Micro-managing arthropod invasions: eradication and control of invasive arthropods with microbes

Non-indigenous arthropods are increasingly being introduced into new areas worldwide and occasionally they cause considerable ecological and economic harm. Many invasive arthropods particularly pose problems to areas of human habitation and native ecosystems. In these cases, the use of environmentally benign materials, such as host-specific entomopathogens, can be more desirable than broader spectrum control tactics that tend to cause greater non-target effects. The majority of successful eradication programs using arthropod pathogens have targeted invasive Lepidoptera with Bacillus thuringiensis kurstaki (Btk), such as eradication efforts against the gypsy moth, Lymantria dispar (L.), in North America and New Zealand. Both Btk and Lymantria dispar nucleopolyhedrovirus have been successfully used in efforts to limit the spread of L. dispar in the United States. For invasive arthropod species that are well established, suppression programs have successfully used arthropod-pathogenic viruses, bacteria, fungi and nematodes for either short- or long-term management. We will summarize the use of pathogens and nematodes in invasive arthropod management programs within a general context, and compare the use of microbes in gypsy moth management with diverse microbes being developed for use against other invasive arthropods.     

Global range expansion of pest Lepidoptera requires socially acceptable solutions

Caterpillars of key moth pests can cause significant losses in cropping systems worldwide, and globalization is spreading such pests. Failure to control some species can jeopardise the economics of food production. A Global Eradication and Response Database (http://b3.net.nz/gerda) was reviewed on known government-level incursion response programs specific to invasive Lepidoptera. Geographic range expansion of Lepidoptera was evident from 144 incursion response programs targeting 28 species in 10 families. The countries involved in responses to Lepidoptera were USA (104), Australia (8), Canada (7), New Zealand (6), Italy (3), Mexico (2), with the remainder with one programme each (Brazil, Czech Republic, France, Hungary, and Spain). Most programs have been undertaken since the 1990’s. Control options exist for the long-term management of Lepidoptera, but most have issues of cost, efficacy or non-target impacts that reduce their acceptance. Pheromone-based technologies are increasingly available and are generally highly compatible with other tactics. The development of tactics for new targets is a major undertaking, although previous programs can be invaluable. New and improved socially-acceptable technologies are needed to counteract range expansion in Lepidoptera, and usually need to be used in combinations to achieve eradication. The sterile insect technique, which involves mass-rearing and release of sterile insects to reduce wild populations of the pest, has been used successfully against a number of lepidopteran species. Several sterile moth programs are under development. New technologies must have a social license to operate in urban areas, where new incursions are frequently detected. This factor is likely to reduce tactical flexibility and increase the complexity of insect eradication.     

Comparison of methods for estimating the spread of a non-indigenous species

Aim  To compare different quantitative approaches for estimating rates of spread in the exotic species gypsy moth, Lymantria dispar L., using county-level presence/absence data and spatially extensive trapping grids.
Location  USA
Methods  We used county-level presence/absence records of the gypsy moth's distribution in the USA, which are available beginning in 1900, and extensive grids of pheromone-baited traps, which are available in selected areas beginning in 1981. We compared a regression approach and a boundary displacement approach for estimating gypsy moth spread based on these sources of data.
Results  We observed relative congruence between methods and data sources in estimating overall rates of gypsy moth spread through time, and among regions.
Main conclusions  The ability to estimate spread in exotic invasive species is a primary concern in management programmes and one for which there is a lack of information on the reliability of methods. Also, in most invading species, there is generally a lack of data to explore methods of estimating spread. Extensive data available on gypsy moth in the USA allowed for such a comparison. We show that, even with spatially crude records of presence/absence, overall rates of spread do not differ substantially from estimates obtained from the more costly deployment of extensive trapping grids. Moreover, these methods can also be applied to the general study of species distributional changes, such as range expansion or retraction, in response to climate change or other environmental effects.     

