Susceptibility of Agrilus planipennis (Coleoptera: Buprestidae) to Beauveria bassiana and Metarhizium anisopliae

The susceptibility of Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) to selected strains of the entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin and Metarhizium anisopliae (Metschnikoff) Sorokin was evaluated through bioassays with direct immersion or foliar exposure under laboratory conditions. Results showed that A. planipennis adults were susceptible to B. bassiana and M. anisoplae. Significant time-mortality response was found for each isolates. Isolate B. bassiana GHA killed A. planipennis adults at a faster rate compared with other isolates tested, with the lowest average time-to-death values. The LC50 values estimated under direct immersion method ranged from 1.7 x 10(5) to 1.9 x 10(7), 3.5 x 10(4) to 5.3 x 10(5), and 4.1 x 10(3) to 2.9 x 10(5) conidia/ml for B. basissiana and from 3.2 x 10(6) to 1.1 x 10(7), 4.5 x 10(3) to 4.5 x 10(5), and 1.4 x 10(2) to 1.2 x 10(5) conidia/ml for M. anisopliae at 4, 5, and 6 d after treatment, respectively. By days 5 and 6, B. bassiana GHA outperformed all other isolates tested except ARSEF 7234, followed by ARSEF 7152, 6393, and 7180. Significant concentration-mortality response was also observed for two B. bassiana GHA formulations, BotaniGard ES and Mycotrol O, and M. anisopliae F52 when insects were treated through foliar exposure. The LC50 values ranged from 114.5 to 309.6, 18.4 to 797.3, and 345.3 to 362.0 conidia/cm2 for BotaniGard, Mycotrol, and M. anisopliae F52, respectively. Based on the results of these bioassays, the efficacy of both B. bassiana GHA formulations and M. anisopliae F52 were similar against adult A. planipennis. The potential use of entomopathogenic fungi for management of A. planipennis in North America is discussed.     

Susceptibility of the cactus weevil Metamasius spinolae to Beauveria bassiana and Metarhizium anisopliae under laboratory and field conditions

Aims: To evaluate different entomopathogenic fungal isolates against the cactus weevil Metamasius spinolae under laboratory and field conditions, and select an isolate to be used as a tool in the management of this insect pest. Methods and Results: Four experiments were carried out. The effect of temperature on the in vitro growth of eight isolates of entomopathogenic fungi (two Metarhizium anisopliae and six Beauveria bassiana) was assessed. The susceptibility of adult M. spinolae to the same isolates was evaluated. Using three selected isolates, the interaction between susceptibility and sex of the insect was studied. Finally, a field experiment was carried out to evaluate infection of adult M. spinolae by the same three isolates under natural abiotic conditions. Overall, growth rate was greatest at 25°C for all the isolates. In vitro growth of M. anisopliae was greater than B. bassiana. Mortality of adult M. spinolae was greater when inoculated with B. bassiana compared with isolates of M. anisopliae. Susceptibility had no interaction with the sex of the insect. The proportion of insects succumbing to infection was smaller when incubated under field conditions than when incubated under laboratory conditions. Conclusions: The experiments described here showed a complex interaction between entomopathogenic fungi and M. spinolae, and these data allows us to select isolate Bb107 as a first step towards its use in the management of this pest insect. Significance and Impact of the Study: Our results showed that entomopathogenic fungi can be used for the control of M. spinolae, which may help reduce the use of chemical insecticides and, therefore, the exposure of Opuntia ficus‐indica producers to pesticides.     

Increased pathogenicity against coffee berry borer, Hypothenemus hampei (Coleoptera: Curculionidae) by Metarhizium anisopliae expressing the scorpion toxin (AaIT) gene

Coffee berry borer (CBB) is the Worlds most devastating coffee pest causing an estimated US$500 million worth of losses annually through damage and control costs. Beauveria bassiana and Metarhizium anisopliae have been employed to control this pest but their low virulence (slow kill and large inoculums) is an important factor constraining their use. M. anisopliae (AaIT-Ma549) has been modified to express the scorpion toxin (AaIT) in insect hemolymph and this greatly increased pathogenicity against Manduca sexta and Aedes aegypti. Here, we demonstrate that AaIT-Ma549 was also dramatically more virulent against CBB, and we provide a much more comprehensive analysis of infection processes and post-mortality development than in the previous research. We evaluated several spore concentrations (10¹ through 10⁷ spores/ml) of both the wild type and recombinant strain. At concentrations of 10¹, 10² and 10³ spores/ml, the recombinant strain significantly increased mortality of CBB by 32.2%, 56.6% and 24.6%, respectively. The medial lethal concentration (LC₅₀) was reduced 15.7-fold and the average survival time (AST) was reduced by 20.1% to 2.98 ± 0.1 days with 10⁷ spores/ml. This is the first occasion that an entomopathogenic fungus has been found to kill CBB in less than 3 days. However, AaIT-Ma549 produces significantly fewer spores on cadavers than the parental strain.     

