Effect of Infestation of &amp;lt;i&amp;gt;Alabama argillacea&amp;lt;/i&amp;gt; (Lepidoptera: Noctuidae) at Different Ages of Cotton Plants in Yield

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

doi:10.4236/ajps.2014.510159

Abstract

The cotton leafworm is an important defoliating pest of cotton in Brazil, and occurs in all regions where the crop is cultivated. The purpose of this study was to evaluate the effect of larval densities of A. argillacea after different infestation periods on the yield components of four cotton cultivars. The experiment was carried out in Pindorama, SP, Brazil, in the 2008/2009 growing season. The cultivars IAC-25, DeltaOPAL, Fibermax 966 and Fibermax 993 were artificially infested with A. argillacea larvae at three times (30, 60 and 90 DAE) and four densities (0, 2, 4, and 6 larvae per plant). The average boll weight (g), fiber percentage (%), 100-seed weight (g) and yield (kg·ha-1) were evaluated. With increasing infestation density of A. argillacea, the cotton yield of the cultivars decreased. The presence of larvae significantly reduced the weight of 100 seeds of cultivar Fibermax 966. Initial infestations reduced the boll weight of IAC-25 and DeltaOPAL, while cultivars Fibermax 966 and Fibermax 993 were most affected by late infestations. Early infestation compromised fiber percentage of cultivar DeltaOPAL and late infestations were most harmful to cultivar Fibermax 966. Early A. argillacea infestation reduced the yield of DeltaOPAL, while infestations 60 DAE caused the most damage to IAC-25, and the other cultivars were not affected by the moment of infestation.

Highlights

Cotton industry is a socially and economic relevant activity in the agricultural scenario of Brazil
The partition analysis of the cotton cultivars and infestation period for the parameter average boll weight indicated that all cultivars were influenced by the time of infestation, so that the average boll weight was lowest when infestation occurred 60 DAE on IAC-25 (4.75 g), 30 DAE (5.18 g) on cultivar DeltaOPAL, and 90 DAE (4.85 and 4.99 g, respectively) on cultivars Fibermax 966 and Fibermax 993 (Figure 1)
The result on this paper shows that higher infestation densities of A. argillacea increase yield reduction and the presence of larvae reduces the 100-seed weight of cultivar Fibermax 966

Summary

Introduction

Cotton industry is a socially and economic relevant activity in the agricultural scenario of Brazil. The cotton leafworm, Alabama argillacea (Hübner, 1818) (Lepidoptera: Noctuidae), is the important defoliating pest of the crop, causing great yield losses if not controlled properly [2] [3]. This pest causes great damage by the high intensity of plant defoliation to meet the larval food demand. The pest can occur from the initial crop development stages to maturation, in all cotton-cultivating regions of Brazil [2] [4] and often reaches the threshold level that makes control measures necessary [5]. According to the researchers [6] [7], the plants are not resistant to high losses of leaf area in the first 45 days of development

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Discussion

Conclusion