Dry-Season Embryonic Dormancy in<i>Deois flavopicta</i>(Homoptera: Cercopidae): Roles of Temperature and Moisture in Nature

Pires, C. S. S.; Sujii, Edison Ryoiti; Fontes, Eliana Maria Gouveia; Tauber, Catherine A.; Tauber, Maurice J.

doi:10.1603/0046-225x-29.4.714

Cited by 46 publications

(19 citation statements)

References 12 publications

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“…Each year this species has three discrete generations, during the rainy season, and it aestivates during the dry season as diapausing eggs (Fontes et al1995). Low temperatures during the early part of the diapause period accelerate diapause development, whereas contact with liquid water determines the timing of post-diapause hatching (Pires et al 2000). With the start of the rainy season, synchronized emergence of first instars occurs after the natural termination of diapause during the dry season (Sujii et al1995).…”

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Predation as a Mortality Factor in Populations of the Spittlebug, Deois flavopicta Stål (Homoptera: Cercopidae)

Sujii¹,

Garcia²,

Fontes³

et al. 2002

Neotrop. Entomol.

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A Predação Como Fator de Mortalidade em Populações da Cigarrinha-das-Pastagens,Deois flavopicta Stål (Homoptera: Cercopidae)RESUMO -A cigarrinha-das-pastagens Deois flavopicta Stål é a principal praga de pastagens cultivadas nos Cerrados do Brasil Central. O inseto apresenta distribuição sazonal com três gerações anuais discretas durante a estação chuvosa (setembro-abril) e população sincronizada de ovos diapáusicos durante a estação seca (maio-agosto PALAVRAS-CHAVE: Insecta, comunidade de insetos, dinâmica populacional, curva de sobrevivência ABSTRACT -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.KEY WORDS: Insecta, insect community, population dynamics, survival curveSince 1960, several grass species of the genus Brachiaria (Poaceae) have been introduced from Africa and planted in extensive areas, from the Central to Northern regions of Brazil (Seiffert 1980). The colonization of new pastures with few natural enemies, along with a phenology that is synchronized with the seasonal change in physical

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Predation as a Mortality Factor in Populations of the Spittlebug, Deois flavopicta Stål (Homoptera: Cercopidae)

Sujii¹,

Garcia²,

Fontes³

et al. 2002

Neotrop. Entomol.

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“…It is possible that the low temperature accelerated diapause development, but retarded postdiapause development, thus reducing the duration of the egg stage and synchronizing hatching after the eggs experienced warm condition (Pires et al, 2000;Tauber et al, 1986). When this happens, quiescence may be the mechanism through which the eggs maintain their low metabolic rate and drought hardiness after diapause has ended.…”

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confidence: 99%

“…In central Brazil this peak coincides with the transition between dry and rainy seasons. Dormancy in eggs of D. flavopicta has, at least two distinct parts: diapause and post-diapause quiescence (Pires et al, 2000). Neither photoperiod (Pires et al, 1991) or temperature and humidity (Pires et al, 2000), are apparently used as environment cues for diapause termination in D. flavopicta.…”

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confidence: 99%

Soil temperature and diapause maintenance in eggs of the spittlebug, Deois flavopicta (Hemiptera: Cercopidae)

et al. 2001

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Diapausing eggs of the neotropical pasture pest, Deois flavopicta (Stal) (Hemiptera: Cercopidae), were exposed to low overnight temperatures that simulated field conditions during the dry season (23/12, 23/15 and 23/18ºC day/night), for different periods (0-60 days). After treatment, eggs were kept at 28ºC and contact water (100% humidity) until hatching. A group of diapausing eggs were kept all the time under this last condition as a control treatment. Time for hatching (in degree-days) was reduced with decrease in low overnight temperature and increase of exposure time to these cold shocks, although there was no interaction between the factors. Regression of exposure time to cold shock influencing the expected mean hatching time produced independent equations for temperatures below 18ºC and 15ºC. We constructed a model that simulates the expected proportion of the population hatching after the beginning of rainy season based on regression equations to mean hatching time and associated standard deviation. The simulation generated for the model correlated significantly with nymphal population observed in the field. These results showed that overnight soil temperatures below 18ºC, as occurs in Central and South-eastern Brazil between May and August, shorten the period of diapause, increase quiescent eggs in the soil, and may synchronize the population hatching.Key words: Insecta, phenology, dormancy, cold treatment, population dynamics. RESUMOTemperatura do solo e manutenção da diapausa em ovos da cigarrinha-das-pastagens, Deois flavopicta (Hemiptera: Cercopidae)Foram expostos ovos diapáusicos da praga de pastagens na região neotropical, Deois flavopicta (Stal) (Hemiptera: Cercopidae), a baixas temperaturas noturnas, simulando condições de campo durante a estação seca (23/12, 23/15 e 23/18ºC dia/noite), por diferentes períodos (0, 15, 30, 40, 50 e 60 dias). Após o tratamento térmico, os ovos foram mantidos a 28ºC e em água de contato (100% de umidade), até a eclosão das ninfas. Um grupo-controle de ovos diapáusicos foi mantido por todo o período experimental em altas temperaturas e umidade. O tempo para eclosão (em graus/dia) foi reduzido devido ao efeito das baixas temperaturas noturnas e ao aumento no período de exposição ao choque frio, embora não tenha sido observada interação significativa entre esses fatores. A regressão do efeito do período de choque frio no tempo médio para eclosão das ninfas provenientes de ovos diapáusicos produziu equações independentes para as temperaturas abaixo de 18ºC e 15ºC. Com base nas equações

