Control efficacy of Bacillus thuringiensis and a new granulovirus isolate against Cydia pomonella in orchards

Abstract

Codling moth, Cydia pomonella, is one of the most serious pests of apple and pear worldwide. This study evaluates the efficacies of a granulovirus, a Bacillus thuringiensis (Bt) strain and their combination in the control of C. pomonella in China. A Cydia pomonella granulovirus (CpGV) was isolated from C. pomonella cadavers in an orchard in Gansu, China. Droplet-feeding bioassays showed the median lethal concentration (LC₅₀) of this CpGV isolate (CpGV-C1) against the third instar C. pomonella larvae was 770 OBs µl^?1. The LC₅₀ values of Bt C-33 and kurstaki HD-1 against the third instar larvae were 26.3 µg ml^?1 and 15.7 µg ml^?1, respectively. Field tests indicated the control efficacies of CpGV-C1 and the combination of CpGV-C1 and Bt against C. pomonella larvae in apple orchards were similar to that of beta-cypermethrin. Our data demonstrated that the combination of CpGV and Bt might effectively protect apple fruits from the damage of C. pomonella larvae and had the potential to be developed as a low-cost, highly effective insecticide.     

First record of an entomopathogenic fungus of tomato leafminer,Tuta absoluta (Meyrick) in Tanzania

Tuta absoluta (Meyrick) is a destructive pest causing adverse environmental and economic effects globally. Management of T. absoluta by synthetic chemicals is of diminutive achievement due to resistance trick of the pest. Harnessing of biocontrols is currently fascinating and efficient for management of the tremendous pests. This study isolated an entomopathogenic fungus from dead larvae of T. absoluta on tomato leaves from farmer’s field Tanzania. Two Aspergillus fungal isolates were isolated and tested against larvae and adults of T. absoluta under conditions of 19.5°C and 50%RH, 30.4°C and 70% RH, respectively, in the laboratory. Sequence analysis of Aspergillus isolates that we referred as A-Tz1 and A-Tz2 were analysed with the BLAST program available at the National Center for Biological Information (NCBI). The two isolates (A-Tz1 and A-Tz2) showed 100% similarity with Aspergillus oryzae of GeneBank accession numbers EF121337.1 and MG519722.1. Such similarity implied that both A-Tz1 and A-Tz2 isolates were A. oryzae. To confirm pathogenicity, bioassays were conducted against the larvae, pupa and adults of T. absoluta. Results showed that at 1.0?×?10⁸?conidia/mL, fungal isolates caused up to 70% larval mortality 3 days post inoculation and consequently inhibited pupation by 84.5% and adult emergence by 74.4%. The identified A. oryzae reduced the life span of adult T. absoluta up to 5 days post inoculation at 1.0?×?10⁸?conidia/mL whereas in control T. absoluta survived up to 25 days. This study found that isolates of Aspegillus species have the potential to be used as active ingrediennt for the formulation of a new bioinjections for application by farmers to control the pest in fields.     

Pathogenicity of Beauveria bassiana isolated from Moroccan Argan forests soil against larvae of Ceratitis capitata (Diptera: Tephritidae) in laboratory conditions

The Mediterranean fruit fly, Ceratitis capitata Wiedemann (Diptera: Tephritidae), is the major tephritid pest in Morocco. This pest survives in Moroccan forests Argania spinosa and continually invades the nearest agricultural areas. Entomopathogenic fungi are an interesting tool for fruit fly control and hold a useful alternative to conventional insecticides. However, primary selection of effective pathogens should be taken in laboratory condition prior to applying them in the field. Here, we used third late instar larvae of C. capitata to investigate the effectiveness of 15 local Beauveria bassiana isolates. Results showed that all isolates were able to infect the larval stage, producing a large mortality rate in puparia ranging from 65 to 95 % and caused significant reduction in adult emergence. The fungal treatments revealed that the mycosis occurred also in adults escaping infection as pupariating larvae. The percentage of mycosed puparia was highest in strain TAM6.2 (95 %) followed by ERS4.16 (90 %), therefore they were the most virulent. Median lethal concentration (LC₅₀) was studied for five isolates at four concentrations ranging from 10⁵ to 10⁸ conidia ml^?1. The results showed that the slopes of regression lines for B. bassiana ERS4.16 (slope = 0.386) and TAM6.2 (slope = 0.41) were the most important and had the lowest LC₅₀ values (2.85 × 10³ and 3.16 × 10³ conidia ml^?1 respectively). This investigation suggests that the soil of Argan forests contains pathogenic B. bassiana isolates and highlights for the first time their potential as biological control toward C. capitata larval stage in Morocco.     

