Colorado Potato Beetle Leptinotarsa Decemlineata Research Articles

Past, present and future of the two-spotted stink bug (Perillus bioculatus) in Europe revealed by citizen science

The introduction of the Nearctic predaceous stink bug species, (Perillus bioculatus) was attempted multiple times in various countries throughout Europe to mitigate the damage caused by the invasive and harmful pest species, the Colorado potato beetle (Leptinotarsa decemlineata). Though these attempts were thought to be unsuccessful for decades, more recent data elucidated that the species have established small self-sustaining populations in the Balkans Peninsula, Southern Russia, and Türkiye and recently began to expand. In the past years, the European range of the species reached Eastern Europe. After the first individuals were found in Hungary in October 2023 a citizen science campaign was launched to investigate the distribution of the species in the country. By June 2024 it became evident that the species is established throughout the country. Furthermore, observations regarding beetle larvae and moth caterpillars as alternative prey were reported supporting the previous assumptions that the naturalization and expansion of the species in Europe is facilitated by dietary drift. Here, we summarize the knowledge on the European presence of the two-spotted stink bug and formulate hypotheses regarding its future distribution and the impact of the species on the insect communities of the newly colonized areas.

Identification and Functional Insights of Knickkopf Genes in the Larval Cuticle of Leptinotarsa decemlineata.

The Colorado potato beetle (Leptinotarsa decemlineata) is a major pest of potato crops. While Knickkopf (Knk) genes are essential for insect cuticle formation, their roles in pests like L. decemlineata remain unclear. This study aims to identify and characterize Knk genes in L. decemlineata and explore their functions in larval development and cuticle integrity. We used genomic and transcriptomic databases to identify LdKnk-family genes, validated through RT-PCR and RACE. Gene expression was analyzed at various developmental stages and tissues using qRT-PCR. RNA interference (RNAi) and Transmission electron microscopy (TEM) were applied to determine the functional roles of these genes. Four LdKnk-family genes were identified. Spatio-temporal expression analysis indicated significant gene expression during larval molting and pupal stages, especially in the epidermis. RNAi experiments showed that silencing LdKnk and LdKnk3-5' led to reduced larval weight, cuticle thinning, and increased mortality, while LdKnk3-FL knockdown caused abnormal cuticle thickening and molting disruptions. LdKnk2 knockdown increased epicuticle and endocuticle thickness without visible phenotypic changes. The study highlights the essential roles of LdKnk-family genes in maintaining cuticle structure and integrity, suggesting their potential as targets for RNAi-based pest control.

Isolation and identification of entomopathogenic fungi strains for Colorado potato beetle (Leptinotarsa decemlineata) control.

The Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae) is the most widespread insect pest that causes major economic losses, especially on potatoes. Due to heavy insecticide use, this species now resists most pesticides, posing a significant control challenge. Frequent pesticide application also harms non-target organisms, the environment, and human health. Hence, utilizing biocontrol agents like entomopathogenic fungi (EPF) offers a viable alternative for pest management. The aim of this study was to identify and characterize new EPF strains isolated from soil samples and evaluate their efficacy against adult L. decemlineata under laboratory conditions. Soil samples were collected in potato fields or uncultivated areas adjacent to the field in the Czech Republic and the EPF strains were isolated using a modified Tenebrio bait method. A total of 20 fungal strains were isolated and identified using morphological and molecular markers based on the 28S rRNA, ITS, and elongation factor 1-alpha gene sequences as Beauveria bassiana (Bals.-Criv.) Vuill., Beauveria brongniartii (Sacc.) Petch, and Cordyceps fumosorosea (Wize) Kepler, B. Shrestha & Spatafora (Hypocreales: Cordycipitaceae), Purpureocillium lilacinum (Thom.) Luangsa-ard, Houbraken, Hywel-Jones & Samson (Hypocreales: Ophiocordycipitaceae), Metarhizium brunneum (Petch), and Metarhizium robertsii Bisch., Rehner & Humber (Hypocreales: Clavicipitaceae). The bioassays revealed high variability among virulence of these strains against L. decemlineata with the shortest median time to death (LT50=5 days) in M. robertsii strain MAN3b. Results shown that some EPF strains, particularly those of genera Metarhizium, can be promising biocontrol agents against the Colorado potato beetle.

