Open Access
Issue
BIO Web Conf.
Volume 18, 2020
IV All-Russian Plant Protection Congress with international participation “Phytosanitary Technologies in Ensuring Independence and Competitiveness of the Agricultural Sector of Russia”
Article Number 00019
Number of page(s) 4
DOI https://doi.org/10.1051/bioconf/20201800019
Published online 06 March 2020

© The Authors, published by EDP Sciences, 2020

Licence Creative Commons
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Beet webworm Loxostege sticticalis (L.) is a dangerous insect pest that damages many agricultural crops such as beets, soybeans, sunflowers, corn and others. It has eruptive type of population dynamics and high migratory activity: adult moths are capable of flying over distances of more than a thousand kilometers. The beet webworm outbreaks are therefore difficult to predict and the pest belongs to the category of highly dangerous pests. At the same time, during periods of depressions this insect is not observed within the most of its range and is very susceptible to infection by pathogens, including various species of microsporidia, some of which are not specific parasites of the order Lepidoptera. The distribution of beet webworms microsporidia in Eurasia is quite extensive (Fig. 1). Beet webworm microsporidia were found in Russia (The Republic of Buryatia, Irkutsk region, Novosibirsk region, Republic of Bashkortostan, Saratov region, Stavropol Territory, Krasnodar Territory, Rostov region) and Moldova. A single record is also attributed to a moth sampling from Hebei, China, but without specimen deposition to our collection.

Biodiversity of beet webworm microsporidia is presented in Table 1. In the 70-80-s of the 20th century, two species of microsporidia were discovered in beet webworm, namely Nosema loxostegi [2] and Vairimorpha (Nosema) thomsoni [3]. During the study period of the beet webworm from 2003 to 2019 we have found 6 species of microsporidia. The parasite list includes not only species known for Lepidoptera, but also Vairimorpha N. ceranae) (according Tokarev et al. (2019) which is the typical pathogen of the honey bee Apis mellifera (L.) (Hymenoptera: Apidae) [4], as well as Endoreticulatus cf poecilimonae [5], a pathogen similar to Endoreticulatus poecilimonae from grasshopper Poecilimon thoracicus (Fieber) (Orthoptera: Tettigoniidae). Moreover, two isolates of the genus Tubulinosema which belong to the group of parasites (family Tubulinosematidae) with a very wide host range, including humans, were identified in the beet webworm [6].

In laboratory experiments, the beet webworm proved high sensitivity to microsporidia N. pyrausta from the corn borer Ostrinia nubilalis (Hübner) (Lepidoptera: Pyralidae) and N. tyriae from the cinnabar moth Tyria jacobaeae (L.) (Lepidoptera: Arctiidae). Its susceptibility to Paranosema locustae from migratory locusts Locusta migratoria (L.) (Orthoptera: Acrididae) has also been discovered.

Such a high diversity of microsporidia has not been detected in other examined species of lepidopteran insects. For example, only one species of microsporidia, N. pyrausta, is characteristic of the corn borer in Eurasia [7]. Three species of microsporidia are known for the corn earworm Helicoverpa armigera (Hübner) and four species for the turnip moth Agrotis segetum (Denis and Schiffermüller) [8].

Our further task is to study the biodiversity of insects that live in the same localities as the beet webworm as possible carriers of microsporidia and other obligate intracellular pathogens. This will provide new knowledge on the role of intracellular pathogens in the phenomenon of outbreak periodicity of the beet webworm.

thumbnail Fig. 1.

Microsporidian beet webworm collection places on the map “Area of distribution and harmfulness of the Beet Webworm (Loxostege sticticalis L.)” [1]

Table 1.

Prevalence rates of Microsporidia in Loxostege sticticalis sampled across Russia, and adjacent territories

References

All Tables

Table 1.

Prevalence rates of Microsporidia in Loxostege sticticalis sampled across Russia, and adjacent territories

All Figures

thumbnail Fig. 1.

Microsporidian beet webworm collection places on the map “Area of distribution and harmfulness of the Beet Webworm (Loxostege sticticalis L.)” [1]

In the text

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