Biocontrol of the oriental armyworm, Mythimna separata, by the tachinid fly Exorista civilis is synergized by Cry1Ab protoxin.
Tritrophic interactions between Mythimna separata, its tachinid parasite Exorista civilis and the Cry1Ab were examined. Although 6th instar M. separata mortality increased with increasing Cry1Ab concentration, some tolerance was evident. Likewise, parasitization by E. civilis resulted in only 18% host mortality. However, combination of Cry1Ab and E. civilis parasitization resulted in a significant Cry1Ab dose-dependent increase in mortality over that of either alone, including a 50-56% synergistic increase in efficacy at the two concentrations tested. Pupal weight, adult emergence and lifetime fecundity of M. separata derived from larvae surviving both agents were negatively affected. The ability of E. civilis to parasitize and subsequently develop on the host was not adversely influenced by Cry1Ab. Instead, pupation rate increased significantly among host larvae fed 3.125 μg/g Cry1Ab diet. Overall, our results demonstrate that use of Cry1Ab to control M. separata not only is compatible with the use of the tachinid parasitoid, but that the two methods can act synergistically to manage this destructive pest, provide support for the safety of transgenic Cry1Ab Bt plants in China. This example of two independent pest management strategies acting synergistically against a difficult pest offers a new perspective of broad significance in striving for agricultural sustainability.
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
Xingfu
X
Jiang
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
Lei
L
Zhang
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.|College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
Haixia
H
Yang
USDA-ARS Corn Insects &Crop Genetics Research Unit, Genetics Laboratory, Department of Entomology, Iowa State University, Ames, IA 50011, USA.
Thomas W
TW
Sappington
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.
Yunxia
Y
Cheng
State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China.|College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.
Li Zhi
LZ
Luo
D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000494:pharmacology*; D002681:China; D004175:Diptera / Q000472:pathogenicity; D004731:Endotoxins / Q000235:genetics / Q000494:pharmacology*; D006460:Hemolysin Proteins / Q000235:genetics / Q000494:pharmacology*; D006790:Host-Parasite Interactions / Q000187:drug effects*; D007814:Larva / Q000187:drug effects / Q000469:parasitology; D009036:Moths / Q000187:drug effects / Q000469:parasitology* / Q000472:pathogenicity; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified / Q000235:genetics; D011679:Pupa / Q000187:drug effects / Q000469:parasitology
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis