Journal of Pest Science最新文献

RNAi-based pesticides have emerged gradually in recent decades and are believed to be the next generation of pesticides. Although resistance to RNA pesticides has been developed and selected in the laboratory in western corn rootworm and Colorado potato beetle, whether RNAi resistance is a general phenomenon in other coleopteran insects and the underlying mechanism of resistance to RNA pesticides are still unclear. Here, we report the development of a highly dsRNA-resistant (> 4110-fold) population (Pv-30R) of Plagiodera versicolora after seven episodes of selection by feeding a laboratory-reared susceptible population (Pv-S) with the leaves of willow plants coated with dsRNA targeting a signal recognition particle protein 54 k (Srp54k) gene. We showed that Pv-30R was cross-resistant to other dsRNAs (dsActin and dsSnap) but susceptible to the Cry3Bb protein from Bacillus thuringiensis, and the resistance was an autosomal and recessive trait. Although no significant differences of the dsRNA stability in the midgut of larvae between Pv-S and Pv-30R were observed, uptake of dsRNA in the midgut tissue of larvae from Pv-30R was disrupted. Overall, these results demonstrate that high levels of resistance to RNA pesticides can developed quickly in P. versicolora in laboratory condition as observed before for other coleopterans, and possibly sharing similar mechanisms of resistance to dsRNA.

In agroecosystems, the efficiency of biocontrol agents could be improved through the artificial selection of specific traits that would enhance their zoophagy level. The aim of this study was to evaluate the impact of artificially selected populations of the omnivorous predatory bug, Nabis americoferus, on the tarnished plant bug, Lygus lineolaris, in organic strawberry crops. Six populations of N. americoferus were selected according to their aggressiveness, three were composed of highly aggressive individuals, whereas the other lines contained docile individuals. The first hypothesis was that, since aggressive predators display a higher attack rate, aggressive lines would exhibit a higher pest control and a better crop protection than docile lines. The second hypothesis was that, when two biocontrol agents species are used conjointly, the presence of at least one docile population would generate a higher synergy between both species. N. americoferus populations were released in an experimental strawberry field, with or without a second intraguild predator, the Anthocorid, Orius insidiosus. Results support the first hypothesis that the aggressive lines generate a better pest control and a better strawberries crop protection than docile lines but only at low pest density. The second hypothesis is neither supported nor rejected since the combination of docile lines and O. insidiosus led to a better pest control at high pest density, but led to a reduced crop protection at low pest density. Our study shows that the artificial selection of aggressiveness has the potential to improve the effectiveness of biocontrol programs.

Rising temperatures due to climate change are predicted to accelerate the life cycle of arthropod herbivores thereby exacerbating pest formation. Notorious pests like spider mites thrive in areas with high temperatures (32–35 °C), and it is predicted that the size and number of such areas will expand in the coming decades. Higher temperatures can directly accelerate population growth, but also indirectly affect them through changes in the plant's defensive mechanisms. Spider mites have been shown to adapt to plant defences, with natural selection favouring defence-suppressing traits. However, it is not known to what extent suppression is affected by rising temperatures and how this might tie into the rate of adaptation and pest damage. In this study, we investigated the effect of two temperatures (25 °C and 32 °C), on the spider mite–tomato interaction, predicting the influence of rising temperatures on favouring defence-adapted mites. We found that all mite strains caused more plant damage at 32 °C, but temperature did not affect the overall patterns of induction and suppression of defence genes. Although fecundity was higher for all strains at 32 °C, juvenile and adult survival was lower, especially for inducer mites. With these data, we parametrized population models for the two strains over three months, indicating that suppressor mites might displace inducers at the higher temperature, either when it is constant or in the form of heat waves. Our models predict that in areas with higher temperatures, defence-suppressing mites are favoured, which will accelerate and consequently spur pest formation.

