Potato Beetle Research Articles

Ceramide Aminoethylphosphonate as a New Molecular Target for Pore-Forming Aegerolysin-Based Protein Complexes.

Ostreolysin A6 (OlyA6) is a 15 kDa protein produced by the oyster mushroom (Pleurotus ostreatus). It belongs to the aegerolysin family of proteins and binds with high affinity to the insect-specific membrane sphingolipid, ceramide phosphoethanolamine (CPE). In concert with its partnering protein with the membrane-attack-complex/perforin domain, pleurotolysin B (PlyB), OlyA6 can form bicomponent 13-meric transmembrane pores in artificial and biological membranes containing the aegerolysin lipid receptor, CPE. This pore formation is the main underlying molecular mechanism of potent and selective insecticidal activity of OlyA6/PlyB complexes against two economically important coleopteran plant pests: the western corn rootworm and the Colorado potato beetle. In contrast to insects, the main sphingolipid in cell membranes of marine invertebrates (i.e., molluscs and cnidarians) is ceramide aminoethylphosphonate (CAEP), a CPE analogue built on a phosphono rather than the usual phosphate group in its polar head. Our targeted lipidomic analyses of the immune cells (hemocytes) of the marine bivalve, the mussel Mytilus galloprovincialis, confirmed the presence of 29.0 mol% CAEP followed by 36.4 mol% of phosphatidylcholine and 34.6 mol% of phosphatidylethanolamine. Further experiments showed the potent binding of OlyA6 to artificial lipid vesicles supplemented with mussel CAEP, and strong lysis of these vesicles by the OlyA6/PlyB mixture. In Mytilus haemocytes, short term exposure (max. 1 h) to the OlyA6/PlyB mixture induced lysosomal membrane destabilization, decreased phagocytic activity, increased Annexin V binding and oxyradical production, and decreased levels of reduced glutathione, indicating rapid damage of endo-lysosomal and plasma membranes and oxidative stress. Our data suggest CAEP as a novel high-affinity receptor for OlyA6 and a target for cytolytic OlyA6/PlyB complexes.

Cry3Aa Toxin Is Not Suitable to Control Lepidopteran Pest Spodoptera littoralis (Boisd.).

The toxicity of the Bacillus thuringiensis (Bt) toxin Cry3Aa—originally used against the main potato pest, the Colorado potato beetle, Leptinotarsa decemlineata—was verified on this species and then evaluated against the Egyptian armyworm, Spodoptera littoralis, which is a pest of several economically important plants. Larvae of S. littoralis were fed a semi-artificial diet supplemented either with a recombinant or with a natural Bt toxin Cry3Aa and with the genetically engineered (GE) potato of variety Superior NewLeaf (SNL) expressing Cry3Aa. Cry3Aa concentration in the diet and the content in the leaves were verified via ELISA (enzyme-linked immunosorbent assay) and HPLC (high-performance liquid chromatography) during and at the end of the experiments. The biological effectiveness of the coleopteran-specific Cry3Aa with previous reports of activity against S. littoralis was tested on five different populations of S. littoralis larvae by monitoring 13 parameters involving development from penultimate instar, weight, the efficiency of food conversion to biomass, ability to reproduce, and mortality. Although some occasional differences occurred between the Cry3Aa treatments and control, any key deleterious effects on S. littoralis in this study were not confirmed. We concluded that the Cry3Aa toxin appears to be non-toxic to S. littoralis, and its practical application against this pest is unsuitable.

