Effects of temperature on the establishment potential in the U.K. of the non-native glasshouse biocontrol agent Macrolophus caliginosus

Abstract This study investigated the effect of temperature on the development and winter survival of the predatory mirid Macrolophus caliginosus Wagner, recently introduced into the U.K. as a biocontrol agent for glasshouse whitefly Trialeurodes vaporariorum . The developmental threshold for M. caliginosus calculated by three methods was between 7.3 and 8.4 °C, with a day-degree requirement per generation varying between 472 and 524 day-degrees. It was estimated that under outdoor conditions M. caliginosus could complete two generations per year in the U.K. All life stages of M. caliginosus had supercooling points around −20 °C, with some pre-freeze mortality evident in both acute and chronic low temperature exposures. Acclimation increased survival of nymphal M. caliginosus from approximately 24–52 days when exposed to a constant 0 °C. Provision of prey extended survival of nymphs in the laboratory at a constant 5 °C from 39 to 64 days and in the field by c . 150 days. The results are discussed in the context of the occurrence and establishment of M. caliginosus in the U.K. and the need to develop a reliable risk assessment system for non-native species used in glasshouse biocontrol.     

Thermal biology of Typhlodromips montdorensis: implications for its introduction as a glasshouse biological control agent in the UK

The recent unexpected local establishment of a non‐native predatory mite, Neoseiulus californicus (McGregor) (Acari: Phytoseiidae), in the UK prompted us to undertake this study, which investigated the thermal biology of an alien species Typhlodromips montdorensis (Schicha) (Acari: Phytoseiidae). Laboratory and field experiments on its cold tolerance were used to assess its establishment potential outside of glasshouse environments in the UK. Currently, T. montdorensis is being tested as a glasshouse biological control agent against thrips and spider mites, but is not yet licensed for release in the UK. Typhlodromips montdorensis has a developmental threshold of between 10.3 and 10.7 °C, and a thermal budget of between 108.7 and 105.3 degree‐days when estimated by weighted and simple linear regression, respectively. Under outdoor conditions, T. montdorensis could theoretically complete up to six generations a year. The supercooling points of female and larval T. montdorensis were ?22 to ?24 °C with 100% pre‐freeze mortality apparent in both acute and chronic low temperature exposures. Typhlodromips montdorensis were unable to enter diapause under a selected laboratory regime. No reproduction occurred in the field from November to March, with 100% mortality within 7–14 days of release during this period. It is concluded that T. montdorensis would be a ‘safe candidate’ for introduction as a glasshouse biological control agent in the UK.     

Effect of temperature on development, overwintering and establishment potential of Franklinothrips vespiformis in the UK

This study investigated the effect of temperature on the development and overwintering potential of the predatory thrips Franklinothrips vespiformis (Crawford) (Thysanoptera: Aeolothripidae), a biological control agent used against glasshouse pests in continental Europe and Israel. Developmental rates increased linearly with rearing temperatures. It was estimated that 304.9 degree days, above a lower threshold temperature of 11.9 °C, were required for F. vespiformis to complete development from egg to adult eclosion. The effect of low temperatures (–5, 0, and 5 °C) was examined on adult female and larval survival. Subsequent reproductive and developmental attributes of survivors were also investigated. Lethal time experiments indicated that larval stages are more cold tolerant than adult F. vespiformis females. Surviving larvae increased their developmental times to adults with decreasing temperature and increasing exposure periods and second instars were significantly more successful than first instars in reaching adulthood. Surviving adult females decreased their oviposition rate with decreasing temperature and increasing exposure periods, and exposures to low temperatures affected the number of viable eggs produced. The results are discussed in the context of overwintering and establishment potential of F. vespiformis in the UK in the event of introducing the predatory thrips as a biological control agent against glasshouse pests.     

