Margaret Skinner

Thrips biology and management.

Introduction to Thrips/Plant Relationships: Thysanoptera as Phytophagous Opportunists L.A. Mound, D.A.J. Teulon. Pest Problems in Field, Forest and Glasshouse Crops: Bionomics of Cotton Thrips: A Review T.F. Leigh. Vectoring of Plant Pathogens: Median Latent Period and Transmission of Tospoviruses Vectored by Thrips I. Wijkamp, et al. Biological Control Agents and Practices: Resources to Implement Biological Control in Greenhouses R.J. Jacobson. Biological Control Using Oligophagous Predators P.M.J. Ramakers. Chemical Control: Insecticide Resistance in Western Flower Thrips K.L. Robb, et al. Integrated Pest Management: IPM of Western Flower Thrips K.L. Robb, M.P. Parrella. Ecology and Behavior: Temporal and Spatial Dynamics of Thrips Populations in a Diverse Ecosystem: Theory and Management A.M. Shelton. Development and Genetics: Morphogenetic Development of Some Species of the Order Thysanoptera (Insecta) G. Moritz. Field Sampling and Laboratory Techniques: Monitoring of Western Flower Thrips on Glasshouse and Vegetable Crops J.L. Shipp. List of Thrips Species and Synonyms. 80 additional articles. Index.

Regional Responses of Hemlock Woolly Adelgid (Homoptera: Adelgidae) to Low Temperatures

Abstract Hemlock woolly adelgid, Adelges tsugae Annand, is an exotic forest pest threatening the health of New England’s eastern hemlock, Tsuga canadensis (L.) Carrière. Research indicates that the northern spread of this insect may be slowed or prevented by cold temperature. We conducted laboratory studies to assess the coldhardiness of A. tsugae, collected at sites within plant hardiness zones 5a (Northern), 6a (Central), and 6b (Southern) in January, February, and March. Adelgids were exposed to −15, −20, −25, −30, and −35°C for 2, 4, or 8 h, and comparisons in survival were made with insects held at 0°C. For all months and sites, mortality increased as temperature decreased, and no survival occurred among those from the Central and Southern sites exposed to −30 and −35°C. In January and February, ≤3% of the adelgids collected from the Northern site survived −30°C, and none survived −35°C in January or March. Adelgids from all sites entered the winter with similar levels of coldhardiness, but those from the Central and Southern sites lost their tolerance to cold earlier in the season than those from the Northern site. In January and February, −25°C was a critical temperature at which significant reduction in coldhardiness was observed. Despite the evidence that adelgids in the Northern site possessed greater tolerance to cold temperatures than the other sites, only 14% survived exposure to −15°C in March. In all sites the actual percentage of adelgids that survived after exposure to −15°C decreased 50–60% from January to March. Our results show that adelgid coldhardiness differs depending on geographical location and time of year, and further confirm that cold temperature has a significant impact on their survival.

Characterization of Beauveria bassiana and Metarhizium anisopliae isolates for management of tarnished plant bug, Lygus lineolaris (Hemiptera: Miridae)

Selected morphological and physiological characteristics of four Beauveria bassiana (Balsamo) Vuillemin isolates and one Metarhizium anisopliae (Metschnikoff) Sorokin isolate, which are highly pathogenic to Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae), were determined. There were significant differences in conidial size, viability, spore production, speed of germination, relative hyphal growth, and temperature sensitivity. Spore viability after incubation for 24h at 20 degrees C ranged from 91.4 to 98.6% for the five isolates tested. Spore production on quarter-strength Sabouraud dextrose agar plus 0.25% (w/v) yeast extract after 10 days incubation at 20 degrees C ranged from 1.6x10(6) to 15.5x10(6)conidia/cm(2). One B. bassiana isolate (ARSEF 1394) produced significantly more conidia than the others. Spore germination was temperature-dependant for both B. bassiana and M. anisopliae. The time required for 50% germination (TG(50)) ranged from 25.0 to 30.9, 14.0 to 16.6, and 14.8 to 18.0h at 15, 22, and 28 degrees C, respectively. Only the M. anisopliae isolate (ARSEF 3540) had significant spore germination at 35 degrees C with a TG(50) of 11.8h. A destructive sampling method was used to measure the relative hyphal growth rate among isolates. Exposure to high temperature (40-50 degrees C) for 10min had a negative effect on conidial viability. The importance of these characteristics in selecting fungal isolates for management of L. lineolaris is discussed.

