Flavio Antonio Lazzari

Correlation between the infestation level of Sitophilus zeamais Motschulsky, 1855 (Coleoptera, Curculionidae) and the quality factors of stored corn, Zea mays L. (Poaceae)

This experiment was carried out in order to evaluate the effect of Sitophilus zeamais on physical, physiological and sanitary quality of stored corn. Samples of 500 g of the hybrid OC-705, in three replicates, were conditioned in glasses covered with a screened lid, and kept in chamber at 25±2oC, 70±5% RH and 12 h of photophase, for 150 days. The infestation levels were 0, 5, 15 and 50 adults/replicate, for the storage periods of 30, 60, 90, 120 and 150 days. The moisture content, classification, weight loss, germination and internal infestation were evaluated monthly. Significant inverse correlations were verified between the number of insects and both the germination and the weight loss; also between the internal infestation and the germination and the standard type. The presence of S. zeamais showed a positive correlation with the weight loss, what means that the internal and external infestations contribute to the reduction of physiological and physical quality of corn seeds. The mean dry matter loss was 0,36%/day, corresponding to a consumption of 0,0001%/insect/month. As the result of those damages, the product suffered reduction of the commercial grade in 30 days, with significant loss in all quality factors.

Avaliação de inseticidas no controle de Sitophilus oryzae (L.) (Coleoptera: Curculionidae), e Rhyzopertha dominica (Fab.) (Coleoptera: Bostrichidae) em arroz armazenado

The efficacy of insecticides was determined in laboratory against Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and Rhyzopertha dominica (Fab.) (Coleoptera: Bostrichidae) exposed to treated shelled corn (Zea mays). Each treatment, which was composed by 1.2 kg of shelled corn, was treated with 5 ml of mixture/kg of corn using a propelling air atomizer. Fifteen days after treatment 200 g of the treated shelled corn, from each treatment, were infested with 40 adult insects of each species and this procedure was repeated every 30 days until 180 days after treatment. The number of dead insects was counted 15 days after each infestation, so the evaluations were made at 30, 60, 90, 120, 150 and 180 days after the insecticide application. After 180 days esfenvalerate + fenitrothion + piperonyl butoxide, esfenvalerate + fenitrothion and fenirothion + deltamethrin + pyperonil butoxide were effective against S. oryzae and R. dominica. Fenitrothion was effective against S. oryzae and deltamethrin + piperonyl butoxide against R. dominica. Esfenvalerate + pyperonil butoxide were ineffective against S. oryzae and the same was observed with fenitrothion against R. dominica. The use of mixtures of organophosphorus plus pyrethroids were more effective against S. oryzae and R. dominica when compared with these insecticides used alone.

Comparação dos sistemas de cultivo nativo e adensado de erva mate, Ilex paraguariensis St. Hil., quanto à ocorrência e flutuação populacional de insetos

This research was carried out in order to compare the occurrence of insects in two mate cultivation systems, native and high tree density. It was performed from August/2000 to September/2001, in a private property in Sao Mateus do Sul county, in Parana State, Brazil. Visual inspections of trees and light traps were used to evaluate insect populations in both areas. For Hedypathes betulinus (Klug) (Coleoptera, Cerambycidae), only six adults were observed in the dense area. Based on presence of sawdust at the basis of the trunk, it was obtained that the number of attacked trees did not surpass 11% in either area. For Gyropsylla spegazziniana (Lizer y Trelles) (Hemiptera, Psyllidae), the number of galls per tree was counted and it was observed that the population peak occurred from November to January. For Hylesia spp. (Lepidoptera, Saturniidae) and Thelosia camina Schaus (Lepidoptera, Eupterotidae), the presence of caterpillars on the trees was noticed from September to February, with the population peak in November and December. Adults of Hylesia spp. were more numerous in February and March. Two species that were not previously recorded for Brazil on mate were identified: Hylesia paulex Dognin (83%) and Hylesia remex Dyer (17%), collected with light traps. The mate caterpillar, T. camina was not collected with these traps. Nymphs and adults of Ceroplastes grandis Hempel (Hemiptera, Coccidae) were observed along the year on the branches, with population peak between April and June for the nymphs and from September to November for the adults. It should be considered that despite higher insect incidence in the dense area compared to the native area, the first presents higher yield, and that with a good pest management program the insect problems can be minimized.

