Kong Luen Heong

A food web approach to evaluating the effect of insecticide spraying on insect pest population dynamics in a Philippine irrigated rice ecosystem

Summary 1. Data from a 645-taxa Philippines-wide food web and multiple regression models were used to predict population fluctuations of insect pests in a rice field. Independent variables of pest models included the biomass of rice plants in the field, the abundance of each pest, and the abundances of five highly correlated enemies of the pest, all as functions of time. 2. To test the ability of the models to reveal effects of insecticide spraying, a rice field at the International Rice Research Institute (IRRI) in the Philippines was divided into deltamethrin-sprayed and unsprayed plots. Data on the abundance of seven pest species (Nephotettix virescens, Recilia dorsalis, Sogatella furcifera, Nilaparvata lugens, Hydrellia philippina, Ne. nigropictus and Cofana spectra) and their natural enemies (predators and parasitoids) were collected during the dry season of 1990. 3. Spraying insecticide disorganized the population dynamics of insect species feeding in the IRRI field. Multiple regression models were less able in the sprayed plot than in the unsprayed plot to forecast the population fluctuations of pest species on the basis of various numbers and combinations of independent variables. For example, current pest abundance, by itself, was a significant predictor of future pest abundance for four of the seven pests (Ne. virescens, R. dorsalis, S. furcifera, H. philippina) in the unsprayed plot, but significant fits were found for only two pests (R. dorsalis, H. philippina) in the insecticide-sprayed plot. 4. In the unsprayed plot, independent variables were significant predictors of future pest abundance in four of seven initial models compared to one of seven models in the sprayed plot. Step-wise removal of independent variables in the models enhanced their forecasting power in both the sprayed and unsprayed plots, but significant models in the unsprayed plot nearly always outnumbered those in the sprayed plot. 5. In the unsprayed plot, Ne. virescens retained five of seven independent variables as significant predictors, compared to four for S. furcifera, three for C. spectra, and one for the remaining four pests. Classical models that contain one or two species as independent variables may not be sufficient to forecast future abundances of some Philippine rice pests in unsprayed and sprayed plots. 6. In general, models that included interaction terms and either the presence or absence of sprays among the independent variables did not improve the forecasting power of models in either the sprayed or unsprayed plot. 7. The methods developed here for studying the impact of spraying on the organization of arthropod communities in rice fields could be applied to other interventions

Multi-country evidence that crop diversification promotes ecological intensification of agriculture

Global food security requires increased crop productivity to meet escalating demand1–3. Current food production systems are heavily dependent on synthetic inputs that threaten the environment and human well-being2,4,5. Biodiversity, for instance, is key to the provision of ecosystem services such as pest control6,7, but is eroded in conventional agricultural systems. Yet the conservation and reinstatement of biodiversity is challenging5,8,9, and it remains unclear whether the promotion of biodiversity can reduce reliance on inputs without penalizing yields on a regional scale. Here we present results from multi-site field studies replicated in Thailand, China and Vietnam over a period of four years, in which we grew nectar-producing plants around rice fields, and monitored levels of pest infestation, insecticide use and yields. Compiling the data from all sites, we report that this inexpensive intervention significantly reduced populations of two key pests, reduced insecticide applications by 70%, increased grain yields by 5% and delivered an economic advantage of 7.5%. Additional field studies showed that predators and parasitoids of the main rice pests, together with detritivores, were more abundant in the presence of nectar-producing plants. We conclude that a simple diversification approach, in this case the growth of nectar-producing plants, can contribute to the ecological intensification of agricultural systems.

Food web dynamics of irrigated rice fields at five elevations in Luzon, Philippines

The above-water food webs of arthropod communities in irrigated rice fields on Luzon Island, Philippines, were studied over the growing season at five sites (Los Banos, Cabanatuan, Bayombong, Kiangan, Banaue) ranging in elevation from 22 m to 1524 m. Arthropod populations were vacuum-sampled at roughly weekly intervals from the date after seedlings were transplanted to flowering at each site. Site- and time-specific webs were constructed from a 687-taxa cumulative Philippines web and time-series of species present. Taxonomic composition, food web structure, and arthropod phenology were broadly similar across different sites. Arthropod abundance was inversely associated with altitude across the five sites, but numbers of taxa and links and six food web statistics showed no obvious increasing or decreasing trend with altitude. The rise of taxa, links and mean food chain length over the growing season at each site reflected an increase in plant size with age and, at some sites, an orderly accumulation of newly arriving herbivore, predator, parasitoid and omnivore species. At each site, herbivores built up faster than predators and parasitoids, and predators arrived faster than parasitoids; the difference between the latest and earliest sampling dates of first arrivals, averaged over the five sites, was 38, 63 and 73 days for herbivores, predators and parasitoids, respectively. Site-to-site consistencies in food web properties and first arrivals suggest that such patterns may be influenced more by crop age than by geography or altitude. Sampled predator, parasitoid and omnivore taxa potentially encountered only a subset of their lifetime prey and predator species at any particular time in the rice field. Prey lists cumulated over time may underestimate the temporal specificity of predation by potential biological control agents. Research opportunities linking rice food webs and integrated pest management with East Indies biogeography are proposed.

