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1.
Bull Environ Contam Toxicol ; 90(1): 39-45, 2013 Jan.
Article in English | MEDLINE | ID: mdl-23132367

ABSTRACT

Podisus distinctus (Heteroptera: Pentatomidae) is an important predator used in biological control of eucalypt defoliating caterpillars, exposed the insecticides. Lower doses of permethrin not affect the values of generation time (T), time necessary to double the population in number of individuals (DT) and intrinsic rate of population increase (r ( m )). Moreover, females of P. distinctus derived from nymphs treated with lower doses of permethrin were more fertile, triggering the effect hormetic in net reproductive rates (Ro). Results showed that low permethrin doses can be used alongside the predatory stinkbug in Integrated Pest Management programs.


Subject(s)
Environmental Exposure , Heteroptera/physiology , Insecticides/pharmacology , Permethrin/pharmacology , Animals , Female , Fertility , Life Expectancy , Male , Nymph/physiology , Ovum/physiology
2.
Bull Environ Contam Toxicol ; 87(6): 608-14, 2011 Dec.
Article in English | MEDLINE | ID: mdl-21947501

ABSTRACT

Stressors can affect reproduction and longevity by impacting endocrine and immune systems but they may increase life span and stimulate reproduction. The effects of sublethal doses of permethrin topically applied on third instar nymphs of Podisus distinctus (Heteroptera: Pentatomidae) was evaluated. The weight of females survival of nymph and adults, number of eggs and nymphs/females of P. distinctus were higher when exposed to lower doses of permethrin. On the other hand, the exposition to the 0.131, 1.315 and 13.15 ppb showed positive effects on the oviposition periods, number of egg masses and longevity of P. distinctus females.


Subject(s)
Dose-Response Relationship, Drug , Heteroptera/drug effects , Hormesis , Insecticides/toxicity , Permethrin/toxicity , Animals , Environmental Exposure , Female , Insect Control , Longevity/drug effects , Nymph/drug effects , Oviposition/drug effects , Ovum/drug effects , Regression Analysis , Stress, Physiological , Toxicity Tests, Subacute/methods
3.
Neotrop. entomol ; 31(3): 463-467, July-Sept. 2002. graf, tab
Article in Portuguese | LILACS | ID: lil-514169

ABSTRACT

Chemical control has been preferentially used to suppress pests by farmers mainly due to low price of the products and immediate action on target organisms. However, wide action range of the compounds, undesirable effects on non target organisms and the contamination of the environment areamong the disadvantages of this method of control. This study evaluated the action of the insecticides chlorpyrifos, disulfoton, ethion and methyl-parathion, normally used to control the coffee leaf-miner, Leucoptera coffeella (Guérin-Mèneville), on the predaceous mite Iphiseiodes zuluagai Denmark & Muma,a control agent of the phytophagous mites Oligonychus ilicis (McGregor) and Brevipalpus phoenicis (Geijskes) in coffee plantation. Discriminatory concentrations (LC99), established on the 3rd instar of L. coffeella, by means of the method of dry insecticide residues impregnated in filter paper, were used toverify the selectivity of the insecticides on the predaceous mite. The insecticide chlorpyrifos caused 100% of mortality in I. zuluagai. Ethion and methyl-parathion showed mortality of 34% and 19%, respectively. Disulfoton presented the highest selectivity for the mite, with no lethal action on the predator. The different effects found on the insecticides’ action show that it is possible to use the selective insecticidesin coffee plantation to preserve populations of I. zuluagai, thus favouring the biological control on phytophagous mite.


O controle químico apresenta vantagens como economicidade e rapidez de ação, e tem sido preferencialmente usado no controle de pragas pelos agricultores. Em contrapartida, entre as desvantagensdestaca-se o largo espectro de ação dos compostos, que atingem espécies não-alvos, como inimigos naturais, além de contaminarem o meio ambiente. O presente trabalho avaliou a ação dos inseticidas clorpirifós, dissulfotom, etiom e paratiom-metílico, normalmente usados para controlar o bicho-mineirodo-cafeeiro Leucoptera coffeella (Guérin-Mèneville), sobre o ácaro predador Iphiseiodes zuluagai Denmark & Muma, agente de controle dos ácaros fitófagos Oligonychus ilicis (McGregor) e Brevipalpus phoenicis (Geijskes) em agroecossistema cafeeiro. Para verificar o efeito seletivo dos compostos sobre oácaro predador, concentrações discriminatórias (CLs99) dos quatros inseticidas foram determinadas parao 3o instar larval de L. coffeella, através do método de bioensaios de concentração-mortalidade em papelfiltro,impregnado com resíduo seco de inseticidas. O clorpirifós causou 100% de mortalidade dos ácaros testados; o etiom e o paratiom-metílico causaram 34% e 19% de mortalidade, respectivamente. Dissulfotom foi o mais seletivo em favor do predador, não mostrando ação letal. O efeito diferenciado dos inseticidas foi desta forma verificado, e tal informação possibilita a utilização dos inseticidas seletivos no agroecossistema cafeeiro, preservando populações de I. zuluagai e favorecendo o controle biológico exercido pelo ácaro predador.

4.
Neotrop. entomol ; 30(1): 139-143, Mar. 2001. tab
Article in Portuguese | LILACS | ID: lil-514339

ABSTRACT

Estudos de toxicidade relativa dos inseticidas organo-fosforados dissulfotom, etiom, paratiom-metílico e clorpirifós às vespas predadoras Brachygastra lecheguana Latreille, Polybia paulista Ihering e Protopolybia exigua Saussure e sua presa, o bicho-mineiro do cafeeiro Leucoptera coffeella (Guérin-Mèneville), foram realizados em condições de laboratório. As concentrações que mataram 99 por cento dos indivíduos de L. coffeella foram: 0,08; 83,95; 0,43; 0,07 mg i.a/cm² para dissulfotom, etiom, paratiom-metílico e clorpirifós, respectivamente. Essas concentrações foram usadas para avaliar a seletividade destes compostos em ensaio com papel de filtro impregnado com resíduo seco dos inseticidas. Paratiom-metílico e clorpirifós foram altamente tóxicos a essas espécies de vespas predadoras, enquanto disulfotom e etiom mostraram-se seletivos em favor delas.


Studies of relative toxicity of the organophosphate insecticides disulfoton, ethion, methyl-parathion e chlorpyrifos to the predatory wasps Brachygastra lecheguana Latreille, Polybia paulista Ihering e Protopolybia exigua Saussure and their prey, the coffee leaf-miner Leucoptera coffeella (Guérin-Mèneville), were carried out in laboratory. The concentrations which killed 99 percent of individuals of L. coffeella were: 0.08; 83.95; 0.43; 0.07 mg i.a/cm² of disulfoton, ethion, methyl-parathion and chlorpyrifos, respectively. These concentrations were used to assess the selectivity of insecticides in impregnated paper filter assays. Methyl-parathion and chlorpyrifos were highly toxic to these wasp species, while disulfoton and ethion were selective in their favour.

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