*2.3.1.3. Seed treatment*

Due to the nocturnal habit of the pest and the difficulty of being hit directly by pesticides, seed treatment with systemic insecticides can be very effective to control this pest. This practice has shown to be even more efficient in areas with history of high occurrence and recurrence.

#### *2.3.1.4. Chemical control*

As an emergency control, chlorpyrifos can be used in spraying, preferably in the early evening.

#### *2.3.1.5. Biotechnology*

The use of genetically modified seeds with insecticidal proteins can be a tool to control this pest but is more effective to control small caterpillars [8].

#### **2.4. Cornstalk borer (***Elasmopalpus lignosellus***)**

It is very difficult to manage cornstalk borer in sandy soils (well drained) and under cerrado vegetation (savannah) (especially in the first year of cultivation) in dry periods with high temperatures, in particular in the first 30 days after emergence. Just as the black cutworm, the cornstalk borer causes damage also known as "dead heart" and causes significant losses in the stand.

The moth of nocturnal habits has a 1.5- to 2.5-cm wingspan and has gray-yellowish wings. It lays eggs preferably in the base of plants or in the soil, which are initially clear, but with the approach of the hatching become dark red. The caterpillar has blue-green color, with brown, purple, or dark brown transverse stripes, and measures about 1.5 cm [8].

It is a sporadic pest, however, polyphagous; it feeds from diverse crops (such as soybeans, maize, and cotton), with great capacity for destruction in a short period of time, especially between VE and V3 stages. After hatching, the caterpillar scrapes the plant leaves and starts its penetration in the stem remaining in this location during the day. It builds a shelter with web and dirt, which is attached to the gallery's opening also made by it, where droppings are being accumulated. Its damages are associated with drought after plant emergence, and the greatest damages are observed in conventionally tilled fields, with light, well-drained soil, and lower damages in sites with tillage and irrigation.

In maize, it feeds inside the stem and goes upward toward the growing point of the plant (apical bud), eventually damaging it, causing reduction in size or even death of the youngest leaves, a symptom known as "dead heart." In certain situations, the attack symptoms of cornstalk borer do not necessarily cause the dead heart but shoots at the base of the plant and present symptoms very similar to the attack of green belly stink bug (*Dichelops* spp.).

In soybeans and cotton, cornstalk borer feeds on the stem and branches of seedlings, causing wilting, drying, tipping, and even death. In larger plants, the pest opens galleries inside the stem. The damage is greater when the attack occurs early in the development of culture, when the young plants are eaten and have less ability to recover. During the larval stage, the insects are highly mobile and can migrate from dead plants to live ones and can cause major damage and even failure in planting lines. They also cause drying and death of plants, necessitating replanting [8].

#### *2.4.1. Methods of control*

*2.3.1.3. Seed treatment*

64 Insecticides Resistance

*2.3.1.4. Chemical control*

*2.3.1.5. Biotechnology*

stand.

Due to the nocturnal habit of the pest and the difficulty of being hit directly by pesticides, seed treatment with systemic insecticides can be very effective to control this pest. This practice has shown to be even more efficient in areas with history of high occurrence and recurrence.

As an emergency control, chlorpyrifos can be used in spraying, preferably in the early evening.

The use of genetically modified seeds with insecticidal proteins can be a tool to control this

It is very difficult to manage cornstalk borer in sandy soils (well drained) and under cerrado vegetation (savannah) (especially in the first year of cultivation) in dry periods with high temperatures, in particular in the first 30 days after emergence. Just as the black cutworm, the cornstalk borer causes damage also known as "dead heart" and causes significant losses in the

The moth of nocturnal habits has a 1.5- to 2.5-cm wingspan and has gray-yellowish wings. It lays eggs preferably in the base of plants or in the soil, which are initially clear, but with the approach of the hatching become dark red. The caterpillar has blue-green color, with brown,

It is a sporadic pest, however, polyphagous; it feeds from diverse crops (such as soybeans, maize, and cotton), with great capacity for destruction in a short period of time, especially between VE and V3 stages. After hatching, the caterpillar scrapes the plant leaves and starts its penetration in the stem remaining in this location during the day. It builds a shelter with web and dirt, which is attached to the gallery's opening also made by it, where droppings are being accumulated. Its damages are associated with drought after plant emergence, and the greatest damages are observed in conventionally tilled fields, with light, well-drained soil, and

In maize, it feeds inside the stem and goes upward toward the growing point of the plant (apical bud), eventually damaging it, causing reduction in size or even death of the youngest leaves, a symptom known as "dead heart." In certain situations, the attack symptoms of cornstalk borer do not necessarily cause the dead heart but shoots at the base of the plant and

In soybeans and cotton, cornstalk borer feeds on the stem and branches of seedlings, causing wilting, drying, tipping, and even death. In larger plants, the pest opens galleries inside the stem. The damage is greater when the attack occurs early in the development of culture, when the young plants are eaten and have less ability to recover. During the larval stage, the insects

present symptoms very similar to the attack of green belly stink bug (*Dichelops* spp.).

purple, or dark brown transverse stripes, and measures about 1.5 cm [8].

pest but is more effective to control small caterpillars [8].

