Journal of Pest Science最新文献

The southern US has a large presence of mosquito vector species for dengue virus (DENV) and experiences thousands of DENV importations every year, which have led to several local outbreaks. Adulticide spraying targeting active mosquitoes is one of the most common insecticide strategies used as a response to an outbreak. The aim of this study is to evaluate the effectiveness of adulticide spraying conducted at different times of the day to curb DENV transmission. Based on unique dataset of Aedes aegypti diel activity patterns in Miami-Dade County, Florida, and Brownsville, Texas, we developed a mechanistic model of DENV transmission, which simulates adulticide spraying interventions. We estimated that spraying adulticide for 14 consecutive days at 7am or 8 pm was highly effective in reducing DENV outbreak probability from 10% in the absence of interventions to 0.1% for Miami-Dade County, and from 7.8 to 0.1% for Brownsville. Moreover, in case of a local outbreak in Miami-Dade County, we estimated the median number of symptomatic infections after the identification of a local outbreak to be reduced from 67.0 (IQR: 25.5–103.0) in the absence of interventions to 1.0 (IQR: 0.0–2.0) when spraying adulticide for 14 consecutive days at 8 pm. In Brownsville, the same intervention is estimated to lead to a decrease from 15.0 (IQR: 7.0–33.0) cases to 1.0 (IQR: 0.0–2.0). Our study highlights the importance of considering diel activity patterns of vector mosquito species in arbovirus preparedness and response planning and provide quantitative evidence to guide the decision-making of mosquito control authorities.

The obscure mealybug, Pseudococcus viburni, is a serious agricultural pest worldwide. The biological control in commercial fields of P. viburni relies on predators and parasitoids, in particular the generalist coccidophagous ladybird Cryptolaemus montrouzieri and the specific parasitoid Acerophagus flavidulus. However, these two natural enemies can establish an intraguild predation interaction, reducing the efficiency of biological control. Cryptolaemus montrouzieri may negatively impact the population dynamics of A. flavidulus if it feeds indifferently on healthy and parasitized mealybugs. With the aim of improving the biological control of P. viburni, in this work, we studied the feeding behavior of C. montrouzieri in the absence or presence of A. flavidulus larvae of different age within mealybugs, in laboratory conditions. Subsequently, with the data obtained, we mathematically modeled the dynamics of P. viburni to study the impact on P. viburni control of different field implementation schedules for the release of ladybird and parasitoid populations. The ladybird fed on parasitized P. viburni but reduced its consumption when they were infested by parasitoids aged of 4 days or more. Modeling results suggest that these feeding preferences of predators may have a positive impact on pest control, that releasing predators and parasitoids together is in general more effective than releasing them independently, and that releasing highly effective predators alone could be the best choice. Modeling results also provide information on different release schedules.

Climatic conditions are key determining factors of whether plant pests flourish. Models of pest response to temperature are integral to pest risk assessment and management, helping to inform surveillance and control measures. The widespread use of meteorological data as predictors in these models compromises their reliability as these measurements are not thermally coupled to the conditions experienced by pest organisms or their body temperatures. Here, we present how mechanistic microclimate models can be used to estimate the conditions experienced by pest organisms to provide significant benefits to pest risk modelling. These well-established physical models capture how landscape, vegetation and climate interact to determine the conditions to which pests are exposed. Assessments of pest risk derived from microclimate conditions are likely to significantly diverge from those derived from weather station measurements. The magnitude of this divergence will vary across a landscape, over time and according to pest habitats and behaviour due to the complex mechanisms that determine microclimate conditions and their effect on pest biology. Whereas the application of microclimate models was once restricted to relatively homogeneous habitats, these models can now be applied readily to generate hourly time series across extensive and varied landscapes. We outline the benefits and challenges of more routine application of microclimate models to pest risk modelling. Mechanistic microclimate models provide a heuristic tool that helps discriminate between physical, mathematical and biological causes of model failure. Their use can also help understand how pest ecology, behaviour and physiology mediate the relationship between climate and pest response.

