Contents - Faperta

Genetic Engineering of Entomopathogenic Microbes for Pest Management 267
receptors. Specifi city differences for Cry1C between S. frugiperda Sf9 cells and Aedes aegypti
(L.) larvae can be changed radically by single point mutations in the loops (Smith and
Ellar, 1994). Domain III has also been implicated in receptor binding of Cry1Ac in H. virescens
(Ge, Shivarova, and Dean, 1989; Ge et al., 1991). Domain switching experiments have
also suggested a role for Cry1Ab domain III in binding to BBMV in S. exigua (de Maagd
et al., 1996b).
Biopesticides Based on Bacillus thuringiensis
Natural isolates of B. thuringiensis produce several crystal proteins, each of which exhibits
different target specifi city (Hofte and Whiteley, 1989; Lambert and Peferoen, 1992). Its
toxins are known to kill insect species belonging to Lepidoptera, Coleoptera, and Diptera
(Hofte and Whiteley, 1989), and nematodes (Feitelson, Payne, and Kim, 1992). The HD
1 strain identifi ed by Dulmage (1981) is the most important Bt product in the market. The
fi rst commercial Bt product, “Sporeine,” was marketed in France (Luthy, Cordier, and
Fischer, 1982). The major breakthrough came with the development of two commercial Bt
products, “Thuricide” and “Dipel” in the 1960s. Formulations based on Bt occupy the key
position, accounting for nearly 90% of the total biopesticide sales worldwide (Neale, 1997),
with annual sales of nearly US$90 million (Lambert and Peferoen, 1992). Certain combinations
of Cry proteins have also been shown to exhibit synergistic effects (Chang et al., 1993;
Crickmore et al., 1995; Lee et al., 1996; Poncet et al., 1995; Wu, Johnson, and Federici, 1994).
There are over 50 registered Bt products with more than 450 formulations (Shewry and
Gutteridge, 1992) (Table 8.3). Bacillus israeliensis has also been used extensively for the control
of mosquitoes (de Barjac and Sotherland, 1990). Bacillus thuringiensis var. morrisoni and
B. israelensis carry four genes that encode mosquito and black fl y toxins CryIVA, CryIVB,
CryIVC, and CryIVD (Bechtel and Bulla, 1976). Bacillus thuringiensis also produces cytotoxins
that synergize the activity of Cry toxins. A conjugation-like system has been used to
transfer Cry-encoding plasmids from one strain to another (González, Brown, and Carlton,
1982), but most cry genes are not readily transmissible by this process. A number of
TABLE 8.3
Natural Bacillus thuringiensis Products in Use for Pest Control
Bt Strain Product Target Insects References
Natural Kurstaki
HD-1
Kurstaki HD-1 Javelin, Steward,
Thuricide, Vault
Biobit, Dipel, Foray Lepidoptera Shah and Goettel (1999), Baum et al.
(1999)
Lepidoptera Shah and Goettel (1999), Baum et al.
(1999)
Kurstaki Bactospeine, Futura Lepidoptera Navon (2000)
Kurstaki Able, Costar Lepidoptera Shah and Goettel (1999), Navon (2000)
Kurstaki Bio-TI Lepidoptera Navon (2000)
Aizawai Florbac, Xentari Armyworms Shah and Goettel (1999), Navon (2000)
Tenebrionis Novodor Coleoptera Shah and Goettel (1999), Navon (2000)
Tenebrionis Trident Coleoptera Shah and Goettel (1999), Navon (2000)
Galleriae Spicturin Lepidoptera Shah and Goettel (1999), Navon (2000)
YB 1520 Mainfeng, Bt 8010 Rijin Lepidoptera
CT 43 Shuangdu Lepidoptera, Coleoptera,
and Diptera
Navon (2000)