**5. The push-pull strategy**

Attract-and-kill systems are more powerful than other semiochemical mediated control strategies such as mating disruption in that male moths are incapacitated and removed from the ecosystem. Yet, this approach has the obvious advantage of limiting any potential nega‐ tive ecological effects of the insecticide, as only those insects coming to the lure will be af‐ fected. These systems has been successfully used against several pests, including the boll weevil*, Anthonomus grandis*; codling moth, *C. pomonella* (Charmillot *et al.* 2000) and apple maggot, *Rhagoletis pomonella* (Bostanian & Racette 2001), oriental fruit moth, *G. molesta*

In fruit production, the fruit flies control is based on the use of insecticides in total cov‐ erage or in the form of toxic lure. The toxic lure is based on the use of food bait associ‐ ated with an insecticide. In this attract-and-kill system, the insects are killed when in contact or ingest the insecticide. Spinosad baits containing spinosad in different concen‐ trations, water, sugar and attractants were effective in controlling the fruit fly, *Ceratitis capitata* and *Anastrepha fraterculus* (Raga & Sato 2005). The formulation SPLAT ®, afore mentioned at mating disruption, is also used in attract-and-kill system, since its formula‐ tion consisting of waxes and oils and allows the inclusion of a wide range of insecti‐ cides and attractants with potential to control several species of fruit flies. SPLAT® system has been evaluated as a strategy to attract-and-kill for fruit flies *Bactrocera dorsa‐ lis* and *Bactrocera cucurbitae* in the United States with promising results (Vargas *et al.* 2008, Vargas *et al.* 2009). There are some reports in the literature of a SPLAT® formula‐ tion containing spinosad 0.10%, which provided control of *C. capitata* adult, even after submitted to simulated rainfall, and showed a smaller effect on the parasitoid *Diachasmi‐*

Although this method presents the advantage of causing less impact on non-target organ‐ isms, some restrictions are observed, for example, the low persistence of toxic lures after rainfall events, as can be seen in the example cited above. These barriers are being solved

Mating disruption and attract-and-kill are similar technologies that have been used to control a wide range of insect pests, typically species in Lepidoptera, Coleoptera, and Diptera (El-Sayed *et al.* 2006). These two technologies may be able to contribute to the eradication of new incursions of invasive species, because like other inversely densitydependent approaches, they have the greatest probability of success against pests at very low density, which is initially the case after an incursion. Making clear the differ‐ ence between these control systems, the mating disruption relies on the principle of pre‐ venting pheromone communication between sexes, but the insects remain alive in this area during the disruption, whereas in attract-and-kill systems they are removed from the population. Besides, attract-and-kill systems for field control typically use insecti‐ cides, while in disruption, insecticides may be used but they are not the primary ap‐

*morpha longicaudata* compared with other toxic baits (Zanardi 2011).

with the advancement of research on this technology.

proach of the system.

(Evenden & Mclaughlin 2004), among others.

184 Insecticides - Development of Safer and More Effective Technologies

Insects control methods exploiting natural chemical messengers, collectively known as semiochemicals, are becoming increasingly familiar. Semiochemicals are substances that, in their natural context, carry information or chemical cues for a given interaction between organisms, triggering a behavior or a physiological response in the receiving individual. They are subdivided into allelochemicals, related to interspecific communications, and pheromones, in intraspecific communications (Vilela & Della Lucia 2001). One major developments now set to revolutionize the use of semiochemicals is the realization that semiochemicals should not be used alone, but be combined with population-reducing agents such as highly selective pesticides or biological control agents.

Thus, it is rare for a single semiochemical to be very effective when used alone. Instead, the usual approach is a 'push-pull' strategy, also called stimulo-deterrent diversion— which involves 'pushing' the insects away from the harvestable, economic crops, and 'pulling' them onto a trap crop where their population is reduced by a biological control agent or highly specific but slow-acting insecticide (Foster & Harris 1997). Therefore, antifeedants, non-host volatiles, compounds associated with plant defense, visual cues, synthetic repellents, alarm pheromones and oviposition deterrents can be used to achieve the 'push', while the sex pheromone, host volatiles, visual, gustatory and oviposition stimulants can be used to 'pull' the insects onto the trap crop (Figure 3).

**Figure 3.** Push-Pull strategies, "pull" and "push" tools and the agents used to reduce pest population.

The olfactory, visual and mechanical stimuli are used by insects to locate and select their hosts. The ones acting at long distance are visual, synthetic repellents, host and non-host plant volatiles, anti-aggregation and alarm pheromones. At short distance, they are called anti-food, oviposition inhibitor and pheromone inhibitor. This technique has been used for a small number of insect pests and needs to be further investigated.

the other hand produce repellent volatile chemicals that push away the stemborer moths. *Desmodium sp.* also controls *S. hermonthica* trough an allelopathic effect of the root exudates, produced independently of the presence of the weed, being responsible for a dramatic weed

