Original scientific paper

Diabrotica virgifera virgifera LeConte Larval Size May Be Influenced by Environmental Conditions in Irrigated Maize Fields in Northwestern Italy

Mauro AGOSTI ; Consorzio di Difesa delle Colture Intensive di Brescia,Brescia, Italy
Lorenza MICHELON ; Consorzio di Difesa delle Colture Intensive di Brescia,Brescia, Italy
C. Richard EDWARDS ; Department of Entomology, Purdue University, Indiana, USA

Abstract

Western corn rootworm, Diabrotica virgifera virgifera LeConte, larvae were collected in different irrigated maize fields in Brescia Province in Northwestern Italy in 2006, 2007 and 2008. Head capsule widths, considered a valid indicator of larval instar stage, were measured for 2063 specimens and data for the three years were combined and grouped in increments of 20 µm width sizes. Frequency of larvae within each grouping was graphed as a histogram and three distinct peaks, interpreted to represent the peak frequency of the head capsule widths of the three larval instars, were observed. Assuming a normal distribution of head capsule widths, a multiple nonlinear Gaussian curve regression was applied to the frequency histogram. The peaks of the fitted normal curves were 227 ± 3 µm, 353 ± 6 µm, and 519 ± 3 µm for the first, second and third instars, respectively. These values are higher than those reported by other authors in similar studies. The possible impact of irrigation and other environmental factors is discussed.

Keywords

Western Corn Rootworm; head capsule width; environmental conditions; irrigation; maize; soil moisture; nonlinear Gaussian curve regression; larval size; larval instars; Diabrotica

Hrčak ID:

48347

URI

https://hrcak.srce.hr/48347

Publication date:

18.11.2009.

Article data in other languages: croatian

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