RESUMO Com o objetivo de criar alternativas no controle químico da formiga-vermelha-de-monte, Acromyrmex heyeri (Forel, 1899) (Hymenoptera: Formicidae, Attini) foram instalados quatro ensaios com formicidas em pó, em Santa Maria, estado do Rio Grande do Sul, entre 1996 e 1998. Avaliaram-se em formigueiros médios (+/- 45cm de diâmetro) ou em formigueiros grandes (diâmetro superior a 60cm), doses de Deltametrina (2g i.a./kg), de Acefato (750g i.a./kg), de Clorpirifós (20g i.a./kg e 50g i.a./kg), de Fentiom (50g i.a./kg) e de Diazinom (10g i.a./kg). Deltametrina e Acefato, partindo-se de 5g/ninho e, Clorpirifós (50g i.a./kg) e Fentiom, partindo-se de 10g/ninho, foram eficazes no controle de formigueiros médios. Clorpirifós (50 g i.a./kg) e Diazinom, com base em 10g/ninho e, Clorpirifós (20g i.a./kg), partindo-se de 30g/ninho controlaram eficientemente os formigueiros grandes dessa espécie.

ABSTRACT Four experiments were carried out to evaluate the efficiency of some powdered formicides on the control of the red leaf cutting ant, Acromyrmex heyeri (Forel, 1899) (Hymenoptera: Formicidae, Attini) in Santa Maria county from 1996 until 1998. Powdered formicides containing Deltamethrin at 2g a. i./kg, Acephate at 750g a. i./kg, Chlorpyrifos at 20g a. i./kg and 50g a. i./kg, Fenthion at 50g a. i./kg and Diazinon at 10g a. i./kg were evaluated on middle nests (+/- 45cm of diameter) and big nests (diameter more than 60cm). Deltamethrin and Acephate, at 5g/nest and, Chlorpyrifos (50g a. i./kg) and Fenthion, at 10g/nest, were efficient to control middle nests. Chlorpyrifos (50g a. i./kg) and Diazinon, at 10g/nest and, Chlorpyrifos (20g a. i./kg) at 30g/nest, were efficient to control the big nests of this leaf cutting ant.

RESUMO Com o objetivo de buscar alternativas no controle químico da formiga-preta-pastadeira, Acromyrmex crassispinus (Forel, 1909) (Hymenoptera: Formicidae), foram instalados quatro ensaios com formicidas em pó, em Santa Maria, Estado do Rio Grande do Sul, entre 1996 e 1998. Avaliaram-se, em formigueiros grandes (80cm ou mais de diâmetro), doses de Fentiom (50g i.a./kg), de Imidacloprid (4g i.a./kg), de Betaciflutrina (2g i.a./kg), de Clorpirifós (20g i.a./kg e 50g i.a./kg), de Deltametrina (2g i.a./kg), de Acefato (750g i.a./kg) e de Diazinom (10g i.a./kg). Acima de 30g do produto comercial, foram eficazes no controle de formigueiros grandes da formiga-preta- pastadeira, as formulações em pó de Fentiom (50g i.a./kg), de Clorpirifós (20g i.a./kg e 50g i.a./kg) e de Diazinom (10g i.a./kg). Acefato (750g i.a./kg) comportou-se como eficiente com base em 3g/ninho e Deltametrina (2g i.a./kg), com 5 g/ninho em época de estiagem e, 30g/ninho, em período chuvoso.

ABSTRACT Four experiments were carried out to evaluate the efficiency of some powdered formicides on the control of the black leaf cutting ant, Acromyrmex crassispinus (Forel, 1909) (Hymenoptera: Formicidae), in Santa Maria county, from 1996 until 1998. Powdered formicides containing Fenthion at 50g a. i./kg, Imidacloprid at 4g a. i./kg, Betacyfluthrin at 2g a. i./kg, Chlorpyrifos at 20g a. i./kg and at 50g a. i./kg, Deltamethrin at 2g a. i./kg, Acephate at 750g a. i./kg and Diazinon at 10g a. i./kg were evaluated on big nests (>80cm of diameter). The big nests of this ant were efficiently controlled with 30g/nest of the commercial formulations of Fenthion, Diazinon and Chlorpyrifos (20g a. i./kg and 50g a. i./kg); with 3g/nest of the formulation of Acephate; with 5g/nest in dry season and 30g/nest in wet season of the powdered formulation of Deltamethrin.