Journal of Pest Science最新文献

This study was designed to investigate the acute toxicity (mortality) and sublethal effects (fertility and potential natality) of carlina oxide, the main constituent of Carlina acaulis essential oil (EO), against adults of Metopolophium dirhodum (Walker) (Hemiptera: Aphididae). Moreover, its toxicity was evaluated against two aphid natural enemies, i.e., Aphidoletes aphidimyza Rondani (Diptera: Cecidomyiidae) and Chrysoperla carnea Stephens (Neuroptera: Chrysopidae). The highest tested concentration (3.0 mL L⁻¹) resulted in 96.7% mortality of adults of the target pest, highlighting that this concentration of carlina oxide had a similar effectiveness as the positive control we used. Furthermore, probit analysis allowed the estimation of a LC₅₀ of 1.06 mL L⁻¹ and a LC₉₀ of 2.58 mL L⁻¹ for the target pest, which resulted in a much higher mortality rate than that found on natural enemies, i.e., A. aphidimyza (6.7 ± 4.7% ± SD when exposed to the aphid LC₉₀) and C. carnea (7.0 ± 5.5% ± SD when exposed to the aphid LC₉₀), showing the limited non-target impact of carlina oxide. The use of LC₃₀ and LC₅₀ of this compound allowed the fertility inhibition of the target pest by 35.68 ± 6.21% and 23.66 ± 10.58%, respectively, and potential natality inhibition of the target pest by 52.78 ± 4.48% and 59.69 ± 5.60%, respectively. Of note, carlina oxide showed excellent insecticidal activity against M. dirhodum, comparable to the commercial insecticide considered. Overall, the low toxicity of carlina oxide toward A. aphidimyza and C. carnea makes it a safe compound for non-target organisms as well as suitable for developing a green insecticide for the management of M. dirhodum and perhaps other insects of agricultural or medical and veterinary interest.

The European spruce bark beetle Ips typographus is a widespread pest in Norway spruce-dominated forests in Eurasia. Predicting its phenology and voltinism is crucial to plan forest management measures and to mitigate mass outbreaks. Current phenology models are based on constant temperatures inferred from laboratory experiments; however, insect life cycles under natural conditions are rather driven by diurnal and seasonal temperature fluctuations. Therefore, phenology models based on fluctuating temperatures would reflect field conditions more realistically and might thus improve model predictions. In a laboratory experiment, we investigated the development of I. typographus, applying mean temperatures between 3 and 35 °C and diurnal temperature oscillations of up to ± 15 °C. Subsequently, we calibrated developmental rate models and applied them to climate data, in order to assess the effect of temperature fluctuations on voltinism under field conditions. Our results showed that diurnal temperature oscillations significantly affected developmental rates. Compared to constant temperatures, development was faster at temperature oscillations falling below the lower developmental threshold, and slower at temperature oscillations exceeding the developmental optimum. Furthermore, short exposures to suboptimal temperatures affected I. typographus less than expected from constant conditions. Natural temperature fluctuations thus accelerate development under cool, shaded conditions, whilst slowing it under hot, sun-exposed conditions, thereby ultimately affecting voltinism. Our findings highlight the importance to account for diurnal temperature fluctuations for more accurate predictions of developmental rates of I. typographus in natural thermal environments, and provide the fundament for improving current phenology models to support effective bark beetle management in a warming climate.

Lepidopteran borers stand out as the most destructive pests in sugarcane, leading to reductions in stalk weight, juice quality and sugar recovery. Presently, integrated pest management (IPM) systems are utilized for sugarcane borer management, employing diverse methods encompassing cropping system, chemical pesticides, behavioral manipulation, biological agents and the selection of resistant varieties. However, the effectiveness of this strategy remains controversial due to concerns about harmful residues, formulation limitations, environmental variability, labor shortages and increased input costs. Currently, multiple lines of transgenic sugarcane expressing insecticidal genes from the bacterium Bacillus thuringiensis (Bt) have been developed globally, offering the prospect of increases production with reduced pesticides application, thereby eliminating the negative effect of IPM. In Brazil, the first genetically modified sugarcane cultivars resistant to the sugarcane borer have been approved and released for commercial cultivation, shedding a bright light on a viable solution for sugarcane borers. This paper reviews borer species and distribution, the significant damage caused by sugarcane borers, current control approaches and the future effective control strategies. Additionally, this work provides comprehensive understanding on Bt sugarcane, serving as an additional tool to complement conventional sugarcane borers control resistance programs.

