Pest Management Science最新文献

Background: Bacterial biofilm is a strong fortress for bacteria to resist harsh external environments, which can enhance their tolerance and exacerbate the drug/pesticide resistance risk. Currently, photopharmacology provides an advanced approach via precise spatiotemporal control for regulating biological activities by light-controlling the molecular configurations, thereby having enormous potential in the development of drug/pesticides.

Results: To further expand the photopharmacology application for discovering new antibiofilm agents, we prepared a series of light-controlled azo-active molecules and explored their photo isomerization, fatigue resistance, and anti-biofilm performance. Furthermore, their mechanisms of inhibiting biofilm formation were systematically investigated. Overall, designed azo-derivative A11 featured excellent anti-Xoo activity with an half-maximal effective concentration (EC₅₀) value of 5.45 μg mL^-1, and the EC₅₀ value could be further elevated to 2.19 μg mL^-1 after ultraviolet irradiation (converted as cis-configuration). The photo-switching behavior showed that A11 had outstanding anti-fatigue properties. An in-depth analysis of the action mechanism showed that A11 could effectively inhibit biofilm formation and the expression of relevant virulence factors. This performance could be dynamically regulated via loading with private light-switch property.

Conclusion: In this work, designed light-controlled azo molecules provide a new model for resisting bacterial infection via dynamic regulation of bacterial biofilm formation. © 2024 Society of Chemical Industry.

Background: The root-knot nematode (RKN), Meloidogyne incognita, affects food production globally and nematicides, such as fosthiazate and fluopyram, are frequently used in Japan to control damage caused by RKN. In aboveground pests, the emergence of a population with developed resistance is frequently found after the continuous use of the same pesticides; however, there are few studies on changes in the sensitivity of plant-parasitic nematodes, including RKN, to nematicides.

Results: We compared the sensitivity of two populations of M. incognita to fosthiazate and fluopyram, one population with a history of exposure to fosthiazate and 1,3-dichloropropene (Ibaraki population) and the other without nematicide use for decades (Aichi population). A concentration of fosthiazate and fluopyram causing 50% mortality at 24 h post-treatment (LC₅₀) was markedly higher in the Ibaraki population (5.4 and 2.3 mg L^-1) than in the Aichi population (0.024 and 0.011 mg L^-1 in fosthiazate and fluopyram, respectively), indicating the low sensitivity of the Ibaraki population to fosthiazate and fluopyram. Experiments using different enzyme inhibitors indicated the involvement of acetylcholinesterase (AChE), which is the target of fosthiazate, and glutathione S-transferase (GST), a typical enzyme related to detoxification, in the low sensitivity mechanism. The activity of AChE was 33-fold higher in the Ibaraki population than in the Aichi population and there were many differences in their nucleotide sequences. In addition, the gene expression level of GST was 239-fold higher in the Ibaraki population than in the Aichi population.

Conclusion: These results revealed differences in the sensitivity to nematicides among RKN populations. Two factors were identified as related to the mechanism of low sensitivity in the Ibaraki population. This is the first report showing the difference in the sensitivity to fluopyram between populations of M. incognita. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Insecticides targeting the nervous system have been the most widely used to control arthropod pests due to their fast onset of action leading to efficient crop protection. With their continued use, resistance has and will become an inevitable challenge that demands continued efforts in identifying and developing new insecticidal chemistries acting on novel targets. In a recent publication, the results of a comprehensive study investigating the mode of action of novel chemical scaffolds based on the 2-(3-ethylsulfonyl-2-pyridyl)-heterocycles, alkylsulfones, was presented, concluding that their primary target is the vesicular acetylcholine transporter. © 2024 Society of Chemical Industry.

Background: Phelipanche ramosa L. (Pomel) is a noxious parasitic weed in field and vegetable crops in Mediterranean countries. Control of this pest is complex and far from being achieved, and new environmentally-friendly strategies are being sought. The present study evaluates the possibility of using (±)-catechins as a natural herbicide against broomrapes.

