Concentrations Of Azinphos-methyl Research Articles

Where’s the Dust? Characterizing Locations of Azinphos-Methyl Residues in House and Vehicle Dust Among Farmworkers with Young Children

Organophosphate pesticides are commonly used in the United States, and farmworkers are at risk for chronic exposure. Using data from a community randomized trial to interrupt the take-home pathway of pesticide exposure, we examined the association between floor surface type (smooth floor, thin carpet, and thick carpet) and rooms in which dust samples were collected (living room vs. non-living room) and concentrations of azinphos-methyl residues in home environments. We also examined the association between vehicle type (truck, auto, or other) and footwell floor surfaces (carpeted, smooth surface, or no mat) and concentrations of azinphos-methyl in vehicle dust samples. Dust samples were collected from 203 and 179 households and vehicles, respectively. All households had at least one child aged 2–6. Vehicle dust samples were collected from footwells of the vehicle used for commuting to and from work. A total of 183 samples were collected from living rooms, and 20 were collected from other rooms in the home. Forty-two samples were collected from thick carpets, 130 from thin carpets, and 27 from smooth floor surfaces. Thick and thin carpets had a significantly greater dust mass than smooth floor surfaces (6.0 g/m2 for thick carpets, 7.8 g/m2 for thin carpets, and 1.5 g/m2 for smooth surfaces). Of the 179 vehicle samples, 113 were from cars, 34 from trucks, and 32 from other vehicles. Vehicles with no mats had a significantly higher mass of dust (21.3 g) than those with hard mats (9.3 g) but did not differ from vehicles with plush mats (12.0 g). Further research is needed to characterize the environment in which children may be exposed to pesticides.

Cross‐resistance between azinphos‐methyl and acetamiprid in populations of codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), from Washington State

Codling moth, Cydia pomonella (L.), has been intensely managed with the organophosphate insecticide azinphos-methyl for 50 years, and populations have developed resistance. New management programs have been developed and implemented that rely more heavily on other classes of insecticides. A prerequisite for developing effective resistance management strategies for these compounds is to establish their current levels of effectiveness. Adult and neonate larval assays were conducted to assess the response of field-collected codling moth populations from apple in Washington State. Male codling moth populations exhibited a range of responses to a discriminating concentration of azinphos-methyl in a survey of 20 populations. Populations from certified organic orchards were more susceptible than those from conventional orchards. Mean fecundity was inversely related to azinphos-methyl tolerance. Male responses to azinphos-methyl and acetamiprid varied significantly among populations and were correlated. The residual effectiveness of field applications of both insecticides varied significantly against neonate larvae. Neonate bioassays with insecticide-dipped fruit found significant differences among populations with azinphos-methyl, acetamiprid, methoxyfenozide and spinosad, but not with esfenvalerate. These results support a concern that alternation of insecticides with different modes of action may not be a sufficient strategy to avoid the evolution of broad-spectrum insecticide resistance by codling moth.

Cholinesterase activity in gilthead seabream (Sparus aurata) larvae: Characterization and sensitivity to the organophosphate azinphosmethyl

Assessment of cholinesterase (ChE) inhibition is widely used as a specific biomarker for evaluating the exposure and effects of non-target organisms to anticholinesterase agents. Cholinesterase and carboxylesterase activities have been measured in larvae of gilthead seabream, Sparus aurata, during the endogenous feeding stage, and ChE was characterized with the aid of diagnostic substrates and inhibitors. The results of the present study showed that whole-body ChE of yolk-sac seabream larvae possesses typical properties of acetylcholinesterase (AChE) with a apparent affinity constant (Km) of 0.163±0.008mM and a maximum velocity (Vmax) of 332.7±2.8nmol/min/mg protein. Moreover, sensibility of this enzyme was investigated using the organophosphorus insecticide azinphosmethyl. Static-renewal toxicity tests were conducted over 72h and larval survival and AChE inhibition were recorded. Mean mortality of seabream larvae increased with increasing concentrations of azinphosmethyl and exposure duration. The estimated 72-h LC50 value to azinphosmethyl was 4.59μg/l (95% CI=0.46–8.71μg/l) and inhibition of ChE activity gave an IC50 of 3.04μg/l (95% CI=2.73–3.31μg/l). Larvae exposed to azinphosmethyl for 72h showed a 70% inhibition of the whole-body acetylcholinesterase activity at approximately the LC50. In conclusion, the results of the present study suggested that monitoring ChE activity is a valuable tool indicating OP exposure in S. aurata larvae and that acetylthiocholine is the most appropriate substrate for assessing ChE inhibition in this early-life stage of the fish.