**2.4. Cornstalk borer (***Elasmopalpus lignosellus***)**

lower damages in sites with tillage and irrigation.

### *2.4.1.1. Chemical control*

Can be accomplished by seed treatment with systemic insecticides. Insecticides applied soon after the appearing of the pest have not shown satisfactory results, making the best option the preventive control.

#### *2.4.1.2. Cultural control*

In regions with high incidence of pest, increased seed density per area may be an alternative. Maintaining humidity also contributes to the decrease of the attack of this pest [8].

#### **2.5. Corn earworm (***H. zea***) and (***H. armigera***)**

Due to the moth habit of depositing eggs on the plant stigma and the caterpillar developing inside the ear, *H. zea* is called corn earworm.

It has pronounced larval movement in different crops and is aggressive when touched, adopting a defensive posture. The pupal development occurs in the soil and can occur optional diapause depending on weather conditions.

*H. armigera* has a higher attack spectrum than *H. zea*. In addition to maize, cotton, soybean, and tomato crops, the preferred targets of *H. zea*, it also attacks beans and sorghum, which causes damages to vegetative and reproductive structures.

Caterpillars of *Helicoverpa* spp. perform predation of other species of caterpillars and also on the same species (cannibalism) [8].

They have a high fertility rate and can occur up to 11 generations of the pest, with night oviposition preferably and capacity of laying 2,200–3,000 eggs on host plants, but with no predilection for specific parts of the plant [8].

For this reason, it feeds inordinately of all plant structures at an early stage, with preference for the reproductive structures in final stages of development [8].

#### *2.5.1. Methods of control*

One of the key points for success in controlling *H. armigera* and *H. zea* is to correctly identify the pest in the field, mainly due to its similarity to *Heliothis virescens*, the tobacco budworm.

It presents different behavior in relation to this pest, with aggression and resistance to insecticides based on synthetic pyrethroid characteristics [11], the joint use of agricultural practices and the integrated management of pests in a correct manner are essential.

#### *2.5.2. Integrated pest management*

The use of integrated agronomic systems, combining knowledge of the target pest, the constant monitoring of the crops that are in the system, and the adoption of practices that aimed cultural control and biological maintenance, combined with the use of biotechnologies to fight pest, are suitable forms of maintenance and control of *Helicoverpa* spp.

#### *2.5.3. Chemical control*

The use of insecticides from the chemical group diamides has shown satisfactory control in the fight against the pest.

#### *2.5.4. Adoption of Bt maize is occurring rapidly*

With only 6 years of the release of its cultivation by CTNBio, over 70% of the Brazilian maize crops were coming from transgenic crops, and it is projected to increase to 81%, which represents the cultivation area with intensive use of technology [12].

#### **2.6. Corn rootworm (***Diabrotica speciosa***)**

Among the six species of *Diabrotica* occurring in the tropics, *Diabrotica speciosa* is distinguished by economic importance to maize crops. This species is a polyphagous pest widely distributed in Brazilian states and in some countries in South America. The adults damage the shoots of various crops such as horticultural crops (solanaceous, cucurbits, crucifers plants), beans, soybeans, sunflower, and maize, causing defoliation and in some cases are vectors of patho‐ gens. When adults feed, it transmits numerous viruses to plants. The viruses are easily transmitted mechanically and produce highly antigenic responses. The transmission of the virus from one insect to another is associated with the contact to the regurgitated material, defecated or through contaminated hemolymph. In the order Coleoptera, species of *Ceroto‐ ma* and *Diabrotica* genres are the most important vectors of viruses in the Americas. The larva has been considered one of the most important underground pests of crops such as maize, wheat, other cereals, and potato. The economical loss caused by the larva for these crops has been significant in the southern states and in some areas of the Southeast and Midwest. In the South, areas where soils are usually rich in organic matter and retain higher humidity favors the biology of larvae. In irrigated areas of the Southeast and Midwest, where several host crops are grown in succession, the damage has been representative. The larvae feed on the roots, reducing the plant's ability to absorb water and nutrients, making them less productive and subject to lodging, causing losses when harvesting is performed mechanically. For the maize crop, losses have been reported in the yield varying between 10% and 13% due to the attack, when high infestation of this pest occurs [13].