Interactions among bethylid parasitoid species attacking the coffee berry borer,Hypothenemus hampei (Coleoptera: Scolytidae)

The question of whether biological control is most likely achieved by deploying single or multiple species of biological control agents is much debated. While utilizing several natural enemies may enhance control, there is also the potential for disruptive inter-specific interactions. Such interactions may be studied in the laboratory by focusing on the details of the interactions themselves and attempting to infer population level consequences from their sum, or by focusing more directly on the overall effects on natural enemy populations: we term these approaches ‘reductionist’ and ‘holistic.’ Here we conduct a holistic laboratory study on interactions between three species of parasitoid wasps that are parasitoids of the coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae): Cephalonomia stephanoderis Betrem, C. hyalinipennis Ashmead and Prorops nasuta Waterston (all Hymenoptera: Bethylidae). We find evidence for both intra- and inter-specific resource competition. Interactions between C. stephanoderis and P. nasuta, both indigenous to Africa, appear to be approximately symmetrical, while C. hyalinipennis, naturally found in the coffee plantations of Chiapas, Mexico, may exert a disruptive influence. C. hyalinipennis also has a low population growth rate. We now consider it to be a detrimental invader of the Mexican coffee agro-ecosystem that should not be encouraged by augmentative release or introduced into other regions. Overall, the most successful species, in terms of both emergence and female production, was P. nasuta. We compare these results with those from prior reductionist and holistic studies, and with observations on patterns of establishment of these bethylid species in the field. Given that it is increasingly clear that disruptive inter-specific interactions are generally common when multiple species are deployed in biological control, screening of potential agents should consider such interactions alongside the more ‘traditional’ focus on host specificity.     

A review of the biology and control of the coffee berry borer, Hypothenemus hampei (Coleoptera: Scolytidae)

The coffee berry borer, Hypothenemus hampei Ferrari, is a serious problem for the majority of the world's coffee growers and has proved to be one of the most intractable of present day pests. Despite a great deal of research, control still depends largely on the application of the organochlorine insecticide endosulfan, which is damaging to the environment, or a series of cultural and biological control methods which give variable and unpredictable results. This review summarizes the most important aspects of the biology and ecology of H. hampei and its control and identifies weak points in the knowledge about this pest. Emphasis is placed upon an analysis of the non-chemical control methods available and suggestions are offered for novel ecological and environmental factors worthy of further research, in the search for viable and sustainable control methods.     

The chemotaxonomy ofBeauveria bassiana (Deuteromycotina: Hyphomycetes) isolates from the coffee berry borerHypothenemus hampei (Coleoptera: Scolytidae)

A preliminary chemotaxonomic analysis was carried out on 16 isolates ofBeauveria bassiana from adults of coffee berry borer (Hypothenemus hampei) from 10 countries in Latin America, Africa, Asia and the Pacific. Thirteen formed an homogeneous group with very similar electrophoretic and physiological profiles. Two isolates differed in esterase and acid phosphatase band patterns, one of which was also deficient in chitin-degrading enzyme production, but both were still relatively similar to the major group compared with the total variability within the species. A third isolate was abnormal and may have degenerated in storage. These results suggest a distinct population of the fungus on this host. The implications for selection of pathogenic isolates for development as biological pesticides are discussed.     

球孢白僵菌和绿僵菌对日本双棘长蠹林间防治效果的研究

日本双棘长蠹（Sinoxylon japonicum）是危害国槐和刺槐等园林树木重要的蛀干害虫。本研究采用喷雾法,用含0.1%（体积分数）吐温-80的1.0×109分生孢子/mL的球孢白僵菌（Beauveria bassiana）和绿僵菌（Metarhizium anisopliae）悬液,分别于日本双棘长蠹生活史各阶段开始时在林间进行喷雾实验。实验结果显示,球孢白僵菌的致死效果比绿僵菌好,前者喷药效果最佳的时期为成虫越冬前期;这个时期折枝内虫体校正死亡率为94.1%,僵虫率为75.0%,相对折枝率为48.9%,相对蛀孔率为49.2%。绿僵菌防治效果最佳时期是成虫羽化期;这个时期折枝内虫体校正死亡率为79.9%,僵虫率为83.3%,相对折枝率为71.0%,相对蛀孔率为54.2%。     