Organophosphate Pesticide Exposure and Work in Pome Fruit: Evidence forthe Take-Home Pesticide Pathway

Organophosphate (OP) pesticides are commonly used in the United States, and farmworkers are at risk for chronic exposure. Using a sample of 218 farmworkers in 24 communities and labor camps in eastern Washington State, we examined the association between agricultural crop and OP pesticide metabolite concentrations in urine samples of adult farmworkers and their children and OP pesticide residues in house and vehicle dust samples. Commonly reported crops were apples (71.6%), cherries (59.6%), pears (37.2%), grapes (27.1%), hops (22.9%), and peaches (12.4%). Crops were grouped into two main categories: pome fruits (apples and pears) and non-pome fruits. Farmworkers who worked in the pome fruits had significantly higher concentrations of dimethyl pesticide metabolites in their urine and elevated azinphos-methyl concentrations in their homes and vehicles than workers who did not work in these crops. Among pome-fruit workers, those who worked in both apples and pears had higher urinary metabolites concentrations and pesticide residue concentrations in dust than did those who worked in a single pome fruit. Children living in households with pome-fruit workers were found to have higher concentrations of urinary dimethyl metabolites than did children of non-pome-fruit workers. Adult urinary concentrations showed significant correlations with both the vehicle and house-dust azinphos-methyl concentrations, and child urinary concentrations were correlated significantly with adult urinary concentrations and with the house-dust azinphos-methyl concentration. The results provide support for the take-home pathway of pesticide exposure and show an association between measures of pesticide exposure and the number of pome-fruit crops worked by farmworkers.

Behavioral and sex ratio modification of Japanese medaka (Oryzias latipes) in response to environmentally relevant mixtures of three pesticides

We exposed Japanese medaka (Oryzias latipes) to environmentally relevant concentrations of azinphos-methyl, chlorothalonil, endosulfan, and mixtures of all three to determine if combinations of these pesticides result in additive, less-than-additive, or more-than-additive effects. Medaka were exposed from fertilization until 7 days posthatching, and end points included survival, time to hatch, size at 7 days posthatching, activity level (as measured by distance swam) and foraging ability at 3 weeks posthatching, and adult size, liver size, and sex ratio at 5 months posthatching. Although exposure to individual pesticides or pesticide mixtures did not affect survival, hatching time, or foraging ability, fry exposed to azinphos-methyl were significantly smaller at 1 week of age, and those exposed to chlorothalonil and a combination of the chemicals showed reduced activity. Adult sex ratios were biased toward females in all groups exposed to pesticides, with those exposed to azinphos-methyl, chlorothalonil, and the pesticide mixture departing significantly from an even sex ratio. There was no evidence of additive or synergistic effects of pesticide mixtures.

Time course of brain cholinesterase inhibition and recovery following acute and subacute azinphosmethyl, parathion and carbaryl exposure in the goldfish ( Carassius auratus)

Laboratory toxicity data contrasting mortality and brain cholinesterase inhibition in the goldfish ( Carassius auratus) are presented. Brain cholinesterase (ChE) was greatly reduced after 96 h of exposure in vivo at sublethal concentrations of azinphosmethyl and parathion. The inhibition of the enzyme was dose dependent, and concentrations higher than 0.1 mg/L caused more than 90% inhibition. The effect of carbaryl was less pronounced, achieving an 86% inhibition at concentrations corresponding to the 96-h LC 50. After in vivo exposure to sublethal concentrations of parathion and azinphosmethyl (0.1 mg/L) and carbaryl (3.0 mg/L), the activity of the goldfish brain ChE was greatly reduced. In the following 96 h of recovery, the enzyme inhibited with carbaryl was restored to 75% activity, while the enzyme inhibited with organophosphates (OPs) required more than 35 days for recovery. Goldfish were able to withstand high percentages of brain ChE inhibition without mortality, suggesting that another target may be responsible for the lethal effects. However, the enzyme is a good biomarker of acute and subacute exposure to OPs and carbamates.

Evaluation of take-home organophosphorus pesticide exposure among agricultural workers and their children.

