Controle biológico natural de pulgões (Hemiptera: Aphididae) em lavoura de trigo por parasitóides (Hymenoptera, Aphidiinae), no município de Medianeira, PR, Brasil

Abstract

ResumoOs pulgões são um dos principais problemas fitossanitários da cultura do trigo no sul do Brasil, sendo alvo de um programa de controle biológico por parasitóides implantado no Brasil a partir da década de 1970. A despeito do sucesso inicial rapidamente obtido não há na região oeste do Paraná nenhum estudo recente avaliando a situação atual do controle biológico dos pulgões, sendo este o objetivo do presente trabalho. Foram realizados levantamentos semanais em uma lavoura comercial de trigo em Medianera, PR, sendo os pulgões identificados e quando parasitados, analisados até a emergência do parasitóide. A população de pulgões não alcançou a média de um inseto/afilho, com a predominância de Rhopalosiphum padi (53%), seguido de Sitobion avenae e R. maidis (19,5%) e Metapophium dirhodum (8%), surgindo principalmente a partir da fase de alongamento do trigo. Os parasitóides foram observados a partir da época de floração do trigo (cerca de três meses após o plantio), sendo identificadas apenas duas espécies de braconídeos Lysiphlebus testaceipes (97,3%) e Diaretiella rapae (2,7%), cujo crescimento populacional acompanhou a população de pulgões, seguindo a mesma tendência após a redução do número de pulgões no campo. Palavras-chave: Manejo integrado de pragas, dinâmica populacional, microhimenópteros AbstractAphids constitute one of the main phytosanitary problems in wheat crops in southern Brazil, and are the target of a biological control program with parasitoids implemented in Brazil since the 1970's. In spite of the initial success quickly achieved, no recent study exists for the west region of the State of Paraná that evaluates the current status of aphid biological control; therefore, this was the object of the present work. Weekly surveys were conducted in a commercial wheat crop in Medianeira, PR. The aphids were identified and, when parasitization was verified, they were analyzed until emergence of the parasitoid. The population of aphids did not reach the mean value of 1 insect/tiller, with predominance of Rhopalosiphum padi (53%), followed by Sitobium avenae and R. maidis (19.5%) and Metopolophium dirhodum (8%), which were verified mostly from the wheat elongation stage. The parasitoids were observed starting at the wheat flowering season (about 3 months after planting), and only two species of braconids, Lysiphlebus testaceipes (97.3%) and Diaeretiella rapae (2.7%), were identified, whose population growth followed the aphids population of, keeping the same trend after the number of aphids in the field was reduced.

<b>Distance from the edge of forest fragments influence the abundance of aphidophagous hoverflies (Diptera: Syrphidae) in wheat fields

“…The highest aphid abundance was reported during the wheat grain stage (Figure 2), which can be explained by the largest occurrence of S. avenae. Unlike the present study, Alves et al (2005) reported highest aphid infestation before the reproductive growth of wheat. However, in that case, R. padi was the predominant species.…”

“…Moreover, the remaining forest fragment may act as an area of refuge to natural enemies during little abundance of pests in crop fields (Koh & Holland, 2015). In Brazil, although several studies have shown that natural enemies are highly efficient in suppressing aphid infestation in wheat crops (Salvadori & Salles, 2002;Alves, Prestes, Zanini, Dalmolin, & Menezes Jr., 2005;Bortolotto, Menezes Jr., Sampaio, & Hoshino, 2012;Bortolotto, Menezes Jr., & Hoshino, 2015), have no investigation about the influence of non-crop fields on these natural enemies. Among the conservative management strategies, the maintenance of noncrop habitats has been studied to understand the importance of natural enemies (Barbosa, 1998;Walton & Isaacs, 2011;Letourneau, Bothwell, & Stireman, 2012;Fahrig et al, 2015).…”

Aphid parasitoids that occur on wheat crops of Northeast of the Parana State with recovery of Aphidius rhopalosiphi in Brazil

“…In the present study, A. colemani and L. testaceipes were the most abundant species in the field. These species were considered predominant in studies done in wheat fields in the west of Paraná State (ALVES et al, 2005, ZANINI et al, 2006a, and according to Starý, Sampaio and Bueno (2007) (ALVES et al, 2005;ZANINI et al, 2006a, b). The establishment of A. rhopalosiphi was confirmed in Brazil with 24 specimens captured with the Malaise trap, but only one individual emerged from parasitized S. avenae host (Table 2).…”

Aphidophagous Parasitoids can Forage Wheat Crops Before Aphid Infestation, Parana State, Brazil

“…In Brazilian fields, most studies have investigated the occurrence of aphid parasitoids in a field by measuring the number of mummies ( Ronquin et al. 2004 , Alves et al. 2005 , Macedo et al.…”