Temporal Changes in Cereal Aphids (Hemiptera: Aphididae) Populations in Northern Rio Grande do Sul, Brazil

Abstract

Cereal aphids (Hemiptera: Aphididae) are economically important pests in all wheat-producing regions of Brazil and about eight species can be found in wheat crops. Aphids acquired the condition of severe pest in wheat in the 1970s, due to the emergence of Metopolophium dirhodum and Sitobion avenae. A successful biological control program of wheat aphids was introduced in southern Brazil in 1978. This study describes temporal changes in aphid populations in a wheat producing area in the northern region of Rio Grande do Sul (RS) state, Brazil. Data from weekly samples (water traps of Moericke type) for the current (May to November 2008November , 2009November and 2010 population frequency of each species was compared with 1970s populations. In addition, their seasonal fluctuations and the influence of rainfall and temperature on their populations were estimated. The species collected, and their frequencies, were as follows: Rhopalosiphum padi (57.6%), Sitobion avenae (31.0 %), Schizaphis graminum (7.7%), Metopolophium dirhodum (1.4%), Rhopalosiphum rufiabdominalis (0.9%), Rhopalosiphum maidis (0.6%), Sipha maydis (0.4%) and Sipha flava (0.4%). Aphids populations in winter cereals in northern RS have changed radically. The high populations of M. dirhodum in wheat in 1970s have been reduced to such levels that rarely have been found. Nowadays, R. padi was the predominant species. When the rainfall remained between 0-20 mm and temperatures between 15-20 ºC, aphid populations were more numerous than the average for the sampling period.

Effect of silicon on aphid populations and wheat yield in Minas Gerais, Brazil

“…This scenario is similar to that observed in Rio Grande do Sul state, in the southern region of Brazil, where in the 1970's, before the increase in oat production areas S. avenae was the most abundant pest reported, exceeding 90 insects/plant (Rebonatto et al, 2015). However, with the increase in winter crop species like rye, barley, wheat, triticale, and principally oat and corresponding cultivation areas in the southern regions of Brazil, R. padi became the most important species of aphids on winter crops in Rio Grande do Sul, increasing from less than 1% in the 1970's to more than 57% of the total aphids in wheat (Lau et al, 2009;Rebonatto et al, 2015). In the state of Paraná, the intermediate region between Rio Grande do Sul and Minas Gerais Cerrado, S. avenae (Zanini, Alves, Menezes, & Prestes, 2006;Bortolotto, Menezes, Hoshino, & Campos, 2016) or R. padi (Bortolotto, Menezes, & Hoshino, 2015) have been reported as the principal aphid species in wheat crops.…”

“…In Minas Gerais Cerrado the main winter crops are poorly cultivated (Castañeda, Figueroa, Fuentes-Contreras, Niemeyer, & Nespolo, 2009). This scenario is similar to that observed in Rio Grande do Sul state, in the southern region of Brazil, where in the 1970's, before the increase in oat production areas S. avenae was the most abundant pest reported, exceeding 90 insects/plant (Rebonatto et al, 2015). However, with the increase in winter crop species like rye, barley, wheat, triticale, and principally oat and corresponding cultivation areas in the southern regions of Brazil, R. padi became the most important species of aphids on winter crops in Rio Grande do Sul, increasing from less than 1% in the 1970's to more than 57% of the total aphids in wheat (Lau et al, 2009;Rebonatto et al, 2015).…”

“…In Brazil, the aphid species that use wheat as a host plant occur, in general, in regions with temperatures ranging from 18 to 24 °C, such as southern Brazil, and parts of the southeast and mid-west regions (Salvadori & Tonet, 2001;Stary, Sampaio, & Bueno, 2007). Consequently, wheat-feeding aphids in Brazil are best known from the southern region, among which the main pest species are Sitobion avenae (Fabricius), Schizaphis graminum (Rondani), and Rhopalosipum padi (Linnaeus) (Rebonatto, Salvadori, & Lau, 2015). However, studies identifying the main aphid species present in the new areas of wheat expansion are lacking.…”

Oscillation, synchrony, and multi-factor patterns between cereal aphids and parasitoid populations in southern Brazil

“…It is possible that these species have been introduced from other regions of the planet along with the primary producers of these trophic networks: cultivated grasses such as wheat, barley, and oat. With the increase of wheat in the area cultivated, initially without effective natural enemies, aphids became important pests (Rebonatto et al ., 2015). Winged aphid oscillation patterns are well described in temperate regions, predominantly in the northern hemisphere (Van den Eynde et al ., 2020).…”

“…Among the existing insect-pest species, aphids are among the most widespread worldwide, damaging wheat crops throughout their entire cycle (Dedryver et al ., 2010; Parizoto et al ., 2013; Rebonatto et al ., 2015; Brewer et al ., 2019). Biological control has been applied through parasitoids to reduce both direct and indirect damages caused by aphids in cereal crops (Andrade et al ., 2016; Yang et al ., 2017; Santos et al ., 2019).…”