葡萄花翅小卷蛾抗药性研究进展

葡萄花翅小卷蛾是葡萄上的重要害虫,具有多食性、多化性等生物学特点,抗逆能力极强。该虫起源于欧洲,现已入侵全球多个国家。葡萄花翅小卷蛾主要以幼虫取食葡萄花序、幼果和成熟果实,给葡萄生产造成重大损失;其危害有利于真菌的侵入,导致灰霉病、白粉病等病害大量发生,从而造成葡萄腐烂。由于该虫入侵风险极高,已被我国列为重要的进境检疫性有害生物。国外对葡萄花翅小卷蛾的防治主要采用化学杀虫剂,由于长期大量且不合理地使用化学杀虫剂,葡萄花翅小卷蛾已对多种不同类型的杀虫剂产生了抗药性。本研究总结了葡萄花翅小卷蛾的抗性测定方法、抗性现状及其抗性机理,同时结合国外葡萄花翅小卷蛾抗性和防治相关研究,提出该虫抗性治理策略,并对我国预防该虫的入侵提出建议。     

Evaluation of extended-life pheromone formulations used with and without dichlorvos for boll weevil (Coleoptera: Curculionidae) trapping

Boll weevil traps baited with a ComboLure (25 of mg grandlure + 30 mg of eugenol + 90 of mg dichlorvos [DDVP]), an extended-release lure (25 mg of grandlure + 30 mg of eugenol + 60 of mg DDVP kill-strip), and extended-release lure with no DDVP were evaluated for boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), captures in South Texas cotton, Gossypium hirsutum L., fields during February-March 2005 and March-April 2006. The traps were serviced once a week for five consecutive weeks by using the same methodology as active boll weevil eradication programs. Mean captured boll weevils from extended-release lures with no DDVP were significantly higher in five of 10 trapping weeks compared with captures of the ComboLure and extended lure. Weekly mortality of boll weevils captured was similar for the ComboLure (72.6 +/- 4.7%) and extended lure + DDVP (73.5 +/- 4.0%), and both were significantly higher than the extended lure (32.8 +/- 5.0%) with no DDVP. The presence or absence of DDVP did not significantly affect the sex ratio of field-captured boll weevils. We found no functional reasoning for using DDVP in large scale trapping of boll weevils regardless of the formulation or presentation in the trap. We conducted two additional trapping evaluations after the 2005 and 2006 studies, but the numbers of boll weevils captured were too low for statistical comparisons, indicating that boll weevil eradication is reducing populations in the Rio Grande Valley of Texas.     

Network theory as a method for developing biosecurity preparedness: Netweork topology of Paratrechina longicornis in the Pacific and within New Zealand

One of the greatest challenges in eradicating pest species is determining when no further individuals remain: terminating the control programme too early means failure to eradicate, whereas continuing for too long can add considerable expense. Since monitoring tools are usually only qualitative and invariably imperfect, there may be considerable uncertainty about when and if eradication has been achieved. However, it is possible to quantify the efficacy of monitoring tools and to use this together with knowledge of the basic ecology of the target pest to robustly quantify the probability of successful eradication over time. Here, I describe one such approach and demonstrate its use in the large-scale eradication of painted apple moth (Teia anartoides) from Auckland, New Zealand. A population model for the production of male moths was used in conjunction with spatially-explicit pheromone trap locations and attraction radii to determine the daily probability of detecting a hypothetical wild population at a particular location. Over time, these probabilities compounded to decrease the likelihood of painted apple moth presence given an ongoing lack of detection. In this way, spatio-temporal risk maps were produced to inform managers and to suggest when eradication had been achieved to a predetermined level of certainty. The model suggested that eradication was likely to have been successful in the main infestation areas by mid 2005, with subsequent catches likely to represent further small incursions, as corroborated by evidence from mitochondrial DNA and stable isotope markers. While it was plausible that a wild population was present in the Otahuhu area in 2005, it was very unlikely that it remained by the end of 2006. Population probability models have potential for much wider use in border biosecurity and establishment of area freedom, particularly in combination with future automated trapping systems.     

