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.     

Inoculation and colonization of coffee seedlings (Coffea arabica L.) with the fungal entomopathogen Beauveria bassiana (Ascomycota: Hypocreales)

The fungal entomopathogen Beauveria bassiana became established as an endophyte in coffee seedlings grown in vitro and inoculated with B. bassiana suspensions in the radicle. The fungus was recovered as an endophyte 30 and 60 days postinoculation, from stems, leaves, and roots, and at 60 days postinoculation one of the isolates was also recovered as an epiphyte. Fusarium sp., Rhodotorula sp., and four bacterial morpho-species were also detected, indicating these were present as endophytes in the seed.     

Climatic factors on entomopathogenic hyphomycetes infection of Trialeurodes vaporariorum (Homoptera: Aleyrodidae) in Mediterranean glasshouse tomato

Collaborative research was conducted at the INRA Research Centers to assess the microbial control potential of Beauveria bassiana- and Lecanicillium lecanii-based formulations against whiteflies in protected crops under Mediterranean conditions. Four series of small-scale glasshouse trials were performed in 1999 and 2000 in southern France. Two applications at 4–5 day intervals of Naturalis-L and Mycotal were conducted on young larvae of the greenhouse whitefly, Trialeurodes vaporariorum, at rates recommended by the manufacturers. Because of the expectation that environmental conditions prevailing in Mediterranean greenhouse crops may lead to greater climatic constraints for mycoinsecticide efficacy than in more temperate areas, manipulation of the greenhouse climate has been used to aim at optimizing mycoinsecticide efficacy. The climatic management strategy was mainly based on closing the ridge vents 2 h more at night-time in so-called “humid” glasshouse compartment than in a “dry” one. Thus, the daily period at high humidity (>90% RH) was two or three times longer in the “humid” compartment than in the “dry” one. In spite of this differential, mycoinsecticide treatments reduced numbers of surviving whitefly larvae by >85% in the “humid” compartment as expected as favorable, as well as in the “dry” compartment, expected as unfavorable. The results indicated clearly that both B. bassiana- and L. lecanii-based mycoinsecticides have a strong potential for microbial control of whitefly larvae infesting tomato crops at moderate ambient humidity in Mediterranean glasshouses. Our investigations provided strong arguments for explaining these unexpected results. The RH conditions prevailing in the targeted insect habitat should be greatly disconnected from that of the ambient glasshouse air. We suggest that strategies of mycoinsecticide optimization against phyllophagous insects in protected crops have to take into account factors acting on the leaf transpiration activity.     

Colonization of tomato greenhouses by the predatory mirid bugs Macrolophus caliginosus and Dicyphus tamaninii

Colonization of tomato greenhouses by native predatory mirid bugs at the end of the spring cycle is common in the western Mediterranean area when no broad-spectrum insecticides are applied. Due to their polyphagy, these predators interact with pest populations and also with other natural enemies present in the crop. In this work we evaluate the abundance and timing of greenhouse colonization by these predators and their interaction with the greenhouse whitefly Trialeurodes vaporariorum, a key crop pest, and its introduced parasitoid Encarsia formosa. Although quite unpredictable, natural colonization of greenhouses by Macrolophus caliginosus and Dicyphus tamaninii, the two predominant species in our location, usually leads to the establishment of predator populations in the crop that subsequently prey on greenhouse whitefly. No preference for parasitized pupae was observed in greenhouse samples, while laboratory experiments revealed a marked tendency to avoid parasitoid pupae. In our area, IPM programs for greenhouse tomatoes and other vegetables should take advantage of the presence of this predator complex by allowing the immigration and establishment of its populations without disturbing them with highly toxic and non-selective insecticides.     

