Characterization of Hellula phidilealis (Lepidoptera: Pyralidae) larval instars by application of the Dyar Rule
Abstract
Hellula phidilealis (Walker) (Lepidoptera: Pyralidae) is a species associated with cultivation of crucifers. The damage it produces depends on the phenological stage of the plants, its population density, and the instar in which it is found. For this reason, it is important to identify the instars of the species to contribute to defining management tactics focused on its control in hosts of economic importance. The Dyar rule establishes that the width of the cephalic capsule of the larvae increases at a regular geometric progression. The objective of this study was to determine the rates of increase in the size of the cephalic capsules to determine the number of larval instars of H. phidilealis. Because it is a species that has recently acquired importance in Mexico, it is necessary to conduct basic research to determine its biology to enable implementation of appropriate management tactics for each instar. To obtain the images, a Carl Zeiss® (SteREO Discovery V.20) microscope equipped with a Canon® (EOS 50D) camera was used, and JPEG images were captured for later measurement with the program Image J (v. 1.53e). The larval instars of H. phidilealis were adjusted to the Dyar rule (R2 = 0.9639) with a change rate of 0.50, 0.58, 0.92, and 0.54 for instars L2, L3, L4, and L5, respectively; the average of the rates was 0.63.
Sumario
Hellula phidilealis (Walker) (Lepidoptera: Pyralidae) es una especie asociada con el cultivo de crucíferas, el daño que produce depende de la etapa fenológica de las plantas, la densidad poblacional y del ínstar en el que se encuentre. Por lo anterior, es de importancia identificar los ínstares de esta especie, lo que coadyuvará a definir las tácticas de manejo enfocadas para su control en hospedantes de importancia económica. La Ley de Dyar establece que la anchura de las cápsulas cefálica de las larvas, se incrementa de acuerdo con una progresión geométrica regular. El objetivo de este trabajo fue determinar las tasas de incremento en el tamaño de las cápsulas cefálicas para determinar el número de ínstares larvales de H. phidilealis. Al ser una especie que recientemente ha adquirido importancia en México, es necesario desarrollar investigación básica que permita conocer la biología de la plaga para implementar las tácticas de manejo pertinentes para cada ínstar. Para la obtención de imágenes, se utilizó un microscopio Carl Zeiss ® (SteREO Discovery V.20) acondicionado con una cámara Canon® (EOS 50D); se capturaron imágenes JPEG de cada espécimen para su posterior medición con el programa Image J (v. 1.53e). Los ínstares larvales de H. phidilealis se ajustaron a la Regla de Dyar (R2 = 0.9639) con una tasa de cambio de 0.50, 0.58, 0.92, y 0.54 para los ínstares L2, L3, L4, y L5, respectivamente, el promedio de las tasas fue de 0.63.
Key Words: change rate, cephalic capsule, management in crucifers
View this article in BioOne
Downloads
Published
Issue
Section
License
Copyright for any article published in Florida Entomologist is held by the author(s) of the article. Florida Entomologist is an open access journal. Florida Entomologist follows terms of the Creative Commons, Attribution Non-Commercial License (cc by-nc). By submitting and publishing articles in Florida Entomologist, authors grant the FOJ and Florida Entomologist's host institutions permission to make the article available through Internet posting and electronic dissemination, and to otherwise archive the information contained both electronically and in a hard printed version. When used, information and images obtained from articles must be referenced and cited appropriately. Articles may be reproduced for personal, educational, or archival purposes, or any non-commercial use. Permission should be sought from the author(s) for multiple, non-commercial reproduction. Written permission from the author(s) is required for any commercial reproduction.