Positional effects of double-stranded RNAs targeting β-Actin gene affect RNA interference efficiency in Colorado potato beetle

Pesticide resistance in pests drives the development of RNA interference (RNAi)-based technology as a novel approach for pest control. To investigate the effects of the positional dependency of double-stranded RNAs (dsRNAs), we newly designed four different 200 bp dsRNAs targeting Colorado potato beetle (CPB) β-Actin gene, termed as dsACT200–1 to dsACT200–4, to compare their insecticidal activity to CPB larvae together with our previously used 200 bp and 700 bp dsRNAs (dsACT200 and dsACT700), respectively (He et al., 2020a). Each of dsRNAs harbors different numbers of expected siRNAs predicted by sequence-based prediction platform, dsACT200 and dsACT200–2 have a relatively higher number of siRNA than other 200 bps dsRNAs. When CPB larvae were fed with in vitro synthesized dsRNA-painted potato leaves, all the tested dsRNAs showed significant effects to protect against CPB larvae. Combined with the survival rate of CPB larvae, β-Actin gene expression level and the surviving CPB larvae weight, various positional dsRNAs from the same allele showed different plant protection activity against CPB larvae and partially correlated with the predicted siRNA numbers and distribution on the target sequence. This study suggests the specific allelic locus for rational dsRNA design triggering RNAi efficiency for target gene silencing is an essential factor in enhancing the insecticidal activity.

Effects of Repeated Short-Term Heat Exposure on Life History Traits of Colorado Potato Beetle.

Simple SummaryColorado potato beetle (CPB), is a serious pest of Solanaceae in China. High temperature under climate change is one of the main factors that affect the growth and fecundity of insects. In this study, CPB eggs and adults were repeatedly heat-treated at 35 °C and 39 °C for 1, 3 and 5 d (4 h a day), and at optimal 27 °C, and its egg hatching and adult reproduction were observed to explore the impact of short-term heat exposure on the population growth of CPBs. Our research has found that short-term heat exposure is not conducive to the development and reproduction of CPBs. These studies can contribute to deeper understanding how short-term heat exposure change CPBs fitness.The Colorado potato beetle Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae) is an internationally recognized destructive pest which has caused serious losses to the potato industry. To clarify the impact of repeated short-term heat exposure on CPB egg hatching and adult fecundity under climate change, CPB eggs and adults were treated with repeated short-term heat exposure in this study. We found that the hatching rate of CPB eggs, the total number of eggs laid per female, the oviposition period, the intrinsic rate of population increase (rm), finite rate of increase (λ), and the net reproductive rate (R0) of CPBs decreased with increasing temperature. The hatching rate and fecundity of CPBs were significantly lower than those of control (CK) after repeated short-term heat exposure. Our research has found that repeated short-term heat exposure is not conducive to the development and reproduction of CPBs.

The Effect of Silicon Dioxide Nanoparticles Combined with Entomopathogenic Bacteria or Fungus on the Survival of Colorado Potato Beetle and Cabbage Beetles.

Three types of modified silicon dioxide nanoparticles (SiO2, 10–20 nm) with additives of epoxy, silane and amino groups, used independently and in combination with the entomopathogenic bacteria Bacillus thuringiensis subsp. morrisoni and fungus Metarhizium robertsii were tested against Colorado potato beetle (Leptinotarsa decemlineata) and cabbage beetles (Phyllotreta spp.). All three nanoparticles were found to have an entomocidal effect on Colorado potato beetle larvae and crucifer flea beetles when ingested. Increased susceptibility of insects to B. thuringiensis or M. robertsii blastospores and their metabolites was shown after exposure to the modified silicon dioxide nanoparticles. The potential of modified silicon dioxide nanoparticles to enhance the efficiency of biopesticides based on the bacteria B. thuringiensis and fungi M. robertsii is considered in the paper.

Effects of Ag/SiO2 Nanoparticles on Gene Expression of Digestive a-Amylase in Colorado Potato Beetle

Insecticidal properties of nanoparticles (NPs) have been considered widely in different studies. In this study, synthesis of Ag/SiO2 NPs is reported and the effect of the nanoparticles on the digestive a-amylase gene expression in the Colorado potato beetle (CPB), Lepidoptera decemlineata say is investigated. For this purpose, the inhibition of fourth instar larval digestive a-amylase with NPs was analyzed by different concentrations, and the highest inhibitory effect was recorded (72%) at 1000 ppm of Ag/SiO2 NPs. Mortality for the reared larvae from the first instar on potato leaves coated with 1000 ppm Ag/SiO2 NPs was 65%, while it is 8% for the control trial. To investigate the process, we conjugated the nanoparticles with extracted RNA, and the photoluminescent (PL) spectra of the obtained materials were measured and investigated. The results indicate that the FRET phenomenon occurs when the RNA reacts with nanoparticles. These results are according to the PL spectra of RNAs extracted from the larval fed with nanoparticles. The structure is simulated and calculated by the DFT method. The obtained results confirm chemical interaction between nanoparticles and nitrogenous bases on the RNA which can decrease gene expression (0.47 fold) compared to control and causes inhibition of larvae’s growth.