Infection of the Coffee Berry Borer Hypothenemus hampei (Coleoptera: Scolytidae) by Brazilian Isolates of the Entomopathogenic Fungi Beauveria bassiana and Metarhizium anisopliae (Deuteromycotina: Hyphomycetes)

The virulence of four fungal isolates (three Beauveria bassiana and one Metarhizium anisopliae ) against adult female coffee berry borers (CBB) was investigated. The most virulent isolate from initial bioassays, B. bassiana LPP1, with a LT 50 of 3.4 days, was further investigated by application to berries prior to infestation and to berries already infested with CBB. At the highest concentration applied to berries (1 ×10 7 conidia mL -1 ), CBB mortality was 83% (berries inoculated prior to infestation) and 62% (berries inoculated after infestation).     

Evaluation of potential entomopathogenic fungus,Beauveria bassiana,for controlling the coffee berry borer Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae) in Taiwan

Hypothenemus hampei (Ferrari) (Coleoptera: Curculionidae: Scolytinae), a coffee berry borer (CBB), is a serious pest of coffee fruits and causes economic losses in the coffee industry. With the concerns of chemical control, an alternative eco-friendly management strategy such as microbial control has emerged as the times require. Herein, a total of thirty-three fungi were isolated from CBB cadavers. Two entomopathogenic fungal isolates, NCHU-271 and NCHU-272, which showed fast insect-killing activity, were subjected to molecular identification and named “Beauveria bassiana-NCHU-271” (Bb-NCHU-271) and “Beauveria bassiana -NCHU-272” (Bb-NCHU-272). Moreover, a virulence test of Bb-NCHU-271 and Bb-NCHU-272 against CBBs was also performed. Both Bb-NCHU-271 and Bb-NCHU-272 caused 100% mortality at 8 days post inoculation (d.p.i.) and a LT₅₀ of Bb-NCHU-271 by spraying 10⁸ conidia/ml was less than Bb-NCHU-272. Therefore, histological evidence of Bb-NCHU-271 infected CBBs was provided to proven the infection process of B. bassiana in CBBs. Furthermore, an infestation test was performed to evaluate the differences in CBB control efficacy between the treatments of “Borers exposed to EPF first” or “Berries exposed to EPF first”. The results revealed that the “Borers exposed to EPF first” of Bb-NCHU-272 caused significantly lower survival rates and higher mycosis rates than those of Bb-NCHU-271. Only slight control effects of Bb-NCHU-271 and Bb-NCHU-272 were also observed in the “Berries exposed to EPF” treatment. In conclusion, Bb-NCHU-271 and −272 showed controlling ability to the CBBs either before or after CBB infestation into coffee berries, while application of EPFs before the CBBs bored into coffee fruits could enhance the control effect.     

Potential of Metarhizium anisopliae and Beauveria bassiana to control Dinoderus porcellus (Coleoptera: Bostrychidae) infesting yam chips

The beetle Dinoderus porcellus Lesne is a serious storage insect pest that causes important losses by destroying stocks of yam chips. In the aim to found an alternative control method to the use of synthetic insecticides for its management, the virulence of the entomopathogenic fungi Beauveria bassiana (Balsamo) Vuillemin (isolate Bb115) and Metarhizium anisopliae (Metschnikoff) Sorokin (isolate Met 31) against adults of D. porcellus was evaluated under laboratory conditions (25 ± 2 °C and 70 ± 5% RH). Then, the effectiveness of the most virulent entomopathogenic fungus as biological agent against D. porcellus was assessed under farmer storage conditions. For each entomopathogenic fungus isolate, four conidial concentration (0, 10⁵, 10⁷, and 10⁹ conidia/mL) at the dose of 1 µL were inoculated topically on D. porcellus adults (3–5 days old). Observations focused on insect mortality, cadaver sporulation and weight loss of yam chips. Lethal dose and lethal time values were estimated using probit analysis. Both fungal isolates at all conidial dose caused more than 50% mortality on day 7, with the highest mortality (94.44%) achieved using B. bassiana at the 10⁹ conidia/mL. LT₅₀ values for B. bassiana and M. anisopliae isolates were 2.63 and 3.35 days, respectively, while their LT₉₀ values were 6.15 and 9.87 days, respectively. Yielding the lower LD₉₀ values and the highest rates of cadaver sporulation, B. bassiana isolate appeared as the most virulent against D. porcellus. After 3 months of storage, comparatively to the control, the B. bassiana isolate at the highest conidial dose (10⁹ conidia/mL) significantly reduced D. porcellus populations, and weight loss of yam chips. This study revealed the potential of B. bassiana and M. anisoplae isolates as biological control agent against D. porcellus for yam chips protection.     

