Elimite
Deposition of malathion and permethrin on sod grass after single, ultra-low volume applications in a suburban neighborhood in Michigan.

Knepper RG, Walker ED, Wagner SA, Kamrin MA, Zabik MJ.

Saginaw County Mosquito Abatement Commission, MI 48602, USA.

Deposition of malathion and permethrin onto grass surfaces, after ultra-low volume (ULV) application, was studied in a suburban neighborhood in Saginaw County, Michigan. Commercial concentrates of malathion (Cythion ULV) and permethrin (Biomist 4 + 12) were sprayed using a truck-mounted ULV aerosol generator. Sod-grass blocks (0.18 m2) were placed in the frontyard and backyard of homes in the neighborhood at 4 distances to 91.4 m from the road where applications were made. Grass samples were taken from the sod blocks before application and at 15 min, 12 h, 24 h, and 36 h after application. Samples were extracted with solvent, and extractions were subjected to gas-liquid chromatography for detection of malathion and permethrin. Ranges of detection for malathion were 0.0-16.6 mg/0.18 m2 and for permethrin were 0.0-25.9 mg/0.18 m2. Most detections were from samples taken nearest the road at 15 min after application. Detections declined as a logarithmic function of time after application and as an exponential function of distance from the road.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8723257&dopt=Abstract permethrin Elimite



Elimite
Permethrin-impregnated bednets are more effective than DDT house-spraying to control malaria in Solomon Islands.

Kere NK, Arabola A, Bakote'e B, Qalo O, Burkot TR, Webber RH, Southgate BA.

Ministry of Health and Medical Services, Solomon Islands, U.K.

A field trial compared DDT house-spraying with permethrin-impregnated bednets for malaria control in Solomon Islands from 1987 to 1991. Mortality-rates of malaria vector Anopheles farauti in exit window traps were 11.6% from an untreated hut, 10.1% from a hut sprayed with DDT 2 g/m2, and 98% of those from a hut in which the occupants used bednets treated with permethrin 0.5 g/m2. Since bioassays of the DDT-sprayed walls (15 min exposure in W.H.O. standard test cones) gave 77% mortality of An.farauti, it was concluded that the insignificant impact of DDT could be explained by the exophilic behaviour of endophagic vectors, whereas the greater impact of permethrin was attributed to the more effective exposure of An.farauti females to the impregnated bednets-attracted by the occupants. The parous rate was higher indoors, except in the area with permethrin-impregnated bednets. It was therefore concluded that permethrin-impregnated bednets reduced the mean longevity of An.farauti and hence its vectorial capacity. The circumsporozoite (CS) antigen positivity rate of An.farauti in the DDT area was 0.18% outdoors, significantly less than 1.42% indoors. In the comparison area CS rates were 0.65% outdoors and 0.75% indoors. CS antigen was not detected in An.farauti from the bednet area, indicating the apparent prevention of malaria transmission. As DDT spraying was so much less effective, it was discontinued in 1993 and permethrin-impregnated bednets are now the principal malaria control method in Solomon Islands.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8744706&dopt=Abstract permethrin Elimite



Elimite
Determination of total free and glucose-conjugated 3-phenoxybenzyl alcohol residues in foods by gas chromatography with electron capture detection.

Mortimer RD, Shields JB.

Health Canada, Bureau of Chemical Safety, Food Research Division, Ottawa, ON, Canada.

A method was developed to determine the combined amounts of residual, free 3-phenoxybenzyl alcohol (permethrin alcohol) and its acetone-extractable glucosides in representative fruits and vegetables after application of pyrethyroid insecticides such as permethrin or cypermethrin. 3-Phenoxybenzyl glucoside was synthesized and used to spike food samples. Conditions were developed for extraction, enzymatic hydrolysis, derivatization with heptafluorobutyric anhydride, and cleanup prior to detection and quantitation by gas chromatography with electron capture detection. Limits of detection in various foods were < or = 0.01 ppm. In addition, 2 sets of field trial samples that were sprayed with permethrin and collected at intervals were also analyzed. In general, the amounts of total permethrin alcohol in foods were small.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8757455&dopt=Abstract permethrin Elimite



Elimite
Malaria control using permethrin applied to tents of nomadic Afghan refugees in northern Pakistan.