Expression of heat shock proteins in response to high and low temperature extremes in diapausing pharate larvae of the gypsy moth,Lymantria dispar

Diapausing pharate first instars of the gypsy moth, Lymantria dispar, respond to high temperature (37–41°C) by suppressing normal protein synthesis and synthesizing a set of seven heat shock proteins with M_rs of 90,000, 75,000, 73,000, 60,000, 42,000, 29,000, and 22,000 as determined by SDS-PAGE. During recovery at 25°C from heat shock, synthesis of the heat shock proteins gradually decreases over a period of 6 h, while normal protein synthesis is restored. A subset of these same heat shock proteins is also expressed during recovery at 4°C or 25°C from brief exposures to low temperature (-10 to 20°C), and its expression is more intense with increased severity of cold exposure. During recovery at 4°C after 24 h at ?20°C, both 90,000 and 75,000 M_r heat shock proteins are expressed for more than 96 h. While normal protein synthesis is suppressed during heat shock and recovery from heat shock, normal protein synthesis coincides with synthesis of the heat shock proteins during recovery from low temperatures, thus implying that expression of the heat shock proteins is not invariably linked to suppression of normal protein synthesis. Western transfer, using a monoclonal antibody that recognizes the inducible form of the human 70,000 M_r heat shock protein, demonstrates that immunologically related proteins in the gypsy moth are expressed at 4°C and during recovery from cold and heat shock.     

Use of Thermal Data as a Screen for the Establishment Potential of Non-native Biological Control Agents in the UK

A series of recent studies have investigated the development, cold tolerance and winter field survival of glasshouse biological control agents that are non-native to the UK: Neoseiulus californicus, Macrolophus caliginosus, Delphastus catalinae, Eretmocerus eremicus and Typhlodromips montdorensis. The combined data sets for these species have been analysed to identify laboratory indices of cold tolerance that correlate with the duration of survival under winter field conditions. A strong correlation was found between the laboratory LTime₅₀ at 5 °C and maximum field survival time. Both N. californicus and M. caliginosus survived substantially longer in the laboratory and in the field than the other species. It is suggested that the LTime₅₀ at 5 °C may provide a reliable ‘first stage’ screen of establishment potential for candidate non-native biological control agents in the UK.     

烟草品种和温度对B型烟粉虱和温室白粉虱生物学参数的影响

在室内20℃、26℃和30℃三个设定温度条件下,研究了CF-965、NC-89和NC-82三个烟草品种对B型烟粉虱和温室白粉虱生长发育和繁殖的影响.结果表明:26℃时两种粉虱在CF-965、NC-89和NC-82三个烟草品种上的发育历期没有明显差异,但温室白粉虱卵期和若虫期的发育历期较烟粉虱依次分别延长了1.32d、2.81d和 2.04d.在CF-965上,B型烟粉虱卵期和若虫期的总存活率和平均单雌产卵量分别为54.19%和55.17粒,温室白粉虱仅分别为31.99%和39.17粒;在NC-89上,B型烟粉虱卵期和若虫期的总存活率和平均单雌产卵量分别为23.47%和37.50粒,温室白粉虱仅分别为15.75%和17.25粒;两种粉虱在NC-82上卵期和若虫期的总存活率和平均单雌产卵量差异不大,表明B型烟粉虱对CF-965和NC-89的适应能力较温室白粉虱强.两种粉虱在20℃时的发育历期最长,32℃时最短,26℃时居中.20°C时烟粉虱卵期和若虫期的存活率20.96%为最低,26℃和32℃时分别达54.19% 和53.29%;而温室白粉虱在32℃条件下存活率11.66%为最低,20℃和 26℃时分别达31 34% 和31.99%.温室白粉虱在20℃时产卵量大于烟粉虱, 在26℃时的产卵量小于烟粉虱,30℃时则不能产卵,但烟粉虱成虫30℃时的产卵量仍可达21.06粒.由此说明烟粉虱在较高温度条件下的适应能力显著强于温室白粉虱.山东烟区烟草生长中期的田间平均温度多在22～30℃,适合B型烟粉虱的发生,应引起高度重视.     