We analyzed organophosphorus pesticide exposure in 218 farm worker households in agricultural communities in Washington State to investigate the take-home pathway of pesticide exposure and to establish baseline exposure levels for a community intervention project. House dust samples (n = 156) were collected from within the homes, and vehicle dust samples (n = 190) were collected from the vehicles used by the farm workers to commute to and from work. Urine samples were obtained from a farm worker (n = 213) and a young child (n = 211) in each household. Dust samples were analyzed for six pesticides, and urine samples were analyzed for five dialkylphosphate (DAP) metabolites. Azinphosmethyl was detected in higher concentrations (p < 0.0001) than the other pesticides: geometric mean concentrations of azinphosmethyl were 0.53 micro g/g in house dust and 0.75 micro g/g in vehicle dust. Dimethyl DAP metabolite concentrations were higher than diethyl DAP metabolite concentrations in both child and adult urine (p < 0.0001). Geometric mean dimethyl DAP concentrations were 0.13 micro mol/L in adult urine and 0.09 micro mol/L in child urine. Creatinine-adjusted geometric mean dimethyl DAP concentrations were 0.09 micro mol/g in adult urine and 0.14 micro mol/g in child urine. Azinphosmethyl concentrations in house dust and vehicle dust from the same household were significantly associated (r2 = 0.41, p < 0.0001). Dimethyl DAP levels in child and adult urine from the same household were also significantly associated (r2 = 0.18, p < 0.0001), and this association remained when the values were creatinine adjusted. The results of this work support the hypothesis that the take-home exposure pathway contributes to residential pesticide contamination in agricultural homes where young children are present.

Rainfall-induced sediment and pesticide input from orchards into the lourens river, western cape, south africa: importance of a single event

Rainfall-induced runoff transported sediments and pesticides into the Lourens River and its tributaries during a 28.8-mm rainstorm in mid-December 1998. Average 1-h peak levels of current-use insecticides applied to adjacent orchard plots were 1.5μgl−1 azinphos-methyl, 0.2μgl−1 chlorpyrifos and 2.9μgl−1 total endosulfan (α, β, S) in the river itself. Respective average 1-h pesticide levels associated with suspended particles were 1247, 924 and 12082μgkg−1, along with 980μgkg−1 of prothiofos. Total suspended solids increased during runoff from 32 to 520mgl−1. The contaminated edge-of-field runoff entered the river via the tributaries directly bordering the orchard-growing areas. Increased concentrations of azinphos-methyl and prothiofos associated with suspended sediments were demonstrated to persist for about 3.5 months without any further input in one of the tributaries. This illustrates that the short-term exposure has the potential to result in long-term contamination of surface waters. In terms of chemical load during the 1-h peak discharge period, the single rainfall event caused a loss of 173gh−1 azinphos-methyl, 55gh−1 chlorpyrifos, 740gh−1 total endosulfan (α, β, S) and 41gh−1 prothiofos. Levels of contamination were extremely high; they exceed the national water quality standards and those established by the US EPA. A comparison with standard toxicity data and 24-h LC50s for the local amphipod species Paramelita nigroculus, obtained during this study, indicates that the concentrations found in the river may result in acute toxic effects on aquatic invertebrates and fishes. A probability analysis of 10-y rainfall data revealed that the frequency of a similar storm event occurring within the main spraying season is 1.7y−1.

Effects of Azinphosmethyl on Some Biochemical Parameters in Blood, Muscle, and Liver Tissues ofCyprinus carpio(L.)

In the present study, the effects of 0.20 and 0.35 ppm azinphosmethyl exposures occurring on days 1, 2, 3, 4, and 15 for on serum enzyme activities and protein and glucose levels in blood, muscle, and liver tissues of fish,Cyprinus carpio(L.), were photometrically investigated. Protein and glycogen contents in muscle and liver tissues were also determined. Azinphosmethyl did not affect the level of total protein in serum. However, there was a decrease in the level of muscle protein in 2 days of treatement while the liver protein elevated after acute exposure to both concentration of azinphosmethyl. It was also found that there was an elevation in the serum glucose content while the muscle and liver glycogen contents were reduced. Serum enzyme activities were also altered. Glutamate-oxaloacetate transaminase and glutamate-pyruvate transaminase activities initially increased following exposure to both concentrations of azinphosmethyl; later there was no change in the activities of these enzymes. Lactate dehydrogenase enzyme activity also increased in the beginning of the experiment, but it was at the control level in 15 days. Alkaline phosphatase enzyme activity decreased on the first of day treatment while it increased second day. However, there was no significant difference during the other exposure times. After acute exposure to 0.35 ppm concentration of azinphosmethyl there was a significant increase in acid phosphatase activity while there was no change in this enzyme activity at the other exposure concentration and periods. Furthermore, sublethal concentrations of azinphosmethyl caused the behavioral and morphological changes inC. carpio.The results of this study showed that tissue necrosis and an elevation of glycogenolysis occurred following acute exposure to azinphosmethyl, but compensatory mechanisms were developed byC. carpioduring chronic exposure.

