ABSTRACT
The maize weevil Sitophilus zeamais Motsch. is an important pest of maize that attacks the grain both in the field and during storage. The damage caused by the maize weevil S. zeamais on maize landraces, Amarelo Antigo, Asteca, Caiano, Carioca, and Ferrinho, was evaluated by no-choice tests under laboratory conditions. The commercial varieties Sol da Manhã, BR 106, BR 451, and the synthetics PC 0203 and PC 9903 were evaluated for comparisons with the maize landraces. The parameters evaluated were susceptibility index, number of weevil progeny, development time, weevil progeny dry weight, and grain dry weight loss. The landraces were more susceptible to the maize weevil as compared to the commercial varieties. Based on the cluster analysis, two groups of susceptibility to the maize weevil were observed: one of more susceptible populations formed by local landraces and BR 451, and another less susceptible, with commercial varieties, synthetics, and the landrace Amarelo.
Subject(s)
Plant Immunity , Weevils/physiology , Zea mays/physiology , Zea mays/parasitology , Animals , Zea mays/classificationABSTRACT
ABSTRACT Microtheca punctigera (Achard) (Coleoptera: Chrysomelidae) is a major pest of Brassicaceae family plants in Brazil and occurs together with M. semilaevis. Occurrence of larvae and adults of M. punctigera and M. semilaevis Stal in five host plants grown in closely patchs was investigated in three periods in the field [Fall/Winter 2001 (May 10 to July 21); Fall 2002 (April 3 to June 12), and Spring 2002 (September 20 to November 15)]. Treatments were Chinese cabbage, mustard, watercress, arrugula and radish. The standard of occurrences of larvae of M. punctigera + M. semialevis was not repeated in the three trials: Chinese and mustard were the preferred food in 2001 Fall Winter while in the 2002 Fall and 2002 Spring preference was predominated for mustard and arrugula. M. punctigera was the predominant species during the experiments and populations were higher in the winter periods. In general, M. punctigera beetles were found mostly on Chinese cabbage and mustard, but in some assessments populations were high also in other hosts (mostly arugula). M. semialevis beetles occurred mostly on Chinese cabbage and mustard.
RESUMO Microtheca punctigera (Achard) é praga primária de plantas da família Brassicaceae no Brasil e ocorre associada com M. semilaevis Stal. Ocorrência de larvas e adultos de M. punctigera e M. semilaevis em cinco plantas hospedeiras em parcelas próximas foi avaliada em três períodos no campo ([outono/inverno, 2001 (10 de maio a 21 de julho); outono, 2002 (3 de abril a 12 de junho), e primavera, 2002 (20 de setembro a 15 de novembro)]. Os tratamentos foram couve chinesa, mostarda, agrião, rúcula e rabanete. O padrão de ocorrência de larva de M. punctigera + M. semialevis não se repetiu nos três períodos de avaliação: couve chinese e mostarda foram os alimentos preferidos no outono/inverno de 2001, enquanto que no outono e primavera de 2002, mostarda e rúcula foram os hospedeiros preferidos.M. punctigera foi a espécie predominante durante os experimentos e as populações foram maiores no período de inverno. De maneira geral, besouros de M. semialevis foram encontrados principalmente em couve chinesa e mostarda, mas em algumas as avaliações populações foram superiores em outros hospedeiros (principalmente em rúcula). Besouros de M. semialevis ocorreram principalmente em couve chinesa e mostarda.