English

Marcos Doniseti Michelotto,Everton Luis Finoto,Antonio Carlos Busoli,José Fernando Jurca Grigolli,Willians Cesar Carrega,Jacob Crosariol Netto,Juliana Altafin Galli

doi:10.14393/bj-v31n5a2015-26433

English

Marcos Doniseti Michelotto, Everton Luis Finoto + Show 5 more

Open Access

https://doi.org/10.14393/bj-v31n5a2015-26433

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Abstract

The cotton leafworm, Alabama argillacea (Hubner, 1818) (Lepidoptera: Noctuidae) is a major defoliating pest that reduces yield and quality of the crop. The purpose of this study was to evaluate the effect of different levels of defoliation caused by different larval densities of A. argillacea on four cotton cultivars in three different plant ages. The experiment was conducted at an experimental station of the Agencia Paulista de Tecnologia dos Agronegocios (APTA), Polo Centro Norte, in Pindorama, SP, Brazil. The experiment was arranged in a factorial randomized block design with 4 replicates: four cultivars (DeltaOPAL, IAC-25, Fibermax 996 and Fibermax 993) x four larval densities (0, 2, 4, and 6 larvae per plant) x three infestation times (30, 60 and 90 days after plant emergence). Fortnightly evaluations carried out based on the production of squares, flowers, fruits and bolls per plant. It was found that the higher infestation level of A. argillacea , the lower was the production of buds per plant and consequently the production of fruits and bolls of the four varieties. Early infestation (30 and 60 DAE) reduced the production of reproductive structures per plant in cultivars more than late infestation (90 DAE).

Highlights

Cotton (Gossypium hirsutum L.), originally a tropical plant, is a high valuated agricultural commodity for more than 8,000 years, and has long been recognized as a vital component of the global economy (ARPAT et al, 2004)
It is important to know the productivity of cultivars when exposed to stressful effects caused by pests, mainly of defoliating species such as the cotton leafworm, Alabama argillacea (HÜBNER, 1818) (Lepidoptera: Noctuidae), which has recently infested the crop in early stages
With regard to the effect of larval infestation on the number of flower buds, it was found that 45, 60 and 70 Days after emergence (DAE), the number of buds was inversely proportional to the number of larvae per plant; the non-infested plants had six flower buds per plant, while plants infested with six A. argillacea larvae had up to three buds per plant (Table 1)

Summary

Introduction

Cotton (Gossypium hirsutum L.), originally a tropical plant, is a high valuated agricultural commodity for more than 8,000 years, and has long been recognized as a vital component of the global economy (ARPAT et al, 2004). It is cultivated economically in subtropical regions and is used for fiber production in over 100 countries (HEDGE et al, 2011). The production and yield of cotton are directly related to the efficiency of pest and disease control. The larvae feed on leaves and, depending on the development stage and population density, as well as on the time of occurrence, can defoliate the cotton plants completely, significantly reducing the yield (GRAVENA; CUNHA., 1991, JÁCOME et al, 2001, QUIRINO; SOARES ,2001)

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