The adults are greenish color presenting three yellow spots on each shard, black tibia and tarsus and brown head, being called "patriot." They measure about 6 mm in length. Males are smaller than females. Adult longevity, the pace of oviposition and fertility depend on the type of food they feed on in the larval and adult stages.

The longevity may vary from 41.8 to 55.5 days for the males and from 51.6 to 58.5 days for the females. The oviposition is held in the soil around the plants. The eggs are yellow and measure 0.5 mm in diameter. The incubation period ranges from 6 to 8 days. The larva phase goes through three instars, and the larvae reaches 10 mm long, with whitish coloring, brown head, and a chitinized dark plate in the last abdominal segment. The average larval period is 18 days. The prepupa average period is 5 days and pupal period is 7 days. The life cycle varies from 24 to 40 days. The temperature is a climate factor that affects the rate of development of the immature stages as well as the longevity of adults and reproduction [13].

#### *2.6.1. Methods of control*

*2.5.2. Integrated pest management*

*2.5.3. Chemical control*

66 Insecticides Resistance

the fight against the pest.

*2.5.4. Adoption of Bt maize is occurring rapidly*

**2.6. Corn rootworm (***Diabrotica speciosa***)**

when high infestation of this pest occurs [13].

of food they feed on in the larval and adult stages.

The use of integrated agronomic systems, combining knowledge of the target pest, the constant monitoring of the crops that are in the system, and the adoption of practices that aimed cultural control and biological maintenance, combined with the use of biotechnologies to fight pest,

The use of insecticides from the chemical group diamides has shown satisfactory control in

With only 6 years of the release of its cultivation by CTNBio, over 70% of the Brazilian maize crops were coming from transgenic crops, and it is projected to increase to 81%, which

Among the six species of *Diabrotica* occurring in the tropics, *Diabrotica speciosa* is distinguished by economic importance to maize crops. This species is a polyphagous pest widely distributed in Brazilian states and in some countries in South America. The adults damage the shoots of various crops such as horticultural crops (solanaceous, cucurbits, crucifers plants), beans, soybeans, sunflower, and maize, causing defoliation and in some cases are vectors of patho‐ gens. When adults feed, it transmits numerous viruses to plants. The viruses are easily transmitted mechanically and produce highly antigenic responses. The transmission of the virus from one insect to another is associated with the contact to the regurgitated material, defecated or through contaminated hemolymph. In the order Coleoptera, species of *Ceroto‐ ma* and *Diabrotica* genres are the most important vectors of viruses in the Americas. The larva has been considered one of the most important underground pests of crops such as maize, wheat, other cereals, and potato. The economical loss caused by the larva for these crops has been significant in the southern states and in some areas of the Southeast and Midwest. In the South, areas where soils are usually rich in organic matter and retain higher humidity favors the biology of larvae. In irrigated areas of the Southeast and Midwest, where several host crops are grown in succession, the damage has been representative. The larvae feed on the roots, reducing the plant's ability to absorb water and nutrients, making them less productive and subject to lodging, causing losses when harvesting is performed mechanically. For the maize crop, losses have been reported in the yield varying between 10% and 13% due to the attack,

The adults are greenish color presenting three yellow spots on each shard, black tibia and tarsus and brown head, being called "patriot." They measure about 6 mm in length. Males are smaller than females. Adult longevity, the pace of oviposition and fertility depend on the type

are suitable forms of maintenance and control of *Helicoverpa* spp.

represents the cultivation area with intensive use of technology [12].

Chemical control has been the most widely used method for controlling various species of *Diabrotica*. In Brazil, research works about the control of *D. speciosa* larvae attacking maize crop are scarce, complicating the recommendation of insecticides and the application method to control this pest, while in other countries, information about the control of other species of the genus is abundant.

The persistence of insecticides has been considered an important factor in the control of *Diabrotica* larvae. Ideally, the pesticide persists in the soil for 6 to 10 weeks, providing protec‐ tion to the plant in the most susceptible period to pest [14]. As a result, treatment of seeds with insecticides has shown problems in the control of the larvae. The use of granular insecticides or spraying in the planting groove is effective alternatives to control the larvae [13].

Biological control is a promising tactic for managing this pest. Several natural enemies are described attacking adults and larvae of *D. speciosa*. The ones with most frequent occurrence are *Celatoria bosqi* (Dip., Tachinidae), *Centistes gasseni* (Hym., Braconidae), fungi *Beauveria bassiana*, *Metarhizium anisopliae*, and *Paecilomyces lilacinus*. The control of larvae, especially with fungi, has great potential to be implemented in field conditions. As a strategy for the use of cultural control, it is important to consider that soil moisture and preparation method can affect the population of larvae. Adults have a clear preference for oviposition in darker soils with higher organic matter levels and moisture [13].
