Contents - Faperta

Genetic Engineering of Natural Enemies for Integrated Pest Management 295
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The gene can be obtained by selection, mutagenesis, or cloning.
The manipulated strain is fi t and effective.
The released strain can be maintained in some form of reproductive isolation.
Some of the biotechnological interventions that can help improve the effi ciency of biological
control of insect pests are discussed below.
Techniques for Genetic Engineering of Arthropods
Genes for use in genetic engineering of arthropods can be isolated from either closely or
distantly related organisms for insertion into the target insect species. It may also be
possible to isolate a gene from the species being manipulated, alter it, and reinsert it into
a germ line. The ability to genetically transform nondrosophilid insects offers new
approaches to analyzing molecular genetic systems in insects. A consequence of increased
knowledge that will arise from these studies will lead to the development of new strategies
for pest control that will be specifi c for the target insect. Most of the research on genetic
engineering of insects has been aimed at gaining an understanding of gene regulation
or developmental processes. Cloned genes could also be modifi ed by in vitro mutation to
achieve a desired phenotype. Various techniques employed for genetic engineering of insects
(Table 9.2) are described below.
DNA Injection into Eggs
Microinjection into eggs has been employed widely to deliver DNA into the embryos of the
target insect species. Different injection methods are required for different insect species
(Miller et al., 1987; McGrane et al., 1988; Milne Phillips and Krell, 1988; Morris, Eggleston,
and Crampton, 1989). The eggs of the phytoseiid mite, M. occidentalis are diffi cult to dechlorinate
and dehydrate, and the needle tip needs to be modifi ed (Presnail and Hoy, 1992).
The DNA can be injected into early preblastoderm eggs present within the adult females
TABLE 9.2
Methods for Genetic Transformation of Arthropods
Technique Example References
Microprojectiles Drosohila embryos Baldarelli and Lengyel (1990)
Electroporation Drosophila Kamdar, von Allmen, and Finnerty (1992)
Maternal microinjection Metaseiulus occidentalis Presnail and Hoy (1992)
Microinjection of eggs Miller et al. (1987), McGrane et al. (1988),
Morris, Eggleston, and Crampton (1989)
Soaking dechlorinated eggs
in DNA
Drosophila Walker (1989)
Sperm as vectors of DNA Lucilia cuprina and Apis mellifera L. Atkinson et al. (1991), Milne, Phillips,
DNA bound externally
and Krell (1988)
Transformation of cultured cells Aedes albopictus (Skuse) Fallon (1991)
Transplant nuclei and cells Drosophila Zalokar (1981)