Non-target impacts of forest defoliator management options: Decision for no spraying may have worse impacts on non-target Lepidoptera than Bacillus thuringiensis insecticides

Management programs for major forest defoliators such as gypsy moths or forest tent caterpillars, and crop pests such as the European corn borer have shifted from broad-spectrum insecticides to more environmentally benign microbial pesticides such as Bacillus thuringiensis (foliage sprays and transgenic toxin expression in plant tissues). Phytochemically resistant host plants and natural enemies have been used as alternative pest management strategies (including generalist tachinid flies such as Compsilura, viruses, microsporidians, and fungi), but all of these have some non-target impacts, as described from literature review. A sequence of lab and field studies were conducted to determine non-target impacts on native Lepidoptera in North America. The conclusions reached are that a decision not to spray Bt pesticides (i.e. to allow defoliation and natural pest outbreaks to run their course) could be as bad or worse for non-target Lepidoptera as the microbial insecticides would be. The important concept that must be maintained is that all pest management programs have some risk of negative non-target impacts, but it is the magnitude and relative importance that will remain the most critical issue for environmental impacts and pest management.     

Abundance and natural control of the woolly aphid <Emphasis Type="Italic">Eriosoma lanigerum</Emphasis> in an Australian apple orchard IPM program

Woolly aphid (Eriosoma lanigerum Hausmann) (Hemiptera: Aphididae), was monitored over three growing seasons (1995--1998) to assess its abundance and management under apple IPM programs at Bathurst on the Central Tablelands of NSW, Australia. Woolly aphid infestations were found to be extremely low in IPM programs utilising mating disruption and fenoxycarb for codling moth Cydia pomonella L. (Lepidoptera: Tortricidae) control. This was the direct result of increased numbers of natural enemies. No insecticides were applied for woolly aphid control. Under the IPM strategies tested the principal control agent was identified as European earwig (Forficula auricularia L.) (Dermaptera: Forficulidae). Earwigs in combination with Aphelinus mali (Haldeman) (Hymenoptera: Aphelinidae) reduced woolly aphid infestations below the action threshold set by commercial growers. However, A. mali together with other flying natural enemies, e.g., ladybirds, lacewings and hoverflies, did not provide commercially acceptable control of woolly aphid in the absence of earwigs. Under the conventional spray program, using the broad-spectrum insecticide azinphos-methyl for codling moth control, the level of woolly aphid infestation increased with each successive season and biological control was not established. When azinphos-methyl was withdrawn, natural enemies migrated in and provided control of woolly aphid within one season. This is the first study to show that the biological control of woolly aphid can be achieved in a commercially viable IPM program.     

Global Spread of the Eel Parasite Gyrodactylus Anguillae (Monogenea)

Gyrodactylus anguillae is known from four continents, and intraspecific variation in the morphology of specimens from each continent is negligible. However, morphological characters alone may not always be adequate for recognizing populations that have been isolated geographically over evolutionary time. We were unable to obtain specimens from Northeast Asia, but G. anguillae collected from North America, Europe and Australia had identical ribosomal DNA sequences (ITS1-5.8SrRNA-ITS2 region). This lack of even minor genetic variation in populations from three remote continents leads us to conclude that they share a contemporary common ancestor. This is one of at least five pests of eels to have invaded new continents as a result of the eel trade in the last four decades; these other known eel pests include Pseudodactylogyrus spp. (Monogenea) and Anguillicola spp. (Nematoda). Their dispersal has probably been secondarily augmented by longshore migration of infected eels, and perhaps also by transportation in ballast waters. The only other known gyrodactylid from eel gills, G. nipponensis from Japanese eel, is not closely related to G. anguillae, because the ITS1 region of the former is short (370 bases) and that of the latter long (685 bases). G. anguillae probably originated in Europe, because it was recorded there over 40 years ago, before the development of the international eel trade. We predict that the worm has a high potential to invade eel populations in East Africa, Southeast Asia, and New Zealand.     