Molecular characterisation of Beauveria bassiana isolates obtained from overwintering sites of Sunn Pests ( Eurygaster and Aelia species)

110 isolates of Beauveria (104 B. bassiana, 5 Beauveria spp., 1 B. brongniartii) were obtained from Sunn Pests (Eurygaster and Aelia species), litter, and other insect samples at overwintering sites in seven countries in the Middle East and West Asia. DNA was extracted from these isolates, and four techniques were used to characterize and to investigate genetic diversity at the molecular level: ITS-RFLP, ITS sequencing, ISSR-PCR, and AFLP. The ITS-RFLP and ITS sequences did not detect significant genetic variation among the isolates. However, both ISSR-PCR and AFLP analyses gave indications of intraspecific groupings correlated with geographical origin and relative genetic diversity among some isolates, but no obvious association with Sunn Pest hosts. There was no obvious genotypic grouping of B. bassiana isolates from E. integriceps, perhaps suggesting the overwintering populations were infected by generalist native isolates rather than by host-specific ones that might be more suitable for biocontrol purposes.

Pathogenicity of Beauveria bassiana, Metarhizium anisopliae (Deuteromycotina: Hyphomycetes), and other Entomopathogenic Fungi Against Lygus lineolaris (Hemiptera: Miridae)

Abstract The pathogenicity of 32 fungal isolates from the genera of Beauveria, Verticillium, Paecilomyces, Metarhizium, Mariannaea, and Hirsutella to second-instar tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), was tested under laboratory conditions. These isolates originated from various insect hosts and substrates from France, Denmark, Austria, Italy, Turkey, Syria, and the United States. A single exposure concentration (1 × 107 conidia/ml) assay for each isolate was first conducted by immersing the insects in 10 ml of a fungal suspension for 5 s. These were followed by concentration-mortality assays on five of the most pathogenic isolates using four test concentrations ranging from 2 × 104 to 2 × 107 conidia/ml. B. bassiana 726 (Bemisia-passaged GHA strain) was used as a standard for comparison in all of the assays. Among the test isolates, three produced mortality not significantly different from the water control. Mortality ranged from 35 to 98% among the other 29 isolates. The LC50 values of the five most pathogenic isolates ranged from 0.8 to 5.0 × 105 conidia/ml. The LT50 values for these isolates ranged from 6.0 to 6.9, 3.1 to 5.1, and 2.5 to 4.0 d for concentrations of 2 × 105, 2 × 106, and 2 × 107 conidia/ml, respectively. Two strains of B. bassiana (ARSEF 1394, 5665) and one M. anisopliae (ARSEF 3540) were more pathogenic to the nymphs than the standard, having significantly lower LC50 and LT50 values. Our results demonstrated that several genera of entomopathogenic fungi have promise as microbial control agents against L. lineolaris.

Colletotrichum acutatum var. fioriniae (teleomorph: Glomerella acutata var. fioriniae var. nov.) infection of a scale insect.

An epizootic has been reported in Fiorinia externa populations in New York, Connecticut, Pennsylvania and New Jersey. Infected insects have profuse sclerotial masses enclosing their bodies. The most commonly isolated microorganism from infected F. externa was Colletotrichum sp. A morphological and molecular characterization of this fungus indicated that it is closely related to phytopathogenic C. acutatum isolates. Isolates of Colletotrichum sp. from F. externa in areas of the epizootic were similar genetically and were named Colletotrichum acutatum var. fioriniae var. nov. based on our findings. In vitro and in planta mating observed between isolates of C. acutatum var. fioriniae could serve as a possible source of genetic variation and might give rise to new biotypes with a propensity to infect insects. Only one other strain, C. gloeosporioides f. sp. ortheziidae, has been reported to show entomopathogenic activity.

Trapping Phyllophaga spp. (Coleoptera: Scarabaeidae: Melolonthinae) in the United States and Canada using sex attractants.

Abstract The sex pheromone of the scarab beetle, Phyllophaga anxia, is a blend of the methyl esters of two amino acids, L-valine and L-isoleucine. A field trapping study was conducted, deploying different blends of the two compounds at 59 locations in the United States and Canada. More than 57,000 males of 61 Phyllophaga species (Coleoptera: Scarabaeidae: Melolonthinae) were captured and identified. Three major findings included: (1) widespread use of the two compounds [of the 147Phyllophaga (sensu stricto) species found in the United States and Canada, males of nearly 40% were captured]; (2) in most species intraspecific male response to the pheromone blends was stable between years and over geography; and (3) an unusual pheromone polymorphism was described from P. anxia. Populations at some locations were captured with L-valine methyl ester alone, whereas populations at other locations were captured with L-isoleucine methyl ester alone. At additional locations, the L-valine methyl ester-responding populations and the L-isoleucine methyl ester-responding populations were both present, producing a bimodal capture curve. In southeastern Massachusetts and in Rhode Island, in the United States, P. anxia males were captured with blends of L-valine methyl ester and L-isoleucine methyl ester. Resumen La feromona sexual del escarabajo, Phyllophaga anxia, es una mezcla de los ésteres metílicos de dos aminoácidos, L-valina y L-isoleucina. Se condujo un estudio de campo usando diferentes mezclas de los dos componentes en 59 sitios de Estados Unidos y Canada. Más de 57,000 machos de 61 especies dePhyllophaga fueron capturados e identificados. Tres de los resultados más importantes incluyen: (1) el extenso uso de los dos componentes [de las 147 especies de Phyllophaga (sensu stricto), en Estados Unidos y Canada, fueron capturados machos de cerca del 40% de ellas.]; (2) para la mayoría de las especies, la respuesta intraespecífica de los machos a las combinaciones de los dos aminoácidos fue consistente entre años diferentes, y en todos los sitios geográficos; y (3) un inusual polymorfismo de la feromona fue descrito para P. anxia. Poblaciones de algunos sitios fueron atrapados sólo con valina, mientras que poblaciones de otros sitios fueron atrapados sólo con isoleucina. También se encontraron sitios donde las poblaciones responden a ambos componentes, valina e isoleucina, produciendo una curva de captura bimodal. En el sureste del estado de Massachusetts y en Rhode Island, en Estados Unidos, machos de P. anxia fueron atrapados en trampas con mezclas de valina e isoleucina.

