Pea Leaf Weevil Research Articles

Potential of Thuja occidentalis L. Essential Oil and Water Extracts against Field Crop Pests.

Thuja occidentalis L. essential oil (EOTO) and its compounds, such as terpinyl acetate, bornyl acetate, and β-thujone, are claimed to be highly effective against some storage pests, sanitary insects, or pests of fruit trees, while data about its use in protecting field crops are very scarce. There is also a lack of information in the literature about the insecticidal value of water extracts from T. occidentalis (WETOs). Both essential oils (EOs) and water extracts (WEs) from various plants have advantages and disadvantages in terms of their use as insecticides. EOs are generally more effective, but their preparation is more complicated and quite expensive. In turn, WEs are simple to prepare and cheap, but they often have limited effectiveness. Moreover, significant differences in responses exist depending on the species of the donor plant, the method of preparing the extract, its concentration, the species of the pest being controlled, the developmental stage, and even the gender of the pest. The goals of the research were to assess the effect of EOTO and WETOs prepared from dry and fresh matter on the mortality, feeding, and body mass changes of important crop pests, i.e., the black bean aphid, pea leaf weevil, and Colorado potato beetle (CPB), respectively, as well as on the mortality and voracity of non-target organism Asian lady beetle young larvae. EOTO showed significant aphicidal activity with LC50 = 0.8267% and 0.2453% after 42 h of the experiment for nymphs and wingless females of black bean aphid, respectively. Adults of CPB were more resistant to EOTO than aphids, with LC50 values for females equal to 1.5327% and 1.3113% after 48 h and after 72 h of the experiment. There was no significant effect of EOTO on CPB foraging. Calculated LC50 values for pea leaf weevil adults were lower than those for CPB (0.9638% and 0.8573% for males after 12 h and 24 h, respectively). In the case of this pest, a clear reduction in foraging was obtained, with higher concentrations of EOTO resulting in more pronounced reductions in foraging behavior. Concentrations of EOTO above 0.5%, which showed efficacy against the aphid, were lethal to 3-day-old larvae of the Asian lady beetle. WETOs, in turn, showed significant potential in inhibiting adult pea leaf weevil feeding, with very low or no effectiveness in reducing A. fabae and CPB, respectively.

Overwintering conditions affect cold hardiness, survival, and post‐overwintering fitness of the pea leaf weevil

AbstractOverwintering conditions affect the physiological state of ectotherms, and therefore, their cold hardiness and survival. A measure of the lethal and sublethal impacts of overwintering conditions on pest populations is crucial to predict population dynamics and to manage pests the following spring. The impact of winter conditions can be most intense for invasive insects undergoing range expansion. Insect herbivores can display plastic host use behaviours that depend on their body condition following winter. The pea leaf weevil, Sitona lineatus L. (Coleoptera: Curculionidae), is an invasive pest of field peas, Pisum sativum L., and faba bean, Vicia faba L. (Fabaceae). Pea leaf weevil has expanded its range in North America to include the Prairie Provinces of Canada. This study investigated the effects of temperature and microhabitat on overwintering survival and cold hardiness of pea leaf weevil in its expanded range. Further, we investigated the sublethal effect of overwintering temperature and duration on post‐overwintering survival, feeding, and oviposition of pea leaf weevil. We also investigated the role of juvenile hormone in modulating body condition of overwintering weevils. The overwintering survival of pea leaf weevil adults increased with soil temperature and varied with region and microhabitat. More weevils survived winters when positioned near tree shelterbelts compared to open alfalfa fields. The supercooling point of pea leaf weevil varied throughout its expanding range but did not differ for weevils held in the two microhabitats. The average threshold lethal temperature of pea leaf weevil at all three sites was −9.4 °C. Weevils that overwintered for a longer duration and at a higher temperature subsequently fed more on faba bean foliage and laid more eggs compared to those which overwintered for a shorter duration at a lower temperature. Our findings highlight that warm winters would increase overwintering survival and post‐overwintering fitness, facilitating further pea leaf weevil invasion northward in the Prairie Provinces of Canada.

