Insecticide dose and seasonal timing of trunk injection in apples influence efficacy and residues in nectar and plant parts

Pesticide residues and risk assessment of trunk-injected pesticides in pine nut (Pinus koraiensis) seeds

Pine nuts, the edible seeds of pines (Family: Pinaceae, Pinus spp.), are popular worldwide, particularly those from the Korean pine tree (Pinus koraiensis), which is economically significant and widely exported. The spread of pine wilt disease (PWD) caused by pinewood nematodes (PWNs) has necessitated the use of trunk injections of pesticides in Korea, raising concerns about pesticide residues in edible pine nuts. This study investigated the concentration of pesticide residues in pine nuts from trunk-injected trees and assessed their potential health risks to consumers. After Korean pine tree was trunk-injected with pesticide, the pine nuts were subsequently harvested and analyzed for pesticide residues using LC‒MS/MS. Short- and long-term risk assessments of trunk-injected pesticides in pine nuts were conducted. Abamectin and emamectin benzoate were not detected, while acetamiprid and sulfoxaflor were detected, but their levels were below the maximum residue limits (MRLs) set by Korea, the EU, and the US. The short-term and long-term risk assessments indicated negligible health risks for consumers from these residues. Despite the low risk, we recommend continued monitoring of pesticide residues in pine nuts intended for sale to ensure consumer safety.

Effects of trunk injection with emamectin benzoate on arthropod diversity

BACKGROUND

Pine wood nematode is a major plant quarantine object in the world. Trunk injection is an effective method for controlling pests that cause disease. To evaluate the ecological safety of trunk injection with emamectin benzoates in forests of Pinus massoniana, the community diversity and community composition of soil arthropods and flying insects (Hymenoptera) were studied at different stages of trunk injection.

RESULTS

The dominant taxonomic groups of soil arthropods were Collembola (30.80%), Insecta (26.42%), and Arachnida (23.84%). The taxonomic groups of flying insects (Hymenoptera) were Ichneumonidae (48.94%), Formicidae (14.10%), and Braconidae (8.44%). Trunk injection with emamectin benzoate has no significant effect on the community diversity indices of total soil arthropods and flying insects (Hymenoptera). However, it has a significant effect on the community diversity indices of detritivores for soil arthropods. It changed the community composition of soil arthropods but did not impact the community composition of flying insects (Hymenoptera). Redundancy analysis of arthropod community structure and environmental variables showed that total potassium, residual of green leaf, and residual of litter leaf have a significant impact on the community structure of soil arthropods, and total phosphorus, total nitrogen, water content, organic matter, and total potassium have a significant impact on the community structure of flying insects (Hymenoptera).

CONCLUSION

Trunk injection with emamectin benzoate is safe for the ecological environment. This study provides a new insight into the field for the prevention and control of pine wood nematode disease, which is of great significance to forest management and pest control. © 2022 Society of Chemical Industry.

Predicting the Potential Distribution of Pine Wilt Disease in China under Climate Change

The primary culprits of pine wilt disease (PWD), an epidemic forest disease that significantly endangers the human environment and the world's forest resources, are pinewood nematodes (PWN, Bursaphelenchus xylophilus). The MaxEnt model has been used to predict and analyze the potential geographic spread of PWD in China under the effects of climate change and can serve as a foundation for high-efficiency monitoring, supervision, and prompt prevention and management. In this work, the MaxEnt model's criteria settings were optimized using data from 646 PWD infestation sites and seven climate variables from the ENMeval data package. It simulated and forecasted how PWD may be distributed under present and future (the 2050s and 2070s) climatic circumstances, and the key climate factors influencing the disease were examined. The area under AUC (area under receiver operating characteristic (ROC) curve) is 0.940 under the parameters, demonstrating the accuracy of the simulation. Under the current climate conditions, the moderately and highly suitable habitats of PWD are distributed in Anhui, Jiangxi, Hubei, Hunan, Guangdong, Guangxi, Sichuan, and other provinces. The outcomes demonstrated that the fundamental climate variables influencing the PWD distribution were rainfall and temperature, specifically including maximum temperature of warmest month, mean temperature of driest quarter, coefficient of variation of precipitation seasonality, and precipitation of wettest quarter. The evaluation outcomes of the MaxEnt model revealed that the total and highly suitable areas of PWD will expand substantially by both 2050 and 2070, and the potential distribution of PWD will have a tendency to spread towards high altitudes and latitudes.

Trunk injection delivery of dsRNA for RNAi-based pest control in apple trees

BACKGROUND

RNA interference (RNAi) is a promising new approach for controlling insect pests without the use of synthetic pesticides. Trunk injection is a delivery system for woody plants that harnesses the vascular system of the tree to transport materials to the tree canopy. Full size apple trees were injected with double-stranded RNA (dsRNA), and season-long leaf samples were taken to measure the vascular mobility and temporal persistence of dsRNA, using quantitative reverse transcription polymerase chain reaction (qRT-PCR).