Identification of the molecular origin and development of a panzootic caused by Beauveria bassiana in praying mantis populations in eastern China

A panzootic in praying mantid species Tenodera sinensis and Statilia maculate, caused by Beauveria bassiana, occurred in north, southwest and southeast regions of Anhui Province, eastern China in Autumn, 2009. A 3-d principal component analysis (PCA) of 123 isolates from three sites revealed that the B. bassiana populations were heterogeneous with obvious dominance. Furthermore, the causal source of the panzootic in Anhui was shown to be polyphyletic. The populations were homogenized into homogenous subunits for investigation of genetic structure by inter-simple sequence repeat (ISSR) markers. Variance was greater than 70%, largely due to genetic differences within populations and subpopulations. Genetic distances and genetic differentiation were negatively associated with geographic distances and it was speculated that this was due to the effects of monsoons and topography. Mantid isolates were divided into five pathotypes based on a two-way cluster analysis of genetic distance. Pathotype I consisted of the predominant subpopulations of Huangcangyu and Chashui populations, with a genetic distance of 0.120 and gene flow up to 1.833. This pathotype caused a widespread epizootic in north and southwest Anhui, and Pathotype III caused enzootic at Site A in September and then epizootic in October, while the other three pathotypes caused enzootics at all three investigation sites. The widespread epizootics and isolated enzootics composed the polyphyletic panzootic in Anhui. A strong gene flow between isolates from the two mantid species was identified, resulting in negligible gene differentiation. This indicated a lack of host specificity in mantid isolates of B. bassiana.     

Evaluation ofAphidoletes aphidimyza [Dip.: Cecidomyiidae] for control ofMyzus persicae [Hom.: Aphididae] in greenhouse and field experiments in the United States

BioControl - Greenhouse and field experiments were conducted to evaluate the potential of inoculative releases of the predatory midge,Aphidoletes aphidimyza (Rondani), on aphid populations on...     

Host plant influences pathogenicity of Beauveria bassiana to Bemisia tabaci and its sporulation on cadavers

Laboratory bioassays were conducted to determine host plant effect on pathogenicity of the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuill. (Ascomycota: Hypocreales) to the sweetpotato whitefly, Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae). Fourth instar B. tabaci reared on cucumber, tomato, melon, green pepper, potato, eggplant, marrow, cabbage, bean or cotton, were treated with 1 × 10⁷ conidia/ml B. bassiana EABb 93/14-Tp isolate. Mortality caused by B. bassiana significantly increased with time and it was significantly affected by the host plant on which the nymphs were reared. Mean mortality of nymphs 8 days after inoculation ranged between 52.3±7.3 for nymphs reared on cotton and 91.8±5.8 for nymphs reared on cucumber. Average survival times of nymphs treated with the fungal suspensions were also significantly influenced by the host plant, with a mean of 4.7±0.1 days for nymphs reared on cucumber, 6.6±0.2 days for cotton and 6.9±0.1 days for green pepper. The production of newly formed conidia was also affected by host plant and varied from 111000±8600 conidia/cadaver for nymphs reared on cotton to 597000±28000 conidia/cadaver for those reared on melon.     

A new bioassay method reveals pathogenicity of Metarhizium anisopliae and Beauveria bassiana against early stages of Capnodis tenebrionis (Coleoptera; Buprestidae)

We used a newly developed bioassay method to demonstrate for the first time the potential of the entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae to be used for the control of neonate larvae of Capnodis tenebrionis, a major threat to stone-fruit orchards in several countries. Four B. bassiana and four M. anisopliae isolates were all pathogenic for neonate larvae of C. tenebrionis; mortality rates 10 days after inoculation by dipping in a suspension with 10(8)conidia/ml varied from 23.5% to 100%. Three of the four M. anisopliae isolates caused 100% mortality. In most cases, postmortem hyphal growth and sporulation of M. anisopliae or B. bassiana was observed covering the larvae in their galleries. The eight isolates were also evaluated for pathogenicity to C. tenebrionis eggs at the same dosage. Only two B. bassiana isolates caused significant egg hatching reduction of 84.5% and 94.5%. Our results indicate that M. anisopliae and B. bassiana may be considered as promising for a new approach to prevent larval infestations by C. tenebrionis.     