Predicting the potential geographical distribution of the harlequin ladybird, Harmonia axyridis, using the CLIMEX model

Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae) is a ladybird beetle native to temperate and subtropical parts of Asia. Since 1916 populations of this species have been introduced throughout the world, either deliberately, or by accident through international transport. Harmonia axyridis was originally released as a classical biological control agent of aphid and coccid pests in orchards and forests, but since 1994 it is also available as a commercial product for augmentative control in field and greenhouse crops. It is a very voracious and effective natural enemy of aphids, psyllids and coccids in various agricultural and horticultural habitats and forests. During the past 20 years, however, it has successfully invaded non-target habitats in North America (since 1988), Europe (1999) and South America (2001) respectively in a short period of time, attacking a wide range of non-pest species in different insect orders. Becoming part of the agricultural commercial pathway, it is prone to being introduced into large areas across the world by accident. We use the CLIMEX programme (v2) to predict the potential geographical distribution of H. axyridis by means of matching the climate of its region of origin with other regions in the world and taking in account biological characteristics of the species. Establishment and spread seem likely in many regions across the world, including those areas which H. axyridis has already invaded (temperate Europe, North America). Based on the CLIMEX prediction a large part of Mediterranean Europe, South America, Africa, Australia and New Zealand seem highly suitable for long-term survival of H. axyridis as well. In addition we evaluate CLIMEX as a strategic tool for estimating establishment potential as part of an environmental risk assessment procedure for biological control agents we discuss biological and ecological aspects necessary to fine-tune its establishment and spread in areas after it has been introduced.     

Transgenic Bt potato and conventional insecticides for Colorado potato beetle management: comparative efficacy and non-target impacts

Field studies were conducted in 1992 and 1993 in Hermiston, Oregon, to evaluate the efficacy of transgenic Bt potato (Newleaf^®, which expresses the insecticidal protein Cry3Aa) and conventional insecticide spray programs against the important potato pest, Leptinotarsa decemlineata (Say), Colorado potato beetle (CPB), and their relative impact on non-target arthropods in potato ecosystems. Results from the two years of field trials demonstrated that Newleaf potato plants were highly effective in suppressing populations of CPB, and provided better CPB control than weekly sprays of a microbial Bt-based formulation containing Cry3Aa, bi-weekly applications of permethrin, or early- and mid-season applications of systemic insecticides (phorate and disulfoton). When compared with conventional potato plants not treated with any insecticides, the effective control of CPB by Newleaf potato plants or weekly sprays of a Bt-based formulation did not significantly impact the abundance of beneficial predators or secondary potato pests. In contrast to Newleaf potato plants or microbial Bt formulations, however, bi-weekly applications of permethrin significantly reduced the abundance of several major generalist predators such as spiders (Araneae), big-eyed bugs (Geocorus sp.), damsel bugs (Nabid sp.), and minute pirate bugs (Orius sp.), and resulted in significant increases in the abundance of green peach aphid (GPA), Myzus persicae (Sulzer) – vector of viral diseases, on the treated potato plots. While systemic insecticides appeared to have reduced the abundance of some plant sap-feeding insects such as GPA, lygus bugs, and leafhoppers, early and mid-season applications of these insecticides had no significant impact on populations of the major beneficial predators. Thus, transgenic Bt potato, Bt-based microbial formulations and systemic insecticides appeared to be compatible with the development of integrated pest management (IPM) against other potato pests such as GPA because these CPB control measures have little impact on major natural enemies. In contrast, the broad-spectrum pyrethroid insecticide (permethrin) is less compatible with IPM programs against GPA and the potato leafroll viral disease.     

History,genetics and pathology of a leaf-cutting ant introduction: a case study of the Guadeloupe invasion

As dominant herbivores and notorious pests in their native Neotropics, introduced leaf-cutting ants have the potential for ecological and economic harm. Although a large-scale invasion of leaf-cutting ants has not occurred, an isolated introduction in the Caribbean islands of Guadeloupe provides useful insight into the progress of such an invasion. Since being first detected in 1954, Acromyrmex octospinosus has colonized virtually all available land area, defying an aggressive control campaign and damaging agriculture. I attempted to reconstruct the origins and spread of the invasion, as well as screen for the presence of garden pathogens, which could be used for biological control. Mitochondrial sequencing of the A. octospinosus complex throughout the Caribbean showed that the probable source of the invasion lies on Trinidad and Tobago or northeast South America. Using historical records and field surveys, the invasion’s rate of spread was estimated at 0.51 km/year. Microsatellite genotyping further confirmed the limited dispersal abilities of A. octospinosus, showing the presence of isolation by distance (even in a relatively small geographic area) and suggested ubiquitous local inbreeding. Although the invasion likely resulted from the introduction of a single colony, microsatellites showed a high level of genetic variation in the introduced population, likely as a consequence of multiple mating by the queen. A survey showed that the specialized fungus garden pathogen Escovopsis exists on the islands, suggesting that the successful spread of the ants was not due to escape from this parasite. Given that chemical control has failed in the past and that biological control using specialized garden pathogens seems improbable, only vigorous quarantine and inspection programs may prevent wide-scale leaf-cutting ant invasions in the future.     