The Use of Behavioral Manipulation Techniques on Synthetic Insecticides Optimization

http://dx.doi.org/10.5772/53354

187

Besides this, the push-pull strategy has been studied for controlling several pests, as for example, *Helicoverpa sp.* in cotton, the Colorado potato beetle in potatoes, *Sitona lineatus* in beans, the pollen beetle in oilseed rape, onion maggot on onions, thrips on chrysanthemums, in forestry as the bark beetles on conifers, for veterinary and medical pests as muscid flies,

According to Cook *et al.* (2007) the stimuli used to achieve the push-pull strategy general‐ ly act by nontoxic mechanisms, thus, integration with population-reducing methods, such insecticides, is also usually needed when the strategies are targeted at pests. The pushpull strategy can be used to displace pests from resources or commodities that are to be protected, and simultaneously lure the pest to an attractant source coupled with an insec‐ ticide. In addition, push-pull strategies are beginning to be seriously considered as plausi‐ ble pest control solutions that help to manage insecticide resistance threats. One study assessing the effects of push-pull strategy with trap crops, neem and Nuclear Ployhedro‐ sis Virus (NPV) in *Helicoverpa armigera* insecticide resistance on cotton, reported that the push-pull strategy was highly effective in reducing the incidence of *H. armigera* and dam‐

The benefits of a push-pull strategy include a lower requirement for broad spectrum pesticides, saving these valuable materials for a 'fire fighting' role. In addition, there is less risk of producing populations of resistant insects. Because the push-pull components are not indi‐ vidually greatly effective, they do not select for resistance as strongly as conventional toxicant

The knowledge of life history traits of the target insect pest is particularly important to determine if this technique can be used. The behavior of the insect in the search of partners or food should be studied to maximize the chances of success in using this strategy. The mass trapping consists of placing a large number of traps with attractants in a crop in order to capture

The purpose is to reduce the number of individuals of the next generation, removing only males or both insect sexes of the area. As bait, sexual or aggregation pheromones, food attractants or volatile can be used. The density and effectiveness of traps are important factors for the success of population suppression and eradication technique (Steiner 1952).The technique is particularly effective when it aims to control insects with gregarious habits. In

mosquitoes and midges and for controlling urban pests such as cockroaches.

reduction in an intercrop with maize (Khan *et al.* 2002).

**5.2. Push-pull strategy and insecticides**

age (Duraimurugan & Regupathy 2005).

the largest possible number of insects.

insecticides.

**6. Mass trapping**

The term push-pull was first conceived as a strategy for insect pest management (IPM) by Pyke et al. in Australia in 1987. The concept was later formalized and refined by Miller & Cowles, who termed the strategy stimulo-deterrent diversion. Most work on push-pull strategies has targeted pest behavior rather than to the manipulation of beneficial organisms. However, it may act to push the beneficial organisms out of the surrounding area and pull them to where they are required for control.

The Push-pull strategies can bring together several pest management tactics, as behavioral manipulation methods, chemical stimuli, habitat diversification strategies (intercropping and trap cropping), biological control and chemical control. According to Cook *et al.* (2007) the principles of the push-pull strategy are to maximize control efficacy, efficiency, sustainability and output, while minimizing negative environmental effects.

### **5.1. The use of push-pull**

The Push-pull strategy successfully controls pests and weeds. The most successful push-pull strategy, indeed the only example currently used in practice, was developed in Africa for subsistence farmers. In Eastern Africa, push-pull works as a novel cropping system developed by the International Centre of Insect Physiology and Ecology (ICIPE) in collaboration with Rothamsted Research (UK), Kenyan Agricultural Research Institute (KARI) and other national partners for integrated pest, weed and soil management in cereal–livestock-based farming systems (Cook *et al.*2007, Hassanali *et al.* 2008, Khan *et al.* 2008).

Millions of rural people in Eastern Africa depend on maize and sorghum for food security and cash income. Despite this, production of these crops is seriously affected by constraints such as stemborers and the parasitic weed *Striga hermonthica* (Nielsen 2001). The push-pull strategy involves the use of behavior-modifying stimuli to manipulate the distribution and abundance of stemborers and beneficial insects in maize or sorghum crops. It is based on in-depth understanding of chemical ecology, agrobiodiversity, plant-plant and insect-plant interac‐ tions, and involves intercropping a cereal crop with a repellent intercrop such as Molasses grass (*Melinis minutiflora*) and Desmodium (*Desmodium uncinatum*) (push), with an attractive trap plant such as Napier grass (*Pennisetum purpureum*) and Sudan grass (*Sorghum vulgare var. sudanense*) (pull) planted as a border crop around this intercrop.

Mated stemborer females are repelled from the main crop and are simultaneously attracted to the trap crop. Napier grass produces significantly higher levels of attractive volatile com‐ pounds (green leaf volatiles), cues used by stemborer females to locate host plants, than maize or sorghum (Khan *et al.* 2001). However, many of the stemborer larvae, about 80%, do not survive as Napier grass tissues produce sticky sap in response to feeding by the larvae which traps them causing their mortality (Midega *et al.* 2006). Legumes in the Desmodium genus, on the other hand produce repellent volatile chemicals that push away the stemborer moths. *Desmodium sp.* also controls *S. hermonthica* trough an allelopathic effect of the root exudates, produced independently of the presence of the weed, being responsible for a dramatic weed reduction in an intercrop with maize (Khan *et al.* 2002).