Selection of promising fungal biological control agent of the western flower thrips Frankliniella occidentalis (Pergande)

Aims: Larval stages of Frankliniella occidentalis are known to be refractory to fungal infection compared with the adult stage. The objective of this study was to identify promising fungal isolate(s) for the control of larval stages of F. occidentalis. Methods and Results: Ten isolates of Metarhizium anisopliae and eight of Beauveria bassiana were screened for virulence against second‐instar larvae of F. occidentalis. Conidial production and genetic polymorphism were also investigated. Metarhizium anisopliae isolates ICIPE 7, ICIPE 20, ICIPE 69 and ICIPE 665 had the shortest LT₅₀ values of 8·0–8·9 days. ICIPE 69, ICIPE 7 and ICIPE 20 had the lowest LC₅₀ values of 1·1 × 10⁷, 2·0 × 10⁷ and 3·0 × 10⁷ conidia ml^?1, respectively. Metarhizium anisopliae isolate ICIPE 69 produced significantly more conidia than M. anisopliae isolates ICIPE 7 and ICIPE 20. Internally transcribed spacers sequences alignment showed differences in nucleotides composition, which can partly explain differences in virulence. Conclusion: These results coupled with the previous ones on virulence and field efficacy against other species of thrips make M. anisopliae isolate ICIPE 69 a good candidate. Significance and Impact of the Study: Metarhizium anisopliae isolate ICIPE 69 can be suggested for development as fungus‐based biopesticide for thrips management.     

Virulence,proteolytic and lipolytic activities of Brazilian Beauveria bassiana s.l. isolates (Hypocreales: Clavicipitaceae) to Rhipicephalus microplus ticks (Acari: Ixodidae)

Beauveria bassiana s.l. is a cosmopolitan fungus used in the control of different species of arthropods. The current study explored the virulence for ticks, proteolytic and lipolytic activities of 10 Brazilian B. bassiana s.l. isolates. For this purpose, Rhipicephalus microplus biological parameters was evaluated after immersion of the engorged females in fungal suspension (10⁸ conidia mL^?1) and the enzymatic activities were performed posteriorly the fungal growth in minimal medium. After the biological assays, five isolates changed all parameters analysed with highest efficacy of approximately 61% (CG 206) and 66% (CG 481). However, we observed that the most virulent isolates did not show the highest enzymatic activities. Interestingly, CG 500, considered an isolate of intermediate efficacy, demonstrated higher enzymatic activities than the other isolates in four of five analyses (total protease, Pr1, Pr2 and lipase; p?相似文献   

Effect of culture medium on the production and virulence of submerged spores of Metarhizium anisopliae and Beauveria bassiana against larvae and adults of Aedes aegypti (Diptera: Culicidae)

Three Metarhizium anisopliae and three Beauveria bassiana isolates were cultivated in media containing casamino acids, soybean flour or sunflower seed flour and were shaken for three days. M. anisopliae presented similar yields of around 10⁶ submerged spores/ml without significant differences among them, whereas B. bassiana produced yields of around 10⁸ spores/ml, of which GHA strain produced more submerged spores in the casamino acids medium. The other two strains showed no significant difference in the production of submerged spores in the three media used. Differences in mortality on Aedes aegypti larvae were observed with the submerged spores of Metarhizium depending on isolate and medium used. M. anisopliae 2157 caused significantly higher mortality (40%) when cultivated in casamino acids medium. It presented an LC₅₀ of 8.93 × 10⁵ submerged spores/ml water against mosquito larvae five days after application, whereas it caused 27% mortality in Ae. aegypti adults 10 days after application. In conclusion, fungal nutrition affected virulence of some isolates of M. anisopliae against Ae. aegypti larvae while such an effect was not noted for B. bassiana isolates.     