The genome history of Bacillus thuringiensis subsp. tenebrionis: From discovery to present day product

AbstractBacillus thuringiensis subsp. tenebrionis (Btt) was discovered in 1982 and has been used as a biological control agent against the Colorado potato beetle (Leptinotarsa decemlineata) since the early 1990s. In this study, we sequenced, assembled and analysed the genome of strain DSM 2803, which is the patent deposit of the original Btt isolate BI 256‐82. A high‐quality reference genome is provided that allows investigating the genomic changes throughout the commercial history of Btt. Strain DSM 2803 (BI 256‐82) is particularly interesting since the subspecies description of ‘tenebrionis’ is based on it and because it represents the genomic origin of the commercial Btt strain currently used in plant protection. Comparative genome analysis of six Btt strains derived from BI 256‐82 revealed that the genomes were generally highly similar. However, some plasticity in the profile of extrachromosomal elements was detected, including recombination‐dependent plasmid differences and the presence/absence of a circular plasmid‐like prophage.

The integral role of de novo lipogenesis in the preparation for seasonal dormancy

Animals can alter their body compositions in anticipation of dormancy to endure seasons with limited food availability. Accumulation of lipid reserves, mostly in the form of triglycerides (TAGs), is observed during the preparation for dormancy in diverse animals, including insects (diapause) and mammals (hibernation). However, the mechanisms involved in the regulation of lipid accumulation and the ecological consequences of failure to accumulate adequate lipid stores in preparation for animal dormancy remain understudied. In the broadest sense, lipid reserves can be accumulated in two ways: the animal either receives lipids directly from the environment or converts the sugars and amino acids present in food to fatty acids through de novo lipogenesis and then to TAGs. Here, we show that preparation for diapause in the Colorado potato beetle (Leptinotarsa decemlineata) involves orchestrated upregulation of genes involved in lipid metabolism with a transcript peak in 8- and 10-d-old diapause-destined insects. Regulation at the transcript abundance level was associated with the accumulation of substantial fat stores. Furthermore, the knockdown of de novo lipogenesis enzymes (ACCase and FAS-1) prolonged the preparatory phase, while the knockdown of fatty acid transportation genes shortened the preparatory phase. Our findings suggest a model in which the insects dynamically decide when to transition from the preparation phase into diapause, depending on the progress in lipid accumulation through de novo lipogenesis.

Reduction of Colorado potato beetle damage by various organic mulches

IntroductionThe Colorado potato beetle (Leptinotarsa decemlineata) (CPB) is a major threat to potato crops in Europe, Asia, and America. In Europe, it is expected that climate change will cause the species to expand its range northwards and allow for an additional generation per year in regions where it is already established. The effectiveness of insecticides, a common method of control, is decreasing due to the emergence of resistance to several substances. Therefore, research into alternative measures is becoming increasingly necessary. One preventive measure that has already been shown to have great effects in past studies is the use of organic mulch. For organic mulching, conserved or freshly cut plant material is spread on the field usually when the potato emerges. Previous research has mainly used cereal straw for this purpose in plots that are relatively small compared to actual agricultural fields. Materials and methodsTo address the lack of large-scale field trials in the literature, a series of on-station and on-farm field trials were conducted in this study. Organic, legume-rich mulches were used primarily, which so far have not been extensively investigated. Over a period of four years and in a total of six field trials, CPB and larval infestations were assessed. Results and discussionOur results show effects on the initial infestation of young plants by adult CPB and on the emergence time of the first two larval stages. By the time of flowering, when the feeding effect of CPB on yield is known to be greatest, L3 and L4 larvae were reduced by about 30% in the on-station trials and by about 40% in the on-farm trials. In addition, when CPB larval stages were used to calculate a weighted daily leaf consumption per stage, total calculated leaf consumption was on average about 40% lower in the mulch treatments across all sampling dates and all trials. The recorded yields were equal or higher in the mulched treatments. In conclusion, organic mulching can effectively reduce CPB damage even on a large scale and can have a positive impact on yield. Further agronomic benefits of mulching, as well as drawbacks and putative mechanisms of action, are discussed.

