Resistance of stored-product insects to phosphine

Abstract

-The objectives of this work were to assess phosphine resistance in insect populations (Tribolium castaneum, Rhyzopertha dominica, Sitophilus zeamais and Oryzaephilus surinamensis) from different regions of Brazil and to verify if the prevailing mechanism of phosphine resistance in these populations involves reduced respiration rates. Sixteen populations of T. castaneum, 15 of R. dominica, 27 of S. zeamais and eight of O. surinamensis were collected from 36 locations over seven Brazilian states. Each population was tested for resistance to phosphine, based on the response of adults to discriminating concentrations, according to FAO standard method. For each insect species, the production of carbon dioxide of the most resistant and of the most susceptible populations was inversely related to their phosphine resistance. The screening tests identified possible phosphine resistant populations. R. dominica and O. surinamensis were less susceptible to phosphine than the other two species. The populations with lower respiration rate showed a lower mortality at discriminating concentration, possibly related to a phosphine resistance mechanism. Phosphine resistance occurs in stored-product insects, in different regions of Brazil, and the resistance mechanism involves reduced respiration rate.Index terms: Oryzaephilus surinamensis, Rhyzopertha dominica, Sitophilus zeamais, Tribolium castaneum, fumigant resistance, respiration rate. Resistência de insetos de produtos armazenados à fosfinaResumo -Os objetivos deste trabalho foram avaliar a resistência à fosfina, em populações de insetos (Tribolium castaneum, Rhyzopertha dominica, Sitophilus zeamais e Oryzaephilus surinamensis), de diferentes regiões do Brasil, e verificar se o mecanismo predominante de resistência à fosfina, nessas populações, envolve a redução das taxas respiratórias. Dezesseis populações de T. castaneum, 15 de R. dominica, 27 de S. zeamais e oito de O. surinamensis foram coletadas em 36 locais de sete estados brasileiros. Cada população foi testada quanto à resistência à fosfina, com base na resposta dos adultos à concentração discriminante, de acordo com o método padrão da FAO. Para cada espécie de insetos, as produções de dióxido de carbono da população mais resistente e a da mais suscetível foram inversamente relacionadas à resistência à fosfina. Os testes de detecção identificaram possíveis populações resistentes à fosfina. R. dominica e O. surinamensis foram menos suscetíveis à fosfina do que as outras duas espécies. As populações com menor taxa respiratória apresentaram menor mortalidade à concentração discriminante, o que está possivelmente relacionado ao mecanismo de resistência à fosfina. A resistência à fosfina ocorre em insetos de produtos armazenados, em diferentes regiões do Brasil, e o mecanismo de resistência envolve a redução da taxa respiratória.Termos para indexação: Oryzaephilus surinamensis, Rhyzopertha dominica, Sitophilus zeamais, Tribolium castaneum, resistência a fumigante, taxa respiratória.

Phosphine‐induced walking response of the lesser grain borer (Rhyzopertha dominica)

“…Here, three populations of the lesser grain borer Rhyzopertha dominica (Coleoptera: Bostrichidae), one of the main worldwide pests of stored cereals, were exposed to sublethal concentrations of phosphine, and their walking behaviour was recorded. These populations differ in their life history traits, particularly in developmental and population growth rates, which had been recognised earlier and associated with phosphine resistance and its associated physiological cost 25, 28, 29. The present hypothesis was that exposure to phosphine would lead to a reduction in walking activity as a protective behaviour.…”

FUMIGATION TOXICITY OF ESSENTIAL OILS AGAINST Rhyzopertha dominica (F.) IN STORED MAIZE GRAIN

“…This insect is mainly controlled using synthetic insecticides (organophosphates or pyrethroids) and fumigation, phosphine being remarkable as the main fumigant used (LORINI;GALLEY, 1999;GONÇALVES et al, 2007). However, studies revealed phosphine resistance in Brazilian R. dominica populations (ATHIÉ et al, 2001;PIMENTEL et al, 2008), which could render the use of these products unviable if alternative methods are not implemented.…”

Toxicity of Aromatic Plants and Their Constituents Against Coleopteran Stored Products Insect Pests

“…Price (1984) suggested that the mechanism is the reduced uptake of phosphine and it is likely to be accepted because respiration is a good factor observing a physiological response of an insect to the environmental changes (Chaudhry et al, 2004). Pimentel et al (2008) also reported that phosphine resistance in four coleopteran insect pests (T. castaneum, R. dominica, S. zeamais, and O. surinamensis) collected from 36 locations over seven Brazilian states is related to the reduced production of carbon dioxide. Comparing with the respiration rates between the most resistant and the most susceptible populations to the fumigant, the carbon dioxide production of the former is significantly (P < 0.05) lower than that of the latter.…”