Development of a direct test of baculovirus resistance in wild codling moth populations

The occurrence of resistance of codling moth (CM, Cydia pomonella L.) to Cydia pomonella granulovirus (CpGV) used as biological control agent revealed the need for fast and reliable resistance monitoring methods. Here, we describe the development of a laboratory resistance test that is directly performed on larvae extracted from infested apples. This test is based on a 14‐day bioassay at a discriminative CpGV concentration of 2 × 10⁵ occlusion bodies/ml diet and can be applied to L1–L4 larvae. Information on virus resistance can be obtained within <4 weeks. In a survey, CM larvae were isolated and tested from 6698 apples from 10 different orchards in Germany, Austria, Switzerland, Italy and the Netherlands. We identified seven CM populations resistant or partly resistant to CpGV isolates. Although some of the orchards were treated with commercial CpGV products, this method allowed us to obtain reliable information about the resistance status of the examined populations.     

Susceptibility of the cattle tick Boophilus microplus (Acari: Ixodidae) to isolates of the fungus Beauveria bassiana

The susceptibility of the tick Boophilus microplus to Beauveria bassiana was evaluated by inoculating eggs, larvae and engorged females of the tick with five fungal isolates at concentrations of 10⁶, 10⁷ and 10⁸ conidia/ml. Tick eggs (0.25 g) were immersed in 1 ml of a suspension of the different conidial concentrations for 1 min. Similar exposure was performed by immersion of 2000 larvae and homogeneous groups of nine engorged females in 2 and 20 ml of conidial suspension, respectively. Treated eggs, larvae and adults were placed in an incubator at 27 ± 1 °C and relative humidity above 80% for evaluation of the fungal action. All fungal isolates applied at all conidial concentrations reduced the hatching rate of larvae from treated eggs by 1.36–65.58% and increased the mortality rate of inoculated larvae by 0.8–70.49%. In the bioassay with engorged females, oviposition period was reduced by 9.69–47.80%, egg mass weight by 4.71–53.87%, estimated reproduction by 8.3–60.62%, egg production index by 5.03–54.20%, percent larval hatching by 0.27–13.96%, and the mortality rate of treated females was increased by 96.60–100%. The reduction of the estimated reproduction obtained for the treated groups ranged from 8.37 to 64.52%. The sporulation of the pathogen on dead females ranged from 3.70 to 88.88% depending on the isolate and concentration used. Isolates AM 09, CB 7 and JAB 07 were the most effective and effectiveness increased with increasing concentrations of conidia in the suspensions.     

Susceptibility of Anopheles messeae Fall. and Culex pipiens pipiens L. Larvae to entomopathogenic Fungi Metarhizium

The mortality rate of Anopheles messeae Fll. and Culex pipiens pipiens L. mosquito larvae infected with entopathogenic fungi Metarhizium brunneum and M. robertsii has been studied in laboratory conditions. It was shown that C. pipiens larvae are more susceptible to a water suspension of fungal conidia treatment while A. messeae larvae are more susceptible to treatment with dry conodia. The mortality of mosquito larvae infected with the most virulent strain and dose of 2 × 10⁶ conidia per cm² was 87.5–92.5%. Prospects for the use of fungi in the biocontrol of bloodsucking mosquitoes are discussed.     

