Pathogenicity of Metarhizium anisopliae (Metch) Sorok and Beauveria bassiana (Bals) Vuill to adult Phlebotomus duboscqi (Neveu-Lemaire) in the laboratory

Background & objectives: Biological control of sandflies using entomopathogenic fungi is a possible alternativeto the expensive synthetic chemical control. It is potentially sustainable, less hazardous, and relatively inexpensiveand merits further investigations. The objective of this study was to identify the most pathogenic fungal isolate(s)to sandflies in the laboratory.Methods: Isolates of entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana were screenedfor their pathogenicity against Phlebotomus duboscqi. Adult flies were contaminated using the technique describedby Migiro et al (2010). Briefly, flies were exposed to 0.1 g of dry conidia evenly spread on a cotton velvet clothcovering the inner side of a cylindrical plastic tube (95 mm long × 48 mm diam). In all 25 sandflies weretransferred into the cylindrical tube and allowed to walk on the velvet for one minute, after which they weretransferred from the velvet into the cages in Perplex. Insects in the control treatments were exposed to fungusfree velvet cloth before being transferred into similar cages. The treatments were maintained at 25 ± 2°C,60–70% RH and 12L: 12D photoperiod. The experiment was replicated 5 times. The most pathogenic isolateswere selected for further studies.Results: A total of 19 isolates were screened against adult sandflies in the laboratory. Mortality in the controlswas approximately 16.8 ± 1.7 %. All the isolates were found to be pathogenic to P. duboscqi. Mortality rangedbetween 76.8 and 100% on all the fungal isolates tested. The lethal time taken to 50% (LT50) and 90% (LT90(mortality ranged from 3.0–7.8 days and from 5.3–16.2 days, respectively. The virulent isolates, causing mortalitiesof 97.5–100%, were selected for further studies.Interpretation & conclusion: The high susceptibility of sandflies to entomopathogenic fungi suggests that fungiare potential alternatives to chemical control methods. We conclude that application of entomopathogenic fungicould result in acute mortalities of sandflies and reduction of parasite transmission and subsequently, reductionof leishmaniasis risk. This method of biological control has great potential as a new strategy for leishmaniasiscontro

Control of Pyrethroid-Resistant Chagas Disease Vectors with Entomopathogenic Fungi

Chagas disease, also known as American Trypanosomiasis, is the most relevant parasitic disease in Latin America, being a major burden that affects mostly poor human populations living in rural areas. The kissing-bugs of the Triatominae family transmit the parasite Trypanosoma cruzi by infectious blood-sucking; Triatoma infestans is the vector of major relevance in the southern Cone of South America. Current control strategies, heavily based on residual insecticide spraying, are threatened by the emergence of pyrethroid-resistant bug populations. Furthermore, ensuring the long-term and sustainable control of this overwhelming disease remains a major challenge. Here we show the utility of a simple, low-cost, biological control methodology against T. infestans bugs, regardless of their susceptibility to pyrethroid insecticides. It is based on the understanding of the initial contact interactions between a mycoinsecticide agent—the fungus Beauveria bassiana—and the host defense barrier, the bug cuticle. The proposed methodology is also supported by present data showing a relationship between the triatomine cuticle width and its hydrocarbon surface components, with insecticide resistance. These results will help to provide a safe and efficient alternative to overcome pyrethroid-resilience of these noxious bugs. A high transfer potential to immediate application in rural communities located in remote areas inaccessible to sanitary control teams, and to the control of other Chagas disease vectors as well, is also envisaged

Can fungal biopesticides control malaria?

Recent research has raised the prospect of using insect fungal pathogens for the control of vector-borne diseases such as malaria. In the past, microbial control of insect pests in both medical and agricultural sectors has generally had limited success. We propose that it may now be possible to produce a cheap, safe and green tool for the control of malaria which, in contrast to most chemical insecticides, will not eventually be rendered useless by resistance evolution. Realising this potential will require lateral thinking by biologists, technologists and development agencie

Antibiosis and antixenosis of two cowpea varieties to the legume flower thrips

(African Crop Science Journal, 1998 6(1): 49-60

Managing termites in maize with the entomopathogenic fungus Metarhizium anisopliae