U.K. winter egg survival in the field and laboratory diapause of Typhlodromips montdorensis

Abstract. Typhlodromips montdorensis has potential for release as a glasshouse biological control agent in the U.K. against thrips and spider mites. This study investigates the field survival in the U.K. of T. montdorensis when released as eggs, and the diapause response when reared in a regime related to its location of origin. All acclimated and nonacclimated eggs of T. montdorensis die in the field within 7 days of exposure. It is not possible to induce diapause in T. montdorensis reared at 21 °C under a LD 11 : 13 h photoperiod. The results presented here support the view that T. montdorensis is unlikely to survive a U.K. winter outside of the glasshouse environment, and contribute to the understanding of the biology of this little known species.     

Effects of temperature on the growth and reproduction characteristics of Bemisia tabaci B‐biotype and Trialeurodes vaporariorum

The development period, survival rate, longevity and fecundity of two whiteflies, Bemisia tabaci B‐biotype and Trialeurodes vaporariorum (Homoptera: Aleyrodidae) were compared under different temperature laboratory conditions (15°C, 18°C, 21°C and 24°C). Egg development of B. tabaci B‐biotype was significantly longer compared with that of T. vaporariorum at 15°C, 18°C and 24°C. Significantly longer pseudo‐pupae development and lower survival rate were found in B. tabaci B‐biotype at 15°C compared with those at 18°C, 21°C and 24°C. Significantly higher fecundity was found in B. tabaci B‐biotype at 24°C compared with that at 15°C, 18°C and 21°C. However, the fecundity of T. vaporariorum was significantly lower at 24°C relative to that at 15°C, 18°C and 21°C. Significantly shorter 1st instar larval development was found in T. vaporariorum compared with that of B. tabaci at 15°C and 18°C. Significantly longer 2nd instar larval development was found in B. tabaci and T. vaporariorum at 15°C compared with that at 18°C, 21°C and 24°C. However, significantly shorter 3rd instar larval development was found in T. vaporariorum compared with that of B. tabaci at 15°C, 18°C and 24°C. The adaptive divergence of tolerance to relatively low temperature may be an important factor that results in the interspecific differentiation between the seasonal dynamics of these two whiteflies in China.     

Assessing potential biological control of the invasive plant, tree-of-heaven, Ailanthus altissima

Tree-of-heaven, Ailanthus altissima, is a deciduous tree indigenous to China and introduced into North America and Europe. It is a serious threat to ecosystems in introduced areas, as the plant is very competitive, and also contains allelopathic chemicals that may inhibit growth of surrounding native plants. In addition, the plant contains secondary chemicals that make it unpalatable to some insects. In this paper we assess potential biological control of this plant by reviewing literature associated with natural enemies of the plant from both its native and introduced regions in the world. Our literature surveys revealed that 46 phytophagous arthropods, 16 fungi, and one potyvirus were reported attacking tree-of-heaven, some apparently causing significant damage in China. Two weevils, Eucryptorrhynchus brandti and E. chinensis, are major pests of the plant in China and are reportedly restricted to tree-of-heaven, showing promise as potential biological control agents. Nymphs and adults of a homopteran insect, Lycorma delicatula and larvae of two lepidopteran species, Samia cynthia and Eligma narcissus, may also cause severe damage, but they are not host specific. Two rust fungi, Aecidium ailanthi J. Y. Zhuan sp. nov. and Coleosporium sp. have been reported on tree-of-heaven in China and are also promising potential candidates for biological control of the plant. Nine insect herbivores and 68 fungi are associated with tree-of-heaven in its introduced range in North America, Europe, and Asia. An oligophagous insect native to North America, the ailanthus webworm, Atteva punctella, may be a potential biocontrol agent for the plant. Among the fungal species, Fusarium osysporum f. sp. perniciosum, caused wilt of tree-of-heaven in North America and may have the potential to control the plant, but its non-target effect should be carefully evaluated. Our review indicates that there is potential for using insects or pathogens to control tree-of-heaven.     

