selected groups of three to four animals from day 7 until day 42 post-treatment. Concentration profiles of the drugs were determined in liver, kidney, muscle and fat tissues. Two nontreated animals were slaughtered in order to obtain blank tissue samples to validate the analytical methodology. Drug concentration profiles were determined by a validated HPLC analytical methodology using fluorescence detection for ABM and UV- detection for TCBZ. The highest concentration of ABM was observed in liver samples (4.02 ng/g) and was maintained for 14 days. In the case of TCBZSO 2 the highest concentration was observed in the kidney (0.79 μg/g) and persisted for a period of 14 days.

Sub-lethal effects of abamectin suppressing colonies of the leaf-cutting antAcromyrmex subterraneus subterraneus

An assessment of the sub-lethal effects of abamectin on queens of the leaf-cutting ant Acromyrmex subterraneus subterraneus (Hymenoptera: Formicidae) was carried out. A concentration-response bioassay was conducted by exposing media workers (head capsule width ranging from 1.69 to 1.83 mm) to filter paper impregnated with abamectin residue. This bioassay allowed selection of the abamectin concentrations (0, 10, 50 and 100 mg AI ml−1) to be used in the experiment in which eight queens were exposed to the insecticide. The highest concentration killed queens, but those exposed to lower concentrations survived and were placed back in their nests. Reductions in leaf consumption, fungus garden volume, and foraging activity were observed in colonies whose queens were exposed to higher abamectin concentration (50 mg AI ml−1). Colonies with queens exposed to 50 mg AI ml−1 were suppressed after 11 weeks. The dissection of queen ovaries revealed a marked decrease in the number of ovarioles per ovary and oocytes per ovariole with increased insecticide concentration. It would appear that, as abamectin-exposed queens became reproductively impaired, producing little or no progeny, colony members were not replaced and this led to colony suppression. © 2000 Society of Chemical Industry

Monitoring the susceptibility of citrus rust mite (Acari: Eriophyidae) populations to abamectin.

A citrus leaf disk bioassay was developed to monitor the susceptibility of citrus rust mite, Phyllocoptruta oleivora (Ashmead), populations to abamectin. Disks from leaves of several citrus cultivars were equally suitable bioassay substrates, and there was no difference in mortality when mites were sprayed directly or exposed to dry abamectin residue. The concentration-response relationship was determined at intervals over 2 yr for a reference population of citrus rust mites that had been maintained in culture and never exposed to acaricides. Three diagnostic concentrations of abamectin were selected based on the response of the reference population and were used to test the susceptibility of 15 populations of mites from commercial citrus groves. Comparisons with the reference population showed reduced levels of susceptibility in some populations. Populations of citrus rust mites from 6 commercial groves were sprayed twice in 1997 with combinations of acaricides designed to exert different intensities of selection pressure from abamectin. None of these populations showed a change in their response to abamectin in pre- and postspray bioassays, although their susceptibility was usually less than that of mites from the susceptible reference population. Biweekly counts of rust mites on fruit in these 6 groves suggested that, relative to groves which received no abamectin or 1 abamectin spray, mite control was not adversely affected in the groves sprayed twice with abamectin. The bioassay method is discussed in relation to factors that affect the interpretation of results from its use, and factors that may affect the development of resistance to abamectin in citrus rust mite populations are presented. This study has provided baseline data with which the results of ongoing tests of the response of citrus rust mite populations to abamectin can be compared.

Effects of Insecticides on Immature and Adult Western Flower Thrips (Thysanoptera: Thripidae) in Israel

A bioassay confining Frankliniella occidentalis (Pergande) to insecticide-treated kidney bean leaves in a modified Munger cell was used to test the effects of insecticides on fecundity, feeding activity, and mortality. Adult thrips were exposed to various concentrations of abamectin, carbosulfan, methiocarb, monocrotophos, methamidophos, cypermethrin, and acrinathrin; and immature thrips were exposed to abamectin, carbosulfan, methiocarb, and acrinathrin. Cypermethrin had no direct effect on adult thrips at concentrations up to 2,000 ppm. Carbosulfan had the highest efficacy against adults in terms of suppression of feeding activity and fecundity, and the lowest LC 90 (11.3ppm). Additionally, F. occidentalis were collected from flower greenhouses in 4 locations where growers reported problems controlling their populations; thrips were tested with abamectin, carbosulfan, and methiocarb. At only 1 collection site was there moderate resistance to carbosulfan and methiocarb; moderate resistance to abamectin was observed only in immature thrips from 1 site.