球孢白僵菌和金龟子绿僵菌不同菌株对黑足角胸叶甲成虫的致病力评价

本研究在测定不同球孢白僵菌Beauveria bassiana和金龟子绿僵菌Metarhizium anisopliae菌株的生长速率与产孢量的基础上, 采用孢悬液浸渍法进行了对油茶新害虫--黑足角胸叶甲Basilepta melanopus成虫的生物测定, 旨在筛选出感染该成虫的高致病力菌株, 为防治该虫提供新的生物资源。结果表明： 不同菌株生长速率和产孢量间存在显著差异, MaYTTR-04, BbFZ-17, MaZPTR-01和BbTK-01生长速率和产孢量均显著高于其他菌株。接种后, 叶甲成虫累积死亡率随时间的增加而逐渐增高, 接种白僵菌7 d后, 成虫校正死亡率全部达到100%; 接种MaZPTR-01和MaYTTR-04两个绿僵菌菌株14 d后, 成虫死亡率分别为80.3%和78.8%。而且接种白僵菌后, 叶甲成虫的僵虫率显著较绿僵菌高, 尤其以BbTK-01和BbFZ-17两个菌株较好, 分别达到85.7%和75.8%。BbXJ-01, BbFZ-17和BbTK-01 3个白僵菌菌株的LT₅₀最小, 分别为3.0, 3.3和3.4 d; MaYTTR-04和MaZPTR-01两个绿僵菌的LT₅₀分别为6.0和6.2 d。结果说明, 白僵菌对叶甲成虫的致病力较强, 尤其是BbTK-01和BbFZ-17两个菌株, 不仅致死率高, 且致死速度快, 僵虫率高, 同时这2个菌株生长速度快、 产孢量大, 具有优良的生产特性, 在黑足角胸叶甲的生物防治中将有重要的应用价值。     

Biological activity of five strains ofMetarhizium anisopliae,upon the coffee berry borerHypothenemus hampei (Col.: Scolytidae)

Five strains of the entomopathogenic fungusMetarhizium anisopliae (Metschnikoff) Sorokin were bioassayed against the coffee berry borerHypothenemus hampei (Ferrari) (Coleoptera: Scolytidae) under laboratory conditions (T=27±2°C; R.H.=90±5% and 12∶12 L∶D light cycle). The LC₅₀ values for the three most virulent strains, Ma4, Ma5 and Ma3, were 4.2, 5.9 and 6.7×10⁶ conidia/ml of suspension respectively and median lethal times (LT₅₀) observed were between 9.7 and 13.8 days. The maximum percentage sporulation was obtained with strains Ma3 and Ma4 both with 90% sporulation and Ma10 with 60.7%. These results suggest that the fungusM. anisopliae could be incorporated into an integrated control programme for the biological control ofH. hampei.

---

Résumé Cinq souches du champignon entomopathogèneMetarhizium anisopliae (Metschnikoff) Sorokin, ont été évaluées dans les conditions du laboratoire, pour mesurer leur activité vis-à-vis du scolyte des fruits du caféierHypothenemus hampei (Ferrari) (Coleoptera: Scolytidae). Les résultats montrent que les souches Ma4, Ma5 et Ma3 sont les plus virulentes contreH. hampei, avec des valeurs de concentration létale moyenne (CL₅₀, valeurs minimales et maximales, ± limite de confiance à 95%) de 0,0226 (0,0195–0,00260), 0,0328 (0,0267–0,0390) et 0,0354 (0,0297–0,0417) équivalentes à 4,2, 5,9 et 6,7×10⁶ conidies/ml de suspension et un temps létal moyen (TL₅₀) entre 9,7 et 13,8 jours. Les pourcentages maximaux de sporulation ont été obtenus avec les souches Ma3 et Ma4 avec 90%, la souche Ma10 présentant le pourcentage le plus bas de sporulation (67%). Ces résultats démontrent queM. anisopliae peut être introduit dans un programme de lutte intégrée contreH. hampei.