Field experiments were conducted for two seasons to assess the efficacy of the entomopathogenic fungus Metarhizium anisopliae in the control of termites in maize. Application of the fungus at planting was found to significantly reduce maize lodging and increase grain yield in both seasons. However, data from treatment application at tasselling were not consistent. Our results suggest that a granular formulation of M. anisopliae might be a useful option for the management of termites in the maize agroecosystem. RÉSUMÉ Des expérimentations en plein champs ont été conduites durant deux saisons afin d'évaluer l'efficacité du champignon entomopathogène Metarhizium anisopliae pour la lutte contre les termites sur les cultures de maïs. L'application du champignon au moment de la semis s'est révélée très efficace en réduisant la chute des plants de maïs d'une part, et en augmentant le rendement en grains d'autre part, pendant les deux saisons. Cependant, les résultats issus des traitements pendant l'inflorescence des plants de maïs n'étaient pas consistants. Nos résultats suggèrent donc que la formulation du champignon M. anisopliae en granules serait une option appropriée pour le contrôle des termites dans les cultures de maïs

Influence de la température sur la croissance in vitro d'hyphomycètes entomopathogènes

L'influence de la température sur la croissance in vitro des principales espèces d'hyphomycètes entomopathogènes a été étudiée avec 31 isolats fongiques : 3 souches de Beauveria bassiana (Balsamo) Vuillemin, 3 souches de B brongniartii (= tenella) (Saccardo) Petch, 8 souches de Metarhizium anisopliae (Metschnikoff) Sorokin, 1 souche de M flavoviride Gams et Rozsypal, 6 souches de Nomuraea rileyi (Farlow) Samson et 10 souches de Paecilomyces fumosoroseus (Wize) Brown et Smith. L'analyse des vitesses de croissance radiale à 10 niveaux de température compris entre 8 et 37 °C montre une variabilité à la fois inter- et intraspécifique, liée à l'origine géoclimatique des isolats fongiques. Les champignons provenant de zones subtropicales humides sont relativement thermophiles avec des gammes d'activité significative de 11 ° et 32 °C (isolats de N rileyi) ou 35 °C (isolats de M anisopliae). Inversement, les souches originaires de zones tempérées et surtout du sol de ces régions (isolats issus d'insectes vivants dans le sol ou d'échantillons de sol) présentent une croissance non négligeable aux basses températures (8 °C pour les isolats de B bassiana et ceux de B brongniartii). Néanmoins, l'optimum thermique de croissance de la plupart des isolats (26 sur 31) se situe à 25 °C. Enfin, si certains isolats ont une gamme thermique d'activité végétative relativement étroite (chez B brongniartii et P fumosoroseus) d'autres sont très thermotolérants (la plupart des isolats de M anisopliae). La tolérance thermique des champignons entomopathogènes apparaît donc comme un critère de sélection des isolats fongiques candidats à la lutte microbiologique mieux adaptés au biotope de l'insecte-hôte visé.Influence of temperature on in vitro growth of entomopathogenic hyphomycetes. Thirty-one isolates of 6 entomopathogenic hyphomycetes, Beauveria bassiana (Balsamo) Vuillemin, B brongniartii (= tenella) (Saccardo) Petch, Metarhizium anisopliae (Metschnikoff) Sorokin, M flavoviride Gams et Rozsypal, Nomuraea rileyi (Farlow) Samsom and Paecilomyces fumosoroseus (Wize) Brown et Smith, were grown in vitro to determine growth rates and ranges of growth at 10 temperatures from 8 to 37 °C in the dark. Radial growth of surface colonies on semisynthetic nutrient agar was recorded by daily measurement of 2 cardinal diameters. Because radial measurements (from day 3 to 12) of surface colonies for each temperature fit a linear model (y = vt+b), growth rates (v in mm x day-1) were used as the main growth parameter to evaluate the influence of temperature. The fungal isolates under study exhibited a wide diversity of responses to temperature according to their provenance. Isolates originating from tropical areas showed a remarkable growth at 35 °C (eg, M anisopliae isolates). By contrast, isolates originating from soil-inhabiting insects of temperate areas (eg B brongniartii isolates) exhibited high growth rates at 8 °C. However, the optimal growth was found at 25 °C for 26 isolates. Upper temperature limits of growth varied from 28-37 °C according to both fungal species and isolates. M anisopliae isolates exhibited an almost ideal combination of high growth rates and in particular a wide temperature range (8-11° to 35-37 °C); only one B bassiana isolate showed similar responses to temperature stimuli. Although the optimal temperature for fungal growth is not necessarily the same as that for fungal infection in insects, temperature ranges established according to in vitro growth data might be used for selecting fungal candidates for microbial control