Distribuição espacial de Empoascakraemeri Ross e Moore, 1957(Hemiptera: cicadellidae) em pinhão-manso

Abstract

The physic nut is a plant that belongs to the family Euphorbiaceae being perennial, crude and adapted to diverse climatic conditions. It`s present in Brazil and in all tropical regions. This plant is great energy source due to the high potential for the production of oil to make biodiesel. But this culture suffers attack of some insect pests, including the green leafhopper Empoascakraemerithat has been reported as one of the most important, because it causes yellowing and shriveling of the leaves and in cases more severe necrosis and leaf drop. Despite its importance, this insect has been little studied in this culture, especially on the ecological characteristics for this population. Thus, the aim of this study was to investigate the pattern of spatial distribution of adults of this pest in the region of Dourados,MS, Brazil, for the subsequent development of adequate plans for sampling. For this research the sample area consisted of 3.000 m2 which was recorded all adult individuals collected at 100 samples units. Each sample unit consisted of yellow sticky traps that were installed within one meter of ground in 25 lines of cultivation, with 20 plants in each row, 4 traps in row. The distance between the lines was 3 meters in each lines and each plants distanced from 2 meters. Fortnightly sampling which consisted in the removal and counting of adult insects trapped in each trap were performed. After replacing these traps were immediately repleced. The sampling period was November 2012 and July 2013 totaling 16 samplings. With the average count values of each sample the following dispersion indexes for determining the spatial distribution were used: varience/meam ratio(I); Morisita index (Id); Green coefficient (Cx); kexponemtof the negative binomial distribuction(k) and Taylor`s power law. The theoretical distribution of frequencies Poisson, negative binomial and positive binomial were calculated, but most of values of the frequency classes observed in the field to the classes of expected frequencieswere the aggregate. The distribution pattern was observed in most samples was added and the negative binomial distribution model that best to adapted the distribution of green leafhopper adults in the culture of physic nut.