In Europe, the recently reported plant pathogen Xylella fastidiosa subsp. multiplex affects several wild, ornamental, and cultivated trees causing scorch diseases. In 2018, the sequence type 87 was reported in Tuscany on Mediterranean shrubs and trees. Although spittlebugs (Hemiptera: Aphrophoridae) were already identified as main vectors of this bacterium in Europe, their role in the transmission of this subspecies has not been ascertained yet. In this study the ability of Philaenus spumarius and Neophilaenus campestris to acquire and transmit Xylella fastidiosa subsp. multiplex sequence type 87 from and to Rhamnus alaternus was evaluated in two-year semi-field experiments. To acquire the bacterium, insects were confined on wild, naturally infected R. alaternus shrubs for 120 h. Then, they were transferred to healthy plants and maintained in cages for 96 h. To follow the infection, plant samples were collected every two months for three times. Tested plants were destroyed at the end of experiments and roots, twigs and leaves were analysed. Philaenus spumarius showed a significantly higher survival rate than N. campestris. The infection status of both insects and plants was assessed through molecular analysis. P. spumarius and N. campestris were able to infect healthy plants although the acquisition rate and the estimated probability of transmission appeared to be low. These findings provide new accounts on the role of two polyphagous insect vectors in spreading a quarantine organism, which is lethal to a huge number of plant species. However, further studies are needed to disclose more specific interactions within this complex pathosystem.

Changes in land use is an important driver of insect pest population dynamics, but the long-term effects of land use may be contingent on changes in some factors. To identify potential effects of change in cropping pattern on agricultural pest population trends, data from large temporal and spatial scales are needed but are rarely available. Here, we used long-term (15 years) pest monitoring data across a regional scale and across independent gradients of land-use intensity at the landscape level (61 agro-landscapes with a radius of 2.0 km), to investigate the effects of the expansion of area devoted to major cereal crops on population trends of polyphagous Helicoverpa armigera in northern China. We found that an increased proportion of the land planted to maize and wheat in the landscape had an indirectly positive effect on the activity density of the summer population of H. armigera by increasing the population density of the preceding spring generations. Stable carbon isotope analysis suggested that maize acted as the source habitat for H. armigera population in the growing season. At the regional level, long-term expansion of maize and wheat production, as well as the contraction of cotton area, was associated with an increased density of H. armigera in spring generations across years, although temperature and precipitation factors also had significant effects on pest population sizes. These results across both temporal and spatial scales indicated that, in addition to Bt cotton contraction, increased cereal crops cultivation was an important driver of the H. armigera population increases in recent decades in northern China.

The Yellow-legged hornet (Vespa velutina nigrithorax) was accidentally introduced into south-western of France in 2004 and rapidly spread throughout France and neighbouring countries. This insect predator hunts honey bees leading to a hornet-mediated beekeeping risk (HBR) with potential mortality of honey bee colonies and important economic costs. However, the spatial distribution of HBR is not yet assessed and is urgently required to formulate suitable management plans in Western Europe. We conducted a two-year citizen science survey in France and Germany to assess the spatial distribution of (1) the hornet and (2) HBR, and to (3) determine the environmental factors involved. A total of 1678 beekeepers participated in the survey. As expected, the hornet was established throughout the French territory, and was mainly detected near the French border in Germany. We found that HBR was substantially lower in Germany than in France. Temperature had a positive effect on both hornet presence and HBR, whereas distance to the introduction point had a negative effect in both France and Germany. These results suggest that the impact of V. velutina on beekeeping is not homogenous across the invasion range and could be reduced on the eastern front due to the continental climate. Taking into account the spatial variability of HBR could help to formulate regionally adapted management plans to limit the impact of V. velutina on biodiversity, human health and economic sectors.

Aromia bungii Faldermann (Coleoptera: Cerambycidae) is an emerging invasive pest of economically important Prunus species that is native to China, Mongolia, the Russian Far East, Korea, and Vietnam. It was recently introduced to Japan, Germany, and Italy, where it is spreading and damaging crops and ornamental trees. It exhibits an adaptable lifecycle, a high reproductive output, and the larvae live concealed under the bark of infested trees, which are traits that promote its invasiveness. Detection and monitoring of A. bungii currently rely upon visual identification of infested trees that are usually already damaged, which is inefficient and not target-specific. Current control methods rely primarily upon the labour-intensive physical removal of infested trees. Although native parasitoid natural enemies of A. bungii provide control in Chinese orchards, none are appropriate for classical biological control in invaded areas due to biosafety concerns surrounding their broad host ranges. However, entomopathogenic fungi and nematodes may provide viable options for biological control in invaded ranges. Recent advancements in semiochemical baited traps may provide sustainable, target-specific, and efficacious methods to monitor and control A. bungii. There remains much to learn about the biology and control of A. bungii, and continued advancements in the study of sustainable control tools are needed for the management of this emerging pest.