Non-target effects of an introduced biological control agent on deer mouse ecology

Release of exotic insects as biological control agents is a common approach to controlling exotic plants. Though controversy has ensued regarding the deleterious direct effects of biological control agents to non-target species, few have examined the indirect effects of a ”well-behaved” biological control agent on native fauna. We studied a grassland in west-central Montana infested with spotted knapweed (Centaurea maculosa) to examine the effects of knapweed invasion and two gall flybiological control agents (Urophora affinis and U. quadrifasciata) on the native deer mouse (Peromyscus maniculatus). Stomach-content analysis revealed that Urophora were the primary food item in Peromyscus diets for most of the year and made up 84–86% of the winter diet. Stomach contents indicated that wild-caught mice consumed on average up to 247 Urophora larvae mouse^–1 day^–1, while feeding trials revealed that deer mice could depredate nearly 5 times as many larvae under laboratory conditions. In feeding trials, deer mice selected knapweed seedheads with greater numbers of galls while avoiding uninfested seedheads. When Urophora larvae were present in knapweed seedheads, deer mice selected microhabitats with moderately high (31–45% cover) and high knapweed infestation (≥46% cover). After Urophora emerged and larvae were unavailable to Peromyscus, mice reversed habitat selection to favor sites dominated by native-prairie with low knapweed infestation (0–15%). Establishment of the biological control agent, Urophora spp., has altered deer mouse diets and habitat selection by effecting changes in foraging strategies. Deer mice and other predators may reduce Urophora populations below a threshold necessary to effectively control spotted knapweed. Received: 04 May 1999 / Accepted: 14 August 1999     

Compatibility of an entomopathogenic fungus with a predator and a parasitoid in the biological control of greenhouse whitefly

An ongoing debate in biological control consists of whether interference between biological agents can disrupt pest control. This study investigated the outcome of interactions between the entomopathogen Beauveria bassiana with the whitefly predator Dicyphus hesperus and the parasitoid Encarsia formosa, as well as their effect on the control of the greenhouse whitefly Trialeurodes vaporariorum on greenhouse tomato crops. Our objective was to determine whether the generalist B. bassiana would disrupt biological control by interfering with D. hesperus or E. formosa. In experimental greenhouses, whitefly, parasitoid and predator populations were established, and over 27 days, tomato plants were sprayed with three applications of the B. bassiana based product BotaniGard® (5.13×10³ conidia/mm²) or water (control). Populations of greenhouse whitefly and biological control organisms were regularly monitored in control and B. bassiana-treated compartments. Overall, 10.6% of all whiteflies in treated compartments were infected, and 0.98% were both infected and parasitized. There were 31.7 and 22.3% fewer immature and adult whiteflies, respectively, on B. bassiana-treated plants relative to controls. Parasitism by E. formosa and predation by D. hesperus occurred at rates of 7.5 and 2.5%, respectively, in B. bassiana-treated compartments, and 5 and 6%, respectively in control compartments. Our study suggests that applications of B. bassiana for short-term biological control of greenhouse whiteflies are compatible with the concurrent use of E. formosa and D. hesperus on greenhouse tomato crops.     

Host specificity testing,release and establishment of Urophora solstitialis (L.) (Diptera: Tephritidae), a potential biological control agent for Carduus nutans L., in Australia

The seed‐fly Urophora solstitialis was imported into Australia from southern France. Previous workers had shown that this seed‐fly limited its attack to selected members of the genus Carduus. Host specificity studies revealed that no native Australian plant tested from the family Asteraceae was a suitable host plant. Permission to release the fly was granted, and it was released in three regions of the New South Wales tablelands. The fly underwent a second generation at two of the release sites, and reasons for its failure to do so at the third are suggested. It has successfully established itself in all three regions, having completed a full seasonal cycle in the field.     