Pea leaf weevil, Sitona lineatus (L.) (Coleoptera: Curculionidae), adult feeding preference and larval development on pulse crop varieties in Montana.

Montana accounts for approximately 45% of US dry pea production and the pea leaf weevil (PLW; Sitona lineatus (L.)) is the most common insect pest in this region. After crop emergence adult PLW feed on the foliage to mature and subsequently mate, and the soil-dwelling larvae feed and develop on the nitrogen-fixing root nodules. Producers commonly apply prophylactic insecticide treatments to the seed at planting as well as one or two post-emergent insecticide sprays to control PLW damage. To develop alternative management strategies based on integrated pest management (IPM), this field study evaluated pulse crops grown in Montana for adult feeding preference and larval development. Ten different field pea varieties, along with two faba bean, lentil and chickpea varieties, were evaluated during the 2020 and 2021 field seasons at the Montana State University Arthur H. Post Agronomy Farm. Significant PLW pest pressure was observed within the research plots during both experimental years. Field pea and faba bean were preferred by the foliage feeding adult stage, with all but one variety averaging 39.2 to 86.3 average notches per plant. The pea variety Lifter was significantly preferred over all other comparisons, averaging 142.4 and 95.0 notches per plant in 2020 and 2021, respectively. Adult PLW feeding on lentil and chickpea was minimal, averaging 3.3 to 8.2 and 0.5 to 1.6 notches per plant, respectively. Numbers of larvae were highest on the roots of pea varieties, a known reproductive host, and almost nil on lentil and chickpea roots. Faba bean is also known as reproductive host, but, unexpectedly, larval populations were also low on the two faba bean varieties. The results from this study provide some limited evidence for alternative IPM strategies for field peas based on host plant tolerance or resistance within the range of varieties tested. Adult preference and larval development of PLW varied between the different pulse crops with field peas and faba beans being the most susceptible and lentils and chickpeas being the least susceptible. Host plant resistance against PLW could provide more sustainable IPM approaches in the future. © 2024 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Diversity and Traits of Multiple Biotic Stressors Elicit Differential Defense Responses in Legumes

In agroecosystems, plants frequently confront multiple biotic stressors, including herbivores and pathogens. The nature of these interactions plays a crucial role in mediating the activation of plant defense mechanisms. However, induction of plant chemical defenses has been more well studied than the induction of physical defenses. Here, we assessed the physical and chemical defense responses of pea (Pisum sativum) plants after exposure to three stressors: a vector herbivore (pea aphid, Acrythosiphon pisum), a non-vector herbivore (pea leaf weevil, Sitona lineatus), and a virus (Pea enation mosaic virus, PEMV). We used various histochemical staining techniques show that viruliferous A. pisum (transmitting PEMV) strongly induced callose deposition (aniline blue staining) and antioxidant-mediated defenses (DAB and NBT staining) in peas, primarily through accumulating reactive oxygen species (ROS). High-throughput phenotyping showed that viruliferous aphids reduced plant photosynthetic efficiency, but plants infected with PEMV had increased cell death (trypan blue staining). However, herbivory by aphids and weevils did not strongly induce defenses in peas, even though weevil feeding significantly reduced pea leaf area. These results show that not all herbivores induce strong defensive responses, and plant responses to vector species depends on their virus infection status. More broadly, our results indicate that variable stressors differentially regulate various plant responses through intricate chemical and physical defense pathways.

