RESUMO
Floral structures, such as stamen appendages, play crucial roles in pollinator attraction, pollen release dynamics and, ultimately, the reproductive success of plants. The pollen-rewarding, bee buzz-pollinated flowers of Melastomataceae often bear conspicuous staminal appendages. Surprisingly, their functional role in the pollination process remains largely unclear. We use Huberia bradeana Bochorny & R. Goldenb. (Melastomataceae) with conspicuously elongated, twisted stamen appendages to investigate their functional role in the pollination process. We studied the effect of stamen appendages on pollinator behaviour and reproductive success by comparing manipulated flowers (appendages removed) with unmanipulated flowers. To assess bee pollinator behaviour, we measured three properties of buzzes (vibrations) produced by bees on Huberia flowers: frequency, duration and number of buzzes per flower visit. We measured male and female reproductive success by monitoring pollen release and deposition after single bee visits. Finally, we used artificial vibrations and laser vibrometry to assess how flower vibrational properties change with the removal of stamen appendages. Our results show that the absence of staminal appendages does not modify bee buzzing behaviour. Pollen release was higher in unmanipulated flowers, but stigmatic pollen loads differ only marginally between the two treatments. We also detected lower vibration amplitudes in intact flowers as compared to manipulated flowers in artificial vibration experiments. The presence of connective appendages are crucial in transmitting vibrations and assuring optimal pollen release. Therefore, we propose that the high diversity of colours, shapes and sizes of connective appendages in buzz-pollinated flowers may have evolved by selection through male fitness.
Assuntos
Melastomataceae , Polinização , Animais , Abelhas , Flores , Pólen , ReproduçãoRESUMO
Nasutitermes corniger (Motschulsky, 1855) (Termitidae: Nasutitermitinae) is an important pest in urban environments and bioinsecticides can be an alternative to its control. Here, we determined the toxicity and repellence of the essential oil (EO) prepared from stems of Aristolochia trilobata L. (Aristolochiaceae) and its major constituents on N. corniger. We also investigated behavioral changes of individuals exposed to limonene. The lethal dose required to kill 50% of N. corniger population (LD50) of EO of A. trilobata was 2.44 µg mg-1. Limonene was the most toxic compound to N. corniger followed by linalool (LD50 = 1.02 and 1.29 µg mg-1, respectively). In addition, all treatments presented median lethal time (LT50) less than 11 h. A. trilobata EO and its constituents showed irritability activity, but only limonene repelled soldiers more than workers. The negative behaviors of N. corniger groups were higher in individuals treated with limonene. A. trilobata EO and its constituents, especially the limonene, are promising for the control of N. corniger due the high toxicity, repellence, and possible disturbance in the colonies.
Assuntos
Aristolochia/química , Inseticidas , Isópteros , Óleos Voláteis , Monoterpenos Acíclicos , Animais , Repelentes de Insetos , Limoneno , Monoterpenos , Óleos de Plantas , Testes de Toxicidade AgudaRESUMO
Leaf-cutting ants belonging to the genus Atta (Formicidae: Myrmicinae) are important pests in agricultural and forest environments. In the present study, we evaluated the formicidal activity of the essential oil of Pogostemon cablin and its nanoformulation on the leaf-cutting ants: Atta opaciceps (Borgmeier, 1939), Atta sexdens (Linnaeus, 1758), and Atta sexdens rubropilosa Forel, 1908. The nanoformulation was developed by magnetic stirring using polyoxyethylene (36%), pure ethanol (36%), essential oil of P. cablin (18%), and water (10%). Bioassays of acute toxicity by fumigation and behavioral bioassays in treated arenas, with and without choice, were performed. The essential oil of P. cablin and its nanoformulation demonstrated efficient insecticidal activity and irritability to ant species. The concentration required to kill 50% of workers varied from 1.06 to 2.10 µL L-1, with a mean time to death of less than or equal to 42 h. The essential oil of P. cablin and its nanoformulation reduced the displacement and velocity speed of the workers of A. opaciceps and A. sexdens rubropilosa in totally treated arenas. In the bioassays with choices, the three species of ants walked less and at a greater speed on the treated side of arena. This work demonstrates the potential of the essential oil of P. cablin and its nanoformulation to the generation of new formicidal products.
