by
Pingyang Zhu, Guihua Chen Jinhua Plant Protection Station, Jinhua, China
Zhongxian Lu, Xusong Zheng, Hongxing Xua, Yajun Yang State Key Laboratory Breeding Base for Zhejiang Sustainable Pest and Disease Control, Institute for Plant Protection and Microbiology, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
Kong Luen Heong, Crop and Environmental Sciences Division, International Rice Research Institute, Los Baños, Philippines, and
Geoff M Gurr, E. H. Graham Centre for Agricultural Innovation, NSW Department of Primary Industries and Charles Sturt University, Australia
Cyrtorhinus (A) and sesame flowers (B)
The mirid bug, an omnivorous predator, Cyrtorhinus lividepennis is a key natural enemy of rice planthoppers. It uses its sucking mouthparts to drink up the content of planthopper eggs embedded in the plant tissues. A video of this feeding behavior is available. In ecological engineering we encourage the diversification of the rice landscape to improve nectar and shelter resources for natural enemies. Hundreds of farmers in Vietnam have adopted such practices and reduced insecticide inputs significantly. In ecological engineering fields the density of Cyrthorhinus significantly increased. In a series of laboratory experiments we found that the survival of adult males and females was increased by the presence of flowering Tagetes erecta, Trida procumbens, Emilia sonchifolia, (Compositae) and sesame, Sesamum indicum (Pedaliaceae) compared with water or nil controls.
Increase in numbers of prey eggs consumed by male C. lividipennis adults
All flower treatments increased consumption of brown plant hopper, and for female C. lividipennis, sesame was most favorable. Another study with a wider range of plant species and varying densities of prey showed that sesame most strongly promoted predation by C. lividipennis. Reflecting this, sesame gave a relatively prey high search rate and low prey handling time so was selected for more detailed studies to check its incorporation into the farming system would not inadvertently benefit Cnaphalocrocis medinalis and Susumia exigua. Adult longevity and fecundity of both pests was comparable for sesame and water treatments and significantly lower than the honey solution treatment.
Common flowers used in experiment. A: Vernonia cinerea, B: Lobularia maritime, C: Portulaca grandflora, D: Tagetes erecta
Another study showed that high nitrogen in plants increased Cyrtorhinus fitness but weakens its predation efficiency. The findings confirm that sesame is well suited for use as an ecological engineering plant in the margins of rice crops. Sesame can be a valuable crop as well as providing benefits to C. lividipennis whilst denying benefit to key pests.
The paper has been submitted for publication in PLOS ONE.
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