Viral diseases like yellow fever, dengue, and Zika have an alarming impact on public health. These diseases can be transmitted by Aedes mosquito species, such as Ae. albopictus, which is now found in many countries outside its original range. Xenorhabdus and Photorhabdus spp. are enteric bacterial symbionts of insect-preying nematodes and are known to produce an array of natural products with various activities including larvicidal activity. In this study, the effects of natural products produced by four Xenorhabdus and one Photorhabdus bacteria on the ovipositional behavior of Ae. albopictus mosquitoes were assessed. Utilizing a binary choice assay in insect cages, gravid female mosquitoes were presented with two oviposition cups containing water supplemented with varying concentrations of bacterial supernatants (50–1% concentrations) versus control medium. After 72 h, the eggs deposited on filter papers were counted. The oviposition attractant index (OAI) feature of the bacterial supernatant was evaluated using the number of eggs laid in the cups. Notably, all tested supernatants exhibited concentration-dependent deterrence of oviposition. Xenorhabdus cabanillasii displayed the strongest deterrent effect, inhibiting egg-laying at 50–5% concentrations (OAI: − 0.87 to − 0.35), followed by X. nematophila (50–10%, OAI: − 0.82 to − 0.52). Xenorhabdus szentirmaii, X. doucetiae, and P. kayaii showed significant deterrence at ≥ 20% concentrations. Using promoter exchange mutants generated by the easyPACId approach, fabclavine from X. szentirmaii was identified as the bioactive compound with evident deterrent effects. Such deterrents targeting egg-laying could be valuable for controlling populations by disrupting their breeding in suitable habitats.

Gelsemium elegans Benth. (Loganiaceae), also known as heartbreak herb, can be used in the manufacture of herbal medicines. Insecticidal activity has also been found and can be used to develop botanical insecticides. This study aimed to reveal the insecticidal mechanism of its extracts against red fire ants and provide strategies for the development of biopesticides and the promotion of green and sustainable agriculture. 16s rRNA, pathohistological, behavioral, and enzyme activity assays were performed to reveal its biological effects, including the effects on non-target organisms. Our results showed that red fire ants exposed to G. elegans extracts exhibited slowed growth, reduced feeding, and decreased aggressiveness. The midgut and its peritrophic membrane of red fire ant were significantly disrupted, the diversity of gut microbial community was reduced, and the balance of microbial composition was disturbed. Significant increases in functional abundance of xenobiotics biodegradation and metabolism pathway and P450s enzyme activity confirmed the toxic stress of G. elegans extract. Functional prediction of Kyoto Encyclopedia of Genes and Genomes pathway showed that the functional abundance of novobiocin biosynthesis, flavonoid biosynthesis, lysosome, proteasome, and wingless/integrated signaling pathways were significantly inhibited in the gut. Besides, G. elegans extracts induced an increase in acetylcholinesterase activity. These results revealed dysregulation of immune system and metabolic functions in red fire ants, as well as toxic effects of G. elegans extracts on physiological functions and nerves. These findings revealed the insecticidal mechanism of G. elegans and supported the development of eco-friendly insecticides for red fire ants.

Abstract

Due to climate change, outbreaks of insect-vectored plant viruses have become increasingly unpredictable. In-depth insights into region-level spatio-temporal dynamics of insect vector migration can be used to forecast plant virus outbreaks in agricultural landscapes; yet, it is often poorly understood. To explore this, we examined the incidence of beet curly top virus (BCTV) in 2,196 tomato fields from 2013 to 2022. In America, the beet leafhopper (Circulifer tenellus) is the exclusive vector of BCTV. We examined factors associated with BCTV incidence and spring migration of the beet leafhopper from non-agricultural overwintering areas. We conducted an experimental study to demonstrate beet leafhopper dispersal in response to greenness of plants, and spring migration time was estimated using a model based on vegetation greenness. We found a negative correlation between vegetation greenness and spring migration probability from the overwintering areas. Furthermore, BCTV incidence was significantly associated with spring migration time rather than environmental conditions per se. Specifically, severe BCTV outbreaks in California in 2013 and 2021 were accurately predicted by the model based on early beet leafhopper spring migration. Our results provide experimental and field-based support that early spring migration of the insect vector is the primary factor contributing to BCTV outbreaks. Additionally, the predictive model for spring migration time was implemented into a web-based mapping system, serving as a decision support tool for management purposes. This article describes an experimental and analytical framework of considerable relevance to region-wide forecasting and modeling of insect-vectored diseases of concern to crops, livestock, and humans.