Population probability models for insect eradication

One of the greatest challenges in eradicating pest species is determining when no further individuals remain: terminating the control programme too early means failure to eradicate, whereas continuing for too long can add considerable expense. Since monitoring tools are usually only qualitative and invariably imperfect, there may be considerable uncertainty about when and if eradication has been achieved. However, it is possible to quantify the efficacy of monitoring tools and to use this together with knowledge of the basic ecology of the target pest to robustly quantify the probability of successful eradication over time. Here, I describe one such approach and demonstrate its use in the large-scale eradication of painted apple moth (Teia anartoides) from Auckland, New Zealand. A population model for the production of male moths was used in conjunction with spatially-explicit pheromone trap locations and attraction radii to determine the daily probability of detecting a hypothetical wild population at a particular location. Over time, these probabilities compounded to decrease the likelihood of painted apple moth presence given an ongoing lack of detection. In this way, spatio-temporal risk maps were produced to inform managers and to suggest when eradication had been achieved to a predetermined level of certainty. The model suggested that eradication was likely to have been successful in the main infestation areas by mid 2005, with subsequent catches likely to represent further small incursions, as corroborated by evidence from mitochondrial DNA and stable isotope markers. While it was plausible that a wild population was present in the Otahuhu area in 2005, it was very unlikely that it remained by the end of 2006. Population probability models have potential for much wider use in border biosecurity and establishment of area freedom, particularly in combination with future automated trapping systems.     

Increased nutrient availability decreases insect resistance in cranberry

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Pheromone‐trapping the nun moth,Lymantria monacha (Lepidoptera: Lymantriidae) in Inner Mongolia,China

The nun moth, Lymantria monacha L., is one of the most important defoliators of Eurasian coniferous forests. Outbreaks during 2011–2015 in the natural/planted larch, and larch‐birch mixed forests of the Greater Khingan Range in Inner Mongolia, China, caused tremendous timber losses from severe defoliation and tree mortality. A series of trapping experiments were conducted in these outbreak areas to evaluate the efficacy of a synthetic species‐specific pheromone lure based on the female pheromone blend of European nun moth populations. Our results clearly show that the nun moth in Inner Mongolia is highly and specifically attracted to this synthetic pheromone, with few gypsy moths (Lymantria dispar) captured. Flight activity monitoring of L. monacha male moths using pheromone‐baited Unitraps at 2 locations during the summer of 2015 indicated that the flight period started in mid‐July, peaking in early August at both locations. Based on male moth captures, there was a strong diurnal rhythm of flight activity throughout the entire scotophase, peaking between 22:00 and 24:00. Unitraps and wing traps had significantly and surprisingly higher catches than the gypsy moth traps. Unitraps fastened to tree trunks 2 m above ground caught significantly more male moths than those at the ground level or at 5 m height. Male L. monacha moths can be attracted to pheromone‐baited traps in open areas 150–200 m distant from the infested forest edge. Our data should allow improvement on the performance of pheromone‐baited traps for monitoring or mass‐trapping to combat outbreaks of this pest in northeastern China.     

Impact of a long-term mating-disruption management in crops on non-target insects in the surrounding area

Protecting insects in agro-ecosystems may result in substantial benefits assuming that numerous species produce ecological services. The impact of pesticides on non-target insects is a function of the number of treatments, chemical product, amount of active ingredients and the method of application in the fields, together with their persistence in the environment. To reduce the use of these products, several methods of integrated pest management were developed in agriculture. Among them mating-disruption (MD) is widely employed, for example against the codling moth Cydia pomonella L., a key pest in apple orchards. MD should minimize the negative impacts of chemical pest management on non-target insects in the vegetation surrounding the orchards. We investigated this hypothesis in a long-term MD program on insect populations in the edges of managed plots, using five gall-inducing aphid species in 135 Pistacia palaestina trees. The highest aphid species richness was found in trees growing away from orchards followed by trees in orchards close to Kiwi patches which were never sprayed with insecticides. Intermediate aphid species richness was revealed in parcels where MD against codling moth has been carried out during the last 18?years. In these plots, reduced number of chemical treatments was used against secondary pests each year. Trees in orchards with intensive chemical treatment with insecticide had almost no galls. In conclusion, the populations of the five non-target species in the adjacent natural environment did not suffer significantly from the few chemical treatments. The long term MD program of C. pomonella has a minimum disruption on non-target species in the orchards and their immediate surroundings.     