Legume plant defenses and nutrients mediate indirect interactions between soil rhizobia and chewing herbivores

Soil bacteria that associate with plant roots promote host vigor. Legume plants form mutualisms with rhizobial bacteria, and legumes grown with rhizobia have more nutrients and defenses than those grown without rhizobia. However, few studies have tested how stressors such as herbivores affect soil rhizobia, and the mechanisms mediating these interactions. Here we tested reciprocal interactions between a chewing herbivore, Sitona lineatus (pea leaf weevil), and Pisum sativum (pea) plants grown with or without rhizobia (Rhizobium leguminosarum biovar. viciae), and the plant-defense and nutritional mechanisms mediating these interactions. We hypothesized that plants grown with rhizobia would have less feeding from S. lineatus due to greater expression of phytohormones or physical defenses. We also predicted that herbivory might impede the mutualism between P. sativum and rhizobia. Our experiments showed that leaf defoliation by S. lineatus was indeed lowest on plants with rhizobia. Plants grown with rhizobia had increased gene transcript expression associated with hormone-related defense (jasmonic acid, ethylene, abscisic acid) as well as physical and antioxidant-related defense, which may explain reduced feeding by S. lineatus. Conversely, S. lineatus feeding reduced the number of root nodules and nodule fresh weight, suggesting a disruption of the symbiosis between plants and rhizobia. Our study shows that aboveground herbivores can engage in mutually antagonistic interactions with soil microbes that are mediated through multiple plant-mediated 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.

Abundance, Harmfulness, and Control of Pea Leaf Weevil in Broad Beans (Vicia faba Linn.)

A field experiment was carried out on broad beans (Vicia faba L.) to investigate the abundance of the pea leaf weevil (Sitona lineatus L.), as influenced by the timing of pest control, using insecticides. The study was conducted in broad bean var. ‘Vertigo’, during the period 2019–2020. The study included six spray regimes, as well as an untreated control. Yellow water traps were used to monitor the occurrence of the pea leaf weevil from the start of germination until harvest. Pea leaf weevil abundance was observed over the growing season. The adult density showed two peaks at two plant phenology stages, at flowering and before harvest (BBCH 89). The amount of damaged root nodules by this pest ranged from 41 to 59%. Data from two years of study suggest that S. lineatus infestation does not result in a seed yield reduction. Spray regimes did not impact larval density. Applying foliar insecticides at the local threshold can be recommended as an effective method to protect broad beans from feeding by pea leaf weevils.

A fluorometric assay to estimate pea leaf weevil (Coleoptera: Curculionidae) larval feeding damage using leghaemoglobin in root nodules of faba bean (Fabaceae)

Abstract The pea leaf weevil, Sitona lineatus Linnaeus (Coleoptera: Curculionidae), is an invasive pest of field pea, Pisum sativum Linnaeus, and faba bean, Vicia faba Linnaeus (Fabaceae). Larvae feed on leguminous root nodules and associated Rhizobium leguminosarum Frank (Rhizobiacea) nitrogen-fixing bacteria. Larval feeding causes economic damage, but the current method to assess nodule damage is laborious. Leghaemoglobin, the oxygen-carrying molecule in root nodules, is degraded as larvae feed. Measurement of leghaemoglobin could be an alternative method to estimate larval damage. Here, we developed a fluorometric assay to measure the variation in haem fluorescence, which relates to leghaemoglobin content, from nodulated roots. Roots were collected from caged faba bean plants with or without weevil infestation. Faba bean yield and haem fluorescence were inversely correlated with the percent damaged nodules. A plant growth score was positively correlated with haem fluorescence. This method can be used to assess nodule damage in pulse crops from pea leaf weevil and potentially from other biotic stresses, and it may have wider application to studies of nitrogen fixation.

Field Efficacy of Pea Leaf Weevil Aggregation Pheromone Combined With Contact Insecticide as an Attract-and-Kill Method, 2020

Field Efficacy of Pea Leaf Weevil Aggregation Pheromone Combined With Contact Insecticide as an Attract-and-Kill Method, 2020

Management of Pea Leaf Weevil (Coleoptera: Curculionidae) and Development of a Nominal Threshold in Faba Beans.

