The Role of Lysobacter antibioticus HS124 on the Control of Fall Webworm (Hyphantria cunea Drury) and Growth Promotion of Canadian Poplar (Populus canadensis Moench) at Saemangeum Reclaimed Land in Korea.

Jae-Hyun Moon,Young Sang Ahn,Jae-Hyeok Choi,Henry B. Ajuna,Su-In Choi,Yong Hun Jo,Chaw Ei Htwe Maung,Sang-Jae Won

doi:10.3390/microorganisms9081580

Abstract

Populus canadensis Moench forests established in Saemangeum-reclaimed land have been invaded by Hyphantria cunea Drury, causing defoliation and stunted growth. This study investigated the biocontrol potential of cuticle degrading chitinase and protease secreted by Lysobacter antibioticus HS124 against H. cunea larvae. In addition, L. antibioticus HS124 was examined for indole-3-acetic acid phytohormone production for plant growth promotion. To determine the larvicidal activity in the laboratory experiments, crude enzymes, bacteria culture, CY medium, and water (control) were sprayed on the larvae reared on natural diet in insect rearing dishes. Treatment with crude enzymes and bacteria culture caused 76.7% and 66.7% larvae mortality, respectively. The larvae cuticle, mainly composed of chitin and proteins, was degraded by cuticle-degrading enzymes, chitinase, and protease in both the bacteria culture and crude enzyme treatments, causing swelling and disintegration of the cuticle. Field application of the bacteria culture was achieved by vehicle-mounted sprayer. Bacterial treatment caused morphological damage on the larvae cuticles and subsequent mortality. Foliar application of the bacteria culture reduced tree defoliation by H. cunea and enhanced growth compared to the control. Especially, L. antibioticus HS124 produced auxins, and increased growth of poplar trees.

Highlights

IntroductionGlobal demand to produce fast-growing forest trees has progressively increased in recent years because of the impact on global climate and concerns about energy security [1,2]
The growth of L. antibioticus HS124 was low until 3 days after inoculation (Figure 2)
Thereafter, growth of L. antibioticus HS124 rapidly increased until 6 days after inoculation, when the growth rate reached a maximum value of 4.6 × 107 cell/mL

Summary

Introduction

Global demand to produce fast-growing forest trees has progressively increased in recent years because of the impact on global climate and concerns about energy security [1,2]. Plantations of woody species with fast growth rates and short cultivation periods are a desirable source of renewable energy [3]. Poplars, are a genus of deciduous trees in the family Salicaceae with more than 30 species grown in Asia, Europe, Africa, and America [4,5]. These species are well known for their adaptability to unfavorable environments, including low fertility and high saline soils [4,5,6].

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