Effect of exposure method to Beauveria bassiana and conidia concentration on mortality, mycosis, and sporulation in cadavers of Chilo partellus (Lepidoptera: Pyralidae)

The effects of exposure methods, conidial concentrations, and temperature on mortality, mycosis and sporulation in second instar Chilo partellus cadavers infected by Beauveria bassiana was investigated in laboratory studies. Larvae directly sprayed with conidia, exposed to conidia-treated leaves, and dipped into conidial suspension resulted in high mortality (98-100%). The longest LT50 (3.5 days) and days to mortality (2.6 days) were observed in the treated-leaves exposure method. The shortest LT50 (1 day) and days to mortality (1 day) were recorded for the dipping method. With increasing conidial concentrations, there were decreasing LT50 and days to mortality. Larvae exposed to treated leaves and larvae directly sprayed with conidial suspensions produced high mycoses in cadavers. Exposure of larvae to treated-leaves resulted in high sporulation. At lower concentrations of conidia, both mycosis and sporulation in cadavers were high. The optimum temperature for mycosis was 20 and 15 degrees C for sporulation.     

Food consumption by Chilo partellus (Lepidoptera: Pyralidae) larvae infected with Beauveria bassiana and Metarhizium anisopliae and effects of feeding natural versus artificial diets on mortality and mycosis

Second and third instar Chilo partellus larvae were infected with Beauveria bassiana and Metarhizium anisopliae (both at 1x10(8)conidia/ml) and daily consumption of maize leaves was measured. Infection by the fungi was associated with reduced mean daily food consumption. Reduction in food consumption became evident 3-4 days after treatment with the fungi for second instar larvae and 4-5 days for third instar larvae. Four conidial concentrations, 1x10(5), 1x10(6), 1x10(7), and 1x10(8)conidia/ml, were tested against second instar larvae. Food consumption dropped by 70-85% when the second instar larvae were treated with the fungi at 1x10(8)conidia/ml. Reduction in food consumption by C. partellus larvae infected with B. bassiana and M. anisopliae may offset the slow speed of kill of the fungi. The effect of artificial versus natural diets on mortality and mycoses of second instar larvae treated with the fungi at 1x10(8)conidia/ml was determined. Larvae provided with artificial diet suffered little mortality and mycoses than larvae provided with maize leaves. The LT(50) was longer for larvae provided with artificial diet.     

Addition of exogenous carbon and nitrogen sources to aphid exuviae modulates synthesis of proteases and chitinase by germinating conidia of Beauveria bassiana

Secretion of catabolic extracellular enzymes (ECE) is the hallmark of the infection of insects through the cuticle by entomopathogenic fungi (EPF). In this paper, we show that germinating conidia of Beauveria bassiana (Bb) regulate the synthesis of ECE through a multiple control mode during the initial stages of germination. We tested Bb conidial growth on aphid exuviae with or without supplementation of additional carbon and/or nitrogen (C/N) compounds. To understand the interrelation between conidial germination during growth, the synthesis of ECE activity, free amino nitrogen (FAN), glucose and fungal dry weight biomass were measured. Immediately (0.25 h) upon incubation of conidia, activity of subtilisin-like Pr1 and trypsin-like Pr2 enzymes and chitinase (NAGase) was observed in the culture filtrates. At 0.25 h, addition of exogenous C-source resulted in higher activities of Pr1 and Pr2, respectively. Conversely at 0.25 h, addition of N-sources repressed the synthesis of Pr2, but that of Pr1. C/N repression was observed only for exponentially growing mycelia. NAGase activity remained at basal level and unaffected by added C/N. We conclude that C/N repression occurs only when it is necessary for the Bb infective structures to establish a nutritional relationship with the host structures.     