Field assessment of a frond-feeding weevil, a successful biological control agent of red waterfern, Azolla filiculoides, in southern Africa

Azolla filiculoides (red waterfern) is a small, floating fern native to South America, that has invaded aquatic habitats, predominantly water resevoirs in southern Africa. A frond-feeding weevil, Stenopelmus rufinasus Gyllenhal (Coleoptera: Curculionidae), was imported from Florida, USA, and released as a biological control agent against this weed in South Africa at the end of 1997. To date, 24,700 weevils have been released, which has resulted in local extinction of red waterfern at 81% of the 112 release sites. The weevil has not failed to control a single site. Several sites were, however, lost due to flooding or drainage of dams. The surface area of weed controlled totalled 203.5 ha. On average, A. filiculoides was controlled in infested sites in 6.9 (±4.3) months. The weed recolonized at 22 of the sites (through either spore germination or dispersal by waterfowl), but the weevils subsequently spread to all of these sites and successfully caused local extinction of the weed at 18 of the sites. Five years after the release of the weevil, the weed no longer poses a threat to aquatic systems in southern Africa. In comparison to other biological control programs of aquatic weeds, the program against A. filiculoides in southern Africa ranks among the most successful cases anywhere in the world.     

外来入侵植物刺萼龙葵的入侵特征与防治策略

刺萼龙葵是原产于北美洲的恶性外来入侵植物,在世界各地广为分布,已入侵我国北方地区,严重威胁我国农牧业安全,亟待明确刺萼龙葵入侵过程与危害,为我国制定刺萼龙葵防治策略提供参考。本文对刺萼龙葵生物学和生态学特性、传播途径、入侵历史和分布特征、危害、现有防除措施及存在等问题进行综述。刺萼龙葵具有花期长、花粉萌发率和结实率高、果实和种子产量大等高繁殖能力特征;能适应多变气候和异质性生境;具有自体传播、风力传播、水力传播、动物传播和人为传播等多种传播途径;已先后入侵了我国9个省级行政区的55个区县,向华北、华中和华东快速入侵的可能性高;刺萼龙葵的植株及分泌物对人畜安全、动物皮毛质量、草地植被结构、农作物产量等方面造成严重危害,并帮助传播植物病虫害。然而,现有的化学和物理防除措施仍不能彻底遏制传播、消除危害和保障生产。为有效防除刺萼龙葵,应开展刺萼龙葵入侵风险评估,针对不同土地利用类型制定防治措施,加强入侵机制和防控技术研究。     

Mating systems inOmphalotus (Paxillaceae, Agaricales)

Pairings of monokaryon cultures representingOmphalotus illudens (eastern North America),O. nidiformis (southeastern Australia),O. olearius (southern Europe),O. olivascens (North American Pacific coast), andO. subilludens (southern North America) showed widely variable compatibility patterns.Omphalotus olearius ×O. subilludens ×O. olivascens showed high compatibility, whileO. illudens was significantly less compatible with all other taxa. Isolates ofOmphalotus nidiformis represented an almost genetically isolated biological species. The role of partial compatibility in nomenclatural ranking is discussed.     

Evidence for the influence of conspecific chemical cues on <Emphasis Type="Italic">Aphthona nigriscutis</Emphasis> (Coleoptera: Chrysomelidae) behaviour and distribution

Although the distribution of biological control agents may have a significant effect upon their impacts, the mechanisms regulating these distributions are often unknown. Such is the case with Aphthona nigriscutis, a classical biological control agent of leafy spurge in North America. These beetles assume aggregated distributions at some sites but disperse rapidly at others. The potential influence of plant and insect-factors upon aggregation and dispersal was investigated to try to explain these observations. Male beetles produce a putative aggregation pheromone. Responses of conspecifics to male-associated cues are greater when beetles are feeding on host plants. Densities of beetle groups greatly impact their attractiveness. Males are more sensitive to dispersal cues and females are more sensitive to congregation cues.     

