Danos de Rhopalosiphum padi (L.) (Hemiptera: Aphididae) no trigo em função da duração e da densidade de infestação

Abstract

-Aphids are considered relevant pests on wheat either by direct damage through sap sucking or by indirect damage vectoring BYDV (Barley yellow dwarf virus). Rhopalosiphum padi L. has been observed infesting wheat fi elds with an increasing frequency. The knowledge and the available technology, besides being more related to other aphids species already recognized as pests, they are insuffi cient to control the specifi c problem of R. padi. Thus, this work evaluated the effects of feeding duration and infestation densities of R. padi on seedlings of wheat cv. Embrapa 16. Grain yield, yield components and the extent of symptoms were recorded. The experiment was carried out in the fi eld under a completely randomized split-plot experimental design with four replications. The main plot was feeding duration (two and seven days) and the sub-plots were infestation densities (zero, two and 10 aphids per plant). Independent on feeding duration, 10 aphids per plant resulted in signifi cant yield losses, reduction of number of heads and tillers per plant. Canopy dry matter was also reduced. Infestations of two and 10 aphids per plant resulted in continuous yellowing of wheat plants from tillering to the end of fl owering stage. When aphids fed for seven days on wheat, more yellowing symptoms were observed at the fl ower stage in comparison with two days feeding.KEY WORDS: Triticum aestivum, bird cherry-oat aphid, BYDV RESUMO -Os pulgões associados ao trigo são considerados pragas relevantes por causarem danos diretos, ao se alimentarem da seiva do fl oema, ou indiretos, ao atuarem como vetores do BYDV (Barley yellow dwarf virus). Rhopalosiphum padi L. tem infestado lavouras com freqüência crescente. O conhecimento e a tecnologia disponíveis, além de estarem mais relacionados a outras espécies de pulgões já reconhecidas como pragas, são insufi cientes para controlar o problema específi co de R. padi. O objetivo do experimento foi avaliar o efeito da duração e da densidade de infestação de R. padi na fase de plântula, na manifestação de sintomas de danos, na produção de grãos e seus componentes e em outras características agronômicas em trigo. O experimento foi conduzido no campo, com a cultivar Embrapa 16, em blocos ao acaso com quatro repetições, em parcelas subdivididas, avaliando-se duas durações (dois e sete dias) e três densidades de infestação (zero, dois e 10 pulgões por planta), sete dias após a emergência das plantas. A densidade de 10 pulgões por plântula de trigo, independente da duração (dois ou sete dias), reduz a produção de grãos, o número de espigas, o número de afi lhos e a massa seca da parte aérea das plantas. Dois e 10 pulgões por plântula provocam amarelecimento de folhas crescente, que se manifesta no afi lhamento, no pré-espigamento e no fi nal do estádio de fl oração das plantas. Sete dias de infestação provoca a manifestação, na fase de fl oração das plantas em grau de amarelecimento maior que dois dias de infestação. PALAVRAS-CHAVE: Triticum aestivum, pulgão, BYDVEntre os problemas que pode...

Faunistic analysis of pest insects and their natural enemies associated with hairy fleabane in soybean crop1

“…Its occurrence was predominant during the winter pasture stage, from April to August (Figure 1). Aphids are an important pest in winter grains and a major cause of yield loss in wheat crops (Roza-Gomes et al 2008). These sap-sucking insects may cause direct damage by feeding on phloem sap and indirect damage as vectors of the barley yellow dwarf virus (Salvadori & Tonet 2001).…”

Entomofauna associated with Avena sativa in southern Mato Grosso do Sul, Brazil

“…On the other hand, some factors may negatively affect yields, especially pests such as the aphid Rhopalosiphum padi (Linnaeus, 1758) (Hemiptera: Aphididae) and the caterpillar of Spodoptera frugiperda (Smith, 1797) (Lepidoptera: Noctuidae), which has a high incidence in oats in traditional growing areas. The effect of the attack of R. padi can be also be exacerbated by the transmission of viruses such as the barley yellow dwarf virus (BYDV) in Winter cereals (ROZA-GOMES et al, 2008).…”

“…Given the few scientific studies on pests of oats, most of the information on pest management has been generally based on other similar crops, such as wheat (ROZA-GOMES et al, 2008;SALVADORI, 2011;PANIZZI et al, 2015). Therefore, information is needed on the diversity of insect species associated with oats in order provide a framework for pest control based on Integrated Pest Management (IPM) (GALLO et al, 2002).…”

Protective effect and economic impact of insecticide application methods on barley

“…There are many studies on wheat for the following variables: cultivar response to damage caused by R. padi (Silva et al, 2004;Savaris et al, 2013); yield response to different locations, aphid abundance, and BYDV incidence (Hesler et al, 2005); R. padi feeding duration and infestation densities (Rosa-Gomes et al, 2008); determination of parents in wheat breeding program to obtain tolerant genotypes to BYDV (Barbieri et al, 2001); and efficiency of insecticides to reduce aphid population (Silva et al, 2004), among others.…”