Virulence potential of some fungal isolates and their control-promise against the Egyptian cotton leaf worm,Spodoptera littoralis

A preliminary virulence test of four fungal isolates, Beauveria bassiana IMI 382302, Beauveria bassiana IMI 386701, Trichoderma harzianum T24 and Aspergillus flavus Link against larvae of Spodoptera littoralis was performed. The most effective isolates against larvae of S. littoralis were B. bassiana 302 and T. harzianum T24, which also showed the lower percentage of pupation compared with the other two isolates under the same conditions of treatments. Three concentrations (1 × 10⁶, 1 × 10⁷ and 1 × 10⁸ ml^?1) of the aqueous conidial suspension of the four tested isolates were carried out against both larval and pupal stages of S. littoralis within five days post-treatment. T. harzianum T24 showed 80% larval mortality only when applied at the highest conidial concentration, while A. flavus showed 100% pupal mortality only, at all of its conidial concentrations. However, B. bassiana IMI 382302 showed relatively high dose-dependant larval and pupal mortalities, while strain IMI 386701 of B. bassiana showed a very weak mortality against pupae at higher concentrations, and no virulence against larvae was recorded. Enzymatic and antibiosis bioassays of the four fungal isolates showed relatively high activities against Fusarium spp. for most of the tested isolates. Clear zone of enzyme activity on agar plates proportionally increased with increasing the concentration of enzyme substrate and prolongation of the incubation period. Mtabolites produced in the agar culture inhibited the growth of Fusarium spp. and the productivity differed greatly among isolates or strains of the same isolate. Volatile and non-volatile compounds produced by A. flavus Link showed a higher inhibition activity against Fusarium spp. compared with the other fungal isolates. The humoral antifungal response of insect host is relatively high compared to the anti-bacterial one. Injection of larvae with the immune sensitive bacteria Micrococcus luteus (5 × 10³ bacteria/larva) showed a detectable humoral response by 2 h, peaked around 12 h and became hardly detectable by 24 h post-injection. Injection of larvae with conidial suspension (5 × 10³ conidia/larva) from each of the fungal isolates showed humoral antifungal activity against B. bassiana IMI 386701 and A. flavus only. This activity was detectable by 12 h, peaked around 36 h and became hardly detectable by 48 h post-injection. Although the humoral antifungal response was started slowly compared to the antibacterial one, it lasted for longer and enabled larvae to withstand the infection with these immune-sensitive fungal strains. No humoral activity was detected against B. bassiana IMI 382302, although however, weak activity was detected against T. harzianum T24 only at the low conidial concentration but not at the higher one (1 × 10⁸ ml^?1). Thus, this study concludes that larvae of S. littoralis showed immune-dependant sensitivity to T. harzianum T24 and B. bassiana IMI 382302. Therefore, this study may recommend these two fungal isolates as mycoinsecticides in the battle against cotton leaf worm in Egypt. Hence, they have been selected for future comprehensive bioassays in the laboratory under conditions similar to that in the field. This, in fact, may help for developing effective mycoinsecticides against this pest. Penetration mechanims of insect cuticle by entomopathogenic fungi will be discussed.     

Pathogenicity, formulation and storage of insect pathogenic hyphomycetous fungi tested against Diabrotica speciosa

Studies were conducted tosearch for fungal strains with potentialpathogenicity against Diabrotica speciosa(Germar) (Coleoptera: Chrysomelidae).Among sixteen fungal isolates screenedthe most virulent was a Beauveria bassiana(Balsamo) Vuillemin isolate (FHD13) thatcaused 70% mortality of D. speciosathird instar larvae. The LC₅₀ value ofB. bassiana isolate FHD13 was3.48 × 10¹⁰ conidia/ml.Different temperatures (4, 17 and 26 °C)and vegetable oils (corn, sunflower and canola)used for storage did not significantly affectviability of conidia. A pathogenicity trialagainst D. speciosa larvae performed withthe corn oil formulation (1 × 10⁸ conidia/mlof oil) caused 65% of mortality.     

