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Title: HISTOPATHOLOGICAL INVESTIGATIONS ON RICKETTSIELLA-LIKE SP. AND NONOCCLUDED VIRUSES INFECTING THE CURCULIO CARYAE (HORN), THE EPILACHNA BOREALIS (FABRICIUS), AND THE EPILACHNA VARIVESTIS MULSANT

Author
item Adams, Jean
item CLARK, TRUMAN - DECEASED
item TOMPKINS, GEORGE - EPA
item NEEL, WILLIAM - RETIRED
item Schroder, Robert
item SCHAEFER, PAUL - 1926-05-00

Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/23/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Insect mass rearing facilities are needed to produce insects for biological testing. Sometimes diseases occur causing problems of economic importance. We received "sick" larval specimens of pecan weevils, squash beetles, and Mexican bean beetles from several insect mass rearing facilities. The primary cause of the disease was a microorganism smaller than bacteria that is called a Rickettsiella -like organism. The beetles were also infected with several small spherical viruses. These microorganisms are specific in activity, infecting only insects, and may be useful in the development of microbial control strategies for controlling these insect pests. All who rear insects in insect mass rearing facilities will benefit greatly from this report since they will be alerted of the possible pathogens that could cause them problems in their efforts to rear "disease-free" insects for biological tests. All scientists who use insects as test insects will benefit by obtaining more reliable data from their tests conducted using of healthy insects.

Technical Abstract: Histopathological investigations were made on diseased specimens of pecan weevils, squash beetles, and Mexican bean beetles. Electron microscopic examinations revealed that the primary pathogen involved was a Rickettsiella-like organism (RLO). Extensive infection occured in the fat body, midgut, and Malpighian tubules with lower infections in heart, muscle, tracheal matrix, silk gland, hypodermis, and blood cells of pecan weevil larvae. The principal tissues infected in the squash beetles and Mexican bean beetles were the midgut, fat body, muscle and tracheal matrix. This RLO is pleomorphic. Elementary bodies or "standard cells", coccoid forms, and "secondary cells" or bacilliform bacteria were found. Pili were observed on "secondary cells" of squash beetles and Mexican bean beetles. No crystals were observed in the specimens examined. Three virus-like particles (VLPs) were observed in these beetles. Spherical VLPs of 39-42 nm diameter were found in vesicles in heart, muscle and tracheal matrix in pecan weevils as well as VLPs of 18 nm diameter in muscle tissues. VLPs of 36 nm were found in degenerating fat body of squash beetle larvae. VLPs of 39-42 nm diameter were found in muscle and tracheal matrix associated with the hypodermis as well as VLPs of 50 nm diameter in viroplasm in the posterior midgut cytoplasm of Mexican bean beetle larvae.