Estimating costs and outcomes of invasive American mink (<Emphasis Type="Italic">Neovison vison</Emphasis>) management in continental areas: a framework for evidence based control and eradication

Introduced predators are a major threat to biodiversity. While in island ecosystems the favoured management option is species eradication, in continental areas most managers tend to control-orientated options, assuming that eradication is an impossible goal. However, many management actions are conducted without precise or quantifiable goals, and their output is difficult to assess due to the lack of experimental approaches and scientific evidence. Here, we analyse the results of a typical small-scale short-term management action consisting of live-trapping and culling invasive American mink. We estimate the American mink population size at the beginning of the study assuming three different scenarios, assess the output of the management action in each scenario and model the results of further trapping efforts. Based on the results we estimate the effort and economic costs required for culling different population percentages per unit area, as well as the costs and feasibility of eradication. Our results provide a basis for planning invasive predator management, setting realistic management goals and estimating funding required, as well as a framework for managers to evaluate on-going management actions. In addition, our results suggest that American mink eradication from some continental areas would be feasible with current techniques at a moderate-low cost. We suggest that invasive predator management in continental areas should move towards eradication when feasible, regarding control as a second option.     

Microencapsulated pear ester enhances insecticide efficacy in walnuts for codling moth (Lepidoptera: Tortricidae) and navel orangeworm (Lepidoptera: Pyralidae)

The efficacy of combining insecticides with a microencapsulated formulation of ethyl (2E,4Z) -2,4-decadienoate (pear ester, PE-MEC) was evaluated in walnuts, Juglans regia L., for codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), and navel orangeworm, Amyelois transitella Walker (Lepidoptera, Pyralidae). Two types of studies were conducted to compare the use of insecticides with and without PE-MEC. In the first study, PE-MEC in combination with reduced rates of insecticides, including chlorpyrifos, phosmet, methoxyfenozide, and codling moth granulovirus were evaluated in single tree replicates. PE-MEC was tested at one to three rates (0.6, 1.8, and 4.4 g active ingredient ha(-1)) with each insecticide. In the second study, seasonal programs including sprays of esfenvalerate, chlorpyrifos, and ethyl parathion at full rates were evaluated in replicated two ha blocks. Significant reductions in nut injury occurred in the single-tree trial with treatments of PE-MEC plus insecticide compared with the insecticides used alone against both pest species; except with methoxyfenozide for navel orangeworm. Similarly, nut injury in the large plots was significantly reduced with the addition of PE-MEC, except for navel orangeworm in one of the two studies. These results suggest that adding pear ester as a microencapsulated spray can improve the efficacy of a range of insecticides for two key pests and foster the development of integrated pest management tactics with reduced insecticide use in walnut.     

分子模拟技术及其在苹果蠹蛾代谢杀虫剂分子机制研究中的应用进展

苹果蠹蛾是世界性重要的果树害虫,也是我国一类进境检疫性有害生物,严重威胁着我国黄土高原和环渤海湾优势苹果产区的果业生产。化学防治是当前苹果蠹蛾防治最经济有效的措施,然而频繁使用化学杀虫剂引发的抗药性问题也在世界范围内相继报道。代谢抗性是苹果蠹蛾抗性中重要的机制,苹果蠹蛾解毒酶代谢杀虫剂的分子机制是当前代谢抗性研究的重点方向。基于分子模拟的方法在相关研究中扮演着越来越重要的角色,本文综述了分子模拟涉及的主要方法及其在苹果蠹蛾代谢杀虫剂分子机制研究中的应用,并展望未来可能的研究方向。     

我国启动重大入侵害虫苹果蠹蛾基因组测序

苹果蠹蛾Cydia pomonella (L.)属鳞翅目卷蛾科,具有极强的适应性和抗逆能力,是仁果类果树的毁灭性害虫。1953年首次在我国新疆库尔勒发现,并迅速扩散危害,1987年随旅客携带物传入甘肃敦煌,造成了重大经济损失,是我国重点防控的检疫对象。近日,由中国农业科学院植物保护研究所、南京农业大学等科研单位联合启动了苹果蠹蛾的基因组测序工作。研究团队对苹果蠹蛾进行了10余代的纯化,建立了纯化品系。利用流式细胞分析和小片段文库前期测序等方法,对苹果蠹蛾基因组进行了初步的基因组前期分析。结果显示,苹果蠹蛾基因组大小约为650 Mb, 17-mer和SNP分析显示杂合度大约在0.3%-0.6%之间。经协商拟定了详细的全基因组鸟枪法测序方案后,基因组测序已经全面启动。苹果蠹蛾的基因组测序,对阐明其入侵机制、抗逆机理及防控等研究具有重要的推动意义。     