Potato productivity on the background of the entomopathogenic fungus <i>Metarhizium robertsii</i> application in production trials

For the first time in Western Siberia (Novosibirsk region), two-year production trials of an experimental prototype of a drug based on the entomopathogenic fungus Metarhizium robertsii have been conducted. Strain P-72 isolated from the dead larvae of Colorado potato beetle Leptinotarsa decemlineata Say from the collection of microorganisms of the Institute of Systematics and Ecology of Animals of the Siberian Branch of the Russian Academy of Sciences was used in this work. Species identification of the fungus was performed based on sequencing of the elongation factor gene region EF1α. The ability of the preparation to significantly increase the parameters of potato yield structure elements throughout the whole vegetation period was shown. A reliable increase in the number of surviving sprouts by 1.4 times, the number of stems and tubers by 1.5 times was found. The growth-stimulating effect of using the preparation based on entomopathogenic fungus was manifested in the increase of plant weight by the flowering phase. The average yield increase for two years amounted to 36.0% in the variant with application of M. robertsii significantly exceeding the productivity of potatoes in the control. The level of profitability of potato production with the use of entomopathogenic fungus M. robertsii increased to 92.0% (with 50.0% in the control) due to the increase in gross yield and improved quality of marketable products. Infestation of new harvest tubers with rhizoctoniose significantly decreased in the variant including treatment with entomopathogenic fungus: the number of tubers with sclerotia decreased 2.8 times compared to the control, which eventually led to an increase in the number of healthy tubers and a significant (2.5 times) decrease in the sclerotial index.

William Lawrence Tower's Beetles: Experimental Evolution and the Manipulation of Inheritance.

William Lawrence Tower's work on the evolution of the Colorado Potato Beetle (Leptinotarsa decemlineata), documenting the environmental induction of mutation and speciation, made him a leading figure in experimental genetics during the first decade of the 20th century. His research program served as a model for other experimental evolution studies seeking to demonstrate the environmental modification of inheritance. Tower enjoyed the support of influential figures in the field, despite well-known problems that plagued Tower's earlier academic career. The validity of his genetic work, and other findings reported by Tower, were later challenged. The Tower affair illustrates how questionable and possibly fraudulent scientific practices can be tolerated to explore certain experimental directions and theoretical frameworks, particularly at the frontier of expanding disciplines. When needed, those explorations can be forestalled or extinguished by exploiting conspicuous vulnerabilities of rogue practitioners. In Tower's case, both unrefuted allegations of scientific misconduct and personal problems dissolved his institutional support, leading to a swift ouster from academic science. Tower's downfall discredited soft inheritance and neo-Lamarckian conceptions in the field of experimental genetics, facilitating the discipline's embrace of a hard inheritance model that featured a hereditary material resistant to environmental modification.

Cyantraniliprole and Thiamethoxam Exposure Changes Expression of Transcripts Associated with Small Non-Coding RNA Processing in the Colorado Potato Beetle.

The Colorado potato beetle (Leptinotarsa decemlineata (Say)) can cause extensive damage to agricultural crops worldwide and is a significant insect pest. This insect is notorious for its ability to evade various strategies deployed to control its spread and is known for its relative ease in developing resistance against different insecticides. Various molecular levers are leveraged by L. decemlineata for this resistance to occur, and a complete picture of the genes involved in this process is lacking. While small non-coding RNAs, including miRNAs, are differentially expressed in insects exposed to insecticides, levels of transcript coding for proteins underlying their synthesis remain to be characterized fully. The overarching objective of this work aims to fill that gap by assessing the expression of such targets in L. decemlineata exposed to cyantraniliprole and thiamethoxam. The expression status of Ago1, Ago2, Ago3, Dcr2a, Dcr2b, Expo-5, Siwi-1 and Siwi-2 transcripts were quantified via qRT-PCR in adult L. decemlineata treated with low and high doses of these compounds for different lengths of time. Variation in Ago1 and Dcr2b expression was notably observed in L. decemlineata exposed to cyantraniliprole, while thiamethoxam exposure was associated with the modulation of Dcr2a and Siwi-1 transcript levels. The down-regulation of Ago1 expression in L. decemlineata using dsRNA, followed by cyantraniliprole treatment, was associated with a reduction in the survival of insects with reduced Ago1 transcript expression. Overall, this work presents the insecticide-mediated modulation of transcripts associated with small non-coding RNA processing and showcases Ago1 as a target to further investigate its relevance in cyantraniliprole response.