Susceptibility of Phyllophaga polyphylla and Anomala cincta larvae to Beauveria bassiana and Metarhizium anisopliae isolates, and the interaction with soil properties

The white grub species Phyllophaga polyphylla and Anomala cincta (Coleoptera: Melolonthidae) are economically important species that affect many crops in Mexico. A series of experiments to study the pathogenic interaction between isolates of Beauveria bassiana and Metarhizium anisopliae and these two insect species were undertaken. First, the susceptibility of third instar P. polyphylla larvae to each of seven isolates representing both species of fungus was evaluated by dipping the insects in 1?×?10⁸ conidia?ml^?1 suspensions. A second study examined the differences in the susceptibility of P. polyphylla and A. cincta larvae to two selected isolates for each of the fungal species. Finally, the susceptibility of A. cincta larvae to one M. anisopliae isolate when incubated in soil collected from four different sites was assessed. No significant differences in proportion of infection of P. polyphylla larvae were observed amongst the fungal isolates tested and mortality due to fungal infection was never greater than 20% after 36?days incubation. Anomala cincta larvae were more susceptible than P. polyphylla larvae, with greater than 90% infection when inoculated with isolates of M. anisopliae whereas mortalities of only 20% where achieved against P. polyphylla larvae. The soil type in which A. cincta were incubated following inoculation with M. anisopliae affected their susceptibility to infection. The results demonstrated that there is a complex interaction amongst entomopathogenic fungi, white grub larvae and soil properties, and points to the need of further investigation of this system in order to optimize the efficacy of entomopathogenic fungi against these insect species.     

Isolation of entomopathogenic fungi from Northern Thailand and their production in cereal grains

Spore productivity in six entomopathogenic fungal strains isolated from insect cadavers at four locations in Chiang Mai province was evaluated in five cereal grains: white-rice, wheat, rye, corn and sorghum. According to sequence analysis of the internal transcribed spacer regions of these isolates, they were closely related to Beauveria bassiana (2 isolates), Metarhizium flavoviride (1 isolate), Metarhizium anisopliae (1 isolate), Paecilomyces lilacinus (1 isolate) and Isaria tenuipes (1 isolate). Among all fungal isolates, the maximum amount of spores (530.0?×?10⁹ conidia/g) was yielded P. lilacinus CMUCDMT02 on sorghum grain followed by white-rice (399.3?×?10⁹ conidia/g). Moreover, the highest number of spore in M. flavoviride was 102.8?×?10⁹ conidia/g sorghum whereas white-rice yielded the greatest amount of spore for B. bassiana CMUCDMF03 (141.0?×?10⁹ conidia/g) after 60?days incubation. The fungal growth rate was found highest in corn for all strains and rye showed the lowest with the exception of P. lilacinus CMUCDMT02 among the tested grains. Spore viability was over 80?% for all isolates that had been inoculated for 60?days. Fungal conidia suspension of P. lilacinus obtained highest virulence against Bactrocera spp. at a concentration of 1?×?10⁶ spore/ml. The strains isolated, exhibited good production of conidia suggesting a promising strategy for the mass production of inoculum as biocontrol agents with low production cost.     

Role of cuticle-degrading enzymes of Beauveria bassiana and Metarhizium anisopliae in virulence on Plodia interpunctella (Lepidoptera,Pyralidae) larvae

Entomopathogenic fungi (EPF) are important biological control agents in pest management programs in agroecosystems against insect pests. EPF such as Beauveria bassiana (Bals.) Vuillemin and Metarhizium anisopliae (Metchn.) Sorokin produce a wide range of extracellular enzymes involved in disturbance of the first barrier in the insect cuticle comprising proteins, chitin, and lipids. Realizing relationships between the expression of these enzymes and fungal virulence might aid in development of effective mycoinsecticides. The virulence of B. bassiana (isolates TV and OZ1) and M. anisopliae (isolate CS1) were investigated on Plodia interpunctella (Hübner) larvae in this study. The third instar larvae were immersed in a suspension containing 1 × 10⁸ conidia mL^?1 of fungal conidial inoculum. The results revealed that all three fungal isolates caused mortality in larvae, but there was a considerable variation in their virulence. Total proteinase, exochitinase and lipase assays were done for these isolates. The TV isolate with the highest mortality with 41.7%, had the highest level of specific activity of exochitinase, protease, and lipase with 0.148, 0.654, and 0.190 U. mg^?1 protein, respectively. In the current study, a positive correlation was determined between the virulence of fungal isolates and the activities of protease and lipase, but this link was not significant for exochitinase. Our results demonstrated that extracellular enzymes, particularly protease and lipase, may play a crucial role in the virulence of these fungal isolates against P. interpunctella larvae.     