Bactrocera dorsalis is a highly invasive fruit pest of economic and quarantine significance. The males are strongly attracted to methyl eugenol (ME). After consumption, ME is converted to metabolites that act as sex pheromones, which increase mating success. ME lure is instrumental in male annihilation technique (MAT) and sterile insect technique (SIT) applications to suppress or eradicate fruit fly populations. A simultaneous MAT-SIT concept is proposed to reduce operational costs and time-to-eradication. However, sterile males released to the field may respond to MAT’s ME-baited traps, reducing the efficacy of SIT. Here, we developed a ME-supplemented diet that reduces males’ response to ME without compromising mating efficiency and survivorship. We offered sugar-yeast diet supplemented with ME (0–5%) to 5-day-old males for 48 h and evaluated their response to ME, mating performance and pheromone production at 3-, 7-, 11- and 15-days post-treatment (DPT), while observing mortality for 60-DPT. Our results indicate that consuming a ME-supplemented diet reduces response to ME lures and enhances mating success, with the 5% ME diet showing the most promising results. The trend of pheromone production at different DPT after consuming various ME-supplemented diets corroborated with those of reduced lure response and mating enhancement. Although diet containing 3 and 5% ME affected males’ survival probability over 60-DPT, the treatment does not impact the survival of all treated males for at least 25-DPT. This finding suggests that pre-release feeding on a 5% ME-supplemented diet by 5-day-old B. dorsalis males is a feasible solution for implementing simultaneous MAT-SIT.

Studying the efficacy of control methods is paramount to successful management of invasive pests and understanding why some colonies survive is important to improve management practices. Here, the bait Vespex® was used to control invasive wasps across 64 ha of forest in an invaded range near Hanmer Springs, New Zealand. Bait was applied across a standard 50 m by 300 m arrangement and made available for 3 days. Nest mortality rates after 19 days were 29.8%, although nearly all nests were affected with a median overall reduction in nest traffic of 96.5%. The results from logistic regression showed that, all else remaining equal, larger wasp nests, nests further from bait stations, and more isolated nests exhibited lower rates of mortality after baiting. Investigating the change in activity at surviving nests, the results from beta regression suggest that declines in nest traffic were less severe with increasing distance to the nearest bait, but more severe with increasing nest size. These results indicate that while smaller nests are at a higher risk of being killed by the bait, they may not encounter bait as regularly as larger nests. Bait uptake varied considerably across bait stations. Wasp nests were not randomly or uniformly distributed in space, and instead were aggregated across our treatment area, likely due to some aspects of environmental conditions. We suggest further research to be focused on developing an understanding of the drivers of wasp nest development and foraging behaviour, to produce a more flexible baiting procedure that will increase both baiting efficiency and efficacy.

The Asian tiger mosquito Aedes albopictus is one of the most invasive species and an efficient vector of several pathogens. RNA interference (RNAi) has been proposed as an alternative method to control mosquito populations by silencing the expression of genes that are essential for their survival. However, the optimal delivery method for dsRNAs to enhance an optimal RNAi remains elusive and comparative studies are lacking. We have, therefore, compared the efficiency of three non-invasive delivery methods to mosquito larvae: soaking, rehydration and nanoparticle ingestion. Each method was tested separately on four genes predicted to code non-essential proteins (i.e., collagenase-like, kynurenine 3-monooxygenase-like, yellow-like and venom serine protease-like) in order to be able to compare the importance of gene knock-down. All tested methods successfully downregulated mosquito gene expression. However, silencing efficiency strongly varies among methods and genes. Silencing (95.1%) was higher for Kynurenine 3-monooxygenase-like with rehydration and nanoparticle ingestion (61.1%). For the Venom serine protease-like, the most efficient silencing was observed with soaking (74.5%) and rehydration (34%). In contrast, the selected methods are inefficient to silence the other genes. Our findings also indicate that gene copy numbers, transcript sizes and GC content correlate with the silencing efficiency. From our results, rehydration was the most specific and efficient methods to specifically knock-down gene expression in Ae. albopictus larvae. Nevertheless, considering the observed variability of efficiency is gene-dependent, our results also point at the necessity to test and optimize diverse dsRNA delivery approaches to achieve a maximal RNAi efficiency.