RESULTS

The qRT-PCR results revealed that the quantities of dsRNA in the apple leaves of treated trees were significantly greater than those in the leaves of untreated trees for both 2019 and 2020 studies. The peak dsRNA concentration in 2019 was 242 pg/30 mg of leaf tissue, and in 2020 was 16.4 pg/30 mg. The persistence of dsRNA in the apple tree canopy in 2019 was at least 84 days, and in 2020 was at least 141 days.

CONCLUSIONS

The highest mean measurement of dsRNA on a single date in 2019 was 242 pg, which is approximately equivalent to 8 ng/1 g leaf tissue. The projection using the highest replicate concentration from the same date is approximately equivalent to 27 ng/1 g leaf tissue, which may be sufficient to be considered biologically active. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Endotherapic treatment to control Toumeyella parvicornis Cockerell infestations on Pinus pinea L

BACKGROUND

The pine tortoise scale, Toumeyella parvicornis (Cockerell, 1897), is a damaging insect pest native to North America. Its accidental introduction into Europe, where it was first reported in central-southern Italy, is leading to severe infestations among stone pine trees, Pinus pinea L. causing severe infestations and generating a major risk to the health and safety of the citizens as well. This preliminary study aimed at finding an effective low-impact control strategy against Toumeyella parvicornis. We evaluated the effect of endotherapic abamectin injected into infested stone pines in the Parco Archeologico di Ostia Antica (Rome).

RESULTS

Results showed that endotherapic abamectin significantly reduced the pine tortoise adult female populations and had a persistence into plants of approximately 60 days. The first trace of abamectin on the plant's crown was detected 1 month after the treatment. Moreover, the survey highlighted a higher presence of the pest on the twigs of the plants than on needles.

CONCLUSIONS

These findings offer an important tool in fighting the damaging activity of this phytophagous, especially in an urban context where interventions with treatments are strictly regulated by national laws. Endotherapy, in fact, would reduce the dispersion of active ingredients by drift, an aspect that could represent a valid alternative to manage plants in public areas. Given the actual lack of scientific information about other control solutions, abamectin endotherapic treatments would be the more effective strategy currently applicable. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Resistance Affects the Field Performance of Insecticides Used for Control of Choristoneura rosaceana in Michigan Apples and Cherries

Field-based residual bioassays and residue analysis were conducted to assess the field performance and toxicity longevity of different insecticides that had previously been associated with resistance of Choristoneura rosaceana populations collected from apple and cherry orchards. In this study, 12-24 h-old larvae of apple and cherry populations were exposed to apple and cherry leaf samples, respectively, at post-application intervals and a susceptible population served as a reference of each. In the apple and cherry trials, the order of residual longevity of insecticides that effectively controlled the tested populations was as follows: bifenthrin and spinetoram (apple: 14, cherry 21-day post-application), phosmet (apple: 7, cherry 14-day post-application), chlorantraniliprole (apple: 7-day post-application), and indoxacarb and emamectin benzoate (apple: 1, cherry 7-day post-application). Compared to the susceptible population, the resistant populations resulted in a measurable loss of field performance, or "practical resistance", for the insecticides emamectin benzoate (at 7-day post-application), chlorantraniliprole (at 21-day post-application), and indoxacarb (at all post-application intervals) in the apple trials, while in cherry trial just indoxacarb at 7-day post-application showed a reduced efficacy. In terms of long-lasting residues, only chlorantraniliprole and indoxacarb maintained measurable leaf residues over all post-application intervals while the leaf residues of the other compounds had largely degraded within the first 7 days. These findings can help fruit growers make adjustments to their spray/re-application intervals and optimally utilize important chemical tools in their integrated pest management programs.

Biopesticide Trunk Injection Into Apple Trees: A Proof of Concept for the Systemic Movement of Mint and Cinnamon Essential Oils