Relationship between azinphos-methyl usage and residues on grapes and in wine in Australia

Azinphos-methyl was applied to Shiraz winegrapes by commercial high-volume and hand-held sprayers during seasons 1993/94 and 1994/95. Residue levels in grapes resulting from treatments applied by commercial sprayer were below the maximum residue level (MRL) of 2 mg kg -1 for grapes in Australia, whereas residues resulting from treatments applied by hand-held sprayer still exceeded the MRL five weeks after final application. There was a strong correlation for most treatments between treatment concentration of azinphos-methyl and residue level in grapes, and in wine made from treated grapes. Applied at the recommended rate (1.2 g litre -1 wettable powder (WP) and 2.4 ml litre -1 suspension concentrate (SC)) by commercial high-volume sprayer, azinphos-methyl residue levels in wine were well below the MRL, and below the MRLs of most importing countries, except Denmark and Sweden. When applied by hand-held sprayer, residue levels in wine were 5.9-29.6 fold higher than those previously obtained by commercial application of insecticide. Since wines are often blends from different grape blocks and grape-growing districts, in practice, this is unlikely to be of concern. Wine made from grapes treated by commercial sprayer showed no detectable residues of azinphos-methyl after one year of storage. In both years, residue levels in grapes of both formulations of azinphos-methyl fluctuated during the five-week post-treatment period, although there was an overall downward trend. Previously unrecorded systemicity in azinphos-methyl was demonstrated in laboratory studies with barley seedlings, and this may explain these fluctuating data in grapes. The reduction of azinphos-methyl residues in grapes over time appears to be a complex phenomenon involving translocation of active ingredient combined with an increase in the size and weight of berries, producing fluctuating residue levels.

Distribution and Persistence of Azinphos‐Methyl and Parathion in Chemigated Cranberry Bogs

AbstractDitches draining two cranberry (Vaccinium spp.) bogs flowing into salmon (Oncorhynchus spp.) bearing waterbodies in the Lower Fraser Valley of British Columbia, Canada, were sampled in 1992 to determine the distribution and persistence of azinphos‐methyl (AZI) and parathion (PAR) following three treatments through an irrigation system (chemigation), to control the black‐headed fireworm (Rhopobota naevana Hbn). One bog was surrounded by a secured dike system for water retention and the other by a leaking dike system, representing a worst‐case scenario. After each treatment, AZI and PAR residues were detected in ditch water (detection limit = 0.05 µg/L) and sediments (detection limit = 5 µg/kg) inside and outside the bogs and they persisted for 72 and 32 d, respectively. The highest concentrations in water were 175 µg/L for AZI and 21 µg/L for PAR. Concentrations of AZI and PAR in sediments ranged from not detected to 1582 µg/kg and persisted for 210 and 13 d, respectively. Low levels of aerial drift resulting from the treatment were detected beyond the outer perimeter of the sprinkler irrigation system in the cranberry bogs. Off‐site release of insecticide residues occurred in the leaking dike system but not in the secured dike system. The released insecticide residues adversely affected nontarget aquatic organisms. Harvested cranberries contained no detectable (detection limit = 5 µg/kg) residues of AZI and PAR.

Temporal and spatial distribution of azinphos-methyl applied to alfalfa

The U. S. Environmental Protection Agency uses a simple exposure nomogram to make preliminary assessments of the pesticide residues concentrations on foods of terrestrial wildlife. This study was conducted to measure the spatial and temporal distribution of the organophosphorus insecticide azinphos-methyl (Guthion® 2S) in a dense alfalfa crop to evaluate the assumptions used in this nomogram and to determine the influences of application rate and spatial distribution of residues on the potential dietary exposure to herbivores. Concentrations of azinphos-methyl were measured on spray cards, soil, and alfalfa plants (top 15 cm and bottom 15 cm) on plots treated at 0, 0.77, 1.55, 3.11, and 4.67 kg active ingredient/ha (4 enclosures/treatment) at 2 h and 2, 6, 14 and 28 days after application. Although the concentrations measured on spray cards were very close to predicted, the concentrations on alfalfa canopy vegetation were higher than expected from the nomogram and increased at a faster rate with increasing application rate than expected. Concentrations were 1.5–2.4 times higher in the alfalfa canopy than on alfalfa near soil level. Variability among alfalfa samples within treatments was high, with part of the variation in canopy samples explained by the distance to the end of the spray boom. Only 16–32% of pesticide reached the soil surface. The calculated half-life of azinophos-methyl was 2.5–4.5 days on vegetation and 19.3 days on soil. Dietary exposure to small herbivores would be expected to exceed nomogram predictions, but be highly variable for individuals due to the patchy nature of the pesticide distribution.