     

Efficacy of Beauveria bassiana applications on coffee berry borer across an elevation gradient in Hawaii

ABSTRACT

The effect of three rates of a commercial formulation of Beauveria bassiana Strain GHA was evaluated against the coffee berry borer (CBB) Hypothenemus hampei Ferrari (Coleoptera: Curculionidae: Scolytinae), at three commercial coffee farms located at different altitudes on the island of Hawaii. H. hampei infestation and natural prevalence of B. bassiana increased with the elevation. At 145 metres above sea level (Farm 1), beetle infestation was 3.9%; at 538?m (Farm 2), beetle infestation was 12.2%; and at 768?m (Farm 3) infestation was 22.3%. The prevalence of natural B. bassiana killing CBB was 5.5% on Farm 1, 3.3% on Farm 2 and 23.1% on Farm 3. Monthly applications of B. bassiana resulted in no significant differences in levels of CBB infestation among treatments. Similarly, rates of infested berries with visually detectable signs of B. bassiana were similar among the B. bassiana treatments, ranging from 0.44% to 4.24%, and those percentages were larger than the treatments without B. bassiana. The percentage of females killed by Beauveria ranged from 69% to 95%. Effect of dose of BotaniGard^® ES was reduced when beetles were in C position compared to A and B positions. B. bassiana can be an important component of an integrated pest management program for CBB.     

Evaluation of Beauveria bassiana (Ascomycota: Hypocreales) as a control of the coffee berry borer Hypothenemus hampei (Coleoptera: Curculionidae: Scolytinae) emerging from fallen,infested coffee berries on the ground

The effects of Beauveria bassiana strains on coffee berry borers (CBB), which emerge from infested berries left on soil, and its impact on the infestation of coffee berries on tree branches were evaluated at two Experimental Stations (Naranjal-Caldas and Paraguaicito-Quindio) in the Colombian coffee zone. Using a completely randomized design with 10 repetitions, 50 coffee berries artificially infested with CBB were placed on the base of a coffee tree. Four treatments including B. bassiana strain Bb9205, a mixture of Cenicafé strains (Bb9001, Bb9024 and Bb9119), a commercial formulation of B. bassiana and a control (water) were sprayed with 1×10⁹ conidia per tree. After 30 days, all fungal strains lowered the infestation levels of the coffee berries on the trees at both locations. The mixture of Cenicafé strains decreased the tree infestation between 50 and 30% at both locations. In the berries dissected from each treated tree, insect mortality was about 40% at both locations compared to 15% in the control. B. bassiana strains also decreased the insect population inside the newly infested berries on the trees by 55–75%. The mixture of Cenicafé strains was the most effective for decreasing insect populations. B. bassiana significantly decreased CBB populations that emerged from fallen, infested, coffee berries and reduced future insect generations.     

Estimation of production losses caused by the coffee berry borer (Coleoptera: Scolytidae) and calculation of an economic damage threshold in Togolese coffee plots

The coffee berry borer, Hypothenemus hampei (Ferrari) (Coleoptera: Scolytidae), which exists in all coffee producing zones, is a major pest. The seriousness of this scolytid was assessed in Togolese plots spread over five agroclimatic zones, by determining the attack rate from a sample of coffee trees. The work was carried out over 2 yr and revealed that weight losses were proportional to the attack rates. The average infestation rates were 5.64% in the first year and 6.36% in the second year, while total production losses amounted to 2.60% and 3.18%, respectively, for the same periods. Generally speaking, attack rates in the plots were low and varied considerably within a given zone. Plantations located on plateau were more severely attacked than those in the plains. A relationship was established between total losses and the cost of insecticide treatment; this relationship was used to calculate an economic damage threshold beyond which control proves to be cost effective.     

