Fungal Associates of Soft Scale Insects (Coccomorpha: Coccidae).

Teresa Szklarzewicz,Katarzyna Michalik,Małgorzata Kalandyk-Kołodziejczyk,Beata Grzywacz,Anna Michalik

doi:10.3390/cells10081922

Abstract

Ophiocordyceps fungi are commonly known as virulent, specialized entomopathogens; however, recent studies indicate that fungi belonging to the Ophiocordycypitaceae family may also reside in symbiotic interaction with their host insect. In this paper, we demonstrate that Ophiocordyceps fungi may be obligatory symbionts of sap-sucking hemipterans. We investigated the symbiotic systems of eight Polish species of scale insects of Coccidae family: Parthenolecanium corni, Parthenolecanium fletcheri, Parthenolecanium pomeranicum, Psilococcus ruber, Sphaerolecanium prunasti, Eriopeltis festucae, Lecanopsis formicarum and Eulecanium tiliae. Our histological, ultrastructural and molecular analyses showed that all these species host fungal symbionts in the fat body cells. Analyses of ITS2 and Beta-tubulin gene sequences, as well as fluorescence in situ hybridization, confirmed that they should all be classified to the genus Ophiocordyceps. The essential role of the fungal symbionts observed in the biology of the soft scale insects examined was confirmed by their transovarial transmission between generations. In this paper, the consecutive stages of fungal symbiont transmission were analyzed under TEM for the first time.

Highlights

Scale insects are plant sap-sucking hemipterans that are considered serious pests in agriculture, horticulture, and forestry
Molecular analyses based on sequences of ITS2 and Beta-tubulin genes revealed that in all the species examined, the symbiotic fungi belonged to the Ophiocordycypitaceae family within the Ascomycota phylum (Ascomycota: Sordariomycetes: Hypocreales: Ophiocordycipitaceae)
Based on the sequences of the Beta-tubulin gene, two groups of symbiotic microorganisms may be distinguished: the first one includes symbionts of Eulecanium tiliae, Parthenolecanium corni, Parthenolecanium pomeranicum, and Parthenolecanium fletcheri, and the second one is comprised of the symbionts of remaining species

Summary

Introduction

Scale insects (coccoids) are plant sap-sucking hemipterans that are considered serious pests in agriculture, horticulture, and forestry. These insects cause direct damage to plants through sap-sucking and the injection of toxic saliva into plant tissue, which is a cause of the retardation of plant growth and recovery, and may lead to the death of the whole or part of the plant if the infestation is severe. After the Diaspididae and Pseudococcidae, the Coccidae (soft scales, coccids) is the third largest family of scale insects in terms of species richness. A large number of soft scale species are notorious plant pests that are of great economic importance to crops. Many pests of the Coccidae have been introduced into new zoogeographical regions, making them cosmopolitan [2]

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