ABSTRACT
Tityus serrulatus Lutz & Mello (Scorpiones: Buthidae) is a scorpion endemic to Brazil adapted to synanthropic life, colonising and proliferating in the most populous urban areas in the country. Here, we evaluated its activity pattern in an urban cemetery in the municipality of Americana, state of São Paulo, Brazil. Additionally, we tested the effects of species reproduction and climatic seasons on the activity pattern. The Saudade Municipal Cemetery was sampled between 17:00 and 22:00 h during 455 nights from April 2006 to December 2013. The circular mean and the peak of activity were quantified for the total number of specimens, and for specimens with and without broods. Activity patterns were inferred using a rosette diagram. Circular analysis of variance was used to investigate if activity patterns changed across climatic seasons (wet and dry seasons). A total of 25,969 records (467 specimens with broods) were obtained in the field. The circular mean varied between 19:44 and 19:48 h, and the peak of activity occurred between 18:00 and 20:00 h for all groups. Peaks of activity differed from that recorded under laboratory conditions (between 21:00 and 23:00 h). Activity patterns did not differ for specimens with broods, suggesting that the reproductive condition does not alter the species activity pattern. The activity pattern differed between wet and dry seasons for all specimens and specimens without broods, but differences were small and probably biologically irrelevant, probably because the species tolerates a wide variation in abiotic conditions. Deepening the knowledge of the behaviour activity of T. serrulatus can have practical applications for health surveillance agencies, aiming to increase the effectiveness of scorpion control in urban areas.
Tityus serrulatus Lutz & Mello (Scorpiones: Buthidae) é um escorpião endêmico do Brasil adaptado à vida sinantrópica, colonizando e proliferando nas áreas urbanas mais populosas do país. Aqui avaliamos seu padrão de atividade em um cemitério urbano no município de Americana, estado de São Paulo, Brasil. Adicionalmente, testamos os efeitos da reprodução da espécie e das estações climáticas sobre o padrão de atividade. O Cemitério Municipal da Saudade foi amostrado entre 17:00 h e 22:00 h durante 455 noites, de abril de 2006 a dezembro de 2013. A média circular e o pico de atividade foram quantificados para o número total de espécimes, espécimes com e sem ninhadas. Os padrões de atividade foram inferidos usando um diagrama de roseta. Análises de variância circular foram utilizadas para investigar se os padrões de atividade mudavam com as estações climáticas (estações chuvosa e seca). Um total de 25.969 registros (467 espécimes com ninhadas) foram obtidos em campo. A média circular variou entre 19:44 h e 19:48 h e o pico de atividade ocorreu entre 18:00 h e 20:00 h para todos os grupos. Os picos de atividade diferiram dos registados em condições de laboratório (entre 21:00 h e 23:00 h). Os padrões de atividade não diferiram para os espécimes com ninhadas, sugerindo que a condição reprodutiva não altera o padrão de atividade da espécie. O padrão de atividade diferiu entre as estações chuvosa e seca para todos os espécimes e os espécimes sem ninhadas, mas as diferenças foram pequenas e provavelmente biologicamente irrelevantes, provavelmente porque a espécie tolera uma grande variação nas condições abióticas. Preencher lacunas sobre o comportamento de T. serrulatus pode ter aplicações práticas para órgãos de vigilância sanitária, visando aumentar a eficácia do controle de escorpiões em áreas urbanas.
ABSTRACT
The objectives of the study are to understand how naïve beetles disperse after emerging as an adult in a homogeneous resource patch. We compared the movement of adult male and female Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) using a laboratory and a field-collected strain during the first 2 d after their emergence from the wheat kernel in which they developed. We first asked if naïve male and female beetles show any innate orientation pattern. Males showed an upward orientation bias during the first day, but not in the second, whereas females had a random pattern of orientation in both days of evaluation. No significant differences were observed between the two strains. Given that males release an aggregation pheromone, we next asked if the upward movement of males improved their ability to be found by a naïve female. The presence of a male, whether above or below a newly emerged female, changed the females' movement direction from random to bias towards the male. In contrast, free-walking males exhibited the same upward movement bias on the first day regardless of the position of the caged male. Only on the second day did male movement change to the opposite direction of the caged male. Here, we report differences between males and females' movement orientation strategies and their response to males producing aggregation pheromone within the grain mass. Our data may improve our understanding of pheromone attraction and help us to develop better monitoring and control tools.