The effect of Xenorhabdus bacteria metabolites on Colorado potato beetle (Leptinotarsa decemlineata) adult feeding and larval survival

Colorado Potato Beetle (CPB) is one of the most destructive potato pests that can quickly develop resistance to insecticides. Therefore, new safe and effective control strategies that are less susceptible to the development of resistance by CPB are urgently needed. Due to their complex mode of action, the likelihood of resistance development by target pests is generally low with antifeedants. In the present study, we assessed the effect of secondary metabolites of various Xenorhabdus bacteria species and strains on CPB adult feeding and on larval development. The metabolites were applied in the form of cell free supernatants (CFSs) from Xenorhabdus cultures. In bioassay 1, leaves treated with ten Xenorhabdus cultures were fed to CPB adults, and their feeding was assessed daily for one week. In bioassay 2, CPB egg masses were placed on the leaves treated with five bacterial cultures, and larval development to pupae was monitored. Out of the ten Xenorhabdus cultures tested, two strains exhibited a significant reduction in the feeding behavior of Colorado Potato Beetle adults, with reductions of up to 70% compared to the control. The effect of CFSs on larval development was variable, and when treated with X. khoisanae SGI 197, over 90% of larvae died in the first few days before reaching the 2nd instar, and complete mortality was achieved on the 8th day of the experiment. Our study is the first study to demonstrate the antifeedant effect of Xenorhabdus cultures towards herbivorous beetles, and the metabolites of these bacteria may have potential for CPB control. Clearly, the metabolites produced by X. khoisanae SGI-197 may be a promising tool for CPB larvae control with the potential to significantly decrease damage to potato plants.

Draft Genome Sequencing of the Bacillus thuringiensis var. Thuringiensis Highly Insecticidal Strain 800/15

The Bacillus thuringiensis serovar thuringiensis strain 800/15 has been actively used as an agent in biopreparations with high insecticidal activity against the larvae of the Colorado potato beetle Leptinotarsa decemlineata and gypsy moth Lymantria dispar. In the current study, we present the first draft genome of the 800/15 strain coupled with a comparative genomic analysis of its closest reference strains. The raw sequence data were obtained by Illumina technology on the HiSeq X platform and de novo assembled with the SPAdes v3.15.4 software. The genome reached 6,524,663 bp. in size and carried 6771 coding sequences, 3 of which represented loci encoding insecticidal toxins, namely, Spp1Aa1, Cry1Ab9, and Cry1Ba8 active against the orders Lepidoptera, Blattodea, Hemiptera, Diptera, and Coleoptera. We also revealed the biosynthetic gene clusters responsible for the synthesis of secondary metabolites, including fengycin, bacillibactin, and petrobactin with predicted antibacterial, fungicidal, and growth-promoting properties. Further comparative genomics suggested the strain is not enriched with genes linked with biological activities implying that agriculturally important properties rely more on the composition of loci rather than their abundance. The obtained genomic sequence of the strain with the experimental metadata could facilitate the computational prediction of bacterial isolates’ potency from genomic data.

Efficacy of three bioinsecticides for control of Colorado potato beetle on potatoes

An experiment was conducted to evaluate the effectiveness of three commercial bioinsecticides based on the spores of Bacillus thuringiensis var. thuringiensis. The control areas were areas where no protective measures were applied. The data showed that all bioinsecticides tested were highly effective against first, second and third instar larvae of the Colorado potato beetle Leptinotarsa decemlineata. The drug “Bitoxibacillin” ensured 100% death of larvae on day 8 at a drug concentration of 10 g/l. Combined preparation “Bitoxibacillin + GUMI” containing spores of Bacillus thuringiensis var. thuringiensis and sodium salts of humic acids, led to 100% death of larvae on the 7th day of observation. As the dosage of the drug was reduced to 5 mg/L, its effectiveness decreased to a 92% mortality rate within 9 days. The complex drug “Bitoxibacillin + Actarofid” contributed to 100% death of Colorado potato beetle larvae of all ages on the 7th day of observation at a concentration of 10 g/l. During the same time interval, 82% and 94% of the larvae died at drug concentrations of 2 mg/l and 5 mg/l, respectively.

Six-year monitoring of pesticide resistance in the Colorado potato beetle (Leptinotarsa decemlineata Say) during a neonicotinoid restriction period.

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.

