Efficacy of Beauveria bassiana against the strawberry pests, Lygus lineolaris, Anthonomus signatus and Otiorhynchus ovatus

There are several insect species causing serious economic losses in strawberry, Fragaria vesca L., productions. In Quebec, Canada, the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), the strawberry bud weevil clipper, Anthonomus signatus (Say) and the strawberry root weevil, Otiorhynchus ovatus (L.) are the most important pests. We tested the susceptibility of these pests to the entomopathogenic fungus Beauveria bassiana under laboratory conditions. Sixteen isolates were evaluated for their insecticide potential against these insects. Adults of each species were infected by the immersion method. All isolates were pathogenic to adults of all three species, causing mortality rates between 23.3% and 100% at a concentration of 1 × 10⁷ conidia/ml. Based on the screening results, isolate INRS‐CFL was selected for its insecticide potential and then used for further analyses against L. lineolaris, A. signatus and O. ovatus adults. Bioassays were performed to evaluate the lethal concentration (LC₅₀) and the average survival time (AST) of this isolate against both insect species. Results of dose–response mortality bioassays using four concentrations – 1 × 10⁴, 1 × 10⁶, 1 × 10⁸ and 1 × 10⁹ conidia/ml – indicated a LC₅₀ values of 5.3 × 10⁵, 1.8 × 10⁷ and 9.9 × 10⁷ conidia/ml at 7 days after inoculation for L. lineolaris, A. signatus and O. ovatus respectively. Using a dose of 1 × 10⁸ conidia/ml, the AST values were estimated at 4.41, 7.56 and 8.29 days, respectively, at a concentration of 1 × 10⁸ conidia/ml. This study demonstrated the potential of B. bassiana for the management of L. lineolaris, A. signatus and O. ovatus. Results also suggest that the heteropteran species is more susceptible than coleopteran species to B. bassiana.     

Biological Control of Tetranychus Urticae (Acari: Tetranychidae) With Naturally Occurring Predators in Strawberry Plantings in Valenica, Spain

Naturally occurring beneficials, such as the phytoseiid mite Amblyseius californicus McGregor and the insects Stethorus punctillum Weise, Conwentzia psociformis (Curtis) and others, controlled Tetranychus urticae Koch in 11 strawberry plots near Valencia, Spain, during 1989–1992. The population levels of spider mites in 17 subplots under biological control were low or moderate, usually below 3000 mite days and similar to seven subplots with chemical control. In most of the crops A. californicus was the main predator, acting either alone or together with other beneficials. Predaceous insects colonized the crop when tetranychids reached medium to high levels. For levels above one spider mite per leaflet, a ratio of one A. californicus per five to ten T. urticae resulted in a decline of the prey population in the following sample (1–2 weeks later). These results suggest that naturally occurring predators are able to control spider mites and maintain them below damaging levels in strawberry crops from the Valencia area.     

Optimum release times for biological control of the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) by Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseidae) on the strawberry in greenhouses

The effectiveness of the predatory mite Phytoseiulus persimilis Athias‐Henriot (Acari: Phytoseidae) in controlling the two‐spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) was evaluated in commercial strawberry greenhouses in two areas of Korea. Optimum release times for P. persimilis were investigated by case studies. Control effects of the two‐spotted spider mite by release of the predatory mite were shown. There was mostly good control by the release of P. persimilis when there were fewer than 0.9 T. urticae per leaf. We recommend it would be ideal to release P. persimilis twice in December and once in February for very early strawberry harvest, and three times from February to March (after overwintering) for early harvest.     

Biological control of strawberry tarsonemid mite Phytonemus pallidus and two-spotted spider mite Tetranychus urticae on strawberry in the UK using species of Neoseiulus (Amblyseius) (Acari: Phytoseiidae)

Two species of Neoseiulus, N. californicus and N. cucumeris, showed potential for biocontrol of phytophagous mites on strawberry. N. californicus controlled Tetranychus urticae on potted strawberry plants in a gauze-sided glasshouse at temperatures comparableto early summer in the UK (8–20°C). Both species of phytoseiid reducednumbers of the tarsonemid Phytonemus pallidus on potted strawberry plants under glasshouse conditions (15–23°C). In several experiments reductions in the range of 71–81% in numbers of tarsonemid active stages and eggs, compared to non-release plants, were obtained. The importance of establishing a suitable predator: prey ratio at an earlystage was demonstrated in an experiment where an initial ratio of 1 N. cucumeris: 10 P. pallidus gave a greater degree of controlthan 1:20 or 1:40.     

广西喀斯特地区割草结合植树方法对飞机草的控制效果

基于树种、植树密度、割草频率3种因素3个水平共9种处理的正交试验,研究了广西喀斯特地区机械割草结合植树的方法对飞机草的控制效果.结果表明:2006—2008年,9种处理下飞机草的相对盖度、高度、密度和生物量均逐年减小,减幅分别为89.7%~99.3%、41.6%~81.2%、61.4%~83.2%、91.7%~97.8%.头状花序的数量在各处理中均显著低于对照(P<0.05).3种因素对飞机草生长影响的顺序为:割草频率>树种>植树密度.控制飞机草的最佳组合方式为每个样方(4 m×4 m)种植茶条木4株、每年割草2次.     