Results: The results show that (±)-catechins have no effect on GR24-induced germination over a wide concentration range (10^-4 to 10^-10 m), nor on radicle elongation after germination, but strongly inhibit, at 10^-4 and 10^-5 m, prehaustorium formation in response to the haustorium-inducing factor, cis/trans-zeatin. Accordingly, pot experiments involving the supplies of 10^-5 m of (±)-catechins to tomato plants infested or not with P. ramosa demonstrate that (±)-catechins do not influence growth of non-parasitized tomato plants and prevent heavy infestation by strongly reducing parasite attachments and inducing parasite necrosis once they are attached.

Conclusion: This study points the potential use of (±)-catechins for parasitic weed control. It raises also the question of the mechanisms involved in the inhibition of prehaustorium formation and the necrosis of parasite attachments in response to (±)-catechins application. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

The spotted wing drosophila (SWD) is supposed to show only two distinct seasonal phenotypes: the dark, diapausing winter morph (WM) and the light, reproductively active summer morph (SM). It is unclear if these phenotypes result from a true developmental switch or from the expression of extreme phenotypes of continuous thermal reaction norms. This study aims to investigate this question by examining traits across a range of temperatures. Using 12 developmental temperatures (8 to 30 °C), we assessed traits including viability, growth, morphology, cold tolerance, metabolic rate, and ovarian maturation. Gradual increases in temperature induced gradual changes in all these traits, indicating classical nonlinear thermal reaction norms. Low temperatures (14 °C and below) produced flies with extended development, dark color, larger size, increased cold tolerance, reduced metabolism, and delayed oogenesis, characteristic of the WM. Given the months required for emergence and egg maturation at cold, distinct generations of SWD may develop in discrete environments resulting in an apparent biphenism. What appears to be distinct phenotypes (WM and SM) may actually result from continuous thermal reaction norms. This implies the need for precise terminology in SWD. We recommend using terms like 'winter-acclimated' or 'winter phenotype' rather than 'winter morph'. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Background: Cross-resistance between pre-emergence herbicides is developing in Australian populations of annual ryegrass (Lolium rigidum Gaud.). A previous study has reported that selection with prosulfocarb (a pro-herbicide requiring bioactivation to its phytotoxic sulfoxide) can decrease metabolic resistance to trifluralin. Metabolism of prosulfocarb and trifluralin was investigated in L. rigidum populations with different levels of resistance to prosulfocarb, trifluralin and also pyroxasulfone, which is detoxified by glutathione (GSH) conjugation.

Results: Coleoptiles and radicles of herbicide-treated seedlings responded differently to the same herbicide. Radicles had a lower capacity for bioactivation of prosulfocarb, and this was correlated with a lower ability to metabolise trifluralin within and among populations. Coleoptile resistance to prosulfocarb sulfoxide was negatively correlated with abundance of a major polar metabolite. There was no evidence of GSH conjugation with the sulfoxide, making any potential links between prosulfocarb and pyroxasulfone resistance less obvious.

Conclusions: Activation and metabolism of prosulfocarb in L. rigidum is complex and differentially regulated in different tissues. Selection with prosulfocarb may ameliorate trifluralin metabolism in the radicles, but the relationship between prosulfocarb and pyroxasulfone resistance is not GSH-mediated. When applying pre-emergence herbicides, care should be taken with the composition of mixtures and rotations to avoid selection of cross-resistance between pyroxasulfone and prosulfocarb. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Background: Invasive ungulates (hoofed mammals), including deer, feral pigs, feral goats, and feral sheep, are known to cause damage to agriculture, property, natural resources, and many other commodities. Most of the information regarding the economic impacts of wild ungulates is from North America, where some of these species are native. To evaluate invasive ungulate damage to livestock producers in the Hawaiian Islands, which have no native ungulates, a survey was distributed to livestock producers across the state.

