Resumo em Inglês:

ABSTRACT The horizontal transmission of the entomopathogenic fungus Beauveria bassiana Unioeste 76 strain among adults of Euschistus heros was evaluated in the laboratory and greenhouse using sporulated cadavers and live insects contaminated as a source of inoculate. Adult insects in the laboratory bioassay either received treatments with dry conidia or were sprayed with an oily dispersion formulation, and the treatments were comprised of 10, 30, or 50% of contaminated insects. For the greenhouse bioassay, nylon cages were prepared, with soybean plants grown in pots. A total of 20 healthy brown stink bugs were released along with one or three sporulated cadavers of brown stink bugs, attached to the plant stem. In the bioassay with live insects, 20 stink bugs were released, and the treatments were comprised of 10, 30, or 50% contaminated insects (2:18, 6:14, and 10:10, fungus-treated insects : healthy insects). In all experiments, the control group was comprised only of healthy insects. Dead stink bugs were daily disinfested and transferred to a wet chamber for confirmation of death by fungus. Confirmed mortality was observed, which shows the occurrence of horizontal transmission. Mortality was higher when more contaminated insects were used in the population, in most treatments. The occurrence of transmission in the laboratory and the greenhouse emphasizes the potential of the Unioeste 76 strain as mortality agent and as an agent for maintaining the inoculum potential for the brown stink bug.

Resumo em Inglês:

ABSTRACT Respiratory tract infections in poultry have become serious problems with negative consequences for poultry production. Among these diseases, mycoplasmosis and avian pneumoviruses stand out, which, despite being relevant in poultry health, have not been systematically investigated in Brazil, especially regarding the interaction between these agents or the occurrence of co-infection in broiler chickens. The present study investigated the occurrence of infection by Mycoplasma gallisepticum (MG) and subtypes A and B of avian metapneumovirus (aMPV) in broiler chickens from commercial poultry flocks kept on farms with high biosecurity standards and located in the Southeast and Midwest regions of Brazil. Polymerase chain reaction (PCR) and reverse transcription nested-PCR techniques were applied to detect and/or identify, respectively, MG and aMPV in samples of nasal and tracheal swabs collected between 2017 and 2018, from 87 batches of broiler chickens from 15 commercial production farms that showed respiratory clinical signs. Two out of 87 batches sampled (2.3%) were positive for MG, while none of them were positive for aMPV. The low or no incidence of these pathogens can be explained by the adoption of increasingly effective health control measures for these agents on farms with high biosecurity standards. In addition, there are clues that other bacterial and viral infectious agents may be involved in the etiology of respiratory problems of these broiler chickens, which showed clinical signs of respiratory diseases upon sample collection.