Ju Il Kim

Effects of Bt Transgenic Chinese Cabbage on the Herbivore Mamestra brassicae (Lepidoptera: Noctuidae) and Its Parasitoid Microplitis mediator (Hymenoptera: Braconidae)

Abstract We investigated the effects of a diamondback moth-resistant Chinese cabbage (Brassica campestris subsp. napus variety pekinensis Makino), expressing the insecticidal protein Cry1A(c) toxin derived from Bacillus thuringiensis, on the nontarget herbivore Mamestra brassicae (L.)(Lepidoptera: Noctuidae) and its parasitoid wasp Microplitis mediator (Haliday) (Hymenoptera: Braconidae). A decreased survival rate at neonate stage was observed in M. brassicae when reared on Bt cabbage, although overall development was not significantly affected. According to enzyme-linked immunosorbent assay test using Cry1A(c) antibody, the Cry toxin was only detected in the alimentary canal, not in the hemolymph or remaining body parts of M. brassicae, indicating that the ingested Cry toxin is neither distributed inside the body nor transferred through the trophic level. As expected, no Cry toxin was found in the larvae and cocoons of M. mediator. In addition, no significant changes were observed in the parasitization rate, larval period, pupal period, cocoon weight, or adult emergence rate when M. mediator wasps were reared on the M. brassicae larvae fed with transgenic Chinese cabbage. In summary, no direct or indirect adverse effects of transgenic Chinese cabbage on the two nontarget insect species were observed, suggestive of low risk in herbivore–parasitoid food chain.

Selection of Insecticide Resistance Markers in Field-collected Populations of Myzus persicae

ABSTRACT: The resistance levels of the green peach aphid, Myzus persicae (Sulzer), against 10 insecticides was checked and selecte d the applicable insecticide resistance markers. We conducted our study in 5 cabbage cultivation regions (Pyeongchang, Hongcheon, Bongwha, Muju, and Jeju) of Korea, over 3 successive years (2009 –2011). We selected a multi-resistant (MR) strain from among the 5 field-collected populations. We analyzed esterase over-expression and mutation(s) in the target sites, by using native isoelect ric focusin g(IEF) and quantitative sequencing (QS). We detected esterase over-expression and StoF mutation in the acetylcholinesterase 1 gene (ace1) in all of the field-collected populations, including the MR strain. We did not detect the LtoF mutation, which is a well-known knockdown resistance ( kdr) mutation in the para-type sodium channel gene ( para), in the MR strain; however, the value of the MR strai nfor bifenthrin was 3,461-fold higher than that of the susceptible strain. Our results indicate that insecticide resistance is m ore effectivel yevaluated using molecular markers than by conducting a bioassay. The molecular markers StoF in ace1 and MtoL in para can easily beapplied in diagnostic methods such as QS or PCR amplification of specific alleles (PASA). These methods may be extended to management of M. persicae resistance in the field.Key words: Myzus persicae, Insecticide resistance, Quantitative sequencing (QS), Esterase over-expression, Mutation초 록: 2009~2011년 동안 국내 주요 배추 재배지 5개 지역(평창, 홍천, 봉화, 무주, 제주)에서 살충제에 대한 복숭아혹진딧물의 저항성 발달 정도를 조사하고, 야외 개체군에 적용 가능한 살충제 저항성 마커를 개발하기 위해 본 연구를 수행하였다 . 조사된 5개 지역 개체군 모두 여러 살충제 종류에 대하여 다양한 저항성을 보였다. 다양한 저항성을 보인 5개 지역 야외 개체군으로부터 여라 살충제에 대하여 복합적으로 저항성을 보이 는복합저항성 계통(MR)을 선발하였고, 이 MR과 모든 지역 채집 개체군에 대해 등전점전기영동과 정량염기서열분석 (quantitative sequencing, QS)을 통하여 에스터레이즈 과발현과 살충제 작용점 내 돌연변이를 확인하였다. MR을 포함한 모든 야외 개체군에서 에스터레이즈의 과발현과 아세틸콜린에스터레이즈 1 유전자(ace1)의 StoF 돌연변이를 확인할 수 있었다. 넉다운 저항성 돌연변이로 잘 알려진 파라 타입 나트륨 채널 유전자(para)의 LtoF 돌연변이는 모든 지역 채집 개체군은 물론 비펜스린에 대해 3,461배 저항성을 보이는 MR에서도 발견되지 않았다. 그 외에 MtoL 돌연변이를 발견하였는데, 생물검정 결과 저항성 수준과 돌연변이 발생 빈도가 일치하였다. 따라서 생물검정 대신, 이러한 분자 마커를 활용 한다면 더 효율적으로 살충제 저항성 평가가 가능할 것이다. 이러한 분자 마커들(ace1의 StoF, para의 MtoL)은 정량염기서열분석, PCR amplification of specific alleles (PASA) 등의 진단 방법에 쉽게 응용이 가능 하고, 이러한 방법은 야외 복숭아혹진딧물 저항성 관리에 적용이 가능 할 것이다.검색어: 복숭아혹진딧물, 살충제 저항성, 정량염기서열분석(QS), 에스터레이즈 과발현, 돌연변이*Corresponding author: forweek@korea.krReceived January 8 2014; Revised March 8 2014Accepted April 3 2014