**5. Final considerations**

Global prospection strategies achieved particular prominence with the use of new technologies of DNA sequencing to characterize transcriptoma (RNA-seq). With RNA-seq strategies, it is possible to generate billion bases of information in single runs (at a much lower cost than Sanger sequencing), which allows access to regulatory genes, represented by one or a few

Although the global strategies of gene prospecting are potentially unlimited, the success of identifying real candidates depends on the development of an efficient experimental design. On the work of Li et al. [37], the defense mechanisms of two soybean varieties, that is, resistant and susceptible to an aphid, were studied using microarrangements of cDNA, and the collection period after an infection determined by the time necessary to the insect reaches the xylem vessel elements in the plant, about 8 hours in the resistant cultivar and 3.5 hours in the

The large-scale study of metabolites produced by plants in the presence of insect pests also consists in an innovative possibility of seeking alternatives for its control and the identification of genes or important metabolic pathways. In soybean leaves [42], it was observed that constitutively leave extracts of PI 227687 contain the isoflavonoid genistein and seven flavonol glycosides, including rutin [43], by studying the leaf extract resistant to insect genotypes PI 274454, "IAC-100," and PI 229358, which identified and quantified the flavonol rutin and the

Their identification and their role in the interactions of insects with soybean plants can guide geneticists in order to keep them in descendant generations as part of the defense armory of plants against herbivores. To study if the insect resistance of genotypes PI 227687, PI 274454, and "IAC 100" is due to chemicals present in their constitution, they used extracts of these genotypes mixed to artificial diet. By the results obtained, Piubelli et al. [43, 44] found that those strata negatively affect the biology of *Anticarsia gemmatalis*. Additionally, studies have

In general, although the *Bt* strategy to control lepidopteran still is the world's most important in controlling pests, new sources of resistance may operate independently or may also be added to the *Bt* strategy so as to promote their own maintenance of *Bt* resistance in commer‐

Molecular biology tools have supplemented the information generated by morphological and behavior studies, contributing to the elucidation of issues in the fields of taxonomy, ecology, pests population genetics, parasitoids, predators, and entomopathogenic bacteria. Its resolving power has allowed increased knowledge on the occurrence of cryptic species, differentiation of insect races, and separation of microorganisms species indistinguishable by morphological characters. These tools also have wide application in genetic studies of resistance to insecticides and toxins and in the determination of genes associated with these phenomena. On the other hand, they have facilitated the breeding works to plant resistance to insects, as well as the transformation of the beneficial organisms to increase pest control potential. Considering its potential and reducing reagent costs and simplifying processes, we expect a growing appli‐

shown that the flavonol rutin causes antibiosis in *Trichoplusia ni* (Hübner) [45, 46].

cation in basic and applied fields of entomology and its related areas.

mRNAs [40] and covering full-length cDNAs [41].

susceptible cultivar.

76 Insecticides Resistance

isoflavonoid genistein.

cialized transgenic plants.

The first challenge will be to develop innovative formulas of the application of integrated pest management concepts that are adequate with the new and dynamic field reality, including the prevalence of tropical regions for soybean cultivation, its integration into more complex production systems and large overlap of common pests to different crops in the same system, and the great extension of crops. Framing this set is a phenomenon that has grown in impor‐ tance over the past decade, greatly worrying farmers, which is the lack of manpower available for the labors on the field.

Developing biological control technologies that are technically feasible and economically competitive will also be a challenge, given the diversity of the production system pests and the impact that other forms of control, especially insecticides and fungicides, will have on biological control agents.

The emergence of *Bt* crops is an important step between the tactics available for pest control in various crops such as maize, canola, cotton, and, in the near future, soybeans. In addition to controlling some important species of Lepidoptera, a positive externality of the use of *Bt* crops will be the preservation of insects that act as predators or parasitoids of pests due to less use of insecticides to control caterpillars, nonselective to these biological control agents. However, there is the ever present risk of emergence of Lepidoptera populations insensitive to the toxin produced by *Bt* crops due to nonuse of refuge by farmers. The events are similar for different crops with *Bt* cultivars or varieties, and some pests attack more than one crop for which there are *Bt* events, increasing the risk of emergence of insensitive populations.
