Multivariate approach to quantitative analysis of Aphis gossypii Glover (Hemiptera: Aphididae) and their natural enemy populations at different cotton spacings

Abstract

The relationship between pests and natural enemies using multivariate analysis on cotton in different spacing has not been documented yet. Using multivariate approaches is possible to optimize strategies to control Aphis gossypii at different crop spacings because the possibility of a better use of the aphid sampling strategies as well as the conservation and release of its natural enemies. The aims of the study were (i) to characterize the temporal abundance data of aphids and its natural enemies using principal components, (ii) to analyze the degree of correlation between the insects and between groups of variables (pests and natural enemies), (iii) to identify the main natural enemies responsible for regulating A. gossypii populations, and (iv) to investigate the similarities in arthropod occurrence patterns at different spacings of cotton crops over two seasons. High correlations in the occurrence of Scymnus rubicundus with aphids are shown through principal component analysis and through the important role the species plays in canonical correlation analysis. Clustering the presence of apterous aphids matches the pattern verified for Chrysoperla externa at the three different spacings between rows. Our results indicate that S. rubicundus is the main candidate to regulate the aphid populations in all spacings studied.

Standardized sampling plan for Aphis gossypii based on the cotton cultivar, plant phenology and crop size

“…The sampling was performed twice in each field, at the vegetative and reproductive stages. To determine the sampling time, samples were collected from field of 1, 5, 10, 50, 100 and 150 ha because cotton fields are currently from a few to thousands of hectares; in addition, 150 ha was the largest field size used to assess the sampling of A. gossypii in cotton (Cao et al, ; Kerns et al, ; Malaquias et al, ; Miranda, ).…”

“…To evaluate the samples, the distance covered in small zones is less than that covered in large zones. Throughout the world, cotton fields range from a few to thousands of hectares (Cao et al, ; Kerns et al, ; Malaquias et al, ). Cotton pest sampling plans should be adapted to each of these situations based on the recommendation that the cotton field zones used for samplings plans should not be larger than 150 ha (Miranda, ).…”

“…In addition, during this sucking process, excessive excretion of carbohydrates derived from the phloem sap favours the incidence of sooty mould fungus (Bachmann, Nault, & Fleischer, 2014;Fernandes et al, 2012). The presence of this fungus on leaves affects the plant's photosynthetic activity, and its presence on fibres decreases boll quality (Chamuene et al, 2018;Malaquias et al, 2017).…”

“…To evaluate the samples, the distance covered in small zones is less than that covered in large zones. Throughout the world, cotton fields range from a few to thousands of hectares (Cao et al, 2008;Kerns et al, 2015;Malaquias et al, 2017).…”

Potassium Phosphite and Water Deficit: Physiological Response of Eucalyptus Using Multivariate Analysis

“…Among the techniques of exploratory data analysis, the multivariate aim to relate groups of treatments with multiple variables simultaneously, allowing for the reduction in the number of variables capable of explaining the biological phenomenon. In addition, it is able to detect similarities or associations and trend of correlation between variables, as well as identifying the most relevant ones, capable of discriminating groups of treatments (Malaquias et al, 2017).…”