Histopathological Investigations on Rickettsiella-like sp. and Nonoccluded Viruses Infecting the Pecan Weevil Curculio caryae, the Squash Beetle Epilachna borealis, and the Mexican Bean Beetle Epilachna varivestis
Electron microscopic observations of abnormal specimens of pecan weevils, Curculio caryae, squash beetles, Epilachna borealis, and Mexican bean beetles, Epilachna varivestis, obtained from insect-rearing facilities and from field collections revealed that rickettsia-like organisms (RLOs) and viruses caused disease in these species. Several pleomorphic forms of the RLOs which were similar to those of Rickettsiella sp. were found in tissues of the fat body, hypodermis, tracheal matrix, muscle, and midgut of each insect species. In addition, RLOs also were found in heart and silk gland tissues of the pecan weevil. Stalked knobs or "pili" were found on the cell membranes of the RLOs in the infected tissues of the pecan weevil and the squash beetle. Crystals often associated with Rickettsiella infections were not observed. Virus-like particles of 18-42 nm were found in various tissues of the three species examined.
Clark
TB
Insect Biocontrol Lab, U.S. Department of Agriculture, ARS, Beltsville, Maryland, 20705
Tompkins
GJ
Neel
WW
Schroder
RF
Schaefer
PW