Pea leaf weevil, Sitona lineatus (L.) (Coleoptera: Curculionidae), can reduce the yield of field pea [Pisum sativum (L.) (Fabales: Fabaceae)] and faba bean [Vicia faba (L.) (Fabales: Fabaceae)]. Adults feed on the foliage and larvae feed on root nodules and nodule-associated Rhizobium Frank (Rhizobiales: Rhizobiacea) bacteria. In this study, we developed a data-based nominal threshold for pea leaf weevil in faba bean. We further tested the efficacy of insecticidal seed treatment and foliar insecticide (thiamethoxam and lambda-cyhalothrin, respectively), and nitrogen amendment for pea leaf weevil control using a multi-year field plot study at two sites in Alberta, Canada. Pea leaf weevil feeding damage significantly reduced faba bean yields. Thiamethoxam reduced adult and larval damage, and protected faba bean yield, while neither lambda-cyhalothrin nor a nitrogen amendment was effective in protecting yield. The percentage of seedlings with feeding on the terminal leaf had a negative relationship with yield and was used to estimate a nominal threshold near 15% of seedlings with terminal leaf damage. Since lambda-cyhalothrin is not effective in managing pea leaf weevil on faba bean, there is a need to research additional integrated pest management strategies to reduce prophylactic insecticidal seed treatments.

Evaluation of foliar and seed treatments for integrated management of root rot and pea leaf weevil in field pea and faba bean

Increased production of field pea (Pisum sativum L.) and faba bean (Vicia faba L.) in Canada has led to a greater incidence of disease and the range expansion of insect pests. Several soil-borne pathogens cause root rot in these crops, while the feeding activity of the pea leaf weevil (Sitona lineatus L.) significantly reduces nitrogen fixation. As pathogens and pea leaf weevil larva are associated with the roots of their mutual host, there is potential for synergistic interactions to occur that may ultimately reduce yield. Field trials at three locations in southern Alberta in 2016 and 2017 evaluated the use of insecticidal and fungicidal seed treatments, a foliar insecticide spray, alone and in combination, and nitrogen amendment as strategies to reduce impacts of both root rots and pea leaf weevil. The fungicides ethaboxam and fludioxonil did not reduce disease severity in pea or faba bean during the two-year field study. Quantitative PCR assays demonstrated that the pathogens Aphanomyces euteiches and Fusarium spp. co-infect pea roots under field conditions, but pathogen levels were not consistently reduced by any of the treatments. The insecticide thiamethoxam reduced nodule and foliar herbivory, whereas the foliar insecticide, lambda-cyhalothrin, and nitrogen fertilization at seeding had no consistent impact. No single or combined treatment protected yield or seed quality, therefore an effective method of managing these constraints to pea and faba bean production is still required.

The Effects of Water Extracts from Tansy on Pea Leaf Weevil and Black Bean Aphid

The Effects of Water Extracts from Tansy on Pea Leaf Weevil and Black Bean Aphid

Effect of temperature, population density, and sex on feeding damage caused by adult pea leaf weevil (Coleoptera: Curculionidae)

Abstract Sitona lineatus (Linnaeus) (Coleoptera: Curculionidae) is an important pest of Pisum sativum Linnaeus (Fabaceae) and Vicia faba Linnaeus (Fabaceae). Managing S. lineatus is difficult. There is currently no forecast that can be used to predict S. lineatus population densities between growing seasons (when management decisions are made). Sitona lineatus populations are monitored in spring by assessing adult-induced feeding damage. We assume the quantity of feeding damage is indicative of population density. However, the effects of abiotic factors, including temperature, on feeding rate are not known. We assessed the effects of temperature, population density, and sex on S. lineatus feeding rate by counting feeding notches on host plants exposed to adult weevils for 24 hours at four densities and under five temperature regimes. Individual females consumed more than male weevils. As expected, feeding damage increased with weevil density. The influence of temperature increased as weevil densities increased. Feeding rate did not differ between constant and fluctuating temperature regimes of equal mean daily temperature. Thus, a model based on mean daily temperature may predict weevil density if temperature and damage levels are known. Historical survey data for S. lineatus could be used to develop and validate new models.