Whey for mass production of Beauveria bassiana and Metarhizium anisopliae

Spore production of Beauveria bassiana and Metarhizium anisopliae was studied in a novel whey-based culture media. Spore yield and viability were determined for two B. bassiana (GHA-726 and CA-603) and two M. anisopliae (CA-1 and IMI 330189) isolates following production in three whey-based systems: solid, liquid, and a diphasic production system. Our study indicated that whey permeate can be used effectively for production of spores of entomopathogenic fungi. However, spore yield and viability were significantly influenced by fungal isolate, whey concentration, and the type of production process used. Under the conditions defined in the present study, spore yields ranging from 1.3x10(9)-10x10(11) spores l(-1) of whey medium could be obtained depending on the strain and production process used. Our study revealed that spores produced by all strains in whey-based solid and liquid media showed between 73-99% viability; germination rates were comparable with those obtained using the standard SDA medium. In the two-stage production process, the viabilities of conidia produced by GHA-726, CA-603, and CA-1 were 35-86, 32-98, and 6-29%, respectively; viability was correlated with whey concentration and isolates. Whey permeate can be used as a growth substrate for mass production of biocontrol fungi. We hypothesize that spore yield and viability could be improved by careful selection of whey content in the medium, incorporation of critical additives and optimization of culture conditions.

Effect of the entomopathogenic fungi on mortality and injury level of western flower thrips, Frankliniella occidentalis.

Abstract The harmfulness of western flower thrips, Frankliniella occidentalis, including insect mortality and plant injury level after the application of three productive and active strains of the entomopathogenic fungi, Metarhizium anisopliae, Lecanicillium lecanii, and Beauveria bassiana, was estimated. LC50 of the M. anisopliae for second instar larvae was twice that of L. lecanii and 1.7 times higher than that of B. bassiana. The average number of damage zones on leaf surfaces after the application of fungi (5×106 spores per ml) constituted 3.0 ± 0.7, 15.9 ± 4.6, and 22.4 ± 4.3 per leaf, respectively (control 67.0 ± 5.7). The total damage area of the leaves was 2.2 ± 0.4, 5.2 ± 0.9, and 4.5 ± 0.6% (control 13.7 ± 3.0%), respectively. Fungi B. bassiana and L. lecanii showed the same level of insect mortality but the number of damage zones and the total damage areas had significant differences. The most effective fungus was found to be M. anisopliae which provided higher plant protection as measured by the decrease in plant injury.

An oil-based formulation of Isaria fumosorosea blastospores for management of greenhouse whitefly Trialeurodes vaporariorum (Homoptera: Aleyrodidae)

BACKGROUND To date, emphasis has been placed on studying the virulence of Isaria fumosorosea conidia rather than the virulence of their blastospores. In the present study, a comparison was made of the efficacy of blastospores of I. fumosorosea (SFP-198) versus conidia against greenhouse whitefly (GWF) Trialeurodes vaporarioum nymphs and thermotolerance at 50 °C. To improve thermotolerance and potency, the blastospores were suspended in corn oil with a wetting and an insect-filming agent. RESULTS Blastospores had similar efficacy against GWF nymphs to conidia in glasshouse conditions but had less thermotolerance than conidia. However, blastospores in corn oil had increased thermotolerance, comparable with that of conidia in corn oil. Application of SFP-198 blastospore oil-based formulation containing isotridecyl alcohol ethoxylated-3EO (TDE-3) and sodium alginate (SA) as adjuvants showed enhanced efficacy (95.7% mortality), compared with the SA-free oil formulation (72.8%) in 10 days. CONCLUSION SFP-198 blastospores can be used as an effective biological control agent, given their virulence against GWF, the enhanced thermotolerance in corn oil and the oil-based formulation studies to enhance their efficacy. Blastospores can be easily produced in liquid cultures in less than 4 days, which is significantly shorter than using traditional solid cultures for conidial production.