In‐Vitro Comparison of the Larvicidal Activity of Moxidectin and Abamectin Against Onthophagus gazella (F.) (Coleoptera: Scarabaeidae) and Haematobia irritans exigua De Meijere (Diptera: Muscidae)

ABSTRACTWhen incorporated directly into cattle dung, a formulation of moxidectin was less toxic to larvae of the dung beetle Onthophagus gazella and the buffalo fly, Haematobia irritans exigua, than an abamectin formulation. Concentrations of moxidectin 64‐fold greater than abamectin concentrations were required to produce equivalent toxicities. Neither moxidectin nor abamectin reduced oviposition by O. gazella. Moxidectin may consequently be less likely than abamectin to affect the decomposition of cattle dung but may have less effect on buffalo fly infestations.

Toxicity of Abamectin to Cockroaches (Dictyoptera: Blattellidae, Blattidae)

Abamectin was fed to German cockroaches, Blattella germanica (L.), in non-choice tests. LT50s and LC50s were estimated by probit analysis. The LT50s for the German cockroach ranged from 4.4 to 1.7 d for males, from 9.0 to 2.4 d for females, and from 4.4 to 1.6 d for nymphs for bait concentrations of abamectin between 0.0025 and 0.0500%. The LC50s of abamectin were 0.0110 and 0.0040% from males, 0.0240 and 0.0090% for females, and 0.0200 and 0.0080% for nymphs at 3 and 6 d, respectively. The LT50 values of 0.0550% abamectin bait were 3.4, 3.4, 2.4, 7.5, 2.9, and 4.5 d for Periplaneta americana (L.), P. fuliginosa (Serville), P. brunnea Burmeister, P. australasiae (F.), Blatta orientalis L., and Supella longipalpa (Serville). Although the bait was effective against various cockroach species, time to death for the larger species was longer than for the German cockroach. In preference tests in which male German cockroaches were allowed to feed on rat chow or abamectin bait, all died within 5 d of exposure to abamectin bait. Abamectin bait consumption was not significantly lower than that of untreated rat chow. Arena tests with 0.0550% abamectin bait resulted in 31-75% mortality of German cockroaches after 9 d, with most control being achieved by treating harborages with the bait. The hydramethylnon standard resulted in 65% mortality after 9 d.

High-Performance Liquid Chromatographic Method for the Determination of Occupational Exposure to the Pesticide Abamectin

As part of a survey of occupational exposure to pesticides in greenhouses for growing ornamentals, analytical methods were developed and validated for the measurement of exposure of workers to the pesticide abamectin. Abamectin consists of a mixture of avermectin-Bla and avermectin-Blb, which are numbers of a class of fermentation products of the soil microorganism Streptomyces Avermitilis. Because of the high molecular weight of the avermectins (>800 daltons), high-performance liquid chromatography (HPLC) was the analytical method of choice. Previously described HPLC methods that used fluorescence detection were adapted and validated for the determination of dermal exposure by the analysis of cotton gloves and foliar dislodgeable residue. IOM samplers (developed at the Institute of Occupational Medicine, Edinburgh, U.K.) for collecting the inspirable fraction of dust or aerosols were tested for the determination of airborne abamectin concentrations in greenhouses. An analytical procedure considerably simpler than published methods appeared suitable for the determination of abamectin residues on cotton gloves and on greenhouse foliage. Analytical recovery from cotton gloves, solutions offoliar dislodgeable residues, and air-sampling filters was essentially complete. However, air concentrations of abamectin could not be reliably Measured by using the IOM sampling device because of breakdown during sampling. Between-day coefficients of variation for solutions of dislodgeable residue and cotton glove extracts were between 3% and 6% for abamectin concentrations between 5 and 140 µg/L.

HIGH-PERFORMANCE LIQUID CHROMATOGRAPHIC METHOD FOR THE DETERMINATION OF OCCUPATIONAL EXPOSURE TO THE PESTICIDE ABAMECTIN

As part of a survey of occupational exposure to pesticides in greenhouses for growing ornamentals, analytical methods were developed and validated for the measurement of exposure of workers to the pesticide abamectin. Abamectin consists of a mixture of avermectin-B1a and avermectin-B1b, which are members of a class of fermentation products of the soil microorganism Streptomyces Avermitilis. Because of the high molecular weight of the avermectins (greater than 800 daltons), high-performance liquid chromatography (HPLC) was the analytical method of choice. Previously described HPLC methods that used fluorescence detection were adapted and validated for the determination of dermal exposure by the analysis of cotton gloves and foliar dislodgeable residue. IOM samplers (developed at the Institute of Occupational Medicine, Edinburgh, U.K.) for collecting the inspirable fraction of dust or aerosols were tested for the determination of airborne abamectin concentrations in greenhouses. An analytical procedure considerably simpler than published methods appeared suitable for the determination of abamectin residues on cotton gloves and on greenhouse foliage. Analytical recovery from cotton gloves, solutions of foliar dislodgeable residues, and air-sampling filters was essentially complete. However, air concentrations of abamectin could not be reliably measured by using the IOM sampling device because of breakdown during sampling. Between-day coefficients of variation for solutions of dislodgeable residue and cotton glove extracts were between 3% and 6% for abamectin concentrations between 5 and 140 micrograms/L.

