Sipha maydis (Hemiptera: Aphididae) in the humid subtropical region of Brazil: distribution, seasonality and biology

Sipha maydis (Passerini) (Hemiptera: Aphididae) is a pest of cultivated cereals and wild grasses introduced into America and first reported in South America at Argentina in 2002. In Brazil, this aphid was detected first in wheat in Oct 2006 at Rio Grande do Sul State. Between 2007 and 2013 the aphid was reported in several localities in the humid subtropical region of Brazil (southern states of Rio Grande do Sul, Santa Catarina, and Parana) on different plant species including Triticum aestivum L., Avena strigosa Schreb., Lolium multiflorum Lam., Hordeum vulgare L., Zea mays L. (all Poaceae) and uncultivated grasses. Sipha maydis also has been captured in yellow tray traps. Peak flight activity for S. maydis occurred in the spring-summer transition and was apparently correlated with average air temperature. Sipha maydis was able to complete its life cycle on A. strigosa, L. multiflo-rum, H. vulgare, Z. mays, and T. aestivum. During the nymphal phase the best hosts were A. strigosa, L. multiflorum, H. vulgare, and T. aestivum. Hordeum vulgare and T. aestivum were the best for the reproductive period and longevity. The intrinsic rate of increase was greatest on A. strigosa, L. multiflorum, and T. aestivum. Generation time was longer on H. vulgare, Z. mays, and T. aestivum. Net rate reproduction was greater in H. vulgare and T. aestivum, and the finite rate of increase was greatest on A. strigosa, L. multiflorum, H. vulgare, and T. aestivum. Although the distribution of S. maydis is expanding and covering the main wheat-growing region of Brazil, and despite the wide range of hosts and the direct damage it causes to local foraging sites, aphid populations are low and their economic importance is limited. However, it reveals that S. maydis has the potential to colonize subtropical regions.