Effects of insecticides used in corn on immature stages of trichogramma atopovirilia (hymenoptera: trichogrammatidae)

The chemical control of Spodoptera frugiperda (Lepidoptera: Noctuidae) is difficult because caterpillars live inside the corn (Zea mays) cob and they do not come into contact with insecticides. Research on the use of parasitoids of the genus Trichogramma (Hymenoptera: Trichogrammatidae) has contributed to advances in alternatives for the control of this pest. However, there is little information on the effects of pesticides used in corn on these parasitoids. Therefore, the objective of this study was to evaluate the physiological selectivity of insecticides for Trichogramma atopovirdia in the egg-larval, pre-pupal and pupal phases. The bioassays were carried out under controlled conditions, exposing eggs of Anagasta (= Ephestia) kuehniella (Lepidoptera: Pyralidae) to parasitism for a 24-h period. The insecticides were sprayed using a Potter tower on host eggs containing the parasitoids in the egg-larval period, pre-pupal and pupal phases. The insecticides evaluated in g a. i. L were: imidaclopric1/beta-cyfluthrin (Connect 100 (TM) SC - 0.033), chlorfenapyr (Pirate 240 (TM) SC - 0.6), chlorpyriphos (Astro 450 (TM) EW - 0.75), novaluron (Rimon 100 (TM) CE - 0.05), spinosad (Tracer 480 (TM) SC - 0.16) and triflumuron (Certero 480 (TM) SC - 0.048). Water was used as a control. According to the results, the products were classified in the following toxicological classes for T atopovirilia: imidacloprid/beta-cyfluthrin, novaluron and triflumuron as harmless (class 1); spinosad and chlorfenapyr as slightly harmful (class 2); and Chlorpyrifos was harmful (class 4) to the parasitoid. Therefore, new studies under greenhouse and field conditions are necessary to confirm these toxicity results.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Nutritive value of corn silage from intensive dairy farms in Brazil

ABSTRACT The objective of this research was to characterize the nutritive value of corn silage made on intensive dairy farms and demonstrate the nutritional variations between silages located at the top and at the center of a bunker silo. Thirty-two dairy farms were visited in four Brazilian states. One corn bunker silo of each farm was chosen and samples were collected from the top and center parts. The nutritive value, fermentation end-products, and microbial counts were assessed. The predicted milk was determined by Milk2006 spreadsheet. The mean, standard deviation, maximum, minimum, and 95% confidence interval of all data were calculated. The ash, neutral detergent fiber (NDF), starch, in vitro NDF, and dry matter (DM) digestibility data were compared with reference value. Both statistical procedures were performed through the PROC MEANS of SAS. The mean values found at the center for NDF, starch, total digestible nutrients (TDN-1x), and estimated milk were 503 g kg−1 DM, 308 g kg−1 DM, 583 g kg−1, and 1,124 kg t−1, respectively. The top silages presented a mean TDN-1x and predicted milk of 559 g kg−1 and 1046 kg t−1, respectively. For NDF digestibility and starch concentration, 53.1% and 62.5% of the center samples presented a value equal to or above the reference value (500 g kg−1 and 300 g kg−1 DM for NDF digestibility and starch concentration, respectively). Overall, the corn silage produced on intensive dairy farms in Brazil has satisfactory nutritive value, especially in terms of starch concentration. Some parameters, such as the concentration of fiber and its digestibility, should be improved. This study also shows that a silo may contain two different types of silage: top and center. This alerts nutritionists and farmers when feeding and sampling corn silage from bunker silos