**9. Biotechnology in IPM**

are collectively referred to as semiochemicals. Generally, semiochemicals is subdivided into two distinct groups including pheromones and allelochemicals (Table 12). The term phero‐ mone is used to describe compounds that operate intraspecifically, while allelochemical is the general term for an interspecific effector [26]. However, the realization that behaviors critical to insect survival were strongly influenced by semiochemicals rapidly led to propos‐

Pheromones *<sup>a</sup>* Sex ph. A volatile chemical substance produced by one sex of an insect which

aggregate or congregate.

individuals in a colony. Allelochemicals *<sup>b</sup>* Allomone A substance produced by a living organism that evokes in receiver a

both sender and receiver.

in the area.

sender.

receiver.

produces some specific reaction in the opposite sex.

Aggregation ph. Also known as arrestants. These are chemicals that cause insects to

Alarm ph. A substance produced by an insect to repel and disperse other insects

followed by another member of the same species.

oviposition to distinguish unparasitized from parasitized hosts.

behavioral or physiological reaction that is adaptively favorable to the

behavioral or physiological reaction that is adaptively favorable to the

behavioral or physiological reaction that is adaptively favorable to

behavioral or physiological reaction that activates a repellent response

to the sender and is unfavorable to both sender and receiver.

or physiological reaction that is adaptively favorable to a receiving organism but detrimental to an organism of another species that may

Trail ph. A substance laid down in the form of a trail by one insect and

Host-marking ph. A substance placed inside/outside of the host body at the time of

Caste-regulating ph. A substance used by social insects to control the development of

Kairomone A substance produced by a living organism that evokes in receiver a

Synomone A substance produced by an organism that evokes in the receiver a

Antimone A substance produced by an organism that evokes in the receiver a

Apneumone A substance emitted by a nonliving material that evokes a behavioral

be found in or on the nonliving material.

als for using these agents as practical tools for pest suppression [180].

Semiochemicals

260 Soybean - Pest Resistance

a

classified according to function

b classified according to the advantage to receiver or sender

**Table 12.** Classification of behavior-modifying chemicals (semiochemicals)

Recent advantage in biotechnology, particularly cellular and molecular biology have opened new avenues for developing resistant cultivars. From this diagnostic perspective, molecular techniques are likely to play an important role in identification, quantification and genetic monitoring of pest populations [183]. The diagnostic information is a necessary prerequisite for implementing rational control strategy. Appropriate molecular techniques can be em‐ ployed to study the species composition of the pest population and to identify strains, races or biotypes of the same species.

Another important application of molecular diagnostic techniques is for monitoring both the presence and frequency of genes of particular interest. For example, genes for resist‐ ance to a specific class of pesticides and their frequency in particular region can be as‐ sessed. Such information is very useful for designing and implementing rational pest management strategies [159].

The most important application of biotechnology in IPM is the introduction of novel genes for resistance into crop cultivars through genetic engineering. HPR is a highly effective man‐ agement option, but cultivated germplasm has only low to moderate resistance levels to some key pests. Furthermore, some sources of resistance have poor agronomic characteris‐ tics. On the other hand, development of cultivars with enhanced resistance will strengthen the control of *H. armigera* in different cropping systems. Therefore, we need to make a con‐ certed effort to transfer pest resistance into genotypes with desirable agronomic and grain characteristics. Recent achievements of genetics and molecular biology have been widely implemented into breeding new crop cultivars and brought in many various traits absent from parent species and cultivars. Furthermore, new progress in biotechnology makes it fea‐ sible to transfer genes from totally unrelated organisms, breaking species barriers not possi‐ ble by conventional genetic enhancement. Today, transgenic plants expressing insecticidal proteins from the bacterium *B. thuringiensis*, are revolutionizing agriculture. *Bacillus thurin‐ giensis* has become a major insecticide because genes that produce *B. thuringiensis* toxins have been engineered into major crops grown on 11.4 million ha worldwide (including soy‐ bean, cotton, peanut, tomato, tobacco, corn and canola). These crops have shown positive economic benefits to growers and reduced the use of other insecticides. Genetically engi‐ neered cottons expressing delta-endotoxin genes from *B. thuringiensis* offer great potential to dramatically reduce pesticide dependence for control of *Helicoverpa* spp. and consequently offer real opportunities as a component of sustainable and environmentally acceptable IPM systems [16]. Certainly, for sustainable management of *H. armigera* in soybean cropping sys‐ tems, such soybean resistant cultivars could play pivotal role. Therefore, to achieve this goal, much works should be conducted in breeding new soybean cultivars expressing *Bt* toxins against *H. armigera*.

interactions among the three or four trophic levels (Figure 6) that characterize most natural systems and agroecosystems has been increased rapidly during the last two decades [26].

Integrated Management of *Helicoverpa armigera* in Soybean Cropping Systems

http://dx.doi.org/10.5772/54522

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**Figure 6.** Simple diagram of multitrophic interactions representing some important causal relationships among the

It is interesting that many traditional cultural practices exert their effects through complex multitrophic interactions, but it is exactly this complexity that makes such systems difficult to assess experimentally or validate conclusively across a broad range of environments. For example, it has been demonstrated that toxic secondary compounds in an herbivore diet may affect development, survivorship, morphology and size of its natural enemies. This ef‐ fect of poor-quality plants can thus indirectly lead to poor-quality natural enemies [186].

As knowledge of interactions across multitrophic systems both in nature and in agroecosys‐ tems expands, researchers and pest management practitioners are beginning to find ways of manipulating interactions across different trophic levels in order to develop more sustaina‐ ble approaches to pest management. Accordingly, population ecologists are actively debat‐ ing the relative importance of bottom-up (resource-driven) and top-down (natural enemydriven) processes in the regulation of herbivores populations [22, 187, 188]. However, there are a number of key areas where manipulation of host plant-pest-natural enemy interactions could provide substantial benefits in pest management systems (manipulation of host plant quality, allelochemicals and crop diversification and genetic manipulation of insect) [26].

For many years, there was a widely held view that HPR should be seen as an integral com‐ ponent of IPM programmes, but it has been demonstrated that HPR is by no means always

trophic levels mediated by some important insect fitness parameters

The potential ecological and human health consequences of *Bt* crops, including effects on nontarget organisms, food safety, and the development of resistant insect populations, are being compared for *Bt* plants and alternative insect management strategies. However, *Bt* plants were deployed with the expectation that the risks would be lower than current or al‐ ternative technologies and that the benefits would be greater. Based on the data to date, these expectations seem valid [16]. The major challenge to sustainable use of transgenic *Bt* crops is the risk that target pests may evolve resistance to the *B. thuringiensis* toxins. *Helico‐ verpa armigera* is a particular resistance risk having consistently developed resistance to syn‐ thetic pesticides in the past [21]. For this reason a pre-emptive resistance management strategy was implemented to accompany the commercial release of transgenic cultivars. The strategy, based on the use of structured refuges to maintain susceptible individuals in the population, seeks to take advantage of the polyphagy and local mobility of *H. armigera* to achieve resistance management by utilizing gene flow to counter selection in transgenic crops. However, refuge crops cannot be treated with Bt sprays, and must be in close proxim‐ ity to the transgenic crops (within 2 km) to maximize the chance of random mating among sub-populations [184].