Evaluation of a granular formulation containing Metarhizium brunneum F52 (Hypocreales: Clavicipitaceae) microsclerotia in controlling eggs of Aedes aegypti (Diptera: Culicidae)

We evaluated the potential of a granular formulation of Metarhizium brunneum F52 containing microsclerotia (MbMSc granules) for control of Aedes aegypti by targeting eggs. MbMSc granules produced infective conidia within 14 days after application to 2.5?g moist potting soil, producing 5.9?×?10⁵, 2.08?×?10⁶ and 6.85?×?10⁶ conidia from 1, 5 and 25?mg MbMSc granules, respectively. Application of MbMSc triggered premature eclosion of eggs (EC_50?=?12?mg) with percentages as high as 31?±?2.9% and 67?±?4.3% of the eggs treated with 5 and 25?mg MbMSc granules, respectively, after 14 days on moist filter paper. Premature eclosion of eggs started at 3 days subsequent to MbMSc granule application and survival of larvae was significantly reduced for granule treated eggs (74?±?2.2%, 39?±?2.0% and 23?±?4.9% larvae survived for 1, 5 and 25?mg granule treatments, respectively, EC₅₀?=?4.9?mg). When MbMSc granules were applied in moist potting soil with mosquito eggs, rates of 1, 5 and 25?mg of MbMSc granules significantly reduced adult emergence with only 81?±?2.1%, 47?±?1.9%, and 34?±?2.1% emergence, respectively (EC₅₀?=?7?mg). Eggs treated with increasing concentrations of fungal conidia enhanced premature eclosion of eggs with an EC₅₀?=?1.6?×?10⁶ conidia/mL. Our results demonstrate that MbMSc granules are a promising candidate for control of A. aegypti and that fermentative production of Mb F52 microsclerotia as the active propagule has the potential for use for mosquito control.     

Comparison of the relative efficacy of an insect baiting method and selective media for diversity studies of Metarhizium species in the soil

Metarhizium are a commonly occurring group of entomopathogenic fungi normally found in soil. The most common methods to assess the diversity of Metarhizium species in soil are (i) the use of selective media and (ii) insect baiting using Galleria mellonella larvae. We compared the recovery efficiency from soil of four common species of Metarhizium (Metarhizium anisopliae, Metarhizium pingshaense, Metarhizium brunneum and Metarhizium robertsii) using these two methods. Firstly, we compared the number of colony forming units (CFU) produced in vitro when grown on two selective media, one containing chloramphenicol, thiabendazole and cycloheximidethe (CTC) and one based on the fungicide dodine (n-dodecylguanidine acetate) (DOD). Secondly, we artificially inoculated natural/non-sterile soil with the four fungal species at a rate of 2×10² and 2×10³ conidia g^?1of soil, baited with G. mellonella, and processed for evaluation using the selective media. The in vitro results showed that the greatest number of CFUs were recorded for M. brunneum. In contrast, when inoculated into soil, more G. mellonella larvae became infected by M. anisopliae. Finally, when using selective media, most CFUs recovered were for M. robertsii. The importance of our results in selecting a method to study the natural occurrence of Metarhizium in soil are discussed.     