Spinosad and Mixtures of an Entomopathogenic Fungus and Pyrethrins for Control of Sitona lineatus (Coleoptera: Curculionidae) in Field Peas.

The pea leaf weevil, Sitona lineatus L., is an important pest of field peas and faba beans in most temperate regions. As no information is currently available on efficacy of biopesticides for S. lineatus control, laboratory bioassays were performed to evaluate the impact of biopesticides (spinosad, Beauveria bassiana strain GHA, pyrethrins, B. bassiana GHA + pyrethrins, and B. bassiana GHA + azadirachtin) against adults of this pest. The concentrations used in this bioassay were 0.1, 0.5, 1.0, and 2.0 times the lowest labeled application rate of each product. Results were further verified in cage experiments by assessing biopesticide effects on adult mortality and feeding damage in pea plants. The impact of biopesticides on mortality of larvae of two beneficial species, Chrysoperla carnea and Adalia bipunctata, was also tested in laboratory conditions. We found spinosad to be the most promising candidate, causing 100% adult mortality at high and medium concentrations. Beauveria bassiana and its combination with pyrethrins caused 60-62% adult mortality, but only at the highest concentration. In contrast, B. bassiana + azadirachtin and pyrethrins treatments caused only minimal adult mortality at all concentrations. In cage experiments, spinosad and B. bassiana + pyrethrins had significant effects on adult mortality and provided foliage protection from adult feeding. Conversely, the fungus treatment alone showed inconsistent performance. Beauveria bassiana and spinosad were generally harmless to C. carnea and A. bipunctata larvae, but B. bassiana + pyrethrins was toxic toward beneficial species. These results could help to improve integrated pest management programs intended to control S. lineatus.

Tri-trophic interactions mediate the spread of a vector-borne plant pathogen.

Many insect herbivores are vectors that transmit plant pathogens as they forage. Within food webs, vectors interact with a range of host plants, other herbivores, and predators. Yet, few studies have examined how tri-trophic interactions involving vectors affect the spread of pathogens. Here we assessed effects of food web structure on aphid vectors and the prevalence of an aphid-borne persistent pathogen (Pea enation mosaic virus, PEMV) in pea plants. We experimentally manipulated ladybird predators, alternative host plants, and non-vector herbivores and assessed responses of pea aphids and PEMV using structural equationmodels. We show that variation in bottom-up, top-down, and horizontal interactions mediated PEMV prevalence. Predators reduced PEMV prevalence by consuming aphids, but an alternative host plant (vetch) had the opposite effect by promoting aphid movement and abundance. Non-vector herbivores (pea leaf weevil) increased PEMV susceptibility in peas. In turn, weevils offset the positive effects of predators on PEMV, but increased the negative effects of vetch. Our results show that tri-trophic interactions within insect and plant food webs can mediate vector biology with synergistic and opposing effects on pathogens. Continuing to assess how community-wide interactions affect vectors will aid in our understanding of vector-borne pathosystems.

Wing polymorphisms of Pterostichus melanarius (Coleoptera: Carabidae) (Illiger, 1978) in Alberta pulse crops