Evaluation of toxic effects of the organophosphorus insecticide azinphos-methyl in experimentally and naturally exposed birds

Laboratory and field studies were conducted to evaluate the effects of the organophosphorus insecticide, azinphosmethyl, on bird populations and into the possibility of assessing toxic hazard by a non-destructive biomarker such as BChE inhibition. Japanese quail were treated with increasing doses of azinphos-methyl (0.5, 5, and 50 mg/kg) and sacrificed 7 and 24 h later. Serum BChE and CbE, brain AChE, and liver microsomal CbE activities showed different patterns of inhibition. The maximum inhibition of BChE and CbE usually occurred 7 h after treatment, whereas the effect on AChE was greater at 24 h. A positive correlation was found between BChE and AChE, 7 and 24 h after treatment. This correlation could serve as the foundation for a theoretical model for assessing toxic hazard through non-destructive biomarkers. The only effect on brain AChE was detected in the group treated with the highest concentrations of azinphos-methyl (50 mg/kg). Fugacity model calculations showed that such massive concentrations are very unlikely to occur under natural conditions after agricultural use of the compound.

Azinphosmethyl Resistance in the Tufted Apple Bud Moth (Lepidoptera: Tortricidae): Reversion, Diagnostic Concentrations, Associated Esterases, and Glutathione Transferases

In 1989 sticky-card bioassays performed on adult males collected in pheromone traps showed 41-fold resistance to azinphosmethyl in a field population of tufted apple bud moth, Platynota idaeusalis (Walker). After 17 generations under laboratory rearing conditions without azinphosmethyl selection, azinphosmethyl resistance in neonates and male adults reverted to a level approaching that of a susceptible strain. Estimated LC95s and LC99s (340 and 760 µg [AI]/g adhesive, respectively) of susceptible moth populations were selected as diagnostic concentrations of azinphosmethyl and used to assay three field populations of adult males for azinphosmethyl resistance in 1990 and 1991. Glutathione-transferase activities were not associated with azinphosmethyl resistance in laboratory strains. Elevated nonspecific-esterase activities were found in resistant laboratory strains and a field population with a high level of resistance. Among the nonspecific esterases, the presence of one esterase (E6) was closely associated with azinphosmethyl resistance in field populations. In this study, nonspecific-esterase assays gave an accurate assessment of azinphosmethyl resistance in this tortricid species, but a specific assay that detects the E6 will provide the sensitivity necessary to detect moderate to low levels of resistance in field populations.

Population Development and Insecticide Susceptibility of Apple Aphid and Spirea Aphid (Homoptera: Aphididae) on Apple2

Colonies of apple aphid, Aphis pomi DeGeer, and spirea aphid, A. spiraecola Patch, were confined separately in bottle cages on apple tree branches to compare population development and susceptibility to insecticides under field conditions. Spirea aphid populations were significantly larger than apple aphid populations eight days after introduction into bottle cages. After two and a half weeks there was a 24-fold and 40-fold increase in the population of apple aphid and spirea aphid, respectively. Apple aphid was more susceptible than spirea aphid to a low concentration of esfenvalerate and to normal field and 2X field concentrations of azinphosmethyl. There was no significant difference between the two aphid species in susceptibility to methomyl, chlorpyrifos and endosulfan. Mortality of apple aphid to the two phosphate insecticides, azinphosmethyl and chlorpyrifos, was similar; however, spirea aphid was more susceptible to chlorpyrifos than to azinphosmethyl. An increased rate of population development and a greater tolerance of azinphosmethyl, the most widely used insecticide for apple insect control, could be contributing factors in the virtually complete domination of spirea aphid over apple aphid in West Virginia apple orchards.

