EFFICACY OF SEVEN PYRETHROIDS AGAINST MUSCA DOMESTICA LINNAEUS, 1758 (DIPTERA, MUSCIDAE)ABSTRACT
Under laboratory conditions the pyrethroids alpha-cypermethrin, cyfluthrin, cypermethrin, deltametrin, fenvalerate, lambda-cyhalothrin and permethrin were tested against a susceptible strain of Musca domestica L. adult. Topical test was used in which the active ingredients were diluted in acetone. LD50, LD90 and LD95 were selected. Results of tests allowed to show in arder of effectiveness the pesticides: deltamethrin was the most effective at LD90 level, about 2.0X; 2.6X; 5.8X; 7.9X; 14.3X and 26.7X less f\g of AI per insect than lambda-cyhalothrin, alpha-cypermethrin, cypermethrin, cyfluthrin, permethrin. The fenvalerate was the least effective pyrethroid it required 31.5X (LD50) and 25.8X (LD95) moref\g of AI per house fly than deltamethrin.
KEY WORDS:
Fly control; Musca domestica, pyrethroids.
RESUMO
Um estudo, em condições de laboratório, permitiu a avaliação dos piretróides alfa-cipermetrina, ciflutrina, cipermetrina, deltametrina, fenvalerato, lambda-cialotrina e permetrina no controle de adultos sensíveis de Musca domestica L. Os produtos, nas formas de ingredientes ativos diluídos em acetona foram testados, por meio de testes tópicos, selecionando-se DL50, DL90 e DL95. Os resultados dos testes permitiram ordenar os inseticidas segundo sua eficiência: deltametrina, o mais eficiente apresentou, considerando DL90, 2,0; 2,6; 5,8; 7,9; 14,3 e 26,7 vezes menos f\g de IA por inseto do que respectivamente lambdacialotrina, alfa-cipermetrina, cipermetrina, ciflutrina, permetrina e fenvalerato, sendo que este último exigiu 31,5 (DL50) e 25,8 (DL95) vezes mais f\g de IA/mosca doméstica do que a deltametrina.
PALAVRAS-CHAVE:
Controle de moscas; Musca domestica, piretróides.
INTRODUCTION
The housefly (Musca domestica) presents problems to public health, it is a mechanical vector for pathogenic agents as virus (poliomyelitis, hepatitis, etc), and bacteria (cholera, enteric infections, etc), affecting humans and domesticated animals. For all these reasons, plus the fact that its mere presence is annoying, the synanthropic housefly should be controlled by every means possible, and one of the main controls continues to be the use of chemical insecticides. This study evaluated the efficacy of modem compounds for the control of houseflies. These compounds, currently available on the market and widely used for this purpose, are the pyrethroids: alpha-cypermethrin, cyfluthrin, cypermethrin, deltamethrin, fenvalerate, lambda-cyhalothrin, and permethrin. Since in topical tests the applications are made to individual flies, the quantity of the active ingredient administered to each can be evaluated with precision. The results of this study may also serve, eventually, as a reference or model for the contrai of other synanthropic diptera.
MATERIAL AND METHODS
The insecticides pyrethroids alphacypermethrin ((IR eis) S + (IS eis) R a racemate of a-cyano-3-phenoxybenzyl-3-(2,2-dichloroviny1)- 2,2-dimethylcyclopropane carboxylate); cyfluthrin ((RS)-a-cyano-4-fluoro-3-phenoxybenzyl (1RS)-cistrans-3-(2,2-dichlorovinyl)-2,2- dimethylcyclopropane carboxylate)); cypermethrin ((RS)-a-cyano-3-phenoxy benzyl (IRS) -cis-trans-3- (2,2-dichlorovinyl) -1,1- dimethyl cyclopropane carboxylate)); deltamethrin ((S)-a-cyano-3-phenoxybenzyl(lR)-cis-3- (2,2-dibromovinyl) -2,2- dimethylcyclopropane carboxylate)); fenvalerate ((RS)- a-cyano-3- phenoxybenzy1 (RS)-2-(4-chloropheny1)-3-methy1 butyrate)); lambda-cyhalothrin ((IR eis) S + (IS eis) R-a-cyano-3-phenoxybenzyl-eis-3- (2-chloro-3,3,3- trifluoropropenyl) -2,2 = dimethyl cyclopropane carboxylate) and permethrin (3-phenoxybenzyl (lRS)- c is, t r a n s - 3 - ( 2, 2 - d i c h lo r o vi n y l) - 2, 2 - dimethylcyclopropane carboxylate)), were each one evaluated as active ingredients (AI), by way of topical tests using a microsyringe of the ARNOLD type (MARCH & METCALF, 1949).
The actual flies used being laboratory-raised since 1962, collected from few counties of São Paulo State (QUEIROZ et al., 1962), and insecticide-sensitive. The flies were three days old (BULL & PRYOR, 1991), not separated according to sex (GEBARA et al., 1989), under controlled conditions of temperature (24±2 ºC), relative humidity (50% - 70%), and lightdark cycle (12:12) (FRUDDEN & WELLSO, 1968; KEIDING, 1986). There were four repetitions, each group with twenty flies. Each fly was immobilized with carbon dioxide and given a topical application of one microliter of insecticide (AI) diluted in acetone. Beyond these four groups there was the control group, which received an application of pure acetone.
The mortality counts were made 24 hours after the treatments with the products (SAITO et al., 1991). A housefly was counted as dead if it was motionless, remaining so even upon stimulation, or ifit was lying on its back (LIU & PLAPP, 1990). The dose-mortality relation was calculated by probit analysis (FINNEY, 1971).
RESULTS AND DISCUSSION
The efficacy data on the various pyrethroids, calculated and expressed in terms of LD50, LD90 and LD95, are presented in Table 1 and empirical probits are shown in Fig. 1. At the time of any of the counts the mortality of the flies in the control group was never more than 5%. For this reason there was no need to make any correction according to the formula of ABBOTT (1925).
Of the pyrethroids tested, deltamethrin, lambdacyhalothrin and alpha-cypermethrin presented the greatest degree of efficacy, followed by cypermethrin, cyfluthrin, permethrin and fenvalerate, in that order. The doses of deltamethrin, to kill the sarne number of flies, were significantly lower than in the case of the other insecticides (p<0.05). The highest values for LD50, LD90 and LD95 are associated with permethrin and fenvalerate. This latter insecticide, nevertheless its unfavorable ranking in terms of dosage, the distribution of tolerances presented the lowest 'spread'. For this insecticide the value of the relation LD90/LD50 was equal to 2.1; the sarne ratio was 2.5 for deltamethrin, and 3.7 and 4.0 respectively for lambda-cyhalothrin and alpha-cypermethrin. At LD90 the dose of deltamethrin is 2.5 hg per fly. Compared to this deltamethrin dose at LD90, that of fenvalerate was 26.6 times greater, that of lambda-cyhalothrin was 2.0 times greater, and that of alpha-cypermethrin was 2.6 times greater, similar ratios being observed at LD95. Despite deltamethrin's being a second generation pyrethroid, in the conditions of this testit was the most efficient product, with lambda-cyhalothrin far behind and alpha-cypermethrin even further back. Cyfluthrin, one of the least efficient, despite being third generation, presented an efficacy comparable to cypermethrin, which is second generation.
Calculations of the lethal doses (LD) for 50, 90 and 95% in11g of the active ingredient (AI) per insect and respective confidence intervals (CI) at 95% probability.
The insecticides tested showed themselves to be lethal to Musca domestica, but with wide variations in the quantities of the active ingredients needed to achieve the desired effects.
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