Investigation of diapause induction in Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) larvae

Document Type : Short communication-Persian

Authors

1 Professor, Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran

2 Ph.D. Graduate of Entomology, Department of Plant Protection, Faculty of Agriculture and Natural Resources, University of Mohaghegh Ardabili, Ardabil, Iran

3 Ph.D. Student of Entomology, Department of Plant Protection, College of Agriculture, Urmia University, Urmia, Iran

Abstract

Background and Objectives
The larvae of the Mediterranean flour moth, Ephestia kuehniella (Zeller), are widely used, as an alternative host, to rear some biocontrol agents such as Habrobracon hebetor (Say) for biological control programs. To enhance the quality of mass production, it is necessary to optimize the rearing of natural enemies on alternative hosts. The aim of this study was to investigate the possibility of diapause induction in the Iranian population of E. kuehniella larvae for optimizing the mass production of biocontrol agents such as H. hebetor.
Materials and Methods
To study the diapause induction in E. kuehniella larvae, the insect eggs (0.04 g) were released on 200 g of wheat flour and kept under optimal rearing conditions (25 ± 1°C, 65 ± 5% relative humidity, and 16:8 (L:D) h). After the emergence of each larval instar, they were divided into two groups. The first group included larvae that had already been reared in each instar (first to fifth instars) at 15 ± 1°C and total darkness for one week and the second group under the same conditions for two weeks. Then, the larvae of both groups were transferred to the optimal rearing conditions. After the emergence of fifth (final) instar, the percentage of larvae entered the diapause where the duration of diapause was evaluated. The control group consisted of larvae that were reared in the optimal rearing conditions.
Results
The results revealed that 8 to 45% of the fifth instar larvae from the first group and 100% of the fifth instar larvae from the second group entered the diapause. The percentage of diapausing larvae from the first group was the highest when they were reared in the fourth or fifth instars at 15°C and total darkness. The duration of diapause in the larvae from the second group (19.41 to 20.56 days) was significantly longer than those from the first group (15.20 to 16.92 days).
Discussion
The present study is the first attempt showing diapause induction in Iranian population of E. kuehniella. By increasing the availability of host larvae by inducing diapause, the efficiency of mass production of biocontrol agents such as H. hebetor can be enhanced.

Keywords

References

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 © 2022 by the authors. Licensee SCU, Ahvaz, Iran. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0 license) (http://creativecommons.org/licenses/by-nc/4.0/
Plant Protection (Scientific Journal of Agriculture)
Volume 45, Issue 2
July 2022
Pages 85-90

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