Flexible Thermal Sensitivity of Mitochondrial Oxygen Consumption and Substrate Oxidation in Flying Insect Species.

Mitochondria have been suggested to be paramount for temperature adaptation in insects. Considering the large range of environments colonized by this taxon, we hypothesized that species surviving large temperature changes would be those with the most flexible mitochondria. We thus investigated the responses of mitochondrial oxidative phosphorylation (OXPHOS) to temperature in three flying insects: the honeybee (Apis mellifera carnica), the fruit fly (Drosophila melanogaster) and the Colorado potato beetle (Leptinotarsa decemlineata). Specifically, we measured oxygen consumption in permeabilized flight muscles of these species at 6, 12, 18, 24, 30, 36, 42 and 45°C, sequentially using complex I substrates, proline, succinate, and glycerol-3-phosphate (G3P). Complex I respiration rates (CI-OXPHOS) were very sensitive to temperature in honeybees and fruit flies with high oxygen consumption at mid-range temperatures but a sharp decline at high temperatures. Proline oxidation triggers a major increase in respiration only in potato beetles, following the same pattern as CI-OXPHOS for honeybees and fruit flies. Moreover, both succinate and G3P oxidation allowed an important increase in respiration at high temperatures in honeybees and fruit flies (and to a lesser extent in potato beetles). However, when reaching 45°C, this G3P-induced respiration rate dropped dramatically in fruit flies. These results demonstrate that mitochondrial functions are more resilient to high temperatures in honeybees compared to fruit flies. They also indicate an important but species-specific mitochondrial flexibility for substrate oxidation to sustain high oxygen consumption levels at high temperatures and suggest previously unknown adaptive mechanisms of flying insects’ mitochondria to temperature.

The importance of protecting potato varieties in the phytosanitary technology of the Trans-Urals

The article examines the elements of the phytosanitary adaptive technology of potato cultivation in the conditions of the Trans-Urals. Prospective varieties of potatoes have been studied. The yield increase for new varieties varied from 3.4 t/ha Colombo to 4.9 t/ha Cavalier, due to the resistance of new varieties to diseases. The data on the protective measures taken in planting potato varieties are presented. This is the use of Akiba disinfectants (imidacloprid - 500 g/l) - 0.1 l/t and King Combi (acetamiprid + fludioxonil + cyproconazole, 100 + 34 + 8.3 g/l) - 0.4 l/t in the fight against the Colorado potato beetle and beetle larvae clickers - wireworms, and also identified the best options for integrated protection of potatoes, which made it possible to save the harvest and increase the yield from 3.9 t/ha to 9.9 t/ha for the Mia variety and from 4.0 t/ha to 11.25 t/ha for the variety Itzil. The maximum increase was found in the variants of complex protection of potatoes from pests and diseases in the conditions of the Trans-Urals. The use of new varieties and plant protection products are important elements of potato cultivation technology.

Repeated exposure of fluazinam fungicides affects gene expression profiles yet carries no costs on a nontarget pest.