Bacillus thuringiensis serovar israelensis is highly toxic to the coffee berry borer, Hypothenemus hampei Ferr. (Coleoptera: Scolytidae)

A native collection of Bacillus thuringiensis strains was screened, once a reliable bioassay technique to assess the toxicity against the coffee berry borer (CBB) first-instar larvae was developed. A first round of bioassays with 170 strains indicated that the great majority of them showed no or very little insecticidal activity and that very few showed significant levels of toxicity. Interestingly, only those strains that had previously been associated with mosquitocidal activity were also toxic to CBB. Qualitative bioassays (using one high dose) were carried out only with those native mosquitocidal strains, corroborating their significant toxicity towards the CBB first-instar larvae. Most of these strains belong to serovar israelensis. In a second approach, strains from the Institut Pasteur type collection, whose mosquitocidal activity had been previously demonstrated, were also subjected to bioassays. Only those strains that showed a comparable protein content in their parasporal crystals to the israelensis type strain also showed high levels of toxicity towards CBB. Finally, an accurate LC(50) was estimated, using purified parasporal crystals from B. thuringiensis serovar israelensis type strain, at 219.5 ng cm(-2) of diet. All the statistical requirements for a reliable estimator were fulfilled. This is the first report of B. thuringiensis serovar israelensis being active against a coleopteran species.     

Comparison of application methods for suppressing the pecan weevil (Coleoptera: Curculionidae) with Beauveria bassiana under field conditions

The pecan weevil, Curculio caryae (Horn), is a key pest of pecans. The entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin is pathogenic to C. caryae. One approach to managing C. caryae may be application of B. bassiana directed toward adult weevils as they emerge from the soil to attack nuts in the tree canopy. Our objective was to compare different application methods for suppression of C. caryae adults. Treatments included direct application of B. bassiana (GHA strain) to soil under the tree canopy, soil application followed by cultivation, soil application in conjunction with a cover crop (Sudan grass), direct application to the tree trunk, and application to the trunk with an UV radiation-protecting adjuvant. The study was conducted in a pecan orchard in Byron, GA, in 2005 and 2006. Naturally emerging C. caryae adults, caught after crawling to the trunk, were transported to the laboratory to determine percentage mortality and signs of mycosis. When averaged over the 15-d sampling period, weevil mortality and signs of mycosis were greater in all treatments than in the nontreated control in 2005 and 2006; >75% average mortality was observed with the trunk application both years and in the trunk application with UV protection in 2005. Results indicated trunk applications can produce superior efficacy relative to ground application, particularly if the ground application is followed by cultivation. Efficacy in the cover crop treatment, however, did not differ from other application approaches. Future research should focus on elucidating the causes for treatment differences we observed and the extent to which B. bassiana-induced C. caryae mortality reduces crop damage.     

Dry mycelium preparations of entomopathogenic fungi,Metarhizium anisopliae and Beauveria bassiana

Several different harvesting procedures were used to obtain dry mycelium preparations of the entomopathogenic fungi, Metarhizium anisopliae and Beauveria bassiana. The effects of these procedures on the survival of the fungal preparations and on their conidiation after short periods of storage at room temperature and at 4°C were examined. Harvesting procedures consisted of filtering the mycelium produced in airlift containers from the culture medium, washing with deionized water, spraying with a sugar solution, and incubating for 18 hr at 4°C before drying. Conidial production of treated mycelia stored 1.5 and 4.5 months at 4°C was not significantly different for and procedure. For dry mycelium of M. anisopliae stored 1.5 months at 4°C and then at room temperature for 3 months, maltose- and sucrose-treated preparations produced more conidia than preparations sprayed with dextrose solution, with water only, or not sprayed. B. bassiana preparations dried soon after mat formation were superior to those incubated at 4°C, and maltose-and dextrose-treated mycelia were superior to other treatments when stored at room temperature.     

Effect of temperature on virulence of Beauveria bassiana and Metarhizium anisopliae isolates to Tetranychus evansi

The virulence of three isolates of Beauveria bassiana (Bals.) Vuill. and 23 isolates of Metarhizium anisopliae (Metschnik.) Sorok. (Ascomycota: Hypocreales) against the tomato spider mite, Tetranychus evansi Baker and Pritchard (Acari: Tetranychidae), was assessed in the laboratory. The effect of temperature on germination, radial growth and virulence of selected isolates (two isolates of B. bassiana and nine of M. anisopliae) on T. evansi was also investigated in the laboratory. All the fungal isolates tested were pathogenic to the adult females of T. evansi, and there were significant differences in mortality between fungal isolates. The lethal time to 50% mortality (LT(50)) values ranged from 4.2 to 8.1 days and the LT(90) values from 5.6 to 15.1 days. Temperature had significant effects on germination, radial growth and virulence of the various isolates. The best fungal germination was observed at 25 and 30 degrees C, while for the fungal radial growth it was 30 degrees C. All the isolates germinated and grew at all temperatures, but germination and radial growth varied with isolate and temperature. The selected isolates were all virulent to T. evansi, but virulence varied also with isolate and temperature.