Bouma MJ, Parvez SD, Nesbit R, Winkler AM.

Medical Department, MSF-Holland, Amsterdam, Netherlands.

Malaria control among nomadic populations has, in the past, posed serious logistic difficulties. Presented in this article are the results of a pilot study in which permethrin was sprayed on the tents of over 26000 nomadic Afghan refugees in an area of Pakistan where seasonal malaria outbreaks occur. In this area Anopheles culicifacies and A. stephensi are the malaria vectors. Population surveys in the year of the study, before and at the end of the transmission season, showed that the increase in the Plasmodium falciparum prevalence among the Afghan nomads was on average significantly less (increase from 6.4% to 15.3%) than that among the resident Pakistani population (from 3.2% to 45.6%). Surveys at the end of the transmission season among primary schoolchildren the year before and the year of the permethrin trial showed that the P. falciparum prevalence among nomadic children decreased significantly (from 46.9% to 16.3%), whereas an increase was observed among the local Pakistani children. The results show that spraying tents with permethrin was a safe and culturally acceptable intervention for the Afghan refugees and that the findings warrant further investigation.

PIP: During 1989-90, in the North-West Frontier Province of Pakistan, a pilot study was conducted in the remote and politically unstable area of South Waziristan Agency (altitude, 1300-1750 m) to determine the feasibility of spraying about 5600 tents (used by more than 26,000 nomadic Afghan refugees) with permethrin and its effect on malaria prevalence. The researchers compared baseline data on the refugees and data from Pakistani schoolchildren with follow-up data on the nomadic Afghan refugees. The mosquito species harboring malaria parasites in the area were Anopheles culicifacies and A. stephensi. An effective permethrin residue persisted for at least 6 months after spraying. Between seasons, the prevalence of Plasmodium falciparum increased at a significantly lower rate among the Afghan nomads (6.4-15.3%) than the resident Pakistan population (3.2-45.6%). Prevalence decreased significantly among nomadic Afghan children after the permethrin intervention (46.9-16.3%; p 0.002). On the other hand, it increased significantly among the local Pakistani children (11.6-40.7%; p 0.001). There were no reports of adverse effects from permethrin spraying operations. The absence of toxic effects, the immediate impact on flies, and the lack of smell or color of the permethrin emulsion made the spraying operation acceptable among the nomads. These findings suggest that spraying tents with permethrin was a safe and culturally acceptable intervention.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8823964&dopt=Abstract permethrin Elimite



Elimite
Comparative susceptibility of larvae of three Aedes species to malathion and permethrin.

Cilek JE, Craig GB Jr, Knapp FW.

John A. Mulrennan, Sr. Research Laboratory, Florida A&M University, Panama City 32405, USA.

Larvae of Aedes hendersoni, Ae. atropalpus, and 6 geographic strains of Ae. triseriatus were compared in terms of their susceptibility to malathion and permethrin. Aedes atropalpus was most tolerant to malathion, whereas Ae. triseriatus (Walton strain) was most tolerant to permethrin. Malathion LC50S for 6 geographic strains of Ae. triseriatus ranked from high to low were: Alabama (ALA) > Michigan (UNDERC) > Indiana (WAL) > Kentucky (UKEN) > Texas (SAL) > Florida (VB); similar ranking of permethrin LC50S resulted in: WAL > VB > SAL > UKEN > UNDERC > ALA. Differences in susceptibility were detected but were not considered large (i.e., over several orders of magnitude). As a result, no change in application rate of malathion or permethrin, from an operational viewpoint, would be warranted if used against these 3 mosquito species or the geographic strains of Ae. triseriatus investigated.

Online source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=8825499&dopt=Abstract permethrin Elimite