ABSTRACT
The parasitic mite Acarophenax lacunatus (Cross & Krantz) is a potentially important biocontrol agent of stored grain insect pests, but its presence in insect mass rearing is undesirable. This study was carried out to evaluate the susceptibility of A. lacunatus to sulfur. The experimental units were petri dishes containing 30 g of whole wheat grains infested with 30 adults of Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae). The treatments consisted of pulverizing the wheat grains with sulfur, at 0, 0.15, 0.3, 0.6, 0.9 and 1.2 mg a.i./g, in five replicates. Three inoculations of A. lacunatus were carried out in each petri dish at five, ten and fifteen days after infestation with R. dominica. The petri dishes were stored for 60 days at 30 +/- 1 degree Celsius, 60 +/- 5% R.H. and 24h scotophase. The parasitic mite was susceptible to all sulfur doses used in the test. The number of eggs of R. dominica parasitized by A. lacunatus showed a decreasing trend with the increase in doses of sulfur, as did the number of physogastric females of the mite. The mite showed a negative correlation of their instantaneous rate of increase with sulfur dose. No mites developed at sulfur doses higher than 0.3 mg a.i./g. The susceptibility of A. lacunatus to sulfur is an important aspect to consider in the control of this parasitic mite in colonies of R. dominica. In addition, this control method has low cost and is easy to use.
Subject(s)
Mites/drug effects , Sulfur/pharmacology , AnimalsABSTRACT
O ácaro parasita Acarophenax lacunatus (Cross & Krantz) pode ser um importante agente de controle biológico de insetos-praga de grãos armazenados, mas sua presença em criações massais desses organismos é prejudicial. O objetivo deste trabalho foi avaliar a susceptibilidade desse parasita ao enxofre. As unidades experimentais consistiram de placas de Petri, contendo 30 g de grãos de trigo infestados com 30 adultos de Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae). Os tratamentos consistiram no polvilhamento dos grãos de trigo com enxofre, nas doses correspondentes a 0; 0,15; 0,30; 0,60; 0,90 e 1,20 mg i.a./g, em cinco repetições. Foram realizadas três inoculações de A. lacunatus por placa de Petri, cinco, dez e quinze dias depois da infestação de R. dominica. Em seguida, as placas foram armazenadas por 60 dias a 30 ± 1°C, 60 ± 5 por cento UR e escotofase de 24h. O ácaro parasita mostrou-se susceptível a todas doses de enxofre avaliadas. O número de ovos de R. dominica parasitados por A. lacunatus apresentou uma tendência decrescentecom o aumento das doses do acaricida, assim como o número de fêmeas fisogástricas do ácaro. A taxa instantânea de crescimento de A. lacunatus se reduziu com o aumento das doses de enxofre, não ocorrendo o desenvolvimento do parasita nas doses superiores a 0,30 mg i.a./g. A suscetibilidade de A. lacunatus ao enxofre é importante, uma vez que não existe na literatura uma alternativa de controle desse parasita sobre criações de insetos. Além disso, esse método de controle apresenta baixo custo e é de fácil utilização.
The parasitic mite Acarophenax lacunatus (Cross & Krantz) is a potentially important biocontrol agent of stored grain insect pests, but its presence in insect mass rearing is undesirable. This study was carried out to evaluate the susceptibility of A. lacunatus to sulfur. The experimental units were petri dishes containing 30 g of whole wheat grains infested with 30 adults of Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae). The treatments consisted of pulverizing the wheat grains with sulfur, at 0, 0.15, 0.3, 0.6, 0.9 and 1.2 mg a.i./g, in five replicates. Three inoculations of A. lacunatus were carried out in each petri dish at five, ten and fifteen days after infestation with R. dominica. The petri dishes were stored for 60 days at 30 ± 1°C, 60 ± 5 percent R.H. and 24h scotophase. The parasitic mite was susceptible to all sulfur doses used in the test. The number of eggs of R. dominica parasitized by A. lacunatus showed a decreasing trend with the increase in doses of sulfur, as did the number of physogastric females of the mite. The mite showed a negative correlation of their instantaneous rate of increase with sulfur dose. No mites developed at sulfur doses higher than 0.3 mg a.i./g. The susceptibility of A. lacunatus to sulfur is an important aspect to consider in the control of this parasitic mite in colonies of R. dominica. In addition, this control method has low cost and is easy to use.