Dispersal of Two Species of Trichoptera from Desert Springs: Conservation Implications for Isolated vs Connected Populations

During the Pleistocene, when the climate was wetter and cooler, aquatic habitats in the Great Basin of western North America were much more extensive and connected. As the climate warmed over the last 10000 years, many of these habitats dried but others remained as isolated springs and inland lakes. The isolation of desert springs and lack of dispersal between populations of non-vagile species (e.g. fish, spring snails) has led to genetic differentiation and speciation. However, the extent to which vagile species of aquatic insects disperse from spring to spring is unknown. We examined the population genetics of two caddisflies, Hesperophylax designatus (Limnephilidae) and Lepidostoma ojanum (Lepidostomatidae) that occur in isolated springs in Nevada and eastern California to determine the extent of their dispersal from spring to spring. Mitochondrial DNA sequences indicate that the populations of L. ojanum are isolated and that the populations represent management units. In contrast, H. designatus individuals are flying from spring to spring and their populations are connected by dispersal. Disturbance impacts (e.g. grazing by ungulates, water extraction) that eliminate poor dispersers (e.g. L. ojanum) locally may result in permanent losses of genetic diversity; this is less likely with broader dispersers such as H. designatus.     

Toxicity of insecticides to obliquebanded leafroller, Choristoneura rosaceana, larvae and adults exposed previously to neem seed oil

Adult and sixth instar obliquebanded leafroller, Choristoneura rosaceana (Harris), exposed previously as fifth instar larvae to sub-lethal concentrations of neem, Azadirachta indica A. Juss., seed oil contained in artificial diet were more susceptible to topically applied pyrethroid, carbamate and organophosphate insecticides than C. rosaceana reared on control diets. Increased susceptibility to insecticides did not result from reduced vigour, as measured by reductions in adult or larval weights, but is instead correlated with previously demonstrated reductions in detoxication enzyme activities. The modest increases in susceptibilities, not exceeding ca. 4.5-fold, for C. rosaceana exposed to neem were achieved with subjects from a susceptible laboratory colony; a larger response could be expected for resistant field populations having elevated detoxication enzyme levels. Neem-based insecticides could be useful tools for the management of orchard pests that have developed resistance to synthetic neurotoxins. These findings also contribute to a better understanding of the numerous physiological changes that occur in larval Lepidoptera following exposure to neem extracts.     

Effect of parasitism on flight behavior of the soybean aphid, Aphis glycines

Many aphid species possess wingless (apterous) and winged (alate) stages, both of which can harbor parasitoids at various developmental stages. Alates can either be parasitized directly or can bear parasitoids eggs or larvae resulting from prior parasitism of alatoid nymphs. Winged aphids bearing parasitoid eggs or young larvae eventually still engage in long-distance flights, thereby facilitating parasitoid dispersal. This may have a number of important implications for biological control of aphids by parasitoids. In this study, we determined the effect of parasitism by Aphelinus varipes (Hymenoptera: Aphelinidae) on wing development and flight of the soybean aphid, Aphis glycines (Hemiptera: Aphididae). We also quantified the influence of aphid flight distance on subsequent A. varipes development. Parasitism by A. varipes was allowed at different A. glycines developmental stages (i.e., alatoid 3rd and 4th-instar nymphs, alates) and subsequent aphid flight was measured using a computer-monitored flight mill. Only 35% of aphids parasitized as L3 alatoid nymphs produced normal winged adults compared to 100% of L4 alatoids. Flight performance of aphids parasitized as 4th-instar alatoid nymphs 24 or 48 h prior to testing was similar to that of un-parasitized alates of identical age, but declined sharply for alates that had been parasitized as 4th-instar alatoid nymphs 72 and 96 h prior to testing. Flight performance of aphids parasitized as alate adults for 24 h was not significantly different from un-parasitized alates of comparable ages. Flight distance did not affect parasitoid larval or pupal development times, or the percent mummification of parasitized aphids. Our results have implications for natural biological control of A. glycines in Asia and classical biological control of the soybean aphid in North America.     

When invasion increases population genetic structure: a study with <Emphasis Type="Italic">Centaurea diffusa</Emphasis>

Biological invasions offer excellent systems to study the evolutionary processes involved in introductions of species to new ranges. Molecular markers can reveal invasion histories and the effects of introductions on amounts and structuring of genetic variation. We used five polymorphic microsatellite loci to elucidate genetic diversity and population structure between native range and introduced range populations of a prominent North American rangeland weed, Centaurea diffusa (Asteraceae). We found that the total number of alleles and the number of private alleles was slightly higher in the native Eurasian range, and that allelic richness did not differ between the ranges, indicating overall levels of diversity were similar in Eurasia and North America. It therefore seems unlikely that this invasion has been affected by genetic bottlenecks or founder effects. Indeed, results of assignment tests suggest that multiple introductions have contributed to North America’s C. diffusa invasion. Additionally, assignment tests show that both Eurasian and North American sites had a strong pattern of mixed genetic ancestry. This mixed assignment corresponded to a lack of geographic population structure among Eurasian samples. The lack of population structure in the native range conflicts with general expectations and findings to date for invasion genetics, and cautions that even species’ native ranges may show signs of recent ecological upheaval. Despite the mixed assignments, North American samples showed strong population structure, suggesting that the invasion has been characterized by long-range dispersal of genetically distinct propagules across the introduced range.     