Biological Control of Botrytis cinerea Pers. ex Fr. in Strawberry by Paenibacillus polymyxa (Isolate 18191)

Isolate 18191, obtained from mature strawberry fruit and determined as Paenibacillus polymyxa has shown an antagonistic potential against Botrytis cinerea , the causal agent of grey mould in strawberries. Germ tube growth of conidia of B. cinerea was strongly inhibited by the culture suspension of the antagonist in aqueous strawberry fruit pulp suspension (1%) but germination rate of conidia was not affected. The application of the culture suspension and the washed cells on detached strawberry leaf discs reduced conidiophore density of B. cinerea by 67 and 84%, respectively. The treatment of detached leaf discs with culture suspensions of different cell densities (1 × 10⁶, 1 × 10⁷, 1 × 10⁸) showed that the lowest density already reduced incidence of B. cinerea by 68% after 8 days incubation period. Investigating the influence of the temperature on the effectiveness of P. polymyxa it was observed that the antagonist was highly effective already at 10°C and reduced incidence and conidiophore density of B. cinerea by 53 and 58%, respectively. In 3-year field trials the effectiveness of P. polymyxa was in a range of 24–36% as compared to the water control.     

太行山中低山区河谷内农田斑块特征及其分布格局—以河北省阜平县胭脂河主流河谷为例

以景观生态学原理为指导,调查了位于太行山中低山区的河北省阜平县胭脂河主流河谷,对河谷内农田斑块的特征及其分布格局进行了分析,结果表明,农田斑块了作河流源头外贯穿整个河谷,从上游向下游,人为活动的增加使农田的比重不断增加,导致自然景观减少,环境异质性降低,农田斑块破碎化和蔼减小,胭脂河河谷总面积为2297.09hm^2,构成河谷景观主体的农田有117个斑块,面积为1027.78hm^2,占河谷面积的44．74％,农田基本紧靠河岸分布,处在水分条件优越但易受洪水威胁的土地带上,农田在河流两侧是非对称分布,其中左岸农田面积587.58hm^2,占57．17％,斑块的宽度呈增加的态势,但变化比较大,基本上以狭长的特征出现。     

Effects of transplant type, plant growth-promoting rhizobacteria, and soil treatment on growth and yield of strawberry in Florida

The effects of transplant type and soil treatment on growth and yield of strawberries (Fragaria x ananassa Duch.) produced in annual hill culture were evaluated for three years in Florida field trials. `Sweet Charlie' and `Camarosa' strawberry transplants were propagated as bare root, plug, and plugs amended with a plant growth-promoting rhizobacterial (PGPR) treatment, LS213. The transplant treatments were evaluated in combination with methyl bromide, 1, 3-dichloropropene (Telone II), an unregistered iodine-based compound (Plantpro 45), and untreated soil. `Camarosa' plugs amended with LS213 had higher overall yields than bare root transplants in all three years. Both `Camarosa' and `Sweet Charlie' plug and LS213 plug plants produced yields approximately two weeks earlier than bare root transplants in all years. Regardless of transplant type, and in both consecutive years of Plantpro 45 and Telone application, treatment with Plantpro 45 resulted in smaller and less healthy root systems than other soil treatments, and treatment with Telone resulted in yields comparable to methyl bromide.     

低海拔种植天山雪莲一年生植株的生物学特性

以低海拔（567 m）人工种植的天山雪莲一年生植株为研究对象,从叶片数、叶长度、根长、单株鲜重等调查其生态表型,分析其生长规律,论述其生物学特性,以期为该种植物的保护及合理开发利用提供理论依据。结果表明：低海拔天山雪莲一年生植株生长特点为播种后至45 d之间生长缓慢,之后其生长速度加快,70 d后又缓慢生长;播种后覆盖草帘子,可提高人工种植的出苗率;其生长具有一定的耐旱性;一年生雪莲植株能刈割两次,刈割后大约20 d时,叶长度和叶片数基本能长至原来植株大小,但丛幅显著变小;刈割能促使其再生、避开高温天气及虫害大发生。     

Ability of the antagonistic yeast Cryptococcus albidus to control Botrytis cinerea in strawberry

The yeast Cryptococcus albidus, originally isolated from mature strawberry fruits, was tested for antagonistic activity against Botrytis cinerea, the causal agent of grey mould in strawberries. Conidial germination and germ tube growth of conidia of B. cinerea were inhibited by a cell suspension of the antagonist in aqueous strawberry fruit pulp suspension (1%) after 6 and 24 hours of incubation. Application of a cell suspension (1 × 10⁶ cells/ml) on detached strawberry leaf disks incubated at 10°C reduced incidence and conidiophore density of B. cinerea by 86 and 99%, respectively, but effectiveness was reduced at higher temperatures. Treatments with C. albidus during bloom of strawberries reduced incidence of grey mould on ripe strawberry fruits after harvest by 33, 28 and 21% in three years of field trials. The effectiveness of the yeast was increased when formulation substances (alginate, xanthan and cellulose) were added to the cell suspension.