Alberto Luiz Marsaro Júnior

Inibidores de amilase em híbridos de milho como fator de resistência a Sitophilus zeamais (Coleoptera: Curculionidae)

Sitophilus zeamais Motschulsky is one of the major pests of stored corn and it is mainly controlled by insecticides. However, due to the undesirable consequences of chemicals on the environment and human health other control measures have been investigated, especially the development of resistant plants. The presence of amylase inhibitors in corn kernels may interfere with the insect digestive process. This research was developed in order to evaluate resistance of corn hybrids to the attack of S. zeamais correlated with amylase inhibitors and nutritional composition of corn kernels. Adults of the maize weevil were exposed to grain samples of different corn hybrids at 27 ± 1°C and 75 ± 5% R.H. Biology, susceptibility index and grain consumption were evaluated. The results were correlated to the grain components (moisture content, ashes, lipids, proteins and carbohydrates) and with the amylase inhibitor activity. The amylase inhibitor activity was determined by incubating the amylase inhibitor with 0.2 units of amylase for 30 min at 25°C, and measuring the residual amylase activity determined by the iodine method. From the nutritional parameters evaluated, only the lipid content correlated significantly with the susceptibility index (r = 0.46). The amylase inhibitors obtained by the extraction with either ethanol or buffer were significantly and negatively correlated with the susceptibility index (r = -0.58), indicating that the inhibitors contribute to the resistance of corn hybrids to the attack of S. zeamais.

Anastrepha species (Diptera: Tephritidae), their hosts and parasitoids in the extreme north of Brazil

This work was carried out in five municipalities of the State of Roraima, Brazil, aiming to record the occurrence of Anastrepha species, their host plants and parasitoids. Fleshy fruits of 21 species of 10 families were sampled from September/2007 to September/2008. We collected 10 species of Anastrepha (Anastrepha bahiensis Lima and Anastrepha montei Lima were reported for the first time in Roraima) and five species of parasitoids (4 Braconidae and 1 Figitidae). Doryctobracon areolatus (Szepligeti) was the most abundant parasitoid.

Natural Enemies Associated with Maconellicoccus hirsutus (Hemiptera: Pseudococcidae) in the State of São Paulo, Brazil

Abstract The pink hibiscus mealybug, Maconellicoccus hirsutus (Green) (Hemiptera: Pseudococcidae), occurs widely in Brazil, causing damage to some crops. However, information on beneficial insects acting to control populations of this pest in Brazil is practically non-existent. A survey was conducted in the state of São Paulo. The insect associates of M. hirsutus recorded on Hibiscus rosa-sinensis L. (Malvales: Malvaceae) were the parasitoid Gyranusoidea indica Shafee, Alam & Agarwal (Hymenoptera: Encyrtidae) and the predators Cycloneda sanguinea (L.), Cryptolaemus montrouzieri Mulsant, Chilocorus nigrita (F.), Exoplectra sp., Harmonia axyridis (Pallas), Tenuisvalvae notata (Mulsant) (Coleoptera: Coccinellidae), and Ceraeochrysa sp. (Neuroptera: Chrysopidae). Cryptolaemus montrouzieri was the most commonly collected species on populations of M. hirsutus infesting plants of H. rosa-sinensis. Chilocorus nigrita, Exoplectra sp., H. axyridis, T. notata, and Ceraeochrysa sp. were associated for the first time with M. hirsutus, and G. indica was recorded for the first time in Brazil.

Efeito protetor e impacto econômico de métodos de aplicação de inseticidas em cevada

The objective of this work was to evaluate the protective effect of different forms of insecticide application on the transmission of yellow dwarf disease in barley cultivars, as well as to determine the production costs and the net profit of these managements. The experiments were carried out during 2011 and 2012 growing seasons, using the following managements at main plots: T1, seed treatment with insecticide (ST) + insecticide on shoots at 15-day interval; T2, just ST; T3, insecticide applied on shoots, when aphid control level (CL) was reached; T4, without insecticide; and T5, ST + insecticide on shoots when CL was reached. Different barley cultivars - BRS Caue, BRS Brau and MN 6021 - were arranged in the subplots. Insecticides lambda cyhalothrin (pyrethroid) and thiamethoxam (neonicotinoid) were used. There were differences on yellow dwarf disease index in both seasons for the different treatments, while damage to grain yield was influenced by year and aphid population. Production costs and net profit were different among treatments. Seed treatment with insecticide is sufficient to reduce the transmission of yellow dwarf disease in years with low aphid population pressure, while in years with larger populations, the application of insecticide on shoots is also required.

New records of whiteflies (Hemiptera Aleyrodidae) in Rio Grande do Sul State, Brazil

espanolEn este trabajo se registran siete especies de moscas blancas, incluyendo los generos Aleurothrixus, Dialeurodicus y Trialeurodes, y el parasitismo de Aleurothrixus floccosus por Signiphora sp. y Cales noacki. Tres nuevos huespedes son reportados a Aleurothrixus aepim. Dialeurodicus cockerellii y Trialeurodes vaporariorum se registran por primera vez en Rio Grande do Sul, Brasil. EnglishThis study reports seven species of whiteflies in the genera Aleurothrixus, Dialeurodicus, and Trialeurodes, as well as parasitism of Aleurothrixus floccosus by Signiphora sp. and Cales noacki. Three new hosts of Aleurothrixus aepim are reported. Dialeurodicus cockerellii and Trialeurodes vaporariorum are reported for the first time in Rio Grande do Sul State, Brazil.