Resistance levels ofTyphlodromus occidentalis (Acari: Phytoseiidae) from Washington apple orchards to ten pesticides

Nine Washington populations ofTyphlodromus (=Metaseiulus) occidentalis Nesbitt collected from commercial apple orchards were surveyed for resistance to ten pesticides. A susceptible population collected from wild blackberry which had no history of pesticide exposure was used in estimating resistance development. All populations from apple orchards were tolerant to high concentrations of azinphosmethyl, diazinon, endosulfan and propargite. Resistance was also apparent to these materials, especially for azinphosmethyl which produced over 100-fold resistance levels for several populations. Moderate to low levels of tolerance and resistance development were seen to field concentrations of cyhexatin, formetanate and carbaryl. Fenvalerate, methomyl and methidathion were all very toxic at field concentrations and little evidence of resistance development was apparent. The use of fenvalerate, methomyl or methidathion at a time whenT. occidentalis is active would likely abrogate favorable biological control of pestiferous orchard mites.

Azinphosmethyl and Fenvalerate Runoff Loss from a Sugarcane‐Insect IPM System

AbstractAzinphosmethyl {0,0‐dimethyl S‐[(4‐oxo‐1,2,3‐benzotriazin‐3(4H)‐yl)methyl] phosphorodithioate} and fenvalerate [(RS)‐α‐cyano‐3‐phenoxybenzyl (RS)‐2‐(4‐chlorophenyl)‐3‐methylbutyrate] were applied to sugarcane (Saccharum officinarum L.) runoff plots at rates of 0.84 and 0.22 kg/ha, respectively, 4 times each year in 1980 and 1981 as part of an insect integrated pest management (IPM) system research evaluation for season‐long control of the primary sugarcane insect pest, the sugarcane borer [Diatraea saccharalis (F.)]. Runoff samples (water + sediment) were collected within 8 h after each storm and analyzed by gas chromatography. In 1980, runoff losses of azinphosmethyl and fenvalerate were 0.08 and 0.02%, respectively, of the amount applied. Runoff in 1981 was about twice that in 1980, partially accounting for larger insecticide runoff losses measured, 0.55 and 0.56% of that applied for azinphosmethyl and fenvalerate, respectively. The larger 1981 losses also were attributed to shorter time intervals between insecticide applications and runoff events. Azinphosmethyl concentrations in runoff do not appear to be harmful to surrounding aquatic habitats, whereas fenvalerate concentrations might present problems, particularly if applied at 0.22 kg/ha rates.

Concentrations of Azinphosmethyl and Fenvalerate in Run-Off Water from Sugarcane, Sugarcane Borer Control, 1980, 1981

Abstract Azinphosmethyl (Guthion) and fenvalerate (Pydrin) were sprayed 4 times in 1980 (Jul 11, 29, Aug 14, and Sep 9) and 1981 (Jul 13, 30, Aug 19, and Sep 12) at a rate of 0.84 and 0.22 kg/ha for the respective insecticides. Each spray concentration was applied io the plant canopy in water at 30 psi with a compressed air knapsack sprayer that delivered 270 liters finished formulations per h.:, The study, designed to measure run-off from 0.016 ha plots under season-long control of sugarcane borer (SCB) infestations, was set up in a randomized complete block experimental design on commerce silt loam (fine-siIty, mixed, non-acid thermic aerie fluvaquents) soil on the St. Gabriel Experiment Station. Run-off was collected in 204 I (54 gal) drums buried in the soil at the downslope end of plots. Samples were collected, and drums emptied and cleaned on the same day of rainfall.

Contact Toxicity of Az1Nphosmethyl and Monocrotophos To 3Rd Stage F] Progeny Of Field-Collected Scb Populations: Insecticide Resistance Screening, 1978

Abstract Colonies of the SCB initially collected in the Fall (1978) from 2 South LA Sugarcane fields near Lockport and St. James (after seasonal insecticide applications had ceased) were maintained on a meredic diet in the laboratory. Responses of the 3rd stage F] larval progeny to topical application of two insecticides labeled for SCB Control in LA (azinphosmethyl and monocrotophos) were compared to (1) toxicity baseline data acquired previously from the 3rd stage F] progeny of a field collected SCB colony that had not been exposed to organophosphorous insecticides and (2) LD50 and LD90 values for 3rd stage F] larval progeny of comparable SCB colonies collected near St. James and Lockport during the fall of 1977. Six concentrations of azinphosmethyl and 5 of monocrotophos were evaluated by applying the required scalar dosage in acetone to individual groups of larvae. One ul of acetone and toxicant was applied to the thoracic surface of each larva with a shardlow micrometer equipped with a 1 ml alga syringe. All larvae were maintained individually in diet cups except during the time when toxicant was applied. Mortality counts were recorded 24 and 72 hr after treatment, however only the 72 hr counts were used for probit analyses and calculation of Ld-p lines (Daum R.J. ESA Bull. 16:10-15).