Insecticidal efficacy of two isolates of Beauveria bassiana (Bals.) (Vuill.), on the second larval stage of Leptinotarsa decemlineata (Say) (Col.: Chrysomelidae)

Leptinotarsa decemlineata is a serious potato pest throughout the world that has developed resistance to many insecticides. This study investigated the virulence of two indigenous isolates of Beauveria bassiana, consisting of DEBI007 and IR1217C. Five different concentrations of each isolate, 1 × 10⁷, 3.1 × 10⁷, 1 × 10⁸, 3.1 × 10⁸ and 1 × 10⁹ conidia ml^?1, were applied in bioassay using dipping method on second instar larvae. Control insects were treated with distilled water containing 0.01% Tween-80 (Sigma, Germany) as surfactant. The results showed that mortality percentages due to DEBI007 and IR1217C isolates in the highest concentration were 60% and 57.77%, respectively. There was a significant difference between efficacies of different conidial concentrations; therefore, with rise in conidial concentration, the mortality percentage was increased. The DEBI007 isolate that was previously isolated from the soil was more effective than IR1217C isolate. Calculated LC₅₀ for this effective isolate was 1.4 × 10⁷ conidia ml^?1, which, respectively, is the highest concentration.     

Ovicidal effects of entomopathogenic fungal isolates on the invasive Fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae)

Maize is a major staple food for over 300 million people in sub‐Saharan Africa. Sustainable productivity of this primary crop has been recently threatened by Fall armyworm (FAW), Spodoptera frugiperda invasion. Due to lack of environmentally safe management strategies, immediate responses by growers and governments to tackle FAW are based on rampant use of pesticides. Looking for efficient biopesticides, twenty entomopathogenic fungal isolates (14 Metarhizium anisopliae and 6 Beauveria bassiana) were screened for their efficacy against eggs and second instar larvae of FAW. A single discriminating concentration of 1 × 10⁸ conidia ml^?1 and four replicates per treatment were used in all experiments. Isolates were assessed for their ability to cause mortality of FAW second instar larvae, eggs and the neonate larvae that emerged from treated eggs. Among the isolates tested, only B. bassiana ICIPE 676 caused moderate mortality of 30% to second instar larvae. Metarhizium anisopliae ICIPE 78, ICIPE 40 and ICIPE 20 caused egg mortalities of 87.0%, 83.0% and 79.5%, respectively, and M. anisopliae ICIPE 41 and ICIPE 7 outperformed all the others by causing 96.5% and 93.7% mortality to the neonate larvae, respectively. The cumulated mortality of eggs and neonates was highest with M. anisopliae ICIPE 41 (97.5%), followed by M. anisopliae ICIPE 7, 655, 40, 20 and 78 with total mortality of 96.0%, 95.0%, 93.5%, 93.0% and 92.0%, respectively. These isolates with high cumulated mortality (≥92%), especially ICIPE 78 and 7, which are already commercialized for spider mites and ticks control respectively, would be good candidates for development as biopesticides for management of FAW in Africa if further evidence of their efficacy is obtained in the field.     

Effectiveness of Metarhizium anisopliae formulations against dengue vectors under laboratory and field conditions

The oviposition behaviour of Aedes aegypti and the effectiveness of Metarhizium anisopliae conidia formulated in water or oil-in-water against A. aegypti adults and eggs were tested in multi-choice and no-choice tests in oviposition devices under laboratory conditions. Both females and males rested in the devices, regardless of the formulation, and were not repelled by the presence of conidia (up to 10⁶?conidia/cm²) without oil or formulated with oil on treated filter paper arranged in the device. However, at higher oil concentrations (≥0.1?μl/cm²), regardless of the presence of conidia, the number of eggs laid by gravid females on the filter paper dropped. The susceptibility of adults, especially of males, to fungal infection increased up to a 15-day incubation. An elevated number of larvae (≥41%) eclosed from eggs laid on the moistened filter paper in the device even without submersion of eggs in water, and these larvae subsequently died. In the laboratory, 1?μl/cm² oil combined with 10⁶?conidia/cm² clearly reduced eclosion to 1.8% after submersion of eggs in water compared to ≥13% eclosion in the control. In field tests in Goiânia, Brazil, eclosion of aedine larvae from eggs laid on filter paper previously treated with oil-in-water formulated conidia dropped to between 0% and 36% compared to 22–50% in the control. Promising results of laboratory and field tests with M. anisopliae formulated in water or oil-in-water and tested in a device emphasised the effectiveness of a fungus-based formulation for aedine mosquitoes in peridomestic areas.