Seasonal and Scale Size Relationships between Citricola Scale (Homoptera: Coccidae) and Its Parasitoid Complex (Hymenoptera: Chalcidoidea) on San Joaquin Valley Citrus

The phenology of citricola scale, Coccus pseudomagnoliarum (Kuwana), and its associated parasitoid complex were studied on citrus in the San Joaquin Valley of central California over the period April 1995–March 1997. A total of 10,237 parasitoid specimens of 10 species were collected. Two of these species, Marietta mexicana (Howard) and Encyrtus lecaniorum (Mayr), each recovered from individually isolated scales, represent new parasitoid records for citricola scale. A third species, Encarsia citrinus citrinus (Craw), may represent a new parasitoid record, but this requires further confirmation because a single (male) specimen was recovered from individually isolated scales. The three most dominant parasitoid species, Coccophagus lycimnia (Walker), Metaphycus helvolus (Compere), and Metaphycus luteolus (Timberlake), accounted for the majority (>97%) of the specimens recovered. In contrast to the situation on citrus in southern California, where citricola scale is under effective biological control and is very rarely seen, citricola scale on citrus in the San Joaquin Valley is reemerging as a major pest, especially in groves employing integrated pest management with minimal use of broad-spectrum insecticides. Possible reasons uncovered in this study for the lack of effective biological control of citricola scale in the San Joaquin Valley include: (i) reduced presence of Metaphycus spp. because of hyperparasitism by the heteronomous hyperparasitoid C. lycimnia; (ii) absence of alternate hosts for those species of Metaphycus present; and (iii) absence of hosts of suitable size for Metaphycus at critical times of the year. Recommendations for improving the level of biological control in the San Joaquin Valley are discussed.     

Biology, ecology and control of the Penthaleus species complex (Acari: Penthaleidae)

Blue oat mites, Penthaleus spp. (Acari: Penthaleidae), are major agricultural pests in southern Australia and other parts of the world, attacking various pasture, vegetable and crop plants. Management of these mites has been complicated by the recent discovery of three cryptic pest species of Penthaleus, whereas prior research had assumed a single species. The taxonomy, population genetics, ecology, biology and control of the Penthaleus spp. complex are reviewed. Adult Penthaleus have a dark blue-black body approximately 1 mm in length, and eight red-orange legs. Within Australia, they are winter pests completing two or three generations a season, depending on conditions. The summer is passed as diapausing eggs, when long-distance dispersal is thought to occur. The Penthaleus spp. reproduce by thelytokous parthenogenesis, with populations comprising clones that differ ecologically. The three pest Penthaleus spp. differ markedly in their distributions, plant hosts, timing of diapause egg production and response to pesticides, highlighting the need to develop control strategies that consider each species separately. Chemicals are the main weapons used in current control programs, however research continues into alternative more sustainable management options. Host plant resistance, crop rotations, conservation of natural enemies, and improved timing of pesticide application would improve the management of these pests. The most cost-effective and environmentally acceptable means of control will result from the integration of these practices combined with the development of a simple field-based kit to distinguish the different mite species.     

North American History of Two Invasive Plant Species: Phytogeographic Distribution, Dispersal Vectors, and Multiple Introductions

The North American historic phytogeographic distribution of mugwort (Artemisia vulgaris) and Japanese knotweed (Polygonum cuspidatum), two invasive perennial species introduced from Eurasia and East Asia respectively, was recreated using herbarium records. The putative initial introduction of these two species differs by c.a. 400 years, but their patterns of geographic distribution, introduction pathways, and local dispersal pathways are similar. Both species showed the expected logistic growth relationship between range size and the time following introduction, with lag phases of nearly 400 and 50 years for mugwort and Japanese knotweed respectively. The intrinsic growth rate was greater in Japanese knotweed than mugwort for the US, Canada, and North America. Both species were frequently found along waterway, railroad, and road rights-of-way. Introduction pathways differed, with Japanese knotweed commonly labeled as an ornamental escape (151 collections), while mugwort was commonly cited as an inadvertent component of ship ballast (20 collections). These potential founding populations were located across the final distribution for both species, suggesting anthropogenic large-scale dispersal across North America with local secondary spread. Range expansion appears to be active for both species in the US while nearing the carrying capacity in Canada. Managers of mugwort and Japanese knotweed can make use of this information on their range expansion dynamics and dispersal pathways by reducing anthropogenic dispersal and focusing resources on satellite populations and invasion corridors.     