Population dynamics and "outbreaks" of diamondback moth (Lepidoptera: Plutellidae) in Guangdong province, China: climate or failure of management?

Diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), became the major pest of Brassica vegetable production in Guangdong, a province in southeastern China, in the late 1980s and has continued to challenge growers, particularly during the spring and autumn. Control has relied on insecticides and, as has happened in other parts of the world, resistance to these has evolved and subsequent field control failures have occurred. We review and summarize the history of diamondback moth management in Guangdong. We show that the geographic distribution of the pest in China is well described by a simple climate niche model. Our model predicts the seasonal phenology and some of the variation in abundance among years in Guangdong. Discrepancies may reflect migration and insecticide use at a landscape level. The scale of the pest problem experienced varies with management practices. Local production breaks, and strict post harvest hygiene are associated with lower pest pressure on large-scale production units. As more and more insecticides become ineffective the need to implement an insecticide resistance management strategy, as well as basic integrated pest management practices, will become more pressing. The potential use and development of a better forecasting system for diamondback moth that will assist these developments is outlined.     

Comparison of four trap types for ambrosia beetles (Coleoptera, Scolytidae) in Brazilian Eucalyptus stands

Eucalyptus spp. plantations represent >60% of the reforested area in Brazil. Although ambrosia beetle attacks on live trees were at first nonexistent, they have begun to appear with greater frequency. Monitoring for pest insects is a key factor in integrated pest management, and baited traps are one of the most widely used methods for insect population detection and survey. We compared the efficiency of the most widely used trap in Brazil to survey for ambrosia beetles and other Scolytidae, the ESALQ-84 type, with other traditionally employed traps: the multiple funnel (Lindgren trap); drainpipe; and slot (Theyson) traps, in a Eucalyptus grandis Hill ex Maiden stand in Brazil. The ESALQ-84 trap was the most efficient in trapping Hypothenemus eruditus Westwood and Hypothenemus obscurus (F.); the multiple funnel trap caught significantly more Cryptocarenus diadematus Eggers; whereas the slot trap caught more Premnobius cavipennis Eichhoff and Xyleborus affinis Eichhoff than the other traps. The drainpipe trap was the least effective trap overall. When corrected for number of beetles caught per trap surface area, catches were significantly higher on the ESALQ-84 trap for the majority of the species analyzed, probably because of a smaller trap surface area. The slot trap was recommended for it caught overall more beetles of the three most economically important scolytid species in eucalypt plantations in Brazil, P. cavipennis, X. affinis, and X. ferrugineus.     

Long range forecasts of the numbers of Helicoverpa punctigera and H. armigera (Lepidoptera: Noctuidae) in Australia using the southern oscillation index and the sea surface temperature

The use of long-term forecasts of pest pressure is central to better pest management. We relate the Southern Oscillation Index (SOI) and the Sea Surface Temperature (SST) to long-term light-trap catches of the two key moth pests of Australian agriculture, Helicoverpa punctigera (Wallengren) and H. armigera (Hübner), at Narrabri, New South Wales over 11 years, and for H. punctigera only at Turretfield, South Australia over 22 years. At Narrabri, the size of the first spring generation of both species was significantly correlated with the SOI in certain months, sometimes up to 15 months before the date of trapping. Differences in the SOI and SST between significant months were used to build composite variables in multiple regressions which gave fitted values of the trap catches to less than 25% of the observed values. The regressions suggested that useful forecasts of both species could be made 6-15 months ahead. The influence of the two weather variables on trap catches of H. punctigera at Turretfield were not as strong as at Narrabri, probably because the SOI was not as strongly related to rainfall in southern Australia as it is in eastern Australia. The best fits were again given by multiple regressions with SOI plus SST variables, to within 40% of the observed values. The reliability of both variables as predictors of moth numbers may be limited by the lack of stability in the SOI-rainfall correlation over the historical record. As no other data set is available to test the regressions, they can only be tested by future use. The use of long-term forecasts in pest management is discussed, and preliminary analyses of other long sets of insect numbers suggest that the Southern Oscillation Index may be a useful predictor of insect numbers in other parts of the world.     