Predator densities alter the influence of non‐consumptive effects on the population dynamics of an agricultural pest

Abstract Augmentative release of predators is used in agriculture to suppress pest populations and minimise crop damage. However, predators affect prey populations not only through consumption but by inducing changes to prey morphology, physiology, behaviour and life history. These risk‐induced trait responses can increase prey fitness, potentially reducing the efficacy of certain predators as biocontrol agents. We investigated how non‐consumptive effects contribute to the overall influence of predators by modelling the effect of the predator Podisus maculiventris on the population dynamics of a major agricultural pest, the Colorado potato beetle (Leptinotarsa decemlineata). We developed a demographic model incorporating both consumption and non‐consumptive Podisus‐induced shifts in beetle reproductive strategy. Our model combines data from multiple mechanistic experiments showing that predator‐exposed beetles produce fewer offspring but increase offspring provisioning, and that provisioned larvae have increased survival when predators are present. We simulated beetle densities across multiple beetle generations and a range of predator densities. The influence of non‐consumptive effects depended on predator density. At low predator densities, non‐consumptive effects strengthened the negative effect of predators by up to 45%, and risk‐induced changes to offspring provisioning had a stronger effect on prey densities than reduced offspring quantity. In contrast, at high predator densities, non‐consumptive effects changed the effect of predators by <5%, likely because beetle densities were very low both with and without non‐consumptive effects. Our results suggest that even adaptive responses to predation risk by prey do not necessarily reduce the ability of predators to suppress pest populations.

Larvae of Colorado potato beetle (Leptinotarsa decemlineata Say) resistant to double-stranded RNA (dsRNA) remain susceptible to small-molecule pesticides.

Implementation of resistance management tools is crucial for the continued efficacy of insect control technologies. An important aspect of insect resistance management (IRM) is the combined or sequential use of different modes-of-action to reduce selection pressure and delay evolution of resistance. This is especially important for insect pests with established ability to develop resistance to insecticides, such as the Colorado potato beetle (Leptinotarsa decemlineata, CPB). A new class of insecticides, based on double-stranded RNA (dsRNA) activating the gene silencing RNA-interference (RNAi) pathway, are currently under review for regulatory approval and commercial use in the USA against CPB. However, there is no information available on the potential for cross-resistance between RNAi insecticides and other classes of insecticides used against CPB. Herein, we aim to fill this knowledge gap by capitalizing on the availability of a CPB strain highly resistant to dsRNAs and test its susceptibility to diverse small-molecule insecticide classes compared to reference dsRNA-susceptible CPB strains. Differences in activity were observed among the four insecticides tested, with abamectin demonstrating highest activity against all three strains of CPB. However, no differences were observed among the dsRNA-resistant and susceptible CPB strains for any of the tested compounds. Overall, these results demonstrate lack of cross-resistance to commonly used chemical insecticides in the dsRNA-resistant strain of CPB. These data support the use of these different insecticide classes along with RNAi-based insecticides as part of an effective insect resistance management framework aimed at delaying resistance in CPB. © 2023 Society of Chemical Industry.

Transgenerational sublethal pyrethroid exposure gives rise to insecticide resistance in a pest insect

The evolution of insecticide resistance has been attributed to strong directional selection by lethal concentrations of insecticides, but there is growing evidence that sublethal doses may also modify resistance through the hormetic effects. Hormesis is a beneficial effect caused by exposure to low doses. However, the role of parental (transgenerational) effects on hormesis, and through that on insecticide resistance, is still unclear. We investigated the effects of several sublethal pyrethroid insecticide (Decis) doses on survival, body mass, and reproduction within four generations (F0, F1, F2, and F3) of the Colorado potato beetle (Leptinotarsa decemlineata). We found that insecticide exposure had mostly linear adverse within-generation effects: decreased larva-to-adult survival, adult body mass, and egg hatching. However, transgenerational exposure led to hormetic effects: increased larva-to-adult survival and pre-diapause adult body mass. Moreover, transgenerational effects were even more positive for offspring exposed to insecticides, leading to decreased larva-to-adult survival, increased body mass, and egg hatching. Our results show that despite mostly negative within-generation effects, transgenerational sublethal exposure to insecticide can cause unwanted positive hormetic effects in their offspring, making them to resist or tolerate the insecticides better, even though the underlying mechanisms are still unclear.