Insect management beliefs and practices of rice farmers in Laos

Abstract Insecticide use in Laos is low, although there is an indication of recent increase. Chemicals hazardous to human health, namely methyl parathion and monocrotophos, are still commonly used. Farmers’ beliefs and attitudes towards insects and insecticide use are similar to other Asian countries. Most farmers strongly believe that insects decrease production and have to be controlled with insecticides. A social psychology framework was used to analyse farmers’ beliefs and norms. Farmers’ spray frequencies were correlated with both the belief and norm indices, implying that farmers’ spray decisions are influenced by these two components. Norm influences seem to be more dominant suggesting that farmers’ perceptions of what referent groups expected of them play an important role. The agricultural technicians seem to have the highest influence. The study showed that Lao farmers are potentially vulnerable to become victims of insecticide misuse as in many Asian countries that implemented rice intensification programmes. Strategic plans in research, education, extension and policies related to pest management and pesticide use need to be developed and implemented in parallel with these programmes. These should include establishing comprehensive pesticide policies, developing extension programmes to educate technicians and farmers on the health hazards and ecological principles related to pesticide use, similar educational programmes for schools and explore for non-face-to-face approaches like radio and television dramas and comic strips that can enhance belief change.

Aspects of brown planthopper adaptation to resistant rice varieties with the Bph3 gene

Despite over 30u2003years of deployment, varieties with the Bph3 gene for resistance to the brown planthopper (BPH), Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), are still effective in much of the Philippines. In the present study, we determined the effects of adaptation to one resistant variety, IR62 – assumed to possess the Bph3 gene – on (1) resistance against a series of varieties with similar biotypical responses (presumed to contain the same major resistance genes), and (2) a differential variety with the bph4 gene that occurs at the same chromosome position as Bph3. We also examined the effects of high soil nitrogen on the effectiveness of Bph3. Feeding, planthopper biomass, and development times were reduced in a wild BPH population when reared on IR62 compared with the susceptible standard variety TN1. However, nitrogen application increased the susceptibility of IR62. After 13 generations on IR62, BPH had adapted to the plant’s resistance. Virulence of the adapted BPH against the variety ‘Rathu Heenati’ supports the idea that Bph3 is present in IR62. Across similar IR varieties (IR60, IR66, IR68, IR70, IR72, and IR74), feeding, planthopper biomass, and development rates were generally higher for IR62‐adapted than for non‐adapted BPH; however, contrary to expectations, many of these varieties were already susceptible to wild BPH. Fitness was also higher for IR62‐adapted BPH on the variety ‘Babawee’ indicating a close relation between Bph3 and bph4. The results indicate that the conventional understanding of the genetics behind resistance in IR varieties needs to be readdressed to develop and improve deployment strategies for resistance management.

Quantifying the Impact of Insecticides on Food Web Structure of Rice-Arthropod Populations in a Philippine Farmer’s Irrigated Field: A Case Study

Rice is grown on 10% of the arable land worldwide and provides one-third of the total calorie supply for two-thirds of the human population (International Rice Research Institute, 1991; Food and Agriculture Organization, 1992). In the middle to late 1960s, the widespread adoption of new high-yield, pest-resistant rice cultivars, nitrogenous fertilizers, and pesticides brought significant increases in rice production (popularly called The Green Revolution (Barker et al., 1985)) in south and southeast Asia. Extensive irrigation systems were built in Asia to capitalize on the insensitivity to the photoperiod of the new cultivars. Eliminating the former fallow period during the dry season removed one form of pest protection and brought new pest problems (Litsinger, 1993). Major outbreaks in the 1970s of the rice brown plant hopper, Nilaparvata lugens (Stal), a secondary rice pest before 1964, were traced to overuse of insecticides (Kenmore, 1980; Kenmore et al., 1984; Heinrichs and Mochida, 1984). The pest problems led to integrated pest management (IPM) strategies for tropical rice in the late 1970s that emphasized host plant resistance, cultural practices, and biological control, minimizing the use of pesticides.