Results: Survey results described how total annual costs are distributed among damage, control, and repairs for survey respondents, who represented a significant percentage of total ranchland acreage across the islands. The estimates, excluding fixed fence installation, revealed an annual cost to livestock producers who responded to the survey of US$1.42 million, which ranged from $3.6 million to $7.5 million when extrapolated to the entire state. The large cost contributors included damage to property, pastureland repair, control costs (excluding fencing), supplemental feed, and predation of calves by wild pigs. Additionally, producers reported spending more than $2 million in upfront fence installation costs. Most of these costs were reported by respondents on the islands of Hawai'i and Moloka'i.

Conclusion: Study results revealed substantial damage to state livestock producers due to wild ungulates and are useful in determining an invasive ungulate management strategy that can appropriately aid the most impacted sectors of Hawai'i. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Background: The chafer beetle, Holotrichia parallela, causes damage to numerous economically significant crops worldwide. Adult beetles exhibit aggregation behavior likely mediated by a male-produced pheromone. Advancements in biological research technology have facilitated the identification of insect aggregation pheromones and promoted their applications as bait for trapping and monitoring pests. Currently, only a few active components of aggregation pheromones from Holotrichia species have been identified. However, the specific components of aggregation pheromones produced by H. parallela remain unknown.

Result: In this study, we initially observed from Y-tube olfactometer assays that both male and female H. parallela were significantly attracted to volatiles emitted by males, but not to those from females. We then collected hindgut crude extracts of male adults and carried out gas chromatography-mass spectrometry analysis to identify potential aggregation pheromone components. Pentadecyl acetate, cis-13-docosenol, and behenic acid were identified as male-specific compounds in comparison to female extracts, serving as components of the aggregation pheromone in H. parallela. We further evaluated their attractiveness to H. parallea in both laboratory and field experiments. In laboratory settings, pentadecyl acetate, cis-13-docosenol, and behenic acid evoked significant responses to both males and females at specific concentrations, as evidenced by both electroantennography tests and behavioral bioassays. Under field conditions, traps baited with these three compounds captured significantly more H. parallela adults compared to control traps.

Conclusion: In this study, we found that pentadecyl acetate, cis-13-docosenol, and behenic acid are specifically present in male H. parallela, serving as aggregation pheromones. Both laboratory and field-trapping experiments suggest their potential as monitoring and controlling tools against H. parallela adults. © 2024 Society of Chemical Industry.

Background: Fusarium verticillioides is a maize fungal phytopathogen and a producer of volatile organic compounds (VOCs) and fumonisin B₁ (FB₁). Our aim was to study the volatilome, conidial production, ergosterol and FB₁ biosynthesis in maize cultures over a 30-day incubation period (5, 10, 15, 20, 25, 30 days post inoculation [DPI]). The effect of pure VOCs on the same parameters was then evaluated to study their potential role as biocontrol agents.

Results: In total, 91 VOCs were detected, with volatile profiles being more similar between 5 and 10 DPI compared with 15, 20, 25 and 30 DPI. Ergosterol content increased steadily with incubation time, and three growth stages were identified: a lag phase (0 to 15 DPI), an exponential phase (15 to 20 DPI) and a stationary phase (20 to 30 DPI). The maximum concentration of FB₁ was detected at 25 (0.030 μg FB₁/μg ergosterol) and 30 DPI (0.037 μg FB₁/μg ergosterol), whereas conidial production showed a maximum value at 15 DPI (4.3 ± 0.2 × 10⁵ conidia/μg ergosterol). Regarding pure VOCs, minimal inhibitory concentration values ranged from 0.3 mm for 4-hexen-3-one to 7.4 mm for 2-undecanone. Pure VOCs reduced radial growth, conidial production and ergosterol and FB₁ biosynthesis.

Conclusions: The marked resemblance between VOC profiles at 5 and 10 DPI suggests that they could act as early indicators of fungal contamination, particularly 4-ethylguaiacol, 4-ethyl-2-methoxyanisole, heptanol and heptyl acetate. On the other hand, their role as inhibitors of fungal growth and FB₁ biosynthesis prove their great potential as safer alternatives to control phytopathogenic fungi. © 2024 Society of Chemical Industry.