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In This Article

  • Summary
  • Abstract
  • Introduction
  • Protocol
  • Representative Results
  • Discussion
  • Acknowledgements
  • Materials
  • References
  • Reprints and Permissions

Summary

Here we present a method for studying Colorado potato beetle hibernation under the natural conditions of the temperate zone as well as a technique for collecting beetles in winter. This method allows to obtain a desired number of overwintering individuals for various analyses at any stage of hibernation.

Abstract

One of the major pests of potato Solanum tuberosum L. in the temperate zone is the insect Colorado potato beetle (CPB). Most studies on the immunity and diseases of the CPB are conducted during active feeding stages. Nonetheless, there are fewer studies on resting stages, although these beetles spend most of their life cycle in a state of winter diapause (hibernation). In this work, a method for investigating CPB hibernation under natural conditions was developed and tested, offering an opportunity to collect a sufficient number of individuals in winter. In this article, CPB survival was assessed, and infectious agents at different stages of hibernation were identified. CPB mortality increased during the hibernation, reaching a maximum in April-May. Entomopathogenic fungi (Beauveria, Isaria, and Lecanicillium) and bacteria Bacillus, Sphingobacterium, Peribacillus, Pseudomonas, and Serratia were isolated from the dead insects. The survival rate of the beetles for the entire hibernation period was 61%. No frozen or desiccated beetles were found, indicating the success of the presented method.

Introduction

The Colorado potato beetle Leptinotarsa decemlineata Say (CPB) is an important pest of Solanaceae plants, predominantly potato Solanum tuberosum L. The geographic range of this species is more than 16 million km2 and constantly expands1. The CPB has facultative winter diapause, and hibernation is obligatory in the temperate zone. The diapause is induced by a short-day photoperiod and modulated by temperature1. These beetles overwinter in the adult stage by burrowing into soil. With increasing latitudes, the duration of the hibernation period extends. In the temperate zone, especially on north....

Protocol

1. Description of the cages for hibernation

NOTE: Depending on the aims of the experiment, the number of cages varies. Use at least three cages per sampling date. To estimate the number of beetles that will emerge, prepare at least three additional cages, which will not be taken out of the soil until spring.

  1. Use cages made of a rigid wooden frame with a size of 25 × 25 × 40 cm (L × W × H).
  2. To build a frame for the c.......

Representative Results

The results below on overwintering CPBs show soil temperature, survival, and infections.

Soil temperature dynamics.
Temperatures below zero in the cages at a depth of 30 cm were registered from the end of November to the beginning of April (Figure 1). The average temperature during this period was minus 3.3 ± 0.1 °C (mean ± standard error). The lowest recorded temperature was minus 7.9 °C in mid-February.

Discussion

This study shows that the proposed method for studying the overwintering of CPBs enables us to obtain a sufficient number of insects in different periods of hibernation. The success of the presented technique depends on several independent factors, the most important of which is weather conditions. In a cold, snowless winter, the soil may freeze to the entire depth of the cage. In this case, the risk of death of all beetles goes up significantly18. The survival of the beetle depends on a combinati.......

Acknowledgements

We thank our colleagues Vladimir Shilo, Vera Morozovа, Ulyana Rotskaya, Olga Polenogova, and Oksana Tomilova for their help with organizing and execution of the field and laboratory procedures.

The research was supported by the Russian Science Foundation, project No. 22-14-00309.

....

Materials

NameCompanyCatalog NumberComments
Agar-agar bacteriological purifieddiaGene1806.5000
Bile Esculin AgarHiMediaM972
Endo Agar HiMediaM029
Glucose monohydrate-DPanReac Applichem143140.1000Φ
Lactic acid PanReac Applichem141034.1211
Luria-Bertani liquid mediumHiMediaG009
15 ml conical centrifuge tubesAxygenSCT-15ML-25-S
PeptoneFBIS SRCAMBMfigure-materials-920030/O61
Phosphate buffered salineMedigenPBS500
Temperatutre and humidity datalogger Ecklerk-M-11RelsibWaterproof datalogger

References

  1. Alyokhin, A., Benkovskaya, G., Udalov, M. Colorado potato beetle. Insect Pests of Potato. , 29-43 (2022).
  2. Alyokhin, A., Kryukov, V. Ecology of a potato field. Insect Pests of Potato. , 451-462 (2022).
  3. Lee Jr, R. E., Costanzo, J. P., Kaufman, P. E., Lee, M. R., Wy....

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Colorado Potato BeetleHibernationOverwinteringExperimental StudyPotato PestTemperate ZoneCage DesignSoilTemperature And HumidityData LoggersPotato PlantsInsect Collection

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