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“…According to those hypothesis, outbreaks of phytophagous insects are caused by changes in biotic and/or physical factors of the environment. The management of an insect population, preventing its outbreak, requires the determination of the factors that have changed in the environment in relation to the problem insect (Sanders & Knigth 1968).The occurrence of high densities of D. flavopicta has been related to various factors such as precipitation, temperature and evapotranspiration (Oomen, 1975, Milanez et al 1981, Melo et al 1984, Sujii et al 1995, Pires et al 2000a, and lack of natural enemies (Hewitt 1986, Hewitt & Nilakhe 1986, Sujii 1998. However, host plant availability and quality may also play a role on spittlebug population dynamics by directly affecting nymph and adult performance (Pires et al 2000b).…”

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“…The occurrence of high densities of D. flavopicta has been related to various factors such as precipitation, temperature and evapotranspiration (Oomen, 1975, Milanez et al 1981, Melo et al 1984, Sujii et al 1995, Pires et al 2000a, and lack of natural enemies (Hewitt 1986, Hewitt & Nilakhe 1986, Sujii 1998. However, host plant availability and quality may also play a role on spittlebug population dynamics by directly affecting nymph and adult performance (Pires et al 2000b).…”

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Effect of Host Plant on the Fecundity of Spittlebug Deois flavopicta Stal (Homoptera: Cercopidae): Implications on Population Dynamics

Sujji¹,

Pires²,

Fontes³

et al. 2001

Neotrop. Entomol.

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Efeito da Planta Hospedeira na Fecundidade da Cigarrinha-das-pastagens Deois flavopictaStal (Homoptera: Cercopidae): Implicações na Dinâmica Populacional RESUMO -A cigarrinha das pastagens Deois flavopicta Stal (Hom.: Cercopidae) ocorre naturalmente em gramíneas nativas no Brasil Central em baixas densidades populacionais. Após a introdução de gramíneas africanas, principalmente do gênero Brachiaria, D. flavopicta passou a produzir explosões populacionais e tornou-se a principal praga das pastagens na região. Estudos visando comparar os efeitos da planta hospedeira nativa e da exótica sobre a fecundidade do inseto foram desenvolvidos. Fêmeas de D. flavopicta, mantidas durante a fase adulta em Brachiaria ruziziensis, produziram mais ovos e tiveram maior longevidade média que aquelas mantidas em Axonopus marginatus, independente da planta hospedeira em que foram criadas durante a fase ninfal. Devido aos danos causados pelos adultos na planta hospedeira, o efeito da densidade de indivíduos em sua própria fecundidade foi avaliado em gaiolas de oviposição contendo plantas de B. ruziziensis padronizadas no comprimento e quantidade de perfilhos. Densidades de um, dois, três, quatro e seis casais com fêmeas virgens foram avaliadas. A densidade populacional de três casais, equivalente a 150 adultos/m 2 , ou maior que esta, reduziu a fecundidade das fêmeas. Estes estudos contribuíram para o entendimento dos mecanismos que influem para as baixas populações de cigarrinha observadas em gramíneas nativas e que promovem explosões populacionais em pastagens cultivadas com plantas introduzidas. PALAVRAS-CHAVE: Insecta, dinâmica de populações, biologia reprodutiva, interação inseto-planta, surtos populacionais.ABSTRACT -The spittlebug Deois flavopicta Stal (Hom.: Cercopidae) occurs naturally on native grasses in Central Brazil in low population densities. After the introduction of African grasses, mainly of the genus Brachiaria, for cattle raising, D. flavopicta began to produce population outbreaks and became a pest. Two studies were conducted, aiming to estimate the effects of a native and an exotic host plant on the fecundity of this insect. Females of D. flavopicta maintained during the adult stage on Brachiaria ruziziensis produced more eggs and lived longer than those maintained on Axonopus marginatus (a native grass widely distributed in Brazil), independently of the host plant on which the nymphs were reared. Due to the severe damage produced by adult D. flavopicta on the host plant, the effect of insect density on its own reproductive capacity was evaluated in oviposition cages containing plants of B. ruziziensis, standardized in height and stem number. Densities of one, two, three, four and six couples with virgin females were evaluated. Population densities of three couples, equivalent to 150 adults/m 2 , or higher decreased insect's fecundity. These results contributed to the understanding of the mechanisms that determine low levels of spittlebug populations in the native grasses and promote population outbreaks in in...

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Dry-Season Embryonic Dormancy inDeois flavopicta(Homoptera: Cercopidae): Roles of Temperature and Moisture in Nature

Cited by 46 publications

References 12 publications

Predation as a Mortality Factor in Populations of the Spittlebug, Deois flavopicta Stål (Homoptera: Cercopidae)

Predation as a Mortality Factor in Populations of the Spittlebug, Deois flavopicta Stål (Homoptera: Cercopidae)

Soil temperature and diapause maintenance in eggs of the spittlebug, Deois flavopicta (Hemiptera: Cercopidae)

Effect of Host Plant on the Fecundity of Spittlebug Deois flavopicta Stal (Homoptera: Cercopidae): Implications on Population Dynamics

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