Suscetibilidade de operárias e larvas de abelhas sociais em relação à ricinina

Abstract

ABSTRACT. Susceptibility of workers and larvae of social bees in relation to ricinine. Many substances of vegetal origin can be toxic or present an insecticidal potential. With the aim of decreasing the environment pollution problem, a few studies are trying to substitute synthetic insecticides with botanical ones. Ricinus communis (Euphorbiaceae) presents a great variety of substances, being the ricinine the main toxic component. Considering that bees are useful as pollinator agents of plants, this study evaluates toxicity potential of ricinine on workers and larvae of Apis mellifera (Linnaeus, 1758) (Hymenoptera, Apidae) and Scaptotrigona postica (Latreille, 1907) (Hymenoptera, Meliponini). In order to determine ricinine toxicity, ingestion tests were carried out with isolated workers bees that received ricinine on its diet. Furthermore, for topic tests, solutions of ricinine in methanol were applied on pronotum of worker bees with an "Agla" brand micrometer syringe outfit. For larvae of bees, ingestion tests were used and mortality rates were calculated. According to the results, it was detected a significant toxic activity (p < 0.0001) of ricinine on the workers of the two bee species at concentrations of 0.1% in the ingestion tests and 0.2% in the topic tests. For all concentrations (0.25%, 0.5% and 1%), a high percentage of larvae bees was negatively affected by ricinine on the first days of life. KEYWORDS. Ricinus communis, Apis mellifera, Scaptotrigona postica, topic test, ingestion test.RESUMO. Muitas substâncias de origem vegetal podem ser tóxicas ou apresentar potencial inseticida. Com o objetivo de diminuir a problemática da poluição ambiental alguns estudos vêm tentando substituir os inseticidas artificiais pelos inseticidas botânicos. Ricinus communis (Euphorbiaceae) apresenta uma grande variedade de substâncias sendo a ricinina o principal componente tóxico. Considerando que as abelhas são insetos benéficos por atuarem como agentes polinizadores das plantas, este estudo teve por objetivo avaliar o efeito tóxico da ricinina para as operárias e larvas de Apis mellifera (Linnaeus, 1758) (Hymenoptera, Apidae) e Scaptotrigona postica (Latreille, 1907) (Hymenoptera, Meliponini). Para isso, foram realizados testes de ingestão em operárias confinadas recebendo ricinina incorporada à dieta e testes de aplicação tópica com a substância solubilizada em metanol e aplicada no pronoto das abelhas com auxílio de uma microseringa. Para as larvas foram realizados testes de ingestão e calculada sua taxa de mortalidade. Os resultados mostram atividade tóxica significativa (p < 0.0001) da ricinina nas abelhas adultas das duas espécies para a concentração 0,1% nos testes de ingestão e 0,2% nos testes de aplicação tópica. Outrossim, uma elevada porcentagem de larvas foi afetada negativamente pela ricinina logo nos primeiros dias de vida para todas as concentrações testadas (0,25%, 0,5% e 1%). PALAVRAS-CHAVE. Ricinus communis, Apis mellifera, Scaptotrigona postica, teste de aplicação tópica, teste de ingestão.Apesar d...

Bioactivity of plant extracts on the larval and pupal stages of Aedes aegypti (Diptera, Culicidea)

“…Hebling 19 , assessed the bioactivity of R. communis on ants and demonstrated its effi cacy in combating Hymenopteran, Burg and Mayer 20 tested the effect of R. communis seed oil on aphids and different species of lice, describing how promising this oil was for the control of these insects. In a study of the effects of aqueous extract from the green fruits of castor on the larvae and pupae of Spodoptera frugiperda, Santiago 21 observed a reduction in the lifetime of these stages, and Rother 22 identifi ed toxic effects of leaf extracts of R. communis on Apis mellifera worker larvae.…”

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“…Integrated pest management programs determine which insecticides are compatible with a biological control agent and to identify the possible effect on them [32]. Biopesticide studies are frequent in an attempt to reduce the ecological impact that chemicals are causing on the environment [33].…”

Observation of Trigona recursa Smith (Hymenoptera: Apidae) Feeding on Crotalaria micans Link (Fabaceae: Faboideae) in a Brazilian Savanna Fragment

“…For example, nicotine at high levels can reduce bees' fitness, although at lower, naturally occurring levels, there are no apparently detrimental effects and the substance can even be beneficial (Kohler et al, 2012). Other toxins produced in flowers have also been shown to reduce the life span of bees in laboratory settings, depending on the dose (Santoro et al, 2004;Rother et al,2009;Rocha-Neto et al,2011). Rother et al (2009) tested the effects of ricinine (a toxic compound of Ricinus communis -Euphorbiaceae) on bees of the species Apis mellifera and Scaptotrigona postica and observed that A. mellifera had a high mortality within 72 hours for two of three concentrations tested (0.05 and 0.1%), while S. postica presented high mortality rate only after 14 days.…”

“…Other toxins produced in flowers have also been shown to reduce the life span of bees in laboratory settings, depending on the dose (Santoro et al, 2004;Rother et al,2009;Rocha-Neto et al,2011). Rother et al (2009) tested the effects of ricinine (a toxic compound of Ricinus communis -Euphorbiaceae) on bees of the species Apis mellifera and Scaptotrigona postica and observed that A. mellifera had a high mortality within 72 hours for two of three concentrations tested (0.05 and 0.1%), while S. postica presented high mortality rate only after 14 days. Santoro et al (2004) demonstrated that A. mellifera was also susceptible to tannins of Stryphnodendron spp.…”