In a 6 week research project, a wing-dimorphic carabid species was studied to identify the proportions of macropterous (large functional wings) individuals and brachypterous (short, rudimentary wings) individuals from different pulse growing regions of Alberta. Pterostichus melanarius I. (Coleoptera: Carabidae) can be short-winged (SW) due to brachyptery being a dominant gene or long-winged (LW) individuals causing macroptery. Although macroptery is a recessive trait, the LW morph persists through the recolonization of populations due to human disturbance. Their ability to fly facilitates their dispersal across Alberta to uncolonized areas. Samples of P. melanarius were captured as bycatch from pea leaf weevil, Sitona lineatus L. (Coleoptera: Curculionidae) pitfall traps from the East, Capital, and Central regions of Alberta. Traps were positioned on a 175 meter transect pea and faba field margins in spring and again in the fall. Captured P. melanarius were identified and separated by collection site and date and stored in 95% ethanol until measurements. The beetles from the bycatch samples were sexed using tarsal characteristics. Anterior tarsal segments of the front pair of tarsi are dilated in males and normal in females. After being identified and recorded as “M” or “F”, they were mounted on a foam board with insect pins for measurement. The elytra (forewings) length and width was measured followed by measurement of their hindwings. They were classified as “SW” or “LW” depending on the functionality of their wings. Out of 440 individuals from the Capital region, 17.1% of captured P. melanarius were LW and 83.0% were SW. From the Central region 21.6% of 495 beetles were LW and 83.4% of them were SW. In the East region less P. melanarius were captured and from 94 individuals, 46.8% were LW and 53.2% were SW. Macropterous individuals are more common in the East region due to recolonization of populations whereas in the Central and Capital region the proportions of SW are much larger. In regions that have established populations of P. melanarius the proportions of SW are greater than LW.

The Effects of Water Extracts from Lemon Balm on Pea Leaf Weevil and Black Bean Aphid Behaviour

The Effects of Water Extracts from Lemon Balm on Pea Leaf Weevil and Black Bean Aphid Behaviour

Interactions between the root rot pathogen Fusarium avenaceum and the pea leaf weevil (Sitona lineatus) in field pea

Root rot caused by Fusarium spp. and nodule herbivory by larvae of the pea leaf weevil, Sitona lineatus, are major factors constraining the production of field pea (Pisum sativum). Interactions between these pests have the potential to increase plant injury and yield loss, but have not been explored. In this study, the relationship between F. avenaceum and larval S. lineatus was evaluated in greenhouse trials. An apparently mutualistic interaction was observed when both species co-occurred in pea roots, in which disease pressure increased and larval mortality decreased. Larval feeding wounds may have facilitated infection by serving as entry points for F. avenaceum. It is not clear why F. avenaceum decreased insect mortality, but fungal detoxification of pea phytoalexins is discussed as a potential mechanism. These results will serve as a basis for further investigation of these interactions under field conditions, and suggest that integrated crop protection measures will be critical in regions where F. avenaceum and S. lineatus co-occur.

Semiochemical-Based Management of the Pea Leaf Weevil (Coleoptera: Curculionidae)

The pea leaf weevil, Sitona lineatus L. (Coleoptera: Curculionidae), is an important pest of pulse crops around the world. Adult pea leaf weevils rely on intra- and interspecific chemical cues to orient within their environment for the purposes of finding food and mates. Early research to identify semiochemical cues used by pea leaf weevils has permitted the development of semiochemical-baited traps that can reliably detect local movements and geographic range expansion of this species even at low population densities. More research is required to realize the potential of semiochemical-based management of the pea leaf weevil.The goals of this review are to: 1) introduce the chemical ecology of the pea leaf weevil and other Sitona species; 2) review the research conducted on semiochemical-based management of the pea leaf weevil in different growing regions; and 3) evaluate important areas of future research in both basic and applied chemical ecology of this pest.

Progress Toward Integrated Pest Management of Pea Leaf Weevil: A Review

The pea leaf weevil, Sitona lineatus (L.; Coleoptera: Curculionidae), is a significant pest of field peas (Pisum sativum L.) and faba bean (Vicia faba L.) in most temperate regions. Considerable research progress has been made towards understanding its basic life cycle, including flight patterns, plant host interactions, and geographic distribution throughout its native and invasive ranges in Europe and North America, respectively. Management tactics investigated include chemical insecticides and tillage, but less work has been done on biological control, host plant resistance, intercropping and trap crops. Future research should focus on better integration of tactics that utilize an ecostacking approach to maximize diversity at various scales to mitigate risks from insect pests and subsequently reduce the need for chemical interventions.