Biopesticides Based on Fungi

Application of fungi in mass inoculations against insect pests began with Krassilstchik in 1888. Indeed, such was the optimism at that time Krassilstchik confidently predicted "the idea of controlling insects by means of artificially induced epidemics, an idea expressed some 20 years ago by scholars, has become a practically feasible one, which in the future will be perfected and broadly utilized" (Krassilstchik 1888). Unfortunately, progress has been much slower than what was predicted. While progress in the early 1900s was promising, the discovery and application of effective chemical pesticides in the 1930-1940s reduced interest in the use of insect pathogens. Insect pathogenic fungi were more difficult to use, and it was not until environmental and health problems associated with the use of chemical insecticides became apparent in the 1960s that interest in fungal biopesticides again increased. Currently, most biopesticides based on entomopathogenic fungi in the market include either B. bassiana or M. anisopliae (Table 1). These two species, the so-called muscardine fungi, have broad host ranges, although individual strains may be restricted in the number of insect species that they can attack. These species are relatively easy to produce, as they produce vast amounts of asexual conidia in culture as well as on insects. They are generally considered to have low mammalian toxicity and few nontarget impacts have been reported (see Section 6).

A number of biopesticides have been based on the white muscardine fungus, B. bassiana (Table 1). The better known products are those of Emerald BioAgriculture (a merger between Mycotech Corporation and Auxein Corporation) such as BotaniGard® and Mycotrol®. BotaniGard is a liquid emulsion formulation of B. bassiana conidia while Mycotrol is based on powdered conidia. There are a number of other products based on Beauveria spp. registered around the world. In France, Ostrinil™, based on B. bassiana has been produced for many years for corn earworm (Ostinia nubalis) control, while in India the biopesticide Dispel is sold for control of podborers (Reddy et al. 2001). Similarly, a number of biopesticides are based on the green muscardine fungus, Metarhizium spp. Biopesticides based on Metarhizium spp. have had a long (if not always successful) history. In the 1980s, Bayer Corporation produced a biopesticide, Bio1020, which was a formulation of M. anisopliae with excellent shelf life and application potential. It was primarily developed for control of black vine weevil (Reinecke et al. 1990), but was tested against a number of other pests [e.g., Tabata (1992)]. However, the product was not commercially successful for a number of reasons (Reinecke et al. 1991) and was unavailable for many years. Recently, Bio1020 has reappeared in the market as Taenure™, sold by Earth Biosciences (

A recent success story for biopesticides has been the development of novel strains of M. anisopliae var. acridium for locust control in several countries. Initially, a strain of this fungus was developed in Africa under a program called LUBILOSA, which led to the biopesticide "Green Muscle" (Lomer et al. 2001). This program has inspired development of indigenous strains of M. anisopliae var. acridium in other countries. For example, in Australia the success of the LUBILOSA program has been duplicated with the development of Green Guard™ based on an Australian isolate of M. anisopliae var. acridium (Milner 2000).

Other biopesticides based on Metarhizium are sold around the world. In Australia, an isolate of M. anisopliae has also been developed as a commercially available biopesticide for the control of sugarcane scarabs, particularly the grayback canegrub, Dermolepida albohirtum. BioCane™ is effective when applied at 33 kg/ha (1 X 1010conidia/m) before filling-in of the planting furrow (Samson et al. 1999), giving 50-60% control of grayback larvae (Logan et al. 2000). In Columbia, a product based on several entomopathogenic fungi (Micobiol) has been tested against Prodiplosis longifila (Diptera: Cecidomyiidae) infesting tomatoes, but was not as effective as conventional control products (Delgado et al.

Several other entomopathogenic fungi have been developed as commercially available biopesticides (Table 1). Fungi such as Paecilomyces and Verticillium are similar in action to Metarhizium and Beauveria. However, a more unusual fungus for development as a biopesticide is the aquatic active, Lagenidium giganteum. This Oomycete fungus is active against mosquito larvae and has been developed into the biopesticide Laginex ™ in California and is now sold by AgraQuest, Inc. In field trials against the mosquito Culex quinquefasciatus, Laginex™ compared favorably with Vectobac™ (based on Bacillus thuringiensis israelensis), in terms of persistence of control (Hallmon et al.

2000). No biopesticides are currently produced using any species of the Entomophthorales, which is a large order containing mainly entomopathogenic fungi. These fungi, which typically forcibly discharge their primary conidia, often cause large-scale epizootics among insects. This suggests huge potential for development of this group of fungi as mass applied biopesticides. However, problems in production and stabilization of the fragile conidia or the more durable resting spores have not been overcome, and economic products are not feasible at this time.

Biopesticide production has increased in many Central and South American nations and some are not strictly commercial. For example, in Cuba where, as a result of the trade embargo, it has been difficult to obtain cheap chemical pesticides, a biopesticide production industry has grown to fill the gap. Under the Cuban Ministry of Agriculture, decentralized laboratories provide insects, nematodes, and entomopathogens (bacteria, fungi, and viruses) throughout Cuba's 15 provinces (Rosset and Moore 1997). These "Centres for the Production of Entomophages and Entomopathogens" (CREEs) have facilitated the rapid adoption of IPM systems in crops previously managed under pesticide-based systems. Several fungal entomopathogens are produced for a number of pests, including B. bassiana for control of coleopteran pests and Verticillium lecanii for whitefly, Bemisia tabaci. In 1994, 781 metric tonnes of B. bassiana, 196 of V. lecanii and 142 of M. anisopliae were produced by the production centers. Similarly, biopesticides based M. anisopliae are produced by some Central American sugar plantations for the control of pests. The sugar companies have their own production facilities for Metar-hizium and Beauveria [e.g., Badilla (2000) and Grimm (2001)]. These localized production facilities produce sufficient quantities of fungal inoculum for control of pests such as the coffee berry borer, the diamondback moth, and spittlebugs.

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