Short Communication |
Corresponding author: Siegfried Keller ( siegfried.keller@bluewin.ch ) Academic editor: Oliver Martin
© 2022 Siegfried Keller.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Keller S (2022) Zoophthora giardii Bałazy and Conidiobolus gustafssonii Bałazy (Fungi, Entomophthorales), two entomopathogens new for Switzerland. Alpine Entomology 6: 19-23. https://doi.org/10.3897/alpento.6.83182
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Meconema meridionale Costa (Orthoptera, Tettigoniidae) infected with Zoophthora giardii Bałazy (Entomophthorales, Entomophthoraceae) were collected at five localities in the northern half of Switzerland. At one of these sites, the fungus caused epizootics in two subsequent years. Symptoms and morphological data coincide with those given by Bałazy who found the fungus on Meconema thalassinum De Geer. Conidiobolus gustafssonii Bałazy (Entomophthorales, Ancylistaceae) was found on a single Ectobius vittiventris Costa (Blattodea, Ectobiidae). Symptoms and dimensions of the primary conidia correspond with the original description given by Bałazy who found the fungus on Ectobius lapponicus L. The two fungi are new for Switzerland and Meconema meridionale and E. vittiventris represent new hosts for these pathogens.
Insect pathogenic fungi, morphology, distribution
The Neozygitales and the Entomophthorales belong to the phylum Entomophthoromycota of the fungal kingdom. They comprise mainly arthropod-pathogenic species but also members with a saprobiontic life style (
Recently, two insect species, the southern oak bush-cricket Meconema meridionale and the amber wood cockroach Ectobius vittiventris were found infected by entomophthoralean fungi in Switzerland. Both insects originate from the mediterranean region but are spreading northwards (T. Haye, pers. comm.). Ectobius vittiventris has colonized Germany up to Nordrhein-Westfalen (
Subsequent microscopic examination of the fungi revealed that they represented members of the genera Zoophthora and Conidiobolus that have not been recorded before in Switzerland. In the present paper, the fungi are described and discussed in detail.
An overview of the collected material is given in Table
Collection data of infected Meconema meridionale and Ectobius vittiventris. The coordinates were taken from www.map.swisstopo.admin.ch. The collection sites are followed by the official abbreviation of the corresponding Swiss canton.
Host | Collection site with coordinates | Host plant | Collector | Date of collection |
---|---|---|---|---|
Meconema meridionale | Bümpliz BE, 46.94187/7.38426 | Catalpa bignonioides | T. Haye | Sept. 17, 2020; Aug. 12, 2021; Aug. 25, 2021 |
Muttenz BL 47.53299/7.63401 | Catalpa bignonioides | T. Haye | Aug. 18, 2021 | |
Duggingen BL 47.53207/7.63426 | Fagus sylvatica | T. Haye | Aug. 18, 2021 | |
Eschenz TG 47.65028/8.85586 47.65228/8.87800 | Corylus avellana and Prunus sp. | S. Keller | Aug. 27, 2021; Sept. 02, 2021 | |
Regensdorf ZH (47.43588/8.4619 | Ceiling of a house entry | G. Graben-weger | Sept. 09, 2021 | |
Ectobius vittiventris | Bern BE 46.934176/7.431215 | Hedera helix | N. Häner | Aug. 25, 2021 |
A selection of infected M. meridionale and the dead E. vittiventris were placed individually in small Petri dishes with water. A microscopic slide was placed above the cadavers to collect the projected primary conidia. Secondary conidia were picked up from the water surface as described by
All measurements were based, if not otherwise stated, on 25 structures per individual host, except cystidia, designated as one series. Usually more than one series was studied from each structure, to assess variation. The number of series is given after the range of the mean values, the range of the extreme values (in brackets) and the ratio length/diameter (L/D).
Zoophthora giardii. 1. Infected male fixed with rhizoids on a leaf. 2. Infected female. Rhizoids between insect body and leaf are visible. 3. Cadaver from the ventral side showing the layer of rhizoids. 4. Compound rhizoids (LPCB). 5. Branched conidiophores (LPCB). 6. Primary conidia, two with capillary tube (LPCB). 7. Type II secondary conidia or capilliconidia with capillary tubes and remnants of primary conidia (LPCB).
The microscopic examination of the M. meridionale material revealed the following: The host body was completely filled with hyphae like hyphal bodies. The rhizoids, which fixed the host tightly to the surface consisted of compound hyphae (Fig.
Zoophthora giardii. Dimensions of the fungal structures in µm (PC = primary conidia, SC type II = secondary conidia of the capillary type, Cap. tube = capillary tube, CP = conidiophore, s.d. = standard deviation), based on 25 measurements each.
Structure and slide number | Length (L) (s.d.) min-max | Diameter (D), (s.d.), min-max | Ratio L/D | Stain |
---|---|---|---|---|
PC 20 | 21.5 (1.14) 20–24 | 7.2 (0.67) 6–8 | 3.00 | LPCB |
PC 24 | 21.6 (1.31) 19–24 | 7.0 (0.80) 6–8 | 3.08 | LPCB |
PC 29 | 20.0 (0.87) 19–21 | 7.0 (0.47) 6–8 | 2.86 | LPCB |
PC 30 | 20.4 (1.31) 19–24 | 6.8 (0.51) 6–7 | 3.01 | LPCB |
PC 34 | 21.2 (1.25) 19–24 | 7.2 (0.76) 6–8 | 2.96 | LPCB |
SC type II 17 | 20.1 (0.87) 19–21 | 5.7 (0.59) 5–7 | 3.55 | LPCB |
SC type II 21 | 20.3 (1.13) 19–22 | 6.0 (0.39) 6–7 | 3.36 | LPCB |
SC type II 24 | 20.8 (0.96) 19–22 | 6.0 (0.47) 5–7 | 3.48 | LPCB |
Cap. tube 17 | 76.5 (5.61) 66–85 | LPCB | ||
Cap. tube 20 | 92.4 (8.08) 80–112 | LPCB | ||
Cap. tube 24 | 75.1 (8.00) 61–94 | LPCB | ||
CP terminal portion | 25.1 (2.22) 21–30 | 5.8 (0.79) 5–7 | 4.36 | LPAO |
The diseased Ectobius was tightly fixed with compound rhizoids on a leaf of Hedera helix with the wings slightly opened. The cadaver was surrounded by a white halo of projected conidia (Fig.
Meconema meridionale and E. vittiventris represent new hosts for the corresponding fungus. Fungal material was deposited at the United Herbaria Zurich under the numbers ZT Myc 66704 and 66705 (Z. giardii) and ZT Myc 66706 (C. gustafssonii).
The description of the fungus attacking Meconema meridionale fits quite well the description of Z. giardii given by
The finding of Zoophthora giardii in Switzerland is not surprising since the species was previously recorded from France, Germany, and Poland (
According to the original description (
With these findings, the number of entomophthoralean fungi in Switzerland increases to 90 species (
The author thanks Tim Haye and Nina Häner, CABI Delémont, who provided fungus material, Giselher Grabenweger and Carmen Naef of Agroscope Reckenholz, who provided the infrastructure of their laboratory and helped with the microphotography, Tim Haye for critically reviewing the manuscript and for providing additional information, and Mark Goettel, formerly at Lethbridge Research Center, Canada, for reviewing the manuscript and helping with the English phraseology.