Resistance in tomato to the greenhouse whitefly: analysis of population dynamics

Life history parameters including longevity, developmental time, and reproduction were determined for whiteflies, Trialeurodes vaporariorum (Westwood), kept in clip-on cages on susceptible parent, Lycopersicon esculentum, resistant parent, L. hirsutum glabratum, and intermediate breeding lines of tomato. Using the Lewontin triangular reproductive function, the intrinsic rate of increase (r_m) was calculated for each genotype. This is an elegant tool for detecting resistance, as it incorporates all salient factors of life history. Comparing r_m to the other parameters measured, selection criteria were chosen. Developmental time is not a suitable selection criterion as it varies very little even between the most susceptible and the most resistant genotypes. Additionally, developmental time of T. vaporariorum offspring was found to be highly significantly correlated to parental age on all tomato genotypes except L. hirsutum glabratum. Total reproduction, truncated population counts, and longevity appear good criteria for selection. This test, focusing on antibiotic factors, shows large differences between the resistant and susceptible parent genotypes, but much smaller differences between the breeding lines and the susceptible parent. Earlier screenings relying on a variety of tests appear to have maintained antixenotic rather than antibiotic properties in the breeding lines.     

Effect of microclimate heterogeneity and ventilation system on entomopathogenic hyphomycete infection of Trialeurodes vaporariorum (Homoptera: Aleyrodidae) in Mediterranean greenhouse tomato

Collaborative research was conducted in the south of France to assess constraints related to both climate heterogeneity and ventilation systems on the control potential of a Lecanicillium muscarium-based formulation against whiteflies in Mediterranean greenhouses. Four series of small-scale greenhouse trials were performed in 2001 and 2002. Two applications at 4–5 day intervals of Mycotal were conducted on young larvae of the greenhouse whitefly, Trialeurodes vaporariorum, at the rate recommended by the manufacturer (ca. 10¹⁰ viable spores per liter of water suspension). The climatic heterogeneity was taken into account by comparing the fungus-induced mortality of nymphs located on lateral row plants to that of nymphs on center row plants. In spite of significant differences in air flows (0.7–1.2 and 0.3 ms⁻¹, respectively) there was no effect on fungus efficacy (53–76% mortality). When comparing the influence of greenhouse equipment (sophisticated glasshouse vs. polyethylene-covered greenhouse), the fungus was not affected (89–96% mortality) in spite of significant differences in ventilation rates. The results confirmed that entomopathogenic Hyphomycetes have a strong potential for microbial control of whitefly larvae infesting tomato crops at moderate ambient humidity in Mediterranean greenhouses in spite of windy periods. These investigations confirmed that microclimatic conditions prevailing in the targeted insect habitat (under-leaf surface boundary layer) are greatly disconnected from that of both outside and inside the greenhouse. In northern Mediterranean greenhouses, non-stressed tomato crops provide unexpected favorable conditions for mycoinsecticide use against a phyllophagous insect.     

Isolation of Beauveria bassiana and Metarhizium anisopliae var. anisopliae from Boophilus microplus tick (Canestrini, 1887), in Rio de Janeiro State,Brazil

The objective of this work were to isolate and identify strains of entomopathogenic fungi from ingurgitated female Boophilus microplus ticks, collected from the soil in the municipality of Paracambi, Rio de Janeiro State, Brazil. The ingurgitated females were inoculated in the selective medium oat dodine agar (oda), where 49 colonies of Beauveria bassiana (71%) and 20 of Metarhizium anisopliae var. anisopliae (29%) were isolated. These isolated strains characterize for the first time in Brazil the natural occurrence of these species of fungi in this tick, and will be used to conduct bioassays to evaluate the pathogenicity and virulence of these strains for ticks of the genus Boophilus microplus. This revised version was published online in June 2006 with corrections to the Cover Date.     

