A method of visualizing and assessing deposits of aerially sprayed insect microbes

A technique is described for visualizing and assessing deposits of various types of insect microbes on membrane filter surface. It is proposed as an accurate method of determining coverage of entomopathogenic microorganisms sprayed in a tower or from an aircraft in microbial control operations. The actual numbers of spores and/or crystals and number of International Units deposited per unit area, spore: crystal ratio, microbial impact droplet size, and spore viability of Bacillus thuringiensis have been determined with simulated aerial applications. The morphological integrity of different types of insect pathogens is easily distinguishable with the technique.Field trials with nuclear polyhedrosis virus of the spruce budworm, Choristoneura fumiferana, demonstrate the utility of the method in insect pest control by aerially applied microbial agents.