Effects of temperature on the establishment potential of the predatory mite Amblyseius californicus McGregor (Acari: Phytoseiidae) in the UK

Amblyseius californicus was introduced into the UK in the early 1990s as a biocontrol agent against glasshouse red spider mite Tetranychus urticae. This study investigated the effects of temperature on the establishment potential of A. californicus in the UK in the light of recent reports of their successful overwintering outside of glasshouse environments. The developmental thresholds were 9.9 and 8.6 °C respectively using simple and weighted linear regression. Using the day-degree requirement per generation calculated by weighted regression (143 day-degrees) in combination with climate data, it was estimated that up to seven generations would be possible annually outdoors in the UK. Non-diapausing adult females froze at −22 °C, with 100% mortality after reaching their freezing temperature. Up to 90% of mites died before freezing after short exposures to low temperatures. Significant acclimation responses occurred; 90% of acclimated individuals survived 26 days exposure at 0 °C and 11 days at −5 °C (acclimated mites were reared at 19 °C, 6L:18D followed by 1 week at 10 °C, 12L:12D). Non-diapausing adult females survived over 3 months outdoors in winter under sheltered conditions and oviposition was observed. The experimental protocol used in this study is discussed as a pre-release screen for the establishment potential of other Amblyseius species, and similar non-native biocontrol agents.     

低温环境下持续性军事职业活动对抑制控制能力的影响

目的:评定低温环境下持续性军事职业活动对抑制控制能力的影响,为精准军事运动训练提供依据。方法:20名健康男性青年学员,平均年龄:(23.32±1.62)岁;身高:(175.34±4.14) cm;体重:(68.19±3.12) kg,分别在常温(16℃～23℃)和低温(-3℃～-1℃)环境下,持续36 h时间内完成多项军事课目,记录全程RR间期和核心温度,活动前后进行斯特鲁普色词测试、闪光融合临界频率测试。结果:与安静状态相比,两次军事职业活动中的心率、运动后的过氧消耗和运动冲量值均显著增加(P<0.05),但两次活动之间并无显著差异(P>0.05);与安静值相比,两次活动平均核心温度和最大核心温度均显著增加(P<0.05),与常温环境相比,低温环境下核心温度的平均值显著增加(P<0.05),但最大核心温度无显著差异(P>0.05);与安静状态相比,两次活动后抑制控制能力均显著降低(P<0.05),且低温环境下显著低于常温环境(P<0.05)。另外,与安静状态相比,两次活动均导致明显的精神疲劳(P<0.05),低温环境下更为严重(P<...     

Release and establishment of a biological control agent, Psyllaephagus pilosus for eucalyptus psyllid (Ctenarytaina eucalypti) in Ireland

An Australian parasitoid wasp, Psyllaephagus pilosus, was collected from a previous release site in France and introduced into a commercial eucalyptus foliage plantation in Co. Kerry in the south west of Ireland to control the eucalyptus (blue gum) psyllid Ctenarytaina eucalypti. The first parasitised psyllid nymphs were observed 26 days after the release was made in late May 1998, and 49 days elapsed before a new generation of adult parasitoids was seen. Visually assessed indices of psyllid parasitism and adult wasp incidence were used to quantify the pattern of adult dispersion and establishment. A second generation of adult wasps emerged in late August, initiating a rapid spread of parasitism throughout the release site during September that culminated in a peak rate of almost 100% parasitism by late October. Subsequently by the end of 1998, an apparently random process of dispersion and successful natural colonisation occurred at eight out of ten monitored plantations at distances up to 70 km from the release point. The first colonisers of the other two sites arrived very late in 1998, and consequently failed to establish viable populations by the following summer. Probably this failure was because the small numbers of colonisers had arrived too late in the growing season to effect population establishment before the onset of winter. Assisted introductions were, therefore, made at these sites in June and August 1999, respectively. Once fully established, the parasitoid had no difficulty in surviving winter conditions at all monitored sites and demonstrated excellent potential as a biological control agent.     

Early establishment and dispersal of the weevil, Mogulones cruciger (Coleoptera: Curculionidae) for biological control of houndstongue (Cynoglossum officinale) in British Columbia, Canada