Resfriamento artificial para o controle de Coleoptera em arroz armazenado em silo metálico

Resfriamento artificial para o controle de Coleoptera em arroz armazenado em silo metalico. O objetivo desta pesquisa foi avaliar o efeito do resfriamento artificial de graos de arroz para o controle de coleopteros-praga. O ar frio foi insuflado pelo sistema de aeracao em um silo metalico com arroz-em-casca. A avaliacao do tratamento foi feita quinzenalmente usando armadilhas caladores. As especies de Coleoptera capturadas foram: Oryzaephilus surinamensis (60%); Cryptolestes ferrugineus (9%); Rhyzopertha dominica (16,5%) e Sitophilus spp. (0,5%). Aos 28 dias, a temperatura media da massa de graos era de 15oC, e o numero medio de insetos havia diminuido 76,8%. A aplicacao de ar frio manteve as populacoes sob controle por aproximadamente 60 dias. Os resultados do monitoramento dos insetos e da temperatura indicaram que um novo ciclo de ar frio deveria ser aplicado nesse periodo para manter as populacoes sob controle. Tambem o manejo adequado da massa de graos faz-se necessario para garantir resultados satisfatorios do resfriamento artificial.

Efficacy of insecticides to control Sitophilus oryzae (Linnaeus) (Coleoptera, Curculionidae) and Rhyzopertha dominica (Fabricius) (Coleoptera, Bostrichidae) in stored wheat

The efficiency of insecticides against Sitophilus oryzae (Linnaeus, 1763) (Coleoptera, Curculionidae) and Rhyzopertha dominica (Fabricius, 1792) (Coleoptera, Bostrichidae) was determined exposing them to treated wheat in laboratory. Each plot, which was composed by 1.2 kg of wheat grain, was treated with 5 ml of the concentration/kg of wheat using a propelling air atomizer. Fifteen days after treatment 50 g samples of the grain were taken, from each plot, placed in plastic jars into which 10 adult insects of each species were released. This was repeated every 30 days until 165 days after treatment. The number of dead insects was counted 15 days after each infestation thus the evaluations were made at 30, 60, 90, 120, 150 and 180 days after the insecticide application. Esfenvalerate+fenitrothion+pyperonil butoxide (0,375+7,5+3,0 and 0,5+10,0+4,0 g a.i./t), fenitrothion+esfen-valerate (7,5+0,375 and 10,0+0,375 g a.i./t), fenitrothion+synergised deltamethrin (7,5+0,375 g a.i./t) and fenitrothion (7,5 g a.i./t) were effective against Sitophilus oryzae until 180 days after treatment. Esfenvalerate+fenitrothion+pyperonil butoxide (0,5+10,0+4,0 g a.i./t), fenitrothion+esfenvalerate (7,5+0,375 and 10,0+0,375 g a.i./t), fenitrothion+synergised deltamethrin (7,5+0,375 g a.i./t) were effective against R. dominica until 180 days after treatment. Synergised deltamethrin (0,375 g a.i./t) was effective against S. oryzae until 150 days and against R. dominica until 120 days after treatment. Esfenvalerate (0,5 g a.i./t) was ineffective against S. oryzae and effective until 60 days after treatment against R. dominica. Fenitrothion (7,5 g a.i./t) was ineffective against R. dominica. The use of mixtures of organophosphorus plus pyrethroids were more effective against S. oryzae and R. dominica when compared with these insecticides used alone.

Resposta de Sitophilus oryzae (L.), Cryptolestes ferrugineus (Stephens) e Oryzaephilus surinamensis (L.) a diferentes concentrações de terra de diatomácea em trigo armazenado a granel

Formulations of diatomaceous earth from different sources show variation in toxicity and in certain physical characteristics which can affect product efficacy. Also, different insect species show variation in their susceptibility to the product. Adults of Sitophilus oryzae (L.), Cryptolestes ferrugineus (Stephens) and Oryzaephilus surinamensis (L.) were exposed to wheat kernels treated with a formulation of diatomaceous earth of Brazilian origin (Keepdry®), at concentrations of 250, 500, 750, 1000, and 1250g t-1 during different exposition periods. The treated kernels, in four replicates of 100g per treatment, were poured in plastic vials and infested with the insects. The vials were placed in environmental chamber at 25°C and 65% RH and the mortality was evaluated periodically. The number of dead insects per treatment was analyzed by the variance analysis and the differences between the means were determined by the Tukey test at 5%. The mortality of the three species was directly related to the diatomaceous earth concentration and to the exposition time, with the best results at concentrations above 500g t-1. The most tolerant species was S. oryzae that reached 100% mortality only at the 14th day of exposition, at 750g t-1. On the other hand, C. ferrugineus was the most susceptible species to diatomaceous earth; it reached 100% mortality at 500g t-1 at the 4th exposition day. It was concluded that the diatomaceous earth used in these experiments presented a satisfactory control level, and that it represents a very efficient grain protector for using in stored wheat insect management programs.