The use of conventional pesticides is debated because of their multiple potential adverse effects on non-target organisms, human health, pest resistance development and environmental contaminations. In this setting, this study focused on developing alternatives, such as trunk-injected essential oil (EO)-based biopesticides. We analysed the ecophysiology of apple trees (Malus domestica) following the injection of Cinnamomum cassia and Mentha spicata nanoemulsions in the tree's vascular system. Targeted and untargeted volatile organic compounds (VOCs) analyses were performed on leaf-contained and leaf-emitted VOCs and analysed through dynamic headspace-gas chromatography-mass spectrometry (DHS-GC-MS) and thermal desorption unit (TDU)-GC-MS. Our results showed that carvone, as a major constituent of the M. spicata EO, was contained in the leaves (mean concentrations ranging from 3.39 to 19.7 ng g_DW ^-1) and emitted at a constant rate of approximately 0.2 ng g_DW ^-1 h^-1. Trans-cinnamaldehyde, C. cassia's major component, accumulated in the leaves (mean concentrations of 83.46 and 350.54 ng g_DW ^-1) without being emitted. Furthermore, our results highlighted the increase in various VOCs following EO injection, both in terms of leaf-contained VOCs, such as methyl salicylate, and in terms of leaf-emitted VOCs, such as caryophyllene. Principal component analysis (PCA) highlighted differences in terms of VOC profiles. In addition, an analysis of similarity (ANOSIM) and permutational multivariate analysis of variance (PERMANOVA) revealed that the VOC profiles were significantly impacted by the treatment. Maximum yields of photosystem II (Fv/Fm) were within the range of 0.80-0.85, indicating that the trees remained healthy throughout the experiment. Our targeted analysis demonstrated the systemic translocation of EOs through the plant's vascular system. The untargeted analysis, on the other hand, highlighted the potential systemic acquired resistance (SAR) induction by these EOs. Lastly, C. cassia and M. spicata EOs did not appear phytotoxic to the treated trees, as demonstrated through chlorophyll fluorescence measurements. Hence, this work can be seen as a proof of concept for the use of trunk-injected EOs given the systemic translocation, increased production and release of biogenic VOCs (BVOCs) and absence of phytotoxicity. Further works should focus on the ecological impact of such treatments in orchards, as well as apple quality and production yields.

Curative Activity of Insecticides Used to Control Spotted-Wing Drosophila (Diptera: Drosophilidae) in Tart Cherry Productions

Spotted-wing drosophila (Drosophila suzukii Matsumura) is a major pest of soft-skinned fruit and due to the low infestation tolerance for marketable fruit, growers take preventive actions to hinder spotted-wing drosophila damages. Insecticides application is one of the measures taken by growers. Although intensive spraying programs have been used to manage spotted-wing drosophila, its early infestation, rapid reproduction, and vast range of host have caused damage to still occur in fruit, including tart cherries, Prunus ceraus (Linnaeus). Therefore, there is a merit for information on insecticide's curative activity to understand whether sprays manage spotted-wing drosophila individuals within infested fruit. Tart cherry fruit were exposed to spotted-wing drosophila adults for 3 d. After this infestation period, insecticides were applied 1 and 3 d later. Small larvae, large larvae, and pupae were counted 9 d after initial infestation. A parallel set of insecticide-treated tart cherries were subjected to residue analysis. Phosmet and spinetoram were able to reduced live spotted-wing drosophila counts compared with the control at all life stages and insecticide application times, whereas zeta-cypermethrin, acetamiprid, and cyantraniliprole were less consistent in reducing spotted-wing drosophila numbers. Chromobacterium subtsugae demonstrated no curative action. Residue analysis demonstrated that zeta-cypermethrin residues mostly remained on fruit surface. Small portions of phosmet, spinetoram, and cyantraniliprole were able to penetrate fruit surfaces and move into subsurface tissues. Acetamiprid was the only compound which >47% penetrated into the fruit subsurface consistently across both years. Curative activity demonstrated in this study can provide additional tactics for spotted-wing drosophila management in tart cherry Integrated Pest Management (IPM) programs.

Organic Control of Pear Psylla in Pear with Trunk Injection

Simple Summary

Organic pear production is challenged, in part, by short lived effects of biopesticides when applied as foliar sprays. Trunk injection may enhance their performance by delivering the biopesticides directly to the vascular system of the tree, right where pear psylla feed. The objective of this study is to compare trunk injections to foliar sprayed applications of two insecticides, azadirachtin and abamectin, on their ability to control pear psylla in pear trees. The azadirachtin and abamectin trunk injected treatments performed equally or better than two foliar applications in the control of the pear psylla. The trunk injected trees from the first season provided a moderate level of control into the second season, one year after the injections. This study suggests that trunk injection is a superior delivery system for biopesticides used in organic pear production.

Abstract

Organic production of pears is challenging in part because OMRI (Organic Materials Review Institute) approved biopesticides are short lived when applied as foliar sprays. Trunk injection is an alternative method of insecticide delivery that may enhance the performance of biopesticides for control of pear psylla. The objective of this study is to compare the efficacy of azadirachtin and abamectin in the control of pear psylla using two different application methods, airblast sprayer and trunk injection. Trunk injections of azadirachtin and abamectin were compared to airblast applications of equal labeled rates on 33-year-old Bartlett Pear trees (Pyrus communis L., var “Bartlett”). The azadirachtin and abamectin trunk injected treatments performed equally or better than the two airblast applications in the control of the pear psylla. The trunk injected trees from the first season provided a moderate level of control into the second season, one year after the injections. This study suggests that trunk injection is a superior delivery system for biopesticides used in organic pear production.