Contents - Faperta

Genetic Engineering of Natural Enemies for Integrated Pest Management 301
Altering Biological Attributes
Altering longevity of certain arthropods might be benefi cial, and research on mechanisms
of ageing may provide useful genes in the future. A cloned catalase gene inserted into
D. melanogaster by P-element-mediated transformation has been shown to provide resistance
to hydrogen peroxide, although it did not prolong the lifespan of fl ies (Orr and
Sohal, 1992). Shortening developmental rate, enhancing progeny production, altering
sex ratio, extending temperature and relative humidity tolerances, and altering host or
habitat preferences could enhance the effectiveness of biological control agents (Hoy, 1976).
O’Brochta and Atkinson (1998) suggested the use of transgenic insects for the control of
insect-borne diseases by making the insects incapable of transmitting the disease.
Quality Control of Insect Cultures and Mass Production
Maintaining quality in laboratory-reared arthropods is diffi cult due to possible genetic
changes caused by inadvertent selection, inbreeding, genetic drift, and founder effects
(Stouthammer, Luck, and Werren 1992; Hopper, Roush, and Powell, 1993). Biotechnological
approaches can be used for mass production and quality control of Trichogramma spp.
(de Almeida, da Silva, and de Medeiros, 1998). If high-quality and inexpensive artifi cial
diets for predators and parasitoids are available, biological control programs would no
longer be restricted by ineffi cient mass production methods. Beckendorf and Hoy (1985)
suggested that recombinant DNA techniques could make arthropod natural enemies more
effi cient and less expensive. Once a gene has been cloned, it can be inserted into a number
of benefi cial species. One of the signifi cant benefi ts of recombinant DNA techniques may
be that it will be easier to maintain quality in transgenic arthropods. The ability to manipulate
and insert genetic material into the genome of Drosophila has been used to develop a
fundamental understanding of genetics, biochemical interactions, development, and behavior
of insects (Lawrence, 1992). Genetic engineering of arthropods other than Drosophila
has been attempted, but with limited success (Walker, 1989; Handler and O’Brochta, 1991;
Hoy, 1994; Kramer, 2004).
Adaptation to Extreme Environmental Conditions
Increased tolerance to cold in frost-susceptible arthropods or tolerance to heat and dry
conditions, for example, in Trichogramma species, can be achieved by genetic transformation
(Figure 9.1). Antifreeze protein genes cloned from the wolf-fi sh, Anarhichas lupus (L.)
have been expressed in transgenic Drosophila (Rancourt et al., 1990; Rancourt, Davies, and
Walker, 1992), using the hsp70 promoter and yolk polypeptide promoters of Drosophila.
Although additional work is required, the results suggest that subtropical or tropical species
of arthropod natural enemies could become adapted to a much broader range of climates.
Improving Resistance to Insecticides
Several insect parasitoids can be improved for resistance to insecticides for use in integrated
pest management (Figures 9.2 and 9.3). Potentially useful resistance genes that have
been cloned include parathion hydrolase gene (opd) from Pseudomonas diminuta Leifson
and Hugh and Flavobacterium, cyclodiene resistance gene (g-aminobutryic acid A, GABA A)
from Drosophila, b-tubulin genes from Neurospora crassa (Draft) and Septoria nodorum (Berk.)
that confer resistance to benomyl, acetylcholinesterase gene (Ace) from D. melanogaster and