RESISTANCE OF PROMISING POTATO VARIETIES TO THE MOST IMPORTANT BEETLE PESTS IN THE CONDITIONS OF THE NORTHWEST OF THE EUROPEAN PART OF RUSSIA AND THE SOUTH OF THE FAR EAST

The article provides the results of evaluation of 10 promising potato varieties for the group resistance to the Colorado potato beetle Leptinotarsa decemlineata Say and to the Potato ladybird Henosepilachna vigintiomaculata Motsch. The researches were performed by field methods with artificial colonization of plants of the studied varieties in 1st instar, in the quantity of 30–100 larvae for each potato variety, and were held: according to the Colorado beetle – on experimental field of the All-Russian Research Institute for Plant Protection (Saint-Petersburg – Pushkin); according to the potato ladybird – on experimental field of the Federal Scientific Center of Agricultural Biotechnology of the Far East named after A.K. Chaikа (Primorsky Krai, Ussuriysk). Examples of potato varieties from the new assortment confirm the significant similarity (parallelism of developing) of the trophic reactions of both species, which have the same type of nutrition and many similar features of development biology. As the first result, it has shown that the Severnyi and Smak varieties have a group resistance to both phytophages with a survival of 10–20% of larvae before pupation. In other side, the Avgustin and Dalnevostochnyi varieties noted as a favourable for the development of these pests with a survival of 45–75% of larvae.

Colorado Potato Beetle (Leptinotarsa decemlineata) Prefer Solanum jamesii Populations on which they Were Originally Observed in the Wild

Colorado Potato Beetle (Leptinotarsa decemlineata) Prefer Solanum jamesii Populations on which they Were Originally Observed in the Wild

Elucidating the genomic history of commercially used Bacillus thuringiensis subsp. tenebrionis strain NB176.

Bacillus thuringiensis subsp. tenebrionis (Btt) produces a coleopteran-specific crystal protoxin protein (Cry3Aa δ-endotoxin). After its discovery in 1982, the strain NB125 (DSM 5526) was eventually registered in 1990 to control the Colorado potato beetle (Leptinotarsa decemlineata). Gamma-irradiation of NB125 resulted in strain NB176-1 (DSM 5480) that exhibited higher cry3Aa production and became the active ingredient of the plant protection product Novodor® FC. Here, we report a comparative genome analysis of the parental strain NB125, its derivative NB176-1 and the current commercial production strain NB176. The entire genome sequences of the parental and derivative strains were deciphered by a hybrid de novo approach using short (Illumina) and long (Nanopore) read sequencing techniques. Genome assembly revealed a chromosome of 5.4 to 5.6 Mbp and six plasmids with a size range from 14.9 to 250.5 kbp for each strain. The major differences among the original NB125 and the derivative strains NB176-1 and NB176 were an additional copy of the cry3Aa gene, which translocated to another plasmid as well as a chromosomal deletion (~ 178 kbp) in NB176. The assembled genome sequences were further analyzed in silico for the presence of virulence and antimicrobial resistance (AMR) genes.

The effects of short-term glyphosate-based herbicide exposure on insect gene expression profiles

Glyphosate-based herbicides (GBHs) are the most frequently used herbicides worldwide. The use of GBHs is intended to tackle weeds, but GBHs have been shown to affect the life-history traits and antioxidant defense system of invertebrates found in agroecosystems. Thus far, the effects of GBHs on detoxification pathways among invertebrates have not been sufficiently investigated. We performed two different experiments—1) the direct pure glyphosate and GBH treatment, and 2) the indirect GBH experiment via food—to examine the possible effects of environmentally relevant GBH levels on the survival of the Colorado potato beetle (Leptinotarsa decemlineata) and the expression profiles of their detoxification genes. As candidate genes, we selected four cytochrome P450 (CYP), three glutathione-S-transferase (GST), and two acetylcholinesterase (AChE) genes that are known to be related to metabolic or target-site resistances in insects. We showed that environmentally relevant levels of pure glyphosate and GBH increased the probability for higher mortality in the Colorado potato beetle larvae in the direct experiment, but not in the indirect experiment. The GBHs or glyphosate did not affect the expression profiles of the studied CYP, GST, or AChE genes; however, we found a large family-level variation in expression profiles in both the direct and indirect treatment experiments. These results suggest that the genes selected for this study may not be the ones expressed in response to glyphosate or GBHs. It is also possible that the relatively short exposure time did not affect gene expression profiles, or the response may have already occurred at a shorter exposure time. Our results show that glyphosate products may affect the survival of the herbivorous insect already at lower levels, depending on their sensitivity to pesticides.