Fungicides are used to control pathogenic fungi of crop species, but they have also been shown to alter behavioral, life history and fitness related traits of nontarget insects. Here, we tested the fungicide effects on feeding behavior, survival and physiology of the nontarget pest insect, the Colorado potato beetle (CPB) (Leptinotarsa decemlineata). Feeding behavior was studied by a choice test of adult beetles, which were allowed to choose between a control and a fungicide (fluazinam) treated potato leaf. Larval survival was recorded after 24 and 72h exposure to control and fungicide-treated leaves with 2 different concentrations. The adults did not show fungicide avoidance behavior. Similarly, survival of the larvae was not affected by the exposure to fungicides. Finally, to understand the effects of fungicides at the physiological level (gene expression), we tested whether the larval exposure to fungicide alter the expression of 5 metabolic pathway and stress associated genes. Highest concentration and 72-h exposure caused upregulation of 1 cytochrome P450 (CYP9Z14v2) and 1 insecticide resistance gene (Ldace1), whereas metabolic detoxification gene (Ugt1) was downregulated. At 24-h exposure, highest concentration caused downregulation of another common detoxification gene (Gs), while both exposure times to lowest concentration caused upregulation of the Hsp70 stress tolerance gene. Despite these overall effects, there was a considerable amount of variation among different families in the gene expression levels. Even though the behavioral effects of the fungicide treatments were minor, the expression level differences of the studied genes indicate changes on the metabolic detoxifications and stress-related pathways.

Effects of Artemisia dracunculus L. Water Extracts on Selected Pests and Aphid Predator Coccinella septempunctata L.

The aim of this study was to determine the effects of water extracts of tarragon (Artemisia dracunculus L.) on the feeding intensity, mortality, and weight gain of selected pests, i.e., adult pea leaf weevils (Sitona lineatus L.), nymphs, wingless females of black bean aphids (Aphis fabae Scop.), and L2 and L4 larvae of Colorado potato beetle (Leptinotarsa decemlineata Say). In addition, the effect of the tarragon extracts on the voracity of the non-target organism Coccinella septempunctata L. L3 larvae was examined. To reduce S. lineatus feeding, at least 10% dry matter (DM) extract and 20% fresh matter (FM) should be used. Tarragon water extract has strong aphicidal potential against A. fabae, with 84% mortality of nymphs at 30% FM and 78% mortality of wingless females at 10% DM after 108 h of exposure. Aphid nymphs turned out to be more sensitive to the extracts prepared from fresh tarragon than from its dry matter. They were also more sensitive than wingless females. The body weight gain of L2 and L4 larvae of Colorado potato beetle was significantly reduced through the application of 10% and 5% extracts prepared from dry matters, respectively, while extracts prepared from fresh matter turned out to be ineffective. L2 larvae were more susceptible to extracts than L4 larvae, which suggests that they should be used as early as possible in the pest season. No negative influence of the extracts used on the voraciousness of C. septempunctata L3 larvae was found.

Citrobacter freundii, a natural associate of the Colorado potato beetle, increases larval susceptibility to Bacillus thuringiensis.

We assume that certain representatives of gut microflora mediate immune changes during dysbiosis, accelerating septicemia caused by Bacillus thuringiensis. Co-introduction of Citrobacter freundii with Bacillus thuringiensis var. tenebrionis (morrisoni) (Bt) led to an increase in Colorado potato beetle (CPB) larval mortality to 69.0% (1.3-5×) and a synergistic effect was observed from day 1 to day 6. Ultrathin sections of the CPB midgut showed autophagosome formation and partial destruction of gut microvilli under the influence of Bt, which was accompanied by pronounced hypersecretion of the endoplasmic reticulum with apocrine vesicle formation and oncotic changes in cells under the action of C. freundii. The destruction of gut tissues was accompanied by suppression of detoxification processes under the action of the bacteria and a decrease (2.8-3.5×) in the concentration of lipid oxidation products during Bt infection. In the first hours post combined treatment, we registered a slight increase in the total hemocyte count (THC) especially a predomination (1.4×) of immune-competent plasmatocytes. Oral administration of symbiotic and entomopathogenic bacteria to the CPB larvae significantly decreased the THC (1.4×) after 24 h and increased (1.1-1.5×) the detoxifying enzymes level in the lymph. These changes are likely to be associated with the destruction of hemocytes and the need to remove the toxic products of reactive oxygen species. The obtained results indicate that feeding of C. freundii and B. thuringiensis to the CPB larvae is accompanied by tissue changes that significantly affect the cellular and humoral immunity of the insect, increasing its susceptibility to Bt. © 2022 Society of Chemical Industry.