Assuntos
Formigas , Inseticidas , Óleos Voláteis , Pogostemon/química , Animais , Comportamento Animal , Testes de Toxicidade AgudaRESUMO
O carrapato bovino Riphicephalus microplus (Acari: Ixodidae) constitui um dos grandes problemas enfrentado pelos pecuaristas de várias partes do mundo. No Brasil este ectoparasita causa grandes prejuízos à bovinocultura devido ao processo de hematofagia e pela transmissão de agentes patogênicos nos animais hospedeiros. Diante dessa situação os produtores normalmente aplicam carrapaticidas organossintéticos de forma indiscriminada. Este método normalmente resulta em: intoxicação dos animais e dos aplicadores, resíduos de carrapaticidas nos produtos de origem animal, resistência dos carrapatos aos carrapaticidas químicos e poluição ambiental. Uma alternativa para diminuir esses problemas é uso de biocarrapaticidas de origem botânica. Os pesticidas botânicos são produtos naturais derivados do metabolismo secundário das plantas. Esse metabolismo produz uma grande diversidade de compostos com ação carrapaticida que podem ser explorados através do uso de óleos essenciais ou como modelo para síntese de pesticidas sintéticos. A necessidade de métodos mais seguros, menos agressivos ao homem e ao meio ambiente, tem estimulado a busca de novos carrapaticidas a partir de produtos vegetais. Assim, acredita-se que o uso de óleos essenciais de plantas medicinais e aromáticas de uma forma isolada ou associada pode reduzir: a velocidade do desenvolvimento da resistência dos carrapatos aos carrapaticidas, os resíduos nos produtos de origem animal e a toxicidade para os animais, aplicadores e meio ambiente.
Assuntos
Plantas Medicinais , Óleos Voláteis , Brasil , RhipicephalusRESUMO
Seasonal population fluctuation of the coffee leafminer, Leucoptera coffeella (Guérin-Méneville & Perrottet) (Lepidoptera: Lyonetiidae), led to an investigation of its natural mortality factors during the rainy season when the population level is low and during the dry season when population peaks occur. Life-table data were collected from insecticide-free plots within a 3 ha coffee plantation on the upper, medium and lower canopy. Leafminer mortality was similar among the canopy parts but varied in the two seasons studied. During the rainy season, the generational mortality averaged 94.3%, with 50.2, 33.7 and 10.4% occurring during egg, larval and pupal stages, respectively. During the dry season, total mortality was 89%, with 13.2, 61.0 and 14.8% occurring during egg, larval and pupal stages, respectively. Marginal mortality rates during the rainy season were highest for physiological disturbances, rainfall and egg inviability; but, in the dry season, they were highest for predaceous wasps, physiological disturbances and parasitoids. Egg and larval stages accounted for most of the mortality variation in the rainy season, while the combination of larval and pupal mortality better described the generational mortality in the dry season. Variation in mortality during the rainy season was primarily associated with egg inviability, rainfall and parasitoids. In contrast, predatory wasps and physiological disturbances were the main factors associated with mortality variation during the dry season. These results suggest that weather conditions, natural enemies and plant quality attributes are the main determinants of the population dynamics of L. coffeella.
Assuntos
Estágios do Ciclo de Vida , Mariposas/crescimento & desenvolvimento , Estações do Ano , Animais , Coffea/parasitologia , Tábuas de Vida , Dinâmica PopulacionalRESUMO
The correct determination of the 24 hours proteinuria (PU24) in the non-hospitalized patients is frequently subject to collection errors. To overcome this problem it has been proposed the use of the proteinuria ratio (PR), obtained by dividing the concentrations of protein/creatinine in random urine samples. In the present investigation PR and PU24 were correlated in 42 patients (22 male and 20 female), aged between 14 and 63 years. Each patient was submitted to a 2 hours creatinine clearance (Ccr), to determination of PU24 and to evaluation of PR in the urine samples. The measures of PU24 were correlated with the values of PR. On linear regression analysis the equation y = 0,517 + 0,759x was obtained, with r = 0,914, suggesting good correlation between PU24 and PR. Values of r greater than 0,9 were always obtained, independently of the values of Ccr and PU24. The results indicate that PR in random urine samples may be practical and reliable in the follow-up of nephrological patients.