基于@RISK番茄潜叶蛾对我国番茄产业造成的经济损失评估

[目的]新发恶性外来入侵物种番茄潜叶蛾的入侵对我国番茄产业的安全生产造成了极大威胁。本文利用@RISK模型对化学防治、生物防治和理化诱控3种不同防治场景下我国番茄产业的潜在经济损失和投入防治后可挽回的经济损失进行综合评估,结果可为我国番茄潜叶蛾综合防治体系的构建提供参考。[方法]基于国内外文献收集到的番茄潜叶蛾危害数据（危害率、番茄产量损失率、防治成本和防治效果）,结合全国农产品商务信息公共服务平台、FAO获得我国番茄的种植面积、产量及价格等相关数据,利用@RISK模型对不防治场景和3种不同防治场景下的番茄产业的经济损失进行评估。[结果]番茄潜叶蛾在不防治场景下每年给我国番茄产业造成的经济损失总量在（8226165.67~41903398.26）万元,在化学防治（使用合成杀虫剂）、生物防治（释放天敌昆虫和微生物制剂）和理化诱控（基于灯光和合成性信息素的诱杀产品）3种不同防治场景下能有效挽回经济损失,分别为89.83%、87.90%和89.19%。[结论]基于不同的防治场景能够有效挽回番茄潜叶蛾造成的经济损失,面对该害虫在我国的严峻扩散形势,建议各级政府和行业部门应高度重视并进一步加强番茄潜叶蛾的防控,保障我国番茄产业的安全生产。     

Synergies between biological and neonicotinoid insecticides for the curative control of the white grubs Amphimallon majale and Popillia japonica

Synergistic combinations of biological and chemical insecticides might yield promising alternatives for soil insect pest management. In turfgrass of the Northeast U.S., control of root-feeding scarab larvae is highly dependent on conventional insecticides. Studies on interactions between entomopathogenic nematodes and neonicotinoid insecticides, however, demonstrate the feasibility of synergies as an approach for reduced-risk curative control. To understand the breadth of potential synergies, we screened numerous combinations of biological control agents with sublethal doses of neonicotinoids against third instars. Interactions were characterized as synergistic, additive or antagonistic. The most promising combinations identified in laboratory bioassays were advanced to greenhouse pot studies and then to field trials featuring microplots with artificially infested populations. To reveal variation across scarab species, trials were conducted on Amphimallon majale and Popillia japonica. Synergies were consistent across trials and specific to white grub species. For A. majale, synergistic combinations of Heterorhabditis bacteriophora with imidacloprid and clothianidin were discernible in laboratory, greenhouse and field trials. For P. japonica, synergistic combinations of Beauveria bassiana and Metarhizium anisopliae with both neonicotinoids were discernible in the laboratory and greenhouse, but not in the field. For both species, antagonistic interactions were discernible between Bt-products and both neonicotinoids. While nematode-neonicotinoid synergies among scarab larvae have been examined before, fungi-neonicotinoid synergies are unreported. In the context of previous studies, however, no patterns emerge to explain variation across target species or control agent. Further study of non-additive interactions will guide how biological and chemical products could be combined to enhance soil insect pest management.     

Effectiveness and pesticide susceptibility of the pyrethroid-resistant predatory mite Amblyseius womersleyi in the integrated pest management of tea pests

To prevent the resurgence of the Kanzawa spider mite, Tetranychus kanzawai Kishida, on tea plants caused by the application of synthetic pyrethroid insecticides (SP), an SP-resistant strain of the predatory mite Amblyseius womersleyi Schicha was released onto tea bushes under SP (permethrin) application. The released predators successfully survived and may be able to suppress T. kanzawai. In the plot where A. womersleyi was released, the damage to new leaves was less severe than in the control plot and the predators remained resistant to the permethrin in the bushes. The selective use of pesticides that are harmless against natural enemies is necessary to achieve a program of integrated tea pest management. Although mortality of adult females of the tested strain in response to SP was from 6.5 to 89.3%, and mortality was more than 95% in response to several carbamate and organophosphate insecticides, usefulness of A. womersleyi as an agent of biological control was successfully demonstrated in the present study.