Biological responses of the Sipha flava (Forbes, 1884) (Hemiptera: Aphididae) fed with different elephant grass genotypes

Abstract

Resumo -Objetivou-se avaliar o efeito de genótipos de capim-elefante, Pennisetum purpureum Schum, sobre alguns aspectos biológicos de Sipha flava (Forbes). Utilizaram-se discos foliares de 15 genótipos de capim-elefante, nos quais ninfas com até 12 horas de idade, foram individualizadas em placas e mantidas à 25 ºC, UR de 70 ± 10% e fotofase de 12 horas. Avaliouse o número de ínstares, a duração e sobrevivência de cada ínstar e período ninfal, a duração do período pré-reprodutivo, reprodutivo e pós-reprodutivo, a capacidade diária e total de produção de ninfas e a longevidade dos adultos e ciclo biológico (ninfa-adulto). As ninfas apresentaram quatro instares, em todos os genótipos estudados. Não foram registradas diferenças significativas na duração do primeiro e último estádios ninfais nos genótipos avaliados, diferentemente do observado para os instares intermediários e período ninfal. Os parâmetros biológicos referentes à fase adulta do afídeo, como período pré-reprodutivo, reprodutivo e pós-reprodutivo e a longevidade foram afetados pelo genótipo. Cameroon de Piracicaba e Guaçu IZ2. Estes genótipos mostraram-se mais adequados ao desenvolvimento do afídeo, proporcionado maiores valores para produção de ninfas/fêmea, produção diária de ninfas/fêmea, período reprodutivo e longevidade do adulto; já o Sem Pêlo proporcionou maiores efeitos negativos nos parâmetros biológicos de S. flava.Palavras-chave -Pulgão-amarelo. Pennisetum purpureum. Biologia. Resistência.Abstract -This work aimed to evaluate the effect of genotypes of elephant grass, Pennisetum purpureum Schum, on some biological aspects of Sipha flava (Forbes). Foliar disks of 15 elephant grass genotypes were used, on which individual nymphs up to 12 hours old were placed in dishes and kept at 25 ºC, RH of 70 ± 10% and 12-hour photophase. We evaluated the number of instars, duration and survival of each instar and the entire nymphal period, duration of the pre-reproductive, reproductive and post-reproductive period, daily and total nymph production capacity and longevity of the adults and biological cycle (nymph-adult). The nymphs passed through four instars on all the elephant grass genotypes studied. There were no significant differences in the duration of the first and last nymph stages on the different genotypes, unlike observed for the intermediate instars and nymphal period. The biological parameters of the adult phase of the aphid, such as pre-reproductive, reproductive and post-reproductive period and longevity, were also affected by the genotype. Cameroon de Piracicaba and Guaçu IZ2 were the most suitable genotypes for development of the aphids, providing higher values for overall production of nymphs/female, daily production of nymphs/female, reproductive period and adult longevity. On the other hand, the Sem Pêlo genotype was the least suitable for the aphids' development and reproduction according to the biological parameters studied.

Effect of Climate Change on Longevity and Reproduction ofSipha flava(Hemiptera: Aphididae)

“…The host plant in all tests was P. purpureum, 'Cameron de Piracicaba', because this genotype is very suitable for the development of S. flava (Oliveira et al 2010). P. purpureum cuttings were each planted in a 1.0-L pot with a plant growth substrate of soil/manure at the ratio 2:1 and kept in the following 3 growth environments: 1) a greenhouse (avg.…”

“…Sipha flava is not only a serious pest of sugarcane (Saccharum spp. ; Poales: Poaceae) , but it infests corn, sor-ghum, wheat, and several other grasses (Webster 1990;Hentz & Nuessly 2004;Oliveira et al 2010). Plant injury caused by this aphid is often severe and is associated with the release of an unidentified toxin followed by leaf chlorosis (Breen & Teetes 1986;Webster 1990).…”

“…Given the potentially large effect of S. flava on P. purpureum (Oliveira et al 2010), it is important to understand how global climatic changes influences this aphid's ecology, and to determine whether future elevated CO 2 levels and temperatures could enhance the destructiveness of this pest. To our knowledge, there has been no previous investigation on the effects of global climatic changes on this pest.…”