Predation As A Mortality Factor In Populations Of The Spittlebug, Deois Flavopicta Stål (homoptera: Cercopidae)

The spittlebug, Deois flavopicta Stål, is the main pest in cultivated pastures of the "Cerrados" (savanna) in the central region of Brazil. The insect has three discrete generations during the rainy season (September-April) and a synchronized population of diapausing eggs during the dry season (May-August). Experiments in cultivated pastures showed that nonspecific predators were able to affect significantly the mortality rates of diapausing eggs and nymphs of D. flavopicta. Predation was a density independent mortality factor that reduced diapausing eggs by approximately 60% and nymphs by 20% to 47%. The nymph mortality rate due to predation did not differ during the first and the second generations of the year. For the third generation however, the mortality rate was lower, related to a greater degree of nymphal aggregation in spatial refuges. Our direct observations indicate that among the types of predators in pastures, ants potentially make the greatest contribution to mortality, although their impact needs experimental verification. High rates of mortality of eggs and nymphs of D. flavopicta exposed to predators indicate that predation can be an important factor determining the size of adult populations. Therefore, management practices that disturb the predator community may increase the population densities of the spittlebug.314581588Barbosa, F.R., Moreira, W.M., Czepack, C., (1984) Beauveria Bassiana (Bals.) Vuill: Promissor Agente de Controle Biológico para a Cigarrinha-das-pastagens Deois Flavopicta (Stal, 1854), 17p. , EMGOPA, Goiânia, (EMGOPA-DDI. Boletim de pesquisa, 2)Begon, M., Harper, J.L., Townsend, C.R., (1996) Ecology: Individuals, Populations and Communities. 3rd Ed., 1068p. , Blackwell Science, OxfordBegon, M., Mortimer, M., (1986) Population Ecology: a Unified Study of Animals and Plants. 2nd Ed., 220p. , Blackwell, OxfordBueno, V.H.P., Aspectos biologicos e ritmo diário das atividades de Porasilus barbiellinii predador da cigarrinha-das-pastagens (1987) Pesq. Agropec. Bras., 22, pp. 903-915Carneiro, M.F., Eficiência de diferentes cepas de Metarhizium anisopliae no controle de Deois flavopicta (1988) Pesq. Agropec. Bras., 23, pp. 685-689Cosenza, G.W., Naves, M.A., (1980) O Controle Da Cigarrinha Das Pastagens, 4p. , EMBRAPA/CPAC, Brasilia, EMBRAPA/CPAC, Comunicado Técnico, 6Cosenza, G.W., De Andrade, R.P., Gomes, D.T., Da Rocha, C.M.C., Resistência de gramíneas forrageiras à cigarrinha-das-pastagens (1989) Pesq. Agropec. Bras., 24, pp. 961-968Faria, M.R., Tigano, M.S., (1996) Coleção de Fungos Entomopatogênicos Do Cenargen, 76p. , Embrapa, Serviço de Produção e Informaçã o, BrasíliaFontes, E.M.G., Pires, C.S., Sujii, E.R., Mixed risk-spreading strategies and the population dynamics of a Brazilian pasture pest, Deois flavopicta (Homoptera: Cercopidae) (1995) J. Econ. Entomol., 88, pp. 1256-1262Hassel, M.P., (1978) The Dynamics of Arthropod Predator-prey Systems, 237p. , Princeton, New Jersey, Princeton University Press Monographs in Population Biology, 13Hewitt, G.B., Enviromental factors affecting spittlebug egg survival during the dry season in Central Brazil (1986) Pesq. Agropec. Bras., 21, pp. 1237-1243Hewitt, G.B., Nilakhe, S.S., Environmental factors affecting the survival of eggs and early instar nymphs of spittlebugs Zulia entreriana and Deois flavopicta during the rainy season in central Brazil (1986) An. Soc. Entomol. Brasil, 15, pp. 61-76Krebs, C.J., (1989) Ecological Methodology, 654p. , Harper Collins, New YorkLevings, S.C., Seasonal, annual, and among-site variation in the ground ant community of a deciduous tropical forest: Some cases of patchy species distributions (1983) Ecol. Monogr., 53, pp. 435-455Marques, I.M.R., Distribuição de Salpingogaster nigra Schiner, 1868 (Diptera: Syrphidae) predador específico de ninfas de cigarrinhas da raiz (Homoptera: Cercopidae) em algumas regiões do Brasil (1988) An. Soc. Entomol. Brasil, 17, pp. 67-74De Menezes, M., El Khadi, M.K., Pereira, J.M., Ruiz, M.A.M., (1983) Bases para o Controle Integrado Das Cigarrinhas-das-pastagens Na Região Sudeste Da Bahia, 33p. , CEPLAC-CEPEC, IlhéusMurray Jr., B.G., On the meaning of density dependence (1982) Oecologia, 53, pp. 370-373Nilakhe, S.S., Evaluation of grasses for resistance to spittlebug (1987) Pesq. Agropec. Bras., 22, pp. 767-783Pires, C.S.S., Fontes, E.M.G., Sujii, E.R., Fernandes, H.M.C., Gomes, D.F., Ocorrência de Anagrus sp. (Homoptera: Mymaridae) parasitando ovos de Deois flavopicta (Homoptera: Cercopidae) em pastagens do Brasil Central (1993) An. Soc. Entomol. Brasil, 22, pp. 411-413Pires, C.S.S., Sujii, E.R., Fontes, E.M.G., Tauber, C.A., Tauber, M.J., Dry-season dormancy in eggs of Deois flavopicta (Homoptera: Cercopidae): roles of temperature and moisture in nature (2000) Environ. Entomol., 29, pp. 714-720Seiffert, N.F., (1980) Gramíneas Forrageiras Do Gênero Brachiaria, 83p. , Embrapa CNPGC, Campo Grande, Embrapa CNPGC. Circular Técnica, 1Sujii, E.R., (1994) Padrão de Distribuição Das Populações Anuais e Modelo Fenológico para o Manejo Da Cigarrinha-das-pastagens, Deois Flavopicta (Homoptera: Cercopidae), 77p. , Dissertação de mestrado, UNICAMP, Campinas, SPSujii, E.R., Garcia, M.A., Fontes, E.M.G., Carvalho, V., Efeito da temperatura e umidade sobre o término da diapausa de ovos e densidade populacional da cigarrinha-das-pastagens, Deois flavopicta (Stal) (Homoptera: Cercopidae) (1995) An. Soc. Entomol. Brasil, 24, pp. 465-478Villacorta, A., Susceptibilidade de ninfas de Deois flavopicta (Stal, 1854) (Homoptera: Cercopidae) a diferentes isolamentos de Metarhizium anisopliae (Metsch) Sorokin (1980) An. Soc. Entomol. Brasil, 9, pp. 33-38Wilkinson, L., (1990) SYSTAT: The System for Statistics: Statistics, 676p. , Evanson, Illinois, SYSTAT In