Detection of sex in adults and larvae of Leptinotarsa decemlineata on principle of copy number variation

The identification of sex in larvae of insects is usually challenging or even impossible, while in adults the sexual dimorphism is usually evident. Here, we used copy number analysis to develop a method of sex detection in Colorado potato beetle (Leptinotarsa decemlineata), which has an X0 sex determination system. The X linked gene LdVssc and autosomal gene LdUBE3B were identified as appropriate target and reference loci, respectively. The copy numbers (CNV) of LdVssc in males and females were estimated using standard droplet digital PCR (ddPCR) and real-time PCR (qPCR). With both methods, CNVs were bimodally distributed (BAddPCR = 0.709 and BAqPCR = 0.683) with 100% ability to distinguish females from males. The use of qPCR-based sex detection in a broad collection of 448 random CPB adults showed a perfect association (Phi = 1.0, p < 0.05) with the true sexes of adults, with mean CNV in females of 2.032 (SD = 0.227) and 0.989 in males (SD = 0.147). In the collection of 50 random 4th instar larvae, 27 females and 23 males were identified, consistent with the expected 1:1 sex ratio (p = 0.689). The method is suitable for sexing in all stages of ontogenesis. The optimal cost-effective application of the method in large populations requires the DNA extraction using CTAB, the qPCR assay in one biological replicate and three technical replicates of each marker, and the use of one randomly chosen male per run to calibrate calculation of CNV.

LDAmy, an α-amylase from Colorado potato beetle (Leptinotarsa decemlineata) with transglycosylation activity

Potential of α-amylase from the gut of Leptinotarsa decemlineata (LDAmy) to catalyse transfer reactions was investigated. LDAmy as a component of insect gut extract showed significant transfer activity on reducing-end- and both-end-protected maltoheptamer substrates. Transfer reaction was examined using purified enzyme, 2-chloro-4-nitrophenyl β-d-glucopyranoside as acceptor and starch and maltooligosaccharides as donors. In addition to suitability of various donors, effect of pH and acetonitrile (MeCN) concentration were also studied. The reactions were followed using separation of reaction products by a reversed phase HPLC method. LDAmy catalysed the hydrolysis and transglycosylation of the both-end-protected substrate 4,6-O-benzylidene-4-nitrophenyl β-maltoheptaoside in parallel reactions. Shorter and longer both-end-protected products with degree of polymerization 4–10 were formed. Identification of products was carried out based on HPLC retention time, UV and mass spectra. Ratio of transglycosylation to hydrolysis reached 0.5 in presence of 20% MeCN as organic solvent. Aromatic protecting group at the non-reducing end was favourable for transfer reaction. Lack of the mobile loop and presence of more nonpolar aromatic moieties near to the active site may be the reason for the enhanced transfer activity of LDAmy based on the comparison of the sequence and structure of mammalian and insect-derived α-amylases. Highlights Transferase activity of Colorado potato beetle derived α-amylase LDAmy is presented. Effect of pH and organic co-solvent on transfer reaction of LDAmy were studied. Shorter and longer products were formed from a both-end protected maltoheptamer. The unusual transfer ability was explained by sequence differences of α-amylases.

Toxicity of a novel dsRNA-based insecticide to the Colorado potato beetle in laboratory and field trials.

The Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae) is one of the most notorious pests of the potato, Solanum tuberosum. Potato beetles are capable of developing resistance to various insecticides in relatively few generations. Novel and effective means of controlling Colorado potato beetle populations are constantly required to protect potato crops and prevent loss of yield. The knockdown of gene function through ribonucleic acid interference has been demonstrated in Colorado potato beetles, suggesting the use of this technology as a means of beetle management. A novel double-stranded RNA-based insecticide with the active ingredient, ledprona, has been tested in variable dose laboratory bioassays, followed by field studies. Exposure to ledprona resulted in both increased beetle mortality and decreased foliage consumption in all four instars and adult beetles. Effects decreased from earlier to later life stages. No ovicidal activity was detected. Onset of mortality was slower compared with existing chemical insecticides. Nevertheless, field applications of formulated ledprona to potato plots resulted in their protection comparable with that provided by spinosad and chlorantraniliprole. Based on the results of this study, formulated ledprona has attributes to become a useful tool in controlling Colorado potato beetle populations that is likely to be a good fit in integrated pest management protocols. © 2022 Society of Chemical Industry.

