Contents - Faperta

Biotechnology, Pest Management, and the Environment: The Future 505
success and practical effectiveness. Some of the problems associated with the use of microbial
pesticides for pest management are:
• Quality and effectiveness;
• Unstable formulations and poor delivery systems;
• Sensitivity to light, relative humidity, and heat;
• Short shelf-life, especially under hot and humid conditions; and
• Limited host range and specifi city to a particular stage of the insect.
Genetic engineering can be used to improve the effi cacy of entomopathogenic microorganisms.
Efforts to improve Bt have largely been focused on increasing its host range
and stability. Work on baculoviruses is largely focused on incorporation of genes that produce
the proteins, which kill the insects at a faster rate (Bonning and Hammock, 1992), and
removal of the polyhedrin gene, which produces the protective viral-coat protein, and its
persistence in the fi eld (Corey, 1991). Neurotoxins produced by spiders and scorpions have
also been expressed in transgenic organisms (Barton and Miller, 1991). Incorporation of
benomyl resistance into Metarhizium anisopliae (Metsch.) and other entomopathogenic
fungi could make entomopathogenic fungi more useful in integrated pest management
(Goettel et al., 1990). The role of neurotoxins from insects and spiders needs to be studied
in greater detail before they are deployed in other organisms because of their possible toxicity
to mammals. Future attention on improvement of microorganisms through genetic
engineering should focus on:
• Improved shelf-life;
• Stability under UV light and extremes of environmental conditions;
• Strains of entomopathogenic fungi with resistance to commonly used fungicides;
• Virulent and effective strains of entomopathogenic bacteria, viruses, fungi, and
nematodes; and
• Interactions with wild relatives and nontarget organisms.
Molecular Markers, Biosystematics, and Diagnostics
Diagnosis and characterization of insect pests and their natural enemies through molecular
approaches will play a major role in pest management. Characterization of natural
enemies is particularly challenging in the tropics, where there is enormous diversity
(Waage, 1991). Biotechnological tools based on molecular markers offer a great promise for
improving biosystematics, and identifi cation of insect pests and natural enemies across a
range on taxonomic groups (Hawksworth, 1994). Molecular markers can be used for rapid
diagnosis even by nontaxonomists in far-fl ung regions. Future research efforts in this area
should focus attention on the development of:
• Molecular markers effective against a wide range of taxa;
•
Kits that are based on both the marker and the gene product;