No abstract

Chemical control of leaf-cutting ants is widely used, but alternative control with toxic plant extracts is promising. Substances with insecticidal potential extracted from plants have numerous ecological advantages. This study evaluated the insecticidal and/or fungicidal potential of the plants Asclepias curassavica (tropical milkweed), Rosmarinus officinalis L. (Lamiaceae) (rosemary) and Equisetum spp. (horsetail) for control of the leaf-cutting ant Atta sexdens rubropilosa Forel, 1908 (Hymenoptera: Formicidae). Forty laboratory-reared colonies of Atta sexdens rubropilosa were used. The plants were collected, dried out in a circulating air oven for 48 hours, ground, and macerated in 96o ethanol until exhaustion. After filtration, the products were evaporated under reduced pressure to obtain the ethanolic extracts. Acceptance of the reagent, topical application of the extracts, and application of baits containing 4% of the plant extracts were tested. The results showed that all plant extracts tested negatively influenced the development of the fungus garden. Baits produced with Asclepias curassavica caused the highest mortality of the colonies within 7 days. In conclusion, the ethanolic extracts of Asclepias curassavica, Rosmarinus officinalis and Equisetum spp. exhibit insecticidal (contact and ingestion) and fungicidal activity in colonies of the leaf-cutting ant Atta sexdens rubropilosa.

Leaf-cutting ants are pests that afflict diverse crops, and are most efficiently controlled by chemical methods that are widely utilized. Other methods have been investigated aiming to efficiently control these insects while reducing the environmental impact of applying such chemical products. Therefore, an assay was conducted to evaluate the efficiency of baits, formulated homeopathically, in nests of the leaf-cutting ant Atta bisphaerica, in the field. Thirty (30) colonies were chosen and divided into 10 repetitions for each of the following treatments: control (without baits), standard (8 g/m2 of loose soil of baits based on sulfluramid 0.3%) and homeopathic (60 g/m2 of loose soil of homeopathic baits parceled into 20g/m2 doses applied on 3 consecutive days). At 24 hours after bait application on active foraging trails of colonies, evaluation of parameters was initiated: loading and return of the baits, foraging and mortality. The completed assay demonstrated that the transport of baits was greater in the standard (80%) than the homeopathic treatment (50%), and, to the contrary, the return of baits was significantly higher in the homeopathic treatment (15%) versus the conventional, where return/rejection did not occur. Colony mortality was 20% under the homeopathic treatment, differing statistically from the 80% value produced by the standard treatment. Thus, the homeopathic treatment is not demonstrated to be efficient at controlling leaf-cutting ants, suggesting new studies with different methodologies.

ResumoA lagarta-das-folhas-do-coqueiro (Brassolis sophorae) (Lepidoptera: Nymphalidae) é uma das principais pragas desta cultura, causando severos danos,. Este trabalho teve como objetivo avaliar o efeito de dois fungos entomopatogênicos no controle de B. sophorae. , causou mortalidade de 48 ± 2,45% , 84 ± 4,00% e 94 ± 2,45%, respectivamente. Este isolado tem possibilidades de ser mais bem investigado para futuras contribuições em programas de manejo da cocoicultura.Palavras-chave adicionais: Cocos nucifera; controle biológico; controle microbiano; fungos entomopatogênicos. AbstractThe coconut leaf caterpillar, Brassolis sophorae (Lepidoptera: Nymphalidae), is one of the major pests in this crop causing severe losses when control measures are not used. This work had the objective of evaluating two entomopathogenic fungi to control the insect. Different concentrations of spore suspensions of Metarhizium anisopliae (UEL50) and Isaria farinosa (URM5026) were sprayed over thirdinstar larvae in acrylic boxes and maintained at 26 o C and photophase of 12 h. Two isolates confirmed mortality B. sophorae The isolate M. anisopliae at concentrations 10 6 , 10 7 , and 10 8 spores mL -1 , caused mortality 12.5 ± 2.5%, 28.8 ± 5.5%, and 42.5 ± 5.3% larval mortality, respectively. Isaria farinosa at 10 6 , 10 7 , and 10 8 spores mL -1 caused, respectively, mortality of 48.0 ± 2.45%, 84.0 ± 4.0%, and 94.0 ± 2.4%. This isolate is likely to be further investigated in future contributions to management programs of coconut growth.