The Colorado potato beetle (CPB; Leptinotarsa decemlineata) is an important potato pest with known resistance to pyrethroids and organophosphates in Czechia. Decreased efficacy of neonicotinoids has been observed in last decade. After the restriction of using chlorpyrifos, thiacloprid and thiamethoxam by EU regulation, growers seek for information about the resistance of CPB to used insecticides and recommended antiresistant strategies. The development of CPB resistance to selected insecticides was evaluated in bioassays in 69 local populations from Czechia in 2017-2022 and in 2007-2022 in small plot experiments in Zabcice in South Moravia. The mortality in each subpopulation in the bioassays was evaluated at the field-recommended rates of insecticides to estimate the 50% and 90% lethal concentrations (LC50 and LC90, respectively). High levels of CPB resistance to lambda-cyhalothrin and chlorpyrifos were demonstrated throughout Czechia, without significant changes between years and regions. The average mortality after application of the field-recommended rate of lambda-cyhalothrin was influenced by temperature before larvae were sampled for bioassays and decreased with increasing temperature in June. Downwards trends in the LC90 values of chlorpyrifos and the average mortality after application of the field-recommended rate of acetamiprid in the bioassay were recorded over a 6-year period. The baseline LC50 value (with 95% confidence limit) of 0.04 mg/L of chlorantraniliprole was established for Czech populations of CPBs for the purpose of resistance monitoring in the next years. Widespread resistance to pyrethroids, organophosphates and neonicotinoids was demonstrated, and changes in anti-resistant strategies to control CPBs were discussed.

• MeSH
• Coleoptera * drug effects   MeSH
• Chlorpyrifos * pharmacology   MeSH
• Insecticides * pharmacology   MeSH
• Larva drug effects   MeSH
• Neonicotinoids * pharmacology   MeSH
• Nitriles pharmacology   MeSH
• Pyrethrins pharmacology   MeSH
• Insecticide Resistance * MeSH
• Solanum tuberosum parasitology   MeSH
• Thiamethoxam MeSH
• Thiazines * MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Czech Republic MeSH
• Names of Substances
• cyhalothrin MeSH Browser
• Chlorpyrifos * MeSH
• Insecticides * MeSH
• Neonicotinoids * MeSH
• Nitriles MeSH
• Pyrethrins MeSH
• thiacloprid MeSH Browser
• Thiamethoxam MeSH
• Thiazines * MeSH

A panel of X-linked microsatellite markers was newly designed using the data from a previous sequencing project available in NCBI and used for a study of the Colorado potato beetle (CPB, Leptinotarsa decemlineata) X-haplotype variability. The analysis of scaffolds 49 and 61 (newly identified as fragments of CPB chromosome X) found ten high-quality markers, which were arranged in two PCR multiplexes and evaluated in both 420 CPB adults, collected from 14 localities of Czechia and Slovakia, and 866 larvae from five single-female families from two more Czech localities. Length polymorphisms found in 6 loci have predicted 192 potential X-haplotypes, however, only 36 combinations were detected in the adult males (N = 189), and seven additional ones in the larvae. The X-haplotypes were also generally unevenly distributed; five of the most frequent haplotypes were detected in 55% of males, 19 repeating up to ten-times in 38.7% of males and the remained 12 occurred uniquely in 6.3% of males. Bulk analysis of X-haplotypes dissimilarity indicated seven haplotype groups diversified by mutations and recombinations. Two haplotypes showed a distinctive regional distribution, which indicates an east-west disruption of CPB migration probably caused by different environments of localities in the South Bohemia region and Vysocina region. On the contrary, the results indicate a south-north migration corridor alongside the Vltava River. In the single-female families, from 6 to 13 distinct paternal haplotypes were detected, which proved and quantified a frequented polyandry in CPB.

• MeSH
• Coleoptera * genetics   MeSH
• Larva genetics   MeSH
• Humans MeSH
• Mutation MeSH
• Polymorphism, Genetic MeSH
• Solanum tuberosum * genetics   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH

The Colorado potato beetle, Leptinotarsa decemlineata (Say), is a serious, widely distributed pest of potato and other crops. This pest is able to defoliate the host plant and cause severe yield loss. Moreover, the pest quickly becomes resistant to many chemical pesticides. Therefore, the development of novel biopesticides targeting this pest is urgently needed. The purpose of this study was to obtain new strains of the entomopathogenic fungus Beauveria bassiana and assess their efficacy against L. decemlineata adults under laboratory conditions. Twelve strains were isolated from cadavers of Colorado potato beetles collected in potato fields in the Czech Republic. Test beetles were treated by suspensions of conidia at the concentration of 1 × 107 spores per milliliter and their survival was recorded daily for three weeks. The results of the bioassays revealed that all new native strains were pathogenic to L. decemlineata adults and caused mortality up to 100% at the end of the trial period with an LT50 of about 7 days. These strains were more virulent than a reference strain GHA and some of them can be recommended for the development of a new mycoinsecticide against L. decemlineata. Our findings also highlight the importance of searching for perspective strains of entomopathogenic fungi among naturally infected hosts.

• Keywords
• biological control, efficacy, entomopathogenic fungi, insect pest, mycoinsecticides, potato,
• Publication type
• Journal Article MeSH

The Colorado potato beetle, Leptinotarsa decemlineata, has developed resistance to most registered pesticides and has become one of the most difficult insect pests to control. Development of new biopesticides targeting this pest might solve the resistance problem and contribute to sustainable crop production. Laboratory experiments were conducted to assess the efficacy of Isaria fumosorosea (syn. Paecilomyces fumosoroseus) strain CCM 8367 against L. decemlineata when applied alone or combined with the entomopathogenic nematode Steinernema feltiae. The last-instar larvae of the Colorado potato beetle showed the highest susceptibility to I. fumosorosea followed by pre-pupae and pupae. The median lethal concentration (LC50) was estimated to be 1.03×106 blastospores/ml. The strain CCM 8367 was more virulent, causing 92.6% mortality of larvae (LT50 = 5.0 days) compared to the reference strain Apopka 97, which caused 54.5% mortality (LT50 = 7.0 days). The combined application of the fungus with the nematodes increased the mortality up to 98.0%. The best results were obtained when S. feltiae was applied simultaneously with I. fumosorosea (LT50 = 2.0 days); later application negatively affected both the penetration rate and the development of the nematodes. We can conclude that the strain CCM 8367 of I. fumosorosea is a prospective biocontrol agent against immature stages of L. decemlineata. For higher efficacy, application together with an entomopathogenic nematode is recommended.

• MeSH
• Pest Control, Biological * MeSH
• Biological Control Agents MeSH
• Biological Assay MeSH
• Coleoptera growth & development   microbiology   MeSH
• Nematoda MeSH
• Hypocreales * MeSH
• Larva microbiology   MeSH
• Multivariate Analysis MeSH
• Paecilomyces * MeSH
• Rhabditida * MeSH
• Temperature MeSH
• Virulence MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Biological Control Agents MeSH