Besides this, the push-pull strategy has been studied for controlling several pests, as for example, *Helicoverpa sp.* in cotton, the Colorado potato beetle in potatoes, *Sitona lineatus* in beans, the pollen beetle in oilseed rape, onion maggot on onions, thrips on chrysanthemums, in forestry as the bark beetles on conifers, for veterinary and medical pests as muscid flies, mosquitoes and midges and for controlling urban pests such as cockroaches.

#### **5.2. Push-pull strategy and insecticides**

The olfactory, visual and mechanical stimuli are used by insects to locate and select their hosts. The ones acting at long distance are visual, synthetic repellents, host and non-host plant volatiles, anti-aggregation and alarm pheromones. At short distance, they are called anti-food, oviposition inhibitor and pheromone inhibitor. This technique has been used for a small

The term push-pull was first conceived as a strategy for insect pest management (IPM) by Pyke et al. in Australia in 1987. The concept was later formalized and refined by Miller & Cowles, who termed the strategy stimulo-deterrent diversion. Most work on push-pull strategies has targeted pest behavior rather than to the manipulation of beneficial organisms. However, it may act to push the beneficial organisms out of the surrounding area and pull them to where

The Push-pull strategies can bring together several pest management tactics, as behavioral manipulation methods, chemical stimuli, habitat diversification strategies (intercropping and trap cropping), biological control and chemical control. According to Cook *et al.* (2007) the principles of the push-pull strategy are to maximize control efficacy, efficiency, sustainability

The Push-pull strategy successfully controls pests and weeds. The most successful push-pull strategy, indeed the only example currently used in practice, was developed in Africa for subsistence farmers. In Eastern Africa, push-pull works as a novel cropping system developed by the International Centre of Insect Physiology and Ecology (ICIPE) in collaboration with Rothamsted Research (UK), Kenyan Agricultural Research Institute (KARI) and other national partners for integrated pest, weed and soil management in cereal–livestock-based farming

Millions of rural people in Eastern Africa depend on maize and sorghum for food security and cash income. Despite this, production of these crops is seriously affected by constraints such as stemborers and the parasitic weed *Striga hermonthica* (Nielsen 2001). The push-pull strategy involves the use of behavior-modifying stimuli to manipulate the distribution and abundance of stemborers and beneficial insects in maize or sorghum crops. It is based on in-depth understanding of chemical ecology, agrobiodiversity, plant-plant and insect-plant interac‐ tions, and involves intercropping a cereal crop with a repellent intercrop such as Molasses grass (*Melinis minutiflora*) and Desmodium (*Desmodium uncinatum*) (push), with an attractive trap plant such as Napier grass (*Pennisetum purpureum*) and Sudan grass (*Sorghum vulgare var.*

Mated stemborer females are repelled from the main crop and are simultaneously attracted to the trap crop. Napier grass produces significantly higher levels of attractive volatile com‐ pounds (green leaf volatiles), cues used by stemborer females to locate host plants, than maize or sorghum (Khan *et al.* 2001). However, many of the stemborer larvae, about 80%, do not survive as Napier grass tissues produce sticky sap in response to feeding by the larvae which traps them causing their mortality (Midega *et al.* 2006). Legumes in the Desmodium genus, on

number of insect pests and needs to be further investigated.

186 Insecticides - Development of Safer and More Effective Technologies

and output, while minimizing negative environmental effects.

systems (Cook *et al.*2007, Hassanali *et al.* 2008, Khan *et al.* 2008).

*sudanense*) (pull) planted as a border crop around this intercrop.

they are required for control.

**5.1. The use of push-pull**

According to Cook *et al.* (2007) the stimuli used to achieve the push-pull strategy general‐ ly act by nontoxic mechanisms, thus, integration with population-reducing methods, such insecticides, is also usually needed when the strategies are targeted at pests. The pushpull strategy can be used to displace pests from resources or commodities that are to be protected, and simultaneously lure the pest to an attractant source coupled with an insec‐ ticide. In addition, push-pull strategies are beginning to be seriously considered as plausi‐ ble pest control solutions that help to manage insecticide resistance threats. One study assessing the effects of push-pull strategy with trap crops, neem and Nuclear Ployhedro‐ sis Virus (NPV) in *Helicoverpa armigera* insecticide resistance on cotton, reported that the push-pull strategy was highly effective in reducing the incidence of *H. armigera* and dam‐ age (Duraimurugan & Regupathy 2005).

The benefits of a push-pull strategy include a lower requirement for broad spectrum pesticides, saving these valuable materials for a 'fire fighting' role. In addition, there is less risk of producing populations of resistant insects. Because the push-pull components are not indi‐ vidually greatly effective, they do not select for resistance as strongly as conventional toxicant insecticides.