Captures of boll weevils (Coleoptera: Curculionidae) in traps associated with different habitats

Programs to eradicate the boll weevil, Anthonomus grandis grandis Boheman, from cotton, Gossypium hirsutum L., in the United States rely heavily on pheromone traps for monitoring weevil populations in both active and posteradication maintenance programs. Modifications to trapping protocols that increase trap effectiveness should contribute to this eradication effort. Between October 1996 and May 1997 and between September 1997 and April 1998, we compared trap effectiveness, indicated by the numbers of captured weevils, in relation to selected habitat types. Each study period was divided into fall, winter, and spring seasons. Traps were closely associated with seven habitat types, including four types with prominent erect vegetation (brush-lined irrigation canal, brush, sugarcane, and resaca or ox-bow lake) and three types with only low-growing or sparse erect vegetation (irrigation drainage canal, unimproved pasture, and fallow fields). Captures of male and female weevils were statistically similar regardless of season or trapping habitat. Although captures differed significantly among habitats, these differences varied among seasons. Trapping habitats with prominent vegetational features generally produced higher weekly captures of weevils than habitats lacking these features. Also, captures in traps associated with prominent vegetation indicated seasonal differences in weevil activity, with highest captures occurring during the fall. Traps associated with habitats lacking prominent vegetation did not statistically demonstrate seasonal differences. Our results indicate that immediate trap surroundings strongly influence the effectiveness of the boll weevil pheromone trap. These results also suggest that effectiveness of current trapping programs may be improved through purposeful association of traps with selected vegetational features.     

不同性诱剂诱芯对小菜蛾引诱效果研究

小菜蛾Plutella xylostella(L.)是我国为害最严重的蔬菜害虫之一,为提高检测和诱捕效率,2009年在广东广州、云南通海和浙江上虞3个试验点测试了5种性诱剂诱芯对小菜蛾的引诱效果,实验结果表明,广东省昆虫研究所研发的性诱剂诱芯在广东试点对小菜蛾诱捕效果最好,持效期在1个月以上,日平均诱蛾量21.3头/盆,是荷兰Koppert公司诱芯的5.3倍,适合应用于广东菜区小菜蛾田间种群的预测预报和综合控制;北京中捷四方商贸有限公司提供的性诱剂诱芯比较适合云南试点的应用,日平均诱蛾量13.6头/盆;中国科学院动物研究所研发的小菜蛾性诱剂诱芯对浙江试点小菜蛾日平均诱捕量13.6头/盆,效果最佳,适合浙江地区小菜蛾田间种群动态的预测预报及综合防控。     

Effects of orchard host plants (apple and peach) on development of oriental fruit moth (Lepidoptera: Tortricidae)

Studies were designed to examine the effects of host plants (apple, Malus domestica Borkh., and peach, Prunus persica L.) on the development of oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae). Oriental fruit moth larvae developed faster on peach than on apple, both on fruit as well as on growing terminal shoots. On fruit, these differences were shown to cause significant changes in both the rate (approximately 20-60 degree-days earlier emergence on peach than on apple) and patterns of adult emergence among several cultivars of peaches and apples. Slopes of female emergence plots varied by host in 2003, with emergence occurring over a longer period on peach cultivars than on apple cultivars (with one exception). Slopes of male emergence curves did not differ by cultivar in 2003. These host-driven effects could impact the efficacy of traditional pest management approaches and probably complicate efforts to predictively model G. molesta populations in mixed cultivar orchards. Such developmental effects may help to explain previously observed differences in patterns of pheromone trap captures in peach versus apple orchards. Host-associated effects should be incorporated into future models to develop more realistic predictive tools and thus improve integrated pest management efforts.