Science-policy interface: beyond Assessments

In their Policy Forum “The biodiversity and ecosystem services science-policy interface” (4 March, p. [1139][1]), C. Perrings et al. frame the new Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) as a body responsible primarily for assessment. They consistently base their elaboration of the work of IPBES on the experiences of past assessments (such as the Millennium Assessment, the Global Biodiversity Outlook, and the Intergovernmental Panel on Climate Change) and interpret the Busan outcome [recommendations made by a 2010 intergovernmental conference ([ 1 ][2])] solely through the lens of how scientific knowledge is assessed. We believe that the blueprint suitability of previous assessments for the IPBES process is very limited. Strengthening the (mainly global-scale) scientific knowledge base behind assessments is important, but the goals of IPBES should be expanded.nnFirst, we should move beyond conventional scientific knowledge assessments that legitimize, almost exclusively, only peer-reviewed material. Knowledge established across all scales (especially the knowledge of local and indigenous peoples) and validated in multiple ways must be eligible for inclusion in IPBES processes. Changes in biodiversity are first experienced locally and thus many forms of local expertise have particular relevance for biodiversity issues ([ 2 ][3]). Second, we should link IPBES assessment results to decision-making at multiple spatial scales (including tackling biodiversity loss at the grassroots level).nnBoth of these goals require all aspects of capacity-building, including empowerment of different kinds of actors, to be reflected in the structural design of IPBES. To achieve this much broader set of objectives as laid out in the Busan outcome, including the explicit incorporation of local and indigenous knowledge, the IPBES structure should knit together existing multiscale networks ([ 3 ][4]) of scientific, policy, and stakeholder communities.nn1. [↵][5] United Nations Environment Programme, “Busan Outcome,” Busan, Korea, 7 to 11 June 2010 ([www.unep.org/pdf/SMT_Agenda_Item_5-Busan_Outcome.pdf][6]).n nn2. [↵][7] 1. W. Reidn et al. , Eds., Bridging Scales and Knowledge Systems: Concepts and Applications in Ecosystems (Island Press, Washington, DC, 2006).n nn3. [↵][8] Leipzig Workshop Recommendations for a Knowledge-Policy Interface for Biodiversity Governance, 4 October 2006 ([www.ufz.de/data/leipzig_recom_final4614.pdf][9]).nn [1]: http://www.sciencemag.org/content/331/6021/1139.fulln [2]: #ref-1n [3]: #ref-2n [4]: #ref-3n [5]: #xref-ref-1-1 View reference 1 in textn [6]: http://www.unep.org/pdf/SMT_Agenda_Item_5-Busan_Outcome.pdfn [7]: #xref-ref-2-1 View reference 2 in textn [8]: #xref-ref-3-1 View reference 3 in textn [9]: http://www.ufz.de/data/leipzig_recom_final4614.pdf

Parasitoids of the rice leaffolder Cnaphalocrocis medinalis and prospects for enhancing biological control with nectar plants

1 The rice leaffolder Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae) is a serious rice pest in Asia. The conspicuous foliar damage caused by C. medinalis larvae leads to early‐season insecticide applications that disrupt the biological control of this and other pest species. 2 Despite the often dramatic impact of C. medinalis, rice plants can tolerate severe defoliation with no impact on grain yield, although persuading farmers to withhold insecticide application has proven very difficult. 3 The present review assesses the prevention of damage caused by C. medinalis via biological control using parasitoids. Information on the indigenous parasitoids of C. medinalis is drawn together for the first time from the non‐English literature published in Asia. This is integrated with the wider English language literature to provide a comprehensive analysis of the parasitoid fauna. 4 Survey studies have been conducted in many Asian countries in recent decades, showing that parasitoids of rice pests can achieve high rates of parasitism but are far from consistent as a mortality factor. There is much less work available on the biology of leaffolder parasitoids in rice and there is an unexpected dearth of studies regarding increasing their performance by providing nectar sources, which is a widely explored approach for other crop systems. 5 It is concluded that the recently reported work in which nectar plants are established on rice bunds to support planthopper parasitoids may have significant benefit for leaffolder parasitoids. The use of plant species, however, that are selective in not allowing adult moths to feed will be essential.

Engaging Local Knowledge in Biodiversity Research: Experiences from Large Inter- and Transdisciplinary Projects

Abstract The management of biodiversity represents a research topic that needs to involve not only several (sub-) disciplines from the natural sciences but, in particular