First released in Canada in 1997 to control the invasive rangeland weed, houndstongue (Cynoglossum officinale), the European root weevil, Mogulones cruciger, is showing early potential as a successful biocontrol agent. Out of 22 experimental releases in southeastern British Columbia, Canada, 100% established, regardless of initial release size (range 100-400). These founding populations persisted beyond 2 years, and quickly dispersed through a treed and variable landscape to colonise new houndstongue patches surrounding the original release patches. Within 3 years, the weevil had moved 1.42 km. Both initial, within-patch and later, between-patch dispersal followed a similar pattern, with M. cruciger adults and/or their feeding/oviposition damage being more concentrated nearest the original points of release and declining with distance. Within-patch, this pattern of distribution and also the rate of spread of weevils were similar regardless of initial release size; suggesting density-independence in dispersal behaviour at this scale. Closer investigation of the sequence of invasion at a larger spatial scale suggested that the weevil arrived at, colonized and increased in number on the closest host patches first. Three years post release, both distance from release patch and the number of M. cruciger released, were significant predictors of the amount of feeding/oviposition damage, and presumably weevil population size, within newly colonized houndstongue patches surrounding the original releases. These data, and the finding that more weevils were retrieved from patches where higher numbers of weevils were released in the previous year (i.e., 300 or 400 vs 100 or 200), suggest that release number and placement of releases within a landscape can be manipulated for effective houndstongue control.     

Preliminary studies on Ramularia crupinae sp. nov. as a potential biological control agent for common crupina (Crupina vulgaris) in the USA

Common crupina, Crupina vulgaris (Asteraceae), is an alien weed of pastures and disturbed noncrop lands in the western USA. Research is underway in Europe to search for the natural enemies to control the weed. Among various natural enemies attacking C vulgaris, a new fungal species, Ramularia crupinae, has been found to cause serious damage to the weed. The fungus has been grown on various media and a modified V8 juice agar has proved to be suitable for both growth and sporulation. Greenhouse and field studies have shown that R. crupinae can kill infected leaves, thus reducing the plant growth, and in severe cases can kill the young plants. During preliminary host-range tests using various members of the Asteraceae, including artichoke and safflower, the fungus attacked only C. vulgaris.     

The effect of application time and soil factors on the occurrence of Beauveria brongniartii applied as a biological control agent in soil

The effects of abiotic and biotic soil factors on occurrence of the entomopathogenic fungus Beauveria brongniartii after application at different times of the year were examined in Switzerland. Applications made from May to August generally resulted in an increase of 1-5 x 10(3) CFU g(-1) dry soil compared to untreated control plots. Conversely, soils treated in October and November yielded no increase. Soil temperatures between 20 and 25 degrees C, and high clay content of the soil had a positive effect on the occurrence and density of B. brongniartii whereas increased catalase activity and temperatures above 27 degrees C had a negative influence. Laboratory experiments revealed that a higher number of CFUs developed after one month of incubation at 22 degrees C than at 12 degrees C. Differences were not detected after three months of incubation, indicating that growth rate was simply slower at sub-optimal temperatures. The increase was different in three native soils, but was not correlated with different clay contents of the soil. In sterilized soil, though, the differences were not detected, suggesting that biotic factors have a greater influence rather than soil texture.     

Mitigating the effects of insecticides on arthropod biological control at field and landscape scales

Integrated pest management (IPM) programs emphasize the combination of tactics, such as chemical and biological control, to maintain pest populations below economic thresholds. Although combining tactics may provide better long-term sustainable pest suppression than one tactic alone, in many cases, insecticides and natural enemies are incompatible. Insecticides can disrupt natural enemies through lethal and sub-lethal means causing pest resurgence or secondary pest outbreaks. Legislative actions such as the Food Quality Protection Act (US) and the Directive on Sustainable Use of Pesticides (EU) have placed greater restrictions on insecticides used in agriculture, potentially enhancing biological control. Here we focus on the effects of insecticides on biological control, and potential mitigation measures that can operate at different scales. At the farm scale, natural enemies can be conserved through the use of selective insecticides, low doses, special formulations, creation of refugia, special application methods, and targeted applications (temporal or spatial). At the landscape scale, habitat quality and composition affect the magnitude of biological control services, and the degree of mitigation against the effects of pesticides on natural enemies. Current research is teasing apart the relative importance of local and landscape effects of pesticides on natural enemies and the ecosystem services they provide, and the further development of this area will ultimately inform the decisions of policy makers and land managers in terms of how to mitigate pesticide effects through habitat manipulation.