Endosymbionts living within insect cells can modify host fitness and could provide new tools for pest control. The endosymbiont Rickettsiella viridis has been transferred experimentally into the green peach aphid, Myzus persicae, a globally important agricultural pest. This Rickettsiella spreads via vertical and horizontal transmission and induces host fitness costs which could potentially suppress pest populations. Endosymbiont prevalence can fluctuate in natural populations, and it is important to identify factors that contribute to their spread or loss. Here, we explore the effects of Rickettsiella infection when aphids are reared on eight different host plants or exposed to thermal, starvation and desiccation stresses. Rickettsiella infection reduced M. persicae fecundity and longevity across all host plants, but the magnitude of costs varied among host plants and generations. Rickettsiella was horizontally transmitted and spread in caged populations at initial ratios of 1:2 Rickettsiella (+): Rickettsiella (−) on all host plants, but with limited long-term persistence under cycling 20–30 °C. We also identified temperature-dependent costs of Rickettsiella infection on heat knockdown time, chill coma recovery, and starvation tolerance. Finally, we present evidence that Rickettsiella infection reduces host activity levels under heat stress. Our results suggest that Rickettsiella infections induce a variety of deleterious effects but with complex environment-dependent interactions. This work helps understand ecological conditions that enhance or limit the spread of these endosymbionts in aphid populations.

The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is one of the most destructive invasive forest pests in North America, where it has killed hundreds of millions of ash (Fraxinus spp.) trees since its first detection in 2002. Native to Asia, female EAB adults lay their eggs between bark crevices or under loose bark of their host trees. Because of this cryptic egg-laying behavior, field detection of EAB eggs has been extremely difficult, resulting in knowledge gaps of EAB egg-laying behavior. In the present study, I tested the potential use of strips of burlap fabric (0.03 m × 1 m) or polypropylene curling ribbon (0.005 m × 2 m) to induce female EAB adults to lay eggs on the trunks or branches of ash covered with these materials in the field. The burlap trap tested in this study detected more than twice as many EAB eggs (4.9 ± 1.1 eggs per burlap trap) as did the polypropylene ribbon trap (1.9 ± 0.5 eggs per ribbon trap). When the surface area of each trap is standardized to one square meter, however, both burlap fabric and polypropylene ribbon traps are equally effective in inducing female EAB adults to lay eggs onto the covered surface of ash trunks or branches. Potential applications of the oviposition traps for effective detection and control of EAB and other jewel beetles are discussed.

Pyrethroid resistance has become one of the largest obstacles to mosquito control, and Anopheles sinensis is the main malaria vector in China and southeast countries. miRNAs play important roles in many biological processes in insects; however, the diversity and regulation of miRNAs associated with pyrethroid resistance are still little understood at the whole-genome level. This study performed the sequencing and analysis of miRNAs relative to pyrethroid resistance in An. sinensis for the first time, and identified 328 miRNAs, of which 247 are new. A total of 39 miRNAs are identified to be significantly downregulated commonly in all three pyrethroid-resistant populations investigated in comparison to the susceptible strain. There are 7475 genes to be predicted to be targeted by the 39 significantly down-regulated miRNAs, and they were enriched to seven pathways. The regulation of Transferrin by asi-miR-87 was verified using dual-luciferase, and the asi-miR-87 might be involved in P450 pyrethroid detoxification with the affection of iron ion transportation and synthesis through Transferrin. In addition, nine miRNAs were identified to be positively relative to eight genes. This is the first systematic study on the diversity and regulation of miRNAs associated with insecticide resistance at the whole-genome level, and provides an information frame for the understanding of miRNAs and their function in insecticide resistance.

The use of semiochemical-baited traps for detection, monitoring, and sampling bark beetles and woodboring beetles (BBWB) has rapidly increased since the early 2000s. Semiochemical-baited survey traps are used in generic (broad community level) and specific (targeted toward a species or group) surveys to detect nonnative and potentially invasive BBWB, monitor established populations of invasive or damaging native species, and as a tool to survey natural communities for various purposes. Along with expansion in use, much research on ways to improve the efficacy of trapping surveys for the detection of specific pests as well as BBWB in general has been conducted. In this review, we provide information on intrinsic and extrinsic factors and how they influence the efficacy of detecting BBWB in traps. Intrinsic factors, such as trap type and color, and other factors are described, as well as important extrinsic factors such as habitat selection, horizontal and vertical placement, and disturbance. When developing surveys, consideration of these factors should increase the species richness and/or abundance of BBWB captured in traps and increase the probability of detecting nonnative species that may be present. During generic surveys, deploying more than one trap type or color, using an array of lures, and trapping at different vertical and horizontal positions is beneficial and can increase the number of species captured. Specific surveys generally rely on predetermined protocols that provide recommendations on trap type, color, lure, and trap placement.