Tropical ants commonly exhibit a hyper-dispersed pattern of spatial distribution of nests. In polydomous species, nests may be satellites, that is, secondary structures of the main nest, where the queen is found. In order to evaluate whether the ant Ectatomma opaciventre Roger (Formicidae: Ectatomminae) uses the strategy of building polydomous nests, the spatial distribution pattern of 33 nests in a 1,800 m 2 degraded area located in Rio Claro, SP, Brazil, were investigated using the nearest neighbor method. To complement the results of this investigation, the cuticular chemical profile of eight colonies was analyzed using Fourier transform infrared photoacoustic spectrosco-py (FTIR-PAS). The nests of E. opaciventre presented a hyper-dispersed or regular distribution, which is the most common in ants. The analysis of the cuticular hydrocarbons apparently con-firmed the hypothesis that this species is polydomous, since the chemical profiles of all studied colonies with nests at different sites were very similar to the chemical signature of the single found queen and were also different from those of colonies used as control.

Apiculture in Brazil is quite profitable and has great potential for expansion because of the favorable climate and abundancy of plant diversity. However, the occurrence of pests, diseases, and parasites hinders the growth and profitability of beekeeping. In the interior of the state of São Paulo, apiaries are attacked by ants, especially the species Camponotus atriceps (Smith) (Hymenoptera: Formicidae), which use the substances produced by Apis mellifera scutellata (Lepeletier) (Hymenoptera: Apidae), like honey, wax, pollen, and offspring as a source of nourishment for the adult and immature ants, and kill or expel the adult bees during the invasion. This study aimed to understand the invasion of C. atriceps in hives of A. m. scutellata. The individuals were classified into castes and subcastes according to morphometric analyses, and their cuticular chemical compounds were identified using Photoacoustic Fourier transform infrared spectroscopy (FTIR-PAS). The morphometric analyses were able to classify the individuals into reproductive castes (queen and gynes), workers (minor and small ants), and the soldier subcaste (medium and major ants). Identification of cuticular hydrocarbons of these individuals revealed that the eight beehives were invaded by only three colonies of C. atriceps; one of the colonies invaded only one beehive, and the other two colonies underwent a process called sociotomy and were responsible for the invasion of the other seven beehives. The lack of preventive measures and the nocturnal behavior of the ants favored the invasion and attack on the bees.

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Abstract. This work evaluated the short-range mortality of workers of Ectatomma brunneum Smith when exposed to ant baits in laboratory, in order to verify if the attractiveness of this non-target species by ant baits intended to be used in the control of leaf-cutting (target) ants might be harmful to the population studied. Workers were exposed in laboratory for 48 hours to ant baits used in pastures to control the leaf-cutting ants Atta capiguara Gonçalves (Formicidae: Attini) and Atta bisphaerica Forel (Formicidae: Attini), the major species that cause damage to pastures. The following formulations of granular bait ant-killer active ingredients sulfluramid 0.3%, fipronil 0.003% and chlorpyrifos 0.45% were used. The experiment outline was composed by groups of 30 workers exposed to 10g of moistened ant baits, using three repetitions. Daily follow-up on mortality was performed for 20 days, recording dead and intoxicated workers. The control group received only 10g of moistened citric pulp. From the results achieved, survival curves as a function of observation time were plotted using the Kaplan-Meier method and compared applying the Logrank test (nonparametric) at 5% significance level. The results revealed that the three active ingredients tested were toxic and the population reduced 35.56% in the treatment with chlorpyrifos, 31.11% with sulfluramid and 30% with fipronil.Keywords: Chlorpiryfos; Fipronil; Poneromorphs; Sulfluramid; Toxicity. Exposição de Operárias de Ectatomma brunneum Smith (Hymenoptera: Formicidae: Ectatomminae) a Iscas Formicidas Contendo Diferentes Ingredientes Ativos em Condições de LaboratórioResumo. Este trabalho avaliou a mortalidade a curto prazo de operárias de Ectatomma brunneum Smith expostas a iscas formicidas em laboratório, a fim de verificar se a capacidade de atração desta espécie não-alvo a formicidas destinadas ao controle de formigas cortadeiras (alvo) pode ser prejudicial para a população estudada. As operárias foram expostas em laboratório por 48 horas a iscas formicidas utilizadas em pastagens para controlar as formigas cortadeiras Atta capiguara Gonçalves (Formicidae: Attini) e Atta bisphaerica Forel (Formicidae: Attini), as principais espécies que causam danos às pastagens. Foram utilizados os seguintes ingredientes ativos: sulfluramida 0,3%, fipronil 0,003% e clorpirifos 0,45%. O experimento foi composto por grupos de 30 operárias expostas a 10g de formicidas, usando três repetições. Foi realizado o acompanhamento diário da mortalidade durante 20 dias, registrando-se o número de operárias mortas e intoxicadas. O grupo controle recebeu apenas 10g de polpa cítrica umedecida. A partir de resultados obtidos, as curvas de sobrevivência em função do tempo de observação foram plotadas usando o método de Kaplan-Meier, e comparadas com aplicação do Logrank test (teste não-paramétrico) em nível de significância de 5%. Os resultados revelaram que os três ingredientes ativos testados foram tóxicos e a população reduzida em 35.56% no tratamento com clorpirifós, 31,11% com sulflurami...

Ectatomma opaciventre Roger é uma espécie de formiga cujas presas incluem espécies de moscas, no entanto, não se conhecia os comportamentos empregados pelas operárias em sua predação. Neste trabalho, foi elaborado um etograma da predação sobre larvas e adultos da mosca Hermetia illucens L. por operárias de E. opaciventre. Foram coletados indivíduos de três ninhos de E. opaciventre, sendo posteriormente transferidos para ninhos artificiais. Para cada um deles, foram oferecidas larvas e adultos vivos de moscas. A partir das observações, em um contexto de predação, os comportamentos observados que apresentavam funções semelhantes foram agrupados em categorias, com quatro delas tendo sido observados na predação sobre larvas e todas as oito na predação sobre adultos. As larvas não chegaram a ser predadas de fato (os comportamentos agressivos, realizados pelas formigas, aparentam estar relacionados à defesa do ninho), porém as moscas adultas serviram realmente como alimento.