Laboratory evaluation of the virulence of Beauveria bassiana isolates to the sorghum shoot borer Chilo partellus Swinhoe (Lepidoptera: Pyralidae) and their characterization by RAPD-PCR

Beauveria bassiana has long been used as a mycopesticide. It has a wide host range; isolates have been reported to differ in host range and virulence to a given insect species. Identification of a molecular marker linked to a virulent phenotype to a target pest would be useful in screening for isolates effective against it. Twenty B. bassiana isolates were tested for their virulence to the second instar larvae of Chilo partellus Swinhoe in laboratory bioassays and their DNA fingerprints were generated by RAPD-PCR. Three arbitrary categories of aggressiveness were chosen; isolates that caused >70%, between 70 and 40% and <40% larval mortality were grouped as highly, medium and less aggressive types, respectively. In the random amplified polymorphic DNA (RAPD) analysis a 30% variability was observed among the isolates; which clustered into three major groups. The groups based on virulence rating did not match with the RAPD clusters. One of the highly aggressive isolates clustered with less aggressive isolates in one cluster and the other grouped along with the medium aggressive isolates in a different cluster. The B. bassiana isolates were classified phenotypically based on the taxonomic order of the original insect host and the climatic zone (tropical/temperate) from which they were isolated. No correlation between the aggressiveness of the isolate and the relatedness of the original insect host to the tested insect was observed; both the highly aggressive isolates were from coleopteran insects. A correlation was found between the RAPD grouping and the phenotypic classification of the isolates. All the lepidopteran isolates grouped into one major cluster, most sub clusters were constituted by isolates from the same climatic zone.     

Application of hydrophilic–lipophilic balance (HLB) number to optimize a compatible non-ionic surfactant for dried aerial conidia of Beauveria bassiana

The hydrophilic–lipophilic balance (HLB) number system was used to optimize a compatible non-ionic surfactant, TDA (polyoxyethylene tridecyl ether) in formulations for two Beauveria bassiana strains, NI8 and GHA. The optimal HLB number for TDA was determined on the basis of wetting times for conidial powders. The results indicated that optimal HLB number of TDA for B. bassiana strain NI8 was 8, while the optimum HLB number for strain GHA was 10. The optimized TDA surfactants required significantly less wetting times than the commonly used laboratory surfactants, Triton X-100, Span 80, and Tween 80. These optimized TDA surfactants were further characterized on their ability to produce conidial suspensions of the two strains after 5 min of mixing, TDA HLB 8 and TDA HLB 10 produced suspensions of 1.8 × 10⁸ and 1.6 × 10⁸ conidia/ml for NI8 and GHA, respectively. These conidial levels were significantly higher than those in Triton X-100, Span 80, and Tween 80 suspensions after the same mixing time. Germination assays showed that TDA HLB 8 promoted significantly higher germination rates of strain NI8 than those observed in other commonly used laboratory surfactants. However, the germination rates of the GHA strain were unaffected by any of the surfactants tested. The efficacy of the conidial suspensions was confirmed with assays against Lygus lineolaris. Bioassay results indicated that there were no significant differences in mortalities because of surfactants. These results suggest optimization based upon HLB number will not negatively impact parameters associated with efficacy, while providing desirable physical properties.     

Response of grassland soil arthropod community to biological and conventional control of a native moth: using Beauveria bassiana and lambda-cyhalothrin for Dalaca pallens (Lepidoptera: Hepialidae) suppression

Conventional and biological control of a native moth, Dalaca pallens (Blanchard) (Lepidoptera: Hepialidae), were evaluated in Southern Chile in relation to changes on community metrics (diversity, species richness, evenness and dominance) of a soil-dwelling invertebrate assemblage. Two experiments were conducted (in winter and spring) to compare non-target effects of Beauveria bassiana (Balsamo) Vuillemin and lambda-cyhalothrin insecticide. The invertebrate community was sampled before and after spraying by extracting soil cores. Estimates of diversity (Shannon index), species richness, evenness (Hurlbert’s Probability of Interspecific Encounter) and dominance indicated that the invertebrate assemblage was strongly disturbed by lambda-cyhalothrin treatment but not by B. bassiana applied in winter, over the sampling period (40 days). Spring results revealed that diversity and evenness at control and at B. bassiana plots were similar between them and higher than at lambda-cyhalothrin plots, while there were no differences between sites 30 days after treatment in species richness. Inundative biological control using B. bassiana strain QU-B931 was considered to pose lower ecological risk than lambda-cyhalothrin, currently one of the most frequently used insecticides for D. pallens control.     