An aqueous ant bait consisting of sucrose (4.55% w/v), essential amino acids (EAAs, 1%), and water is known to be highly appealing to multiple ant species throughout the foraging season. Here, we tested whether this bait, combined with boric acid as the lethal agent, has potential for control of pest ants. Specifically, we: (1) assessed bait lethality to diverse species of ants (European fire ants, Myrmica rubra, western carpenter ants, Camponotus modoc, thatching ants, Formica oreas); (2) tested the effect of boric acid concentration on mortality of M. rubra workers and colonies; (3) compared consumption, and demise timeline, of lethal liquid baits and lethal gel baits; and (4) investigated whether lethal liquid baits reduce the size of M. rubra colonies. In laboratory experiments, the bait induced rapid worker mortality (< 22 days) in all three species of ants tested. Increasing the concentration of boric acid from 1% to 5.4% accelerated the demise of only worker ants, but not queen ants, in M. rubra colonies, indicating that 1% boric acid is sufficiently lethal. Worker ants of M. rubra strongly preferred liquid baits to gel baits of identical nutrient composition, with the former bait accelerating worker demise. In a field experiment in a public park heavily infested with M. rubra, the 12 treatment colonies provided with a lethal liquid bait (4.55% sucrose; 1% EAAs; 1% boric acid) over 114 days significantly declined, whereas the 12 control colonies provided with the corresponding non-lethal bait did not. The bait, with appropriately adapted bait deployment protocol, should be tested for control of other pest ants, particularly those that preferentially feed on liquid foods.

Whole ecosystem-based approaches are becoming increasingly common in pest management within agricultural systems. These strategies consider all trophic levels and abiotic processes within an ecosystem, including interactions between different factors. This review outlines a whole ecosystem approach to the integrated pest management of pear psyllid (Cacopsylla pyri Linnaeus) within pear (Pyrus communis L.) orchards, focusing on potential disruptions as a result of climate change. Pear psyllid is estimated to cost the UK pear industry £5 million per annum and has a significant economic impact on pear production globally. Pesticide resistance is well documented in psyllids, leading to many growers to rely on biological control using natural enemies during the summer months. In addition, multiple insecticides commonly used in pear psyllid control have been withdrawn from the UK and Europe, emphasising the need for alternative control methods. There is growing concern that climate change could alter trophic interactions and phenological events within agroecosystems. For example, warmer temperatures could lead to earlier pear flowering and pest emergence, as well as faster insect development rates and altered activity levels. If climate change impacts pear psyllid differently to natural enemies, then trophic mismatches could occur, impacting pest populations. This review aims to evaluate current strategies used in C. pyri management, discuss trophic interactions within this agroecosystem and highlight potential changes in the top-down and bottom-up control of C. pyri as a result of climate change. This review provides a recommended approach to pear psyllid management, identifies evidence gaps and outlines areas of future research.

The “ecology of fear”, i.e., physiological and behavioral alterations displayed by pests in response to predation risk, has recently been proposed as a sustainable alternative to chemicals for pest control. However, the development of such a strategy requires a detailed understanding of the signals and cues underlying the pest-antagonist interaction and eliciting the prey behavioral alteration. Here, we characterized the substrate-borne vibrations produced during the interaction between the green peach aphid Myzus persicae and its antagonists, the parasitoid wasp Aphidius colemani and the ladybug Adalia bipunctata. Thereafter, coupling the electrical penetration graph (EPG) with a stimulus controller, we evaluated whether the playback of the vibrations, alone and in combination with the alarm pheromone, impacted aphid probing behavior and interaction with the host plant. Aphids responded to vibrations exhibiting longer non-probing, shorter intracellular probes, i.e. the behavior through which the insect evaluates host plant quality, delay in accessing the phloem vessels and decrease of the frequency of phloem salivation events. In contrast, on plants treated with the alarm pheromone, insects displayed longer intracellular probes. We hypothesize that the alarm pheromone, signaling a distant threat, might induce a careful evaluation of the host plant in order to decide the magnitude of the reaction. On the other hand, vibrations might indicate a closely approaching threat pushing the aphid to rush the host evaluation process and the whole feeding process. The possible repercussion of the behavioral alterations observed on the dynamics of aphid-borne plant virus transmission is also discussed.