Producing Cry-Toxins Endophytic Bacteria as an Alternative to Transgenic Plants to Protect Potato Plants against Colorado Potato Beetle

Producing Cry-Toxins Endophytic Bacteria as an Alternative to Transgenic Plants to Protect Potato Plants against Colorado Potato Beetle

Перспектива использования ингибиторного барьера в селекции картофеля на устойчивость к колорадскому жуку

Abstract. The purpose of the work is the determination of the most effective method of using the inhibitory barrier in potato breeding for resistance to damage by the Colorado potato beetle. Methods. In the work, the method of setting up a field experiment was used, as well as a laboratory method for assessing the inhibition of the activity of lipases and proteinases was carried out using substrates immobilized in an agarose gel. Results. On the basis of field experiments, it was found that the level of relative resistance of potato varieties and hybrids to damage by the Colorado potato beetle, a decrease in the survival rate of insect larvae and loss of tuber yield are associated with a high activity of lipase and proteinase inhibitors and an intensive development of a hypersensitivity reaction to phytophage egg clutches. In laboratory experiments, it was established that the activity of trypsin inhibitors increased during the laying of phytophage eggs on the leaves of potato varieties Bashkirskiy. Scientific novelty. Based on the analysis of the results of world practice and our own long-term attempts to use the inhibitory barrier in breeding potatoes for resistance to the pest, a new approach has been proposed to involve genes encoding the synthesis and accumulation of protease and lipase inhibitors in tissues when creating potato resistance to damage by the Colorado potato beetle. In this case, the methodological approach should be based on the registration of the modification of the inhibitory activity of hydrolases in hybrids with an intense microwave reaction of the leaf tissue to the clutches of the Colorado potato beetle, which will significantly reduce the volume of laboratory assessment of the material. Genotypes that do not respond to egg clutches with a microwave reaction with a high degree of probability will also not modify the activity of hydrolase inhibitors. Genotypes with local short-term accumulation of inhibitors of the lipoproteinase complex in the zone of hatching of the pest offspring create the greatest depressing biological effect for the survival of 1-2 instar larvae. The creation of such genotypes is likely to be a promising model for highly resistant varieties of the Colorado potato beetle.

RNA interference targeting Ras GTPase gene Ran causes larval and adult lethality in Leptinotarsa decemlineata.

RNA interference (RNAi) is a breakthrough technology in pest control. It is highly efficient to Coleopteran pests such as the Colorado potato beetle Leptinotarsa decemlineata, a serious pest defoliator mainly attacking potatoes worldwide. The first step for effective pest control by RNAi is the development of effective and reliable target genes. Our results revealed that continuous ingestion of dsLdRan for 3 days successfully silenced the target gene, inhibited larval growth and killed 100% L. decemlineata larvae. When the bioassay began at the second-, third/fourth-instar larval stages, the larval lethality mainly occurred at the fourth larval instar and prepupal stages, respectively. Importantly, consumption of dsLdRan for 3 days by the newly-emerged males and females effectively knocked down the target transcript, reduced fresh weights and caused 100% of lethality within a week. The LdRan females possessed underdeveloped ovaries. Considering that the larvae, adults and eggs are simultaneously sited on the potato plants, bacterially-expressed dsLdRan is a potential RNAi-based strategy for managing L. decemlineata in the potato field. © 2022 Society of Chemical Industry.

The biological and physiological responses of Leptinotarsa decemlineata Say (Col. Chrysomelidae) to different potato cultivars.