The bark beetle Ips acuminatus is an important pest in pine-dominated forests of Eurasia. Recently, the frequency of I. acuminatus outbreaks and mortality of host trees have increased, most likely as a result of climate change-related alterations in environmental conditions. Therefore, detailed information on the species’ natural history is essential to understand its potential to damage forests and to apply sustainable management measures. We provide a comprehensive overview on the life history of I. acuminatus, focusing on traits that might explain outbreaks and the ability to cause tree mortality. We review its importance for European forestry, outbreak behavior, host plant usage, reproductive biology, temperature-dependent development, diapause and overwintering behavior, and interactions with fungi, bacteria, nematodes and other arthropods. Interestingly, I. acuminatus has a strong nutritional dependency on the fungus Ophiostoma macrosporum, underlined by the presence of a prominent oral mycetangium, a spore-carrying organ, in females, which is not known for other Ips species. Moreover, I. acuminatus can reproduce sexually and asexually (pseudogamy). Additionally, information on the species’ evolutionary past provides valuable insights into the origin of certain traits. We present a phylogeny of the genus Ips and examine selected life-history traits in an evolutionary context. Together with its sister species Ips chinensis, I. acuminatus forms a separate clade within Ips. The ancestor of Ips bark beetles originated about 20 million years ago and was a pine-colonizing species inhabiting the Holarctic. Finally, open fields of research are identified to guide future work on this ecologically and economically important pine bark beetle.

A breeding population of the tree-killing European spruce bark beetle Ips typographus was detected in England for the first time in 2018 and was initially assumed to have arrived with infested timber. To test the hypothesis that the beetles are dispersing naturally across the English channel, extensive trap networks were deployed in 2021 and 2022 to track the flight activity of the beetles from an outbreak hotspot in France and Belgium to southern England, including parallel ‘coastal’ traps on either side of the channel. Beetles were caught all along the transect, decreasing in abundance with distance from the outbreak area. Linear modelling indicates that beetles dispersed into England during 2021 and 2022, and that during a large-scale dispersal event in June 2021, beetles could have penetrated more than 160 km inland. The 2021 dispersal event initiated new incursions of the beetle in southeast England and demonstrates the extraordinary distance I. typographus may move under outbreak conditions. Our findings support the hypothesis of a damaging forest pest aerially dispersing across the barrier of the English channel and suggest that future incursions of this and other plant-associated pests may move via the same pathway.

Abstract

Omnivores obtain resources from more than one trophic level, choosing food based on quantity and quality. They usually engage in intraguild predation (IGP) when prey is scarce. Orius laevigatus is an example of omnivore that becomes superior predator of the predatory mite Amblyseius swirskii when released in a combined system under low levels of the preferred prey, the thrips Frankliniella occidentalis. Here, we test two genetically enhanced O. laevigatus strains for bigger size and better fitness feeding on pollen (BIG30 and 2POL-11, respectively), hence with a wider dietary diversification, to elucidate the potential effects on prey preference and IGP on the predatory mite, in comparison with a commercial population of O. laevigatus. To do that, predation rates were registered on adult phytoseiids solely or in a choice situation at different availability ratios of adult thrips under laboratory conditions. The effect of pollen as supplemental food on IGP and prey preference was examined, too. We found that our two enhanced lines killed up to 9% less predatory mites and fed preferably on adult thrips, compared to the commercial population. While BIG30 showed a significantly higher total predation rate, killing up to 150% more adult thrips, 2POL-11 is defined as an efficient user of resources, switching between different prey and pollen showing low IGP. Pollen supplementation had a significant effect on reducing IGP, but only for 2POL-11 the influence on prey preference was significant. The theory of intraguild predation and the impact of prey switching on food webs and biological control strategies are also discussed.

The effect of environmental change on activity of insecticides against insects has been greatly debated, and it is of significance to evaluate general patterns of change and explore the potential mechanisms that drive the changes in the context of global climate change. To that end, we constructed three multilevel meta-analyses and phylogenetically-corrected models based on 810 individual effect sizes of insecticide activity from 95 studies with variable levels of temperatures, humidities, and CO₂ concentrations. We found that increasing temperatures could overall increase the insecticidal activity of insecticides by 1.33 times. Increasing temperatures will boost the activity of some types of insecticides (e.g., acetylcholinesterase inhibitors), but decrease the activity of some other types (e.g., sodium channel modulators). Activities of stomach toxicants and fumigants are overall more sensitive to increasing temperatures than other insecticides. The sensitivity of insects in Hemiptera, Coleoptera, and Diptera to insecticides will also tend to increase significantly due to increasing temperatures. The magnitude of warming was found to have strong interactive effects with both insecticide class and insect group. Although moisture changes were showed to have no significant effects on insecticidal activity overall, our meta-regression analyses identified a positive relationship between insecticide activity and the magnitude of humidity change. No significant relationships between changes in CO₂ concentrations and insecticide activity were identified. Our results are critical in adaptation of insecticide application and pest management strategies, and forecasting insecticide risks (e.g., resistance development) across global climate regions under future warming conditions.