Pathogenicity of <Emphasis Type="Italic">Beauveria bassiana</Emphasis> and <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis> to the tobacco spider mite <Emphasis Type="Italic">Tetranychus evansi</Emphasis>

Seventeen isolates of Metarhizium anisopliae (Metschnikoff) Sorokin and two isolates of Beauveria bassiana (Balsamo) Vuillemin were evaluated for their pathogenicity against the tobacco spider mite, Tetranychus evansi Baker & Pritchard. In the laboratory all the fungal isolates were pathogenic to the adult female mites, causing mortality between 22.1 and 82.6%. Isolates causing more than 70% mortality were subjected to dose–response mortality bioassays. The lethal concentration causing 50% mortality (LC₅₀) values ranged between 0.7×10⁷ and 2.5×10⁷ conidia ml⁻¹. The lethal time to 50% mortality (LT₅₀) values of the most active isolates of B. bassiana and M. anisopliae strains varied between 4.6 and 5.8 days. Potted tomato plants were artificially infested with T. evansi and treated with B. bassiana isolate GPK and M. anisopliae isolate ICIPE78. Both fungal isolates reduced the population density of mites as compared to untreated controls. However, conidia formulated in oil outperformed the ones formulated in water. This study demonstrates the prospects of pathogenic fungi for the management of T. evansi.     

Influence of Temperature on Virulence of Fungal Isolates of <Emphasis Type="Italic">Metarhizium anisopliae</Emphasis> and <Emphasis Type="Italic">Beauveria bassiana</Emphasis> to the Two-Spotted Spider Mite <Emphasis Type="Italic">Tetranychus urticae</Emphasis>

Twenty-three isolates of Metarhizium anisopliae (Metschnikoff) Sokorin and three isolates of Beauveria bassiana (Balsamo) Vuillemin (Ascomycota: Hypocreales: Clavicipitaceae) were assessed for their virulence against the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Based on the screening results, nine isolates of M. anisopliae and two isolates of B. bassiana were tested for their virulence against young adult (1- to 2-day-old) female T. urticae at constant temperatures of 20, 25, 30 and 35°C. At all temperatures tested, all the fungal isolates were pathogenic to T. urticae but mortality varied with isolates and temperatures. Fungal isolates were more virulent at 25, 30 and 35°C than at 20°C. The lethal time to 50% mortality (LT₅₀) and lethal time to 90% mortality (LT₉₀) values decreased with increased temperature. There were no significant differences in virulence between fungal isolates at 30 and 35°C; however, significant differences were observed at 20 and 25°C.     

Colonization and predation of thrips (Thysanoptera: Thripidae) by Orius spp. (Heteroptera: Anthocoridae) in sweet pepper greenhouses in Northwest Italy

Frankliniella occidentalis (Pergande) and Thrips tabaci Lindeman (Thysanoptera: Thripidae) are major pests of sweet pepper for direct damage and tospovirus transmission. To control their infestations, Orius laevigatus (Fieber) (Heteroptera: Anthocoridae) is produced by many commercial insectaries and widely used on IPM vegetable crops of Europe. This predator is naturally widespread along the Mediterranean and Atlantic coasts, and not in more continental areas, where other Orius spp. are more common. Research was conducted in a continental area of Northwest Italy in 2002–2003 to assess the natural presence of anthocorids on pepper, and to compare their colonization and predatory ability with those of the species artificially introduced. Experiments were conducted in 12 sweet pepper greenhouses, in six of which O. laevigatus release was made. From late May to early October, thrips and anthocorids were sampled on pepper by collecting flowers; Orius spp. were also collected on neighboring wild flora. Independently of the releases, Orius specimens were found in all surveyed greenhouses, but O. niger Wolff, also captured on various wild plants, was the most abundant species. It naturally colonized crops from late June and proved to be the most efficient predator on sweet pepper in the surveyed area, if not disturbed by pesticide application. Contrarily, O. laevigatus was rarely found and only in the greenhouses in which it had been released. However its introduction resulted in thrips control before natural colonization by the native species occurred.