The use of pest-resistant or less susceptible plant varieties is of great importance for integrated pest management programs. This study was conducted to evaluate the resistance of seven potato cultivars to a major pest, namely the Colorado potato beetle (CPB), by measuring its bio-physiological aspects. The longest developmental time and the lowest survival rate of CPB were detected on cultivar 'Manitou.' Although the larvae fed voraciously, the food conversion efficiency was the lowest on this cultivar leading to the lowest relative growth rate. Furthermore, larvae reared on Manitou had the lowest total protease activity and specific activity values of cathepsin B compared to the larvae reared on other cultivars. Additionally, the cluster analysis showed that the Manitou cultivar was the least suitable (partially resistant) CPB. Moreover, the results indicated that the protein content was the lowest in the Manitou cultivar; conversely, this cultivar was rich in polyphenol and flavonoid compared to Agria and Santae cultivars. The overall results in this study indicated that the Manitou cultivar might be a good candidate to be incorporated into integrated pest management programs. © 2022 Society of Chemical Industry.

Colorado potato beetle exploits frass-associated bacteria to suppress defense responses in potato plants.

Colorado potato beetle (CPB; Leptinotarsa decemlineata) is a destructive quarantine pest that develops broad physiological adaptations to potato plants. During feeding, CPB deposits a copious amount of wet frass onto the surface of leaves and stems that remains in place for long periods. Insect behaviors such as feeding, crawling and oviposition are able to mediate plant defenses. However, the specific role of CPB defecation-associated cues in manipulating plant defenses remains unclear. CPB larval frass significantly suppressed potato polyphenol oxidase activity and enhanced larval growth on treated potato plants. The incorporation of antibiotics into larval frass triggered higher jasmonic acid (JA)-regulated defense responses in potato plants compared with antibiotic-free frass. Four bacterial symbionts belonging to the genera Acinetobacter, Citrobacter, Enterobacter and Pantoea were isolated from larval frass and suppressed plant defenses. After reinoculation of these bacteria into axenic larvae, Acinetobacter and Citrobacter were found to be highly abundant in the frass, whereas Enterobacter and Pantoea were less abundant probably due to the negative effect of potato steroidal glycoalkaloids (SGA) such as α-solanine. Furthermore, direct application of Acinetobacter and Citrobacter to wounded potato plants significantly inhibited the expression of genes associated with the JA-mediated defense signaling pathway and SGA biosynthesis. Our findings demonstrate that CPB exploits frass-associated bacteria as a deceptive strategy of plant defense suppression, adding an interesting dimension to our understanding of how CPB successfully specializes on potato plants. © 2022 Society of Chemical Industry.

Influence of insecticides on the harvest and quality of potato stubs in the conditions of West Kazakhstan region

The article presents the results on the yield of potatoes, on the starch content in the tubers, which determined a certain degree of damage to the tops of the Colorado potato beetle. The lowest yield was obtained in the control, and in the variants with the use of insecticides against the Colorado potato beetle, compared with the control, it increased in all experimental variants, depending on the chemical preparation used, in 2017 by 1.8-4.5 times, the lowest indicator by the variant with the preparation cytcor, in 2018 the yield showed a difference of 1.8-4.05 times, it was also the smallest on the variant with cytcor, in 2019 the yield increased 1.81-4.41 times and here the lowest indicator was also when using cytkor. Potato yield on average for 3 years with the use of insecticides in the fight against the Colorado potato beetle was obtained in the range of 12.6 - 16.9 t / ha in the variants of cytkor, aktara, akarin, confidor, bankol, kinmix. A high yield (25.4 t / ha) was obtained when potato plantings were treated with fastacprofi, 28.8 t / ha - in the variant using karate zeon and 29.6 t / ha when decis expert was used. The starch content in potato tubers in the control untreated variant was 10.1 - 10.3%, and in the variants with pesticides - 15.0 - 16.4%, or 4.9 - 6.1% more than in the control. Potato yield and starch content in tubers depend directly on damage to potato plants by the Colorado potato beetle.