Assessment of Trichogramma japonicum and T. chilonis as Potential Biological Control Agents of Yellow Stem Borer in Rice.

Rui Tang,Feng Zhang,Mao-Lin Hou,Min Kang,Kai Song,Dirk Babendreier

doi:10.3390/insects8010019

Abstract

Two species of Trichogramma wasps were assessed for their effectiveness against yellow stem borer Scirpophaga incertulas. A laboratory cage test with T. japonicum and T. chilonis showed that both species parasitized yellow stem borer egg masses at 60.0% ± 9.13% and 40.7% ± 7.11%, respectively, with egg parasitism rates of 15.8% ± 22.2% for T. japonicum and 2.8% ± 5.0% for T. chilonis. Once the host eggs were parasitized, emergence rates were high for both species (95.7% ± 0.12% for T. japonicum and 100% for T. chilonis). In paddy field trials, the two Trichogramma species were released at three densities (50,000/ha, 100,000/ha and 200,000/ha) in Southwestern China. Egg mass parasitism was 9% ± 7.7% for T. japonicum and 15% ± 14.1% for T. chilonis, and again only a relatively small fraction of eggs was successfully parasitized. No clear conclusion could be drawn on the most efficient release rate as no significant differences were found among the three release rates. A comparison of field-collected T. japonicum with T. japonicum and T. chilonis mass reared on Corcyra cephalonica showed significantly larger body size and ovipositor length in field-collected wasps, suggesting potentially higher effectiveness on yellow stem borer eggs after at least one generation on the target host. Factors contributing to the low field parasitism rates are discussed.

Highlights

Rice (Oryza sativa L.) is the most important crop in the world [1] and plays a central part inAsian food security [2]
Atotal of 77 yellow stem borer (YSB) egg masses were collected from the cage tests, 37 for the T. chilonis treatment and 40 for the T. japonicum treatment
We tested two Trichogramma species collected in the target region for their potential as a biological control agent of YSB, the main pest of rice in the target region

Summary

Introduction

Rice (Oryza sativa L.) is the most important crop in the world [1] and plays a central part in. Asian food security [2]. This crop is widely distributed especially in Southern parts of China [3]. Where rice accounts for 88.7% of the total agricultural acreage [3]. Yunnan Province is located in the Southwest of China, and is considered to be part of the Greater Mekong Subregion, together with. Rice covers over half of the cropping lands in this region [5] and is considered to be the most important crop there [5,6]. Rice production in this area is suffering from serious pest and disease damage [7,8,9,10] causing substantial yield losses every year [6,11,12,13].

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