SELECTION OF ENTOMOPATHOGENIC FUNGI AND NEMATODES TO THE COFFEE ROOT MEALYBUG DYSMICOCCUS TEXENSIS (TINSLEY)

ABSTRACT

There are some differences between fungi and nematodes infecting insects, such as in their mode of action or in their adaptation to the environment, that demonstrate the importance of a selection phase before using them to control a certain pest. The objective of this work was to select a fungus strain and a nematode species (total tested: 81 fungi and four nematodes) with high virulence to Dysmicoccus texensis. The fungi were applied on D. texensis at the concentration of 1 x 10⁸ conidia/mL, in 9 cm diameter Petri dishes containing 20 g of sterilized sand and a potato sprout, in which the insects were placed. The dishes were mantained in closed plastic boxes and kept in controlled conditions of temperature and humidity. The mortality evaluation was made at seven days after inoculation. Ten fungi strains were selected by causing higher mortality levels and submitted to a new bioassay to determine TL₅₀. Four nematode species were evaluated at the concentrations 25, 50 and 100 IJ/mealybug. The mortality evaluation was made daily until eight days after inoculation. The fungus Beauveria bassiana (UEL 114) and the nematode Steinernema carpocapsae were selected by causing high mortality in short time periods in adult females of this mealybug.

KEY WORDS:
Biological control; Coffea spp.; Insecta; subterranean pest.