Electrophysiological Responses and Reproductive Behavior of Fall Webworm Moths (Hyphantria cunea Drury) are Influenced by Volatile Compounds from Its Mulberry Host (Morus alba L.).

Rui Tang,Feng Zhang,Zhong-Ning Zhang

doi:10.3390/insects7020019

Abstract

Hyphantria cunea (Drury) is an invasive pest of Morus alba L. in China. β-ocimene and cis-2-penten-1-ol among eleven electro-physiologically active leaf volatiles from M. alba have been reported to influence captures of Hyphantria cunea moths when added into sex pheromone traps. This study further investigated influences of volatile types and their dosages on the electro-physiological responses in the antennae of male and female moths, as well as on mating and oviposition behaviors. Females were, regardless of dosages, more sensitive to β-ocimene and cis-2-penten-1-ol in electro-physiological response tests than males. For males, a dose response was detected, i.e., a dosage of 10 μg and 100 μg of either chemical stimulated higher electric response in their antennae than 1 μg. Moth pairs either exposed respectively to a herbivore-induced M. alba volatile blend (HIPV), to a mechanically-damaged M. alba volatile blend (MDV), to β-ocimene, to cis-2-penten-1-ol, or to pentane as a control showed that pairs exposed to β-ocimene most likely mated, followed by HIPV blends and least by the other volatiles or the control. In contrast, β-ocimene induced about 70% of the female oviposition behaviors and was nearly 4.5 times the oviposition rate than cis-2-penten-1-ol and 2 times than the control. However, none of the chemicals had any effect on the 48 h fecundity or on egg sizes. In conclusion, β-ocimene from mulberry plants alone could promote mating and oviposition in H. cunea at a dosage of 1 mg. The results indicate that reproductive behaviors of H. cunea moths can be enhanced through HIPV blends and β-ocimene induced by feeding of larvae. This contra phenomenon has revealed a different ecology in this moth during colonizing China as local pests would commonly be repelled by herbivore induced chemicals. These chemicals can be used for the development of biological control approaches such as being used together with sex pheromone traps.

Highlights

The fall webworm, Hyphantria cunea Drury (Lepidoptera: Arctiidae), is native to North America but spread into central Europe and eastern Asia in the 1940s [1,2]
We found that Herbivore-induced plant volatiles (HIPVs) from mulberry could significantly increase the mating rate compared with the solvent control
We showed an increased mating as a result of HIPV in our study, the oviposition rate was not enhanced, and this might be the result of potential bioactive compounds in the blends of HIPV

Summary

Introduction

The fall webworm, Hyphantria cunea Drury (Lepidoptera: Arctiidae), is native to North America but spread into central Europe and eastern Asia in the 1940s [1,2]. In 1979, this insect was first recorded in China in Liaoning Province, and it has continued to spread through much of the country [3]. Hyphantria cunea has caused extensive damage during its 30-year invasion because it feeds on 175 species of host plants [4]. It prefers to eat mulberry (Morus alba L., Moraceae), rock. Insects 2016, 7, 19 maple (Acer saccharum Marshall, Sapindaceae), poplar (Populus tremula L., Salicaceae), and ailanthus (Ailanthus altissima (Mill.) Swingle, Simaroubaceae) in China [3]. Economically-important mulberry plants are mostly heavily damaged because of their long cultivation history over 4000 years, board area across the country and high densities in China [5]

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