Camouflaged Nests of Mischocyttarus mirificus (Hymenoptera, Vespidae).

Social wasps present various architectural patterns for their nests, which may differ in shape, size, color, and material used in construction. The distribution pattern of comb cells presented by Mischocyttarus mirificus (Zikán, 1935) is vertical with a single cell of width, resulting in a filiform shape that camouflages in the middle of the substrate. There are few studies regarding this architectural pattern for social wasps and their role in camouflage, and this study aims to detail the nesting habits of this species. In total, 40 colonies were analyzed in their natural habitat and six were dissected in the laboratory. Aspects about the construction of the nests and nesting environment have been described. A test was carried out with nest photographs, to quantify their camouflage percentage within the nesting substrate. The colonies were found mainly in riparian forests where there were elements in the environment that favored their camouflage. According to the nest photograph analysis, their camouflage levels can vary according to the position from which the photograph is taken. It is evident that M. mirificus founders select sites where they can camouflage their colonies, and this gives them advantages in exploring a new environment.

Acaricidal activity of the essential oils from Eucalyptus citriodora and Cymbopogon nardus on larvae of Amblyomma cajennense (Acari: Ixodidae) and Anocentor nitens (Acari: Ixodidae).

The present study evaluated the acaricidal activity of essential oils from Eucalyptus citriodora and Cymbopogon nardus on non-engorged larvae of Amblyomma cajennense and Anocentor nitens. In order to carry out the study, six groups were formed, each concentration being a treatment (6.25%, 12.5%, 25%, and 50%, respectively) and also with the creation of a control group (distilled water) and a positive control (Deltametrine). For each treatment, approximately 100 larvae of these ticks were placed onto filter papers (2 x 2 cm) impregnated with the concentrations used to test. Next, the envelopes were closed bearing inside the filter paper with measurements of 6 x 6 cm. For each group, six repetitions were performed, and after 24 h live and dead larvae were counted. This procedure was carried out for two essential oils on the two species of ticks. For A. cajennense, the acaricide efficacy of E. citriodora oil was of 10.8%, 35.3%, 34.5%, and 53.1%, whereas the efficacy of C. nardus was of 0.0%, 0.0%, 0.0%, and 61.1% at concentrations of 6.25%, 12.5%, 25.0%, and 50.0%, respectively. In relation to A. nitens, the acaricide efficacy of E. citriodora oil was of 20.1%, 84.5%, 89.2%, and 100.0%, whereas the efficacy of C. nardus was of 0.0%, 90.8%, 100.0%, and 100.0% at concentrations of 6.25%, 12.5%, 25.0%, and 50.0%, respectively. The results indicate that the essential oils tested showed a promising acaricidal activity mainly on A. nitens larvae.