ABSTRACT
Trigona spinipes Fabricius (Apidae: Meliponini), is a common stingless bee widely seen in urban and rural areas in Brazil, popularly known as irapuá, arapuá or bee-dog. Although these bees are considered pollinators of some cultivated plants, they are better known for the damage they cause in different crops. During experimental agroecological cultivation of Artemisia (Artemisia annuaLinn, Asteraceae), in Jaguariúna (SP, Brazil), stingless bees Trigona spinipes (Fabricius) were observed sucking phloem sap directly from the plant, a phenomenon not yet described in scientific literature. This study aimed to register and describe the phloem sap-sucking behavior performed by T. spinipesfor the first time, as well as to assess the potential impact of this behavior on A. annuacultivation. The behavior and the material collected by bees and the severity of attack were also analyzed. The aging and premature death of observed A. annuaspecimens occurred because of extensive lesions caused by T. spinipes, confirming the negative consequence of sap-sucking attacks of T. spinipesbees on the plants. Factors that could induce this unusual behavior were presented, pointing out the need for future studies on the development of strategies to protect plants, without causing damage to the T. spinipesbee populations, which are elements of Brazilian bee fauna and, therefore, protected by law.
Subject(s)
Animals , Bees/chemistry , Artemisia annua/cytology , Phloem/chemistry , Plants, Medicinal , Organic AgricultureABSTRACT
ABSTRACT: This study aimed to investigate the diurnal variation of methane (CH4) emission in a flooded-irrigated rice field at different stages of the plant development under tropical climate in three growing seasons, in order to determine the most appropriate time for gas sampling in the Brazilian Southeast region. It aimed also to verify correlations between CH4 flux and air, water and soil temperatures, and solar radiation. The CH4 emissions were measured every 3-hour interval on specific days in different development stages of the flooded rice in the Experiment Station of the Agência Paulista de Tecnologia dos Agronegócios (APTA), Pólo Regional Vale do Paraíba, at Pindamonhangaba, State of São Paulo (22°55' S, 45°30' W), Brazil. Different CH4 emission rates were observed among the plant growth stages and also among the growing seasons. The CH4 emission showed high correlation with the soil temperature at 2cm depth. At this depth, the CH4 emission activation energy in response to soil temperature was higher in the stage R2. Emission peaks were observed at afternoon, while lower fluxes were recorded at the early morning. The most appropriate local time for gas sampling was estimated at 12:11:15a.m.±01:14:16 and 09:05:49p.m.±01:29:04.
RESUMO: Este estudo teve como objetivo investigar a variação diurna de emissões de metano (CH4) em uma lavoura de arroz irrigado por inundação em diferentes estágios de desenvolvimento de plantas de arroz irrigado, sob clima tropical, em três estações de crescimento, para determinar o período de tempo mais apropriado à amostragem de gás na região Sudeste do Brasil. O trabalho objetivou também verificar correlações entre o fluxo de CH4 e as temperaturas do ar, da água e do solo e a radiação solar. As emissões diurnas de CH4 foram medidas a cada intervalo de três (3) horas em dias específicos em diferentes estágios de desenvolvimento da planta de arroz inundado na Estação Experimental da Agência Paulista de Tecnologia dos Agronegócios (APTA), Pólo Regional Vale do Paraíba, em Pindamonhangaba, Estado de São Paulo (22°55' S, 45°30' W), Brasil. Diferentes taxas de emissão foram observadas entre os estágios de desenvolvimento da planta avaliados e também entre as estações de cultivo. A emissão de CH4 mostrou alta correlação com a temperatura do solo a 2cm de profundidade. Nesta profundidade, a energia de ativação da emissão de CH4 em resposta à temperatura do solo foi maior no estágio R2. Os picos de emissão foram observados no período da tarde, enquanto que menores fluxos foram registrados no início da manhã. O horário mais apropriado para amostragem de gás foi estimado em 12:11:15a.m.±01:14:16 and 09:05:49p.m.±01:29:04.