Investigation on the Microflora of White Peach Scale Pseudaulacaspis pentagona (TargioniTozzetti) (Hemiptera: Diaspididae) in Order to Assess Its Significance as Vector of Pathogenic Microorganisms

Abstract

Studies on the microflora of white peach scale Pseudaulacaspis pentagona (Targioni-Tozzetti) (Hemiptera: Diaspididae) on Morus alba L. and Prunus persica (L.) were performed to assess its pathogenic potential. Sixteen microorganisms were isolated from scales developing on mulberry. Gram-negative species of the family Enterobacteriaceae were prevailing. Of them pathogenic for plants is Erwinia amylovora, while pathogenic potential for animals and humans have Proteus myxofaciens, Providencia rettgeri, Hafnia alvei, Serratia ficaria, Xanthomonas maltophilia, as well as the Gram-positive staphylococci, bacilli and clostridia. A similarity between external and internal microflora was not established. Oval fungi were not isolated, but filamentous species were detected only in the digestive tract: Penicillium brevicompactum, Aspergillus fumigatus (pathogenic for mammals and birds) and Nectria auranticola (pathogenic for scale insects). In the scales developing on peach the Gram-positive species prevailed, presented by cocci, bacilli, clostridia, listeria and fungi. The Gram-negative bacteria isolated were conditionally pathogenic to animals and humans. Diversity of representatives of the family Enterobacteriaceae was greatest, followed by Pseudomonas diminuta, Flavimonas oryzihabitans and Acinetobacter sp. Bacteria of the genera Enterobacter, Citrobacter and Acinetobacter were detected only in the digestive tract of the insects studied. Hafnia alvei was isolated also from their surface, while Klebsiella pneumoniaе rhinoscleromatis was part only of the surface microflora. A great similarity in Gram-positive species with exogenous and endogenous localization was noted. The quantities of microorganisms isolated from the inside of the insects, exceed those of the same species found on their surface, with the exception of Hafnia alvei. The same filamentary fungi as in scales from mulberry were established, but supplemented by Candida tropicalis, Candida krusei and Monilia sp.