Vol.:(0123456789) 1 3 Paddy and Water Environment https://doi.org/10.1007/s10333-018-0662-y ARTICLE Enhancing the parasitism of insect herbivores through diversification of habitat in Philippine rice fields Quynh Vu 1,2,3  · Angelee F. Ramal 3,9  · James M. Villegas 3,10  · Alexandra Jamoralin 4  · Carmencita C. Bernal 3  · John M. Pasang 4  · Maria Liberty P. Almazan 3  · Daniel Ramp 5  · Josef Settele 2,6,7  · Finbarr G. Horgan 5,8 Received: 11 July 2017 / Revised: 13 December 2017 / Accepted: 7 June 2018 © The International Society of Paddy and Water Environment Engineering and Springer Japan KK, part of Springer Nature 2018 Abstract The diversification of farming landscapes is proposed as a method to increase farm productivity while at the same time enhancing pest regulation services provided by the natural enemies of insect herbivores. In this study, areas of diversified and conventional rice fields (with 2–14 fields per area = 0.42–1.31 ha) were established at three sites in the Philippines. The diversified areas had a series (> 40 per hectare) of small (< 2 m 2 ) vegetable patches interspersed along rice bunds (levees). The abundance of planthopper and lepidopteran pests in these areas was monitored during two consecutive cropping seasons using sweep nets with rice yield and damage recorded at the end of each season. Mortality of brown planthopper (Nilaparvata lugens) and yellow stemborer (Scirpophaga incertulas) eggs was monitored through field exposures of infested rice plants. There were no differences in rice yields between the conventional and diversified areas; however, a range of vegetables were produced as a supplementary product from the diversified rice areas. Diversification had no effect on planthopper or leaf- folder (Cnaphalocrocis medinalis) abundance at the sites. Adult stemborers (Scirpophaga incertulas) were more abundant in the diversified areas; however, stemborer damage was similar between area treatments in both years. Vegetable patches did not increase parasitism of planthopper eggs; however, egg parasitism was highest close to the vegetable patches, suggesting that egg parasitoids interacted with the patches. Mortality of stemborer eggs was higher in the diversified areas than in the conventional areas. Parasitism due to Trichogramma japonicum and other egg parasitoids was also higher in the diversified areas. These results indicate the potential for vegetable patches to enhance the biological control services provided by egg parasitoids in rice fields; however, the study also indicates a need to carefully select vegetable crops that avoid any potential benefits for rice pests. We discuss the need for further research into diversified farms as a means of achieving sustainable rice production in Asia. Keywords Biodiversity · Crop diversification · Ecosystem services · Ecological engineering · Stemborers · Planthoppers · Flower strips * Finbarr G. Horgan finbarr.horgan@uts.edu.au; f.g.horgan@gmail.com 1 Cuulong Delta Rice Research Institute, Tan Thanh, Thoi Lai District, Can Tho, Vietnam 2 Helmholtz Centre for Environmental Research - UFZ, Theodor-Lieser-Str. 4, 06120 Halle, Germany 3 International Rice Research Institute, DAPO 7777, Metro Manila, Philippines 4 Lipa Agricultural Experiment Station, DA Region 4A, Maraouy, Lipa City, Rizal, Philippines 5 University of Technology Sydney, 15 Broadway, Ultimo, Sydney, NSW 2007, Australia 6 German Centre for Integrative Biodiversity Research (iDiv), Leipzig, Germany 7 Institute of Biological Sciences, University of the Philippines Los Baños, College, 4031 Los Baños, Laguna, Philippines 8 Tropical Ecosystem Research Network, 30C Nirodha, Dampe Road, Piliyandala, Sri Lanka 9 School of Environmental Science and Management, University of the Philippines, Los Baños, 4030 Los Baños, Laguna, Philippines 10 Louisiana State University, Baton Rouge, LA 70803, USA