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Biological control
Biological control is an important tool for keeping H. Armigera under control. Natural enemies, like parasitoids, predators and
ontomopathogens, are relevant components in integrated cotton pest management. “Among the available biological agents for
keepingunder control theworms of the subfamilyHeliothinae there is theparasitoidTrichogrammapretiosumRiley (Hymenoptera:
Trichogrammatidae) and the predator Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae)”, explains researcher Carlos Alber-
to Domingues da Silva. The technologies for mass production of these agents are available to cotton farmers at Embrapa Cotton.
O
n account of its voracity and
amount of damage, the cot-
ton bollworm (H. armigera)
has climbed to the position
as second most severe cot-
ton pest in Brazil. With a high destructive
power, its presence in the cotton fields
leaves the farmers jittery. The first re-
ports on its outbreaks in the Country go
back to 2013, in soybean, corn and cot-
ton fields. However, according to Embra-
pa Cotton, there are signs of its presence
in the national territory since 2008, when
its population was still small.
Nowadays, Helicoverpa armigera also
infects crops like beans, millet, sorghum,
tomato, red pepper, coffee and citrus,
a fact that was responsible for a bigger
number of sprayings in these activities
– a part of the cultivation system used in
the Cerrado. According to researcher Car-
los Alberto Domingues da Silva, this quar-
entenary, exotic and polyphasic pest has
a high reproductive capacity, develops
fast and adapts to different environments.
Furthermore, it has a big potential to de-
velop resistance to insecticides.
“In the world, the damages caused by
H. armigera infestations of different crops
are estimated at about US$ 5 billion”, he
says. In Brazil, the most severe infesta-
tions take place in the Cerrado regions of
the States of Bahia, Goiás and Mato Gros-
so, all of them relevant growers of cotton,
corn and soybean. Moreover, their cultiva-
tion systems comprise huge areas, locat-
ed next to one another, with a small num-
ber of vegetable species.
Silva clarifies that, in the cotton fields,
the worms may feed on leaves and twigs,
but theyprefer the reproductive structures,
like flower buttons and bolls. “The flower-
ing period of the cotton plants, about 40
days after planting, exerts attraction and
stimulates the moths, which feed on the
nectar present in the flowers, with an influ-
ence onoviposition”, he explains. Moths lay
eggs at night and they are placed isolatedly
and, preferably, on leaves, flowers, bracts,
flower buttons and fruit.
According to the Mato Grosso Agricul-
tural Surveillance Institute (Indea), the esti-
mated losses caused by H. armigera in the
soybean, corn and cotton fields in the State
amount to upwards of R$ 1 billion, in 2017.
In order to keep the pest under control in
cotton farming, the major control strate-
gies are based on the use of resistant trans-
genic cotton varieties, along with biolog-
ical control consisting of natural parasite
killers, predators and entomopathogens,
besides cultural control through the uni-
formization of the planting time. Other effi-
cient practices consist in soil conservation,
correct fertilization and seeding in linewith
technical recommendations.
Hard
tokill
detectedinBraziliancottonfieldsin2013,
growsfastandadaptstodifferentenvironments
Cotton bollworm,first
Inor Ag. Assmann
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