Differential Susceptibilities of Green Peach Aphid (Homoptera: Aphididae) and Two Endoparasitoids (Hymenoptera: Encyrtidae and Braconidae) to Pesticides

Mortality of green peach aphid, Myzus persicae Sulzer and two of its hymenopteran parasitoids, Aphelinus semiflavus Howard and Diaeretiella rapae (McIntosh) was evaluated after treatment with four pesticides commonly applied in greenhouses. Mortality of adult green peach aphid, D. rapae , and A. semiflavus was evaluated after exposure to five different concentrations of abamectin, bifenthrin, endosulfan, and acephate in a treated-vial bioassay. Concentrations included recommended label rates and multiple serial dilutions. Ranges in sensitivity of adults of each species were observed with the four compounds tested. Two concentrations of bifenthrin and one concentration of endosulfan produced significantly lower mortality in D. rapae than in green peach aphid. Immature stages of D. rapae and A. semiflavus were also evaluated for mortality by dipping leaf tissues containing mummified aphids into concentrations of either abamectin or endosulfan recommended on the label. The mummy stage of these parasitoids is resistant to abamectin and endosulfan at concentrations that are lethal to green peach aphid. This result suggests that these materials can be used selectively to integrate chemical and biological controls.

Relative Toxicity of Abamectin to the Predatory Mite Phytoseiulus persimilis (Acari: Phytoseiidae) and Twospotted Spider Mite (Acari: Tetranychidae)

The relative toxicity of abamectin to the predator Phytoseiulus persimilis Anthias-Henriot and the spider mite Tetranychus urticae Koch was assessed in laboratory studies. Eggs and female adults of both species were placed on bean ( Phaseolus vulgaris L.) leaf disks dipped in several concentrations of abamectin. Abamectin was much less toxic to the predator than to the spider mite. At concentrations of 0.08-16 ppm, abamectin did not significantly affect the survival and mobility of P. persimilis , but reproduction was significantly reduced at high concentrations (8 and 16 ppm). Adult female predators survived on a diet of spider mites intoxicated with abamectin, although their reproductive rate was decreased by 27 to 53%. At 1-16 ppm, abamectin did not affect the hatch of P. persimilis eggs or the developmental time of resulting immature predators. Survival of immature predators was not significantly affected at 1-4 ppm, but was reduced to an average of 54.3% at 8 and 16 ppm. The mobility of immature P. persimilis was slightly affected only at 16 ppm. Abamectin at selective sublethal concentrations (i.e., 1-4 ppm) could be of value in adjusting predator /prey ratios in integrated management of spider mites.

Selection of the Western Predatory Mite, Metaseiulus occidentalis (Acari: Phytoseiidae), for Resistance to Abamectin

A heterogeneous colony of Metaseiulus occidentalis (Nesbitt) was selected 20 times with increasing concentrations of abamectin. Selection yielded a gradual and modest shift in concentration-mortality lines. The resistance obtained, a 3.8-fold increase at LC50 not only resulted in an increased rate of survival of adult females but resulted in an increase in the number of eggs the surviving females produced. The diversity of resistances in this predator (to organophosphates, carbamates, pyrethroids, sulfur, and abamectin) iscomparable with that of many pest arthropods. Availability of an abamectin-resistant strain could be of practical value in integrated pest management programs if the resistant strain is released, established, and is efficacious in deciduous orchards and vineyards.

EFFECTS OF ABAMECTIN ON PHIDIPPUS AUDAX (HENTZ) (ARANEAE: SALTICIDAE) WHEN INGESTED FROM PREY1

Phidippus audax (Hentz) were allowed to feed on bollworm, Heliothis zea (Boddie), larvae which had ingested diet containing three concentrations of abamectin. Significantly reduced weight gain was noted for spiders feeding on the treated larvae and toxicity effects were visible in most of the spiders within 48 h. Over 80% of the spiders that fed on larvae from diet containing 10 ppm abamectin were either torpid or dead, and 100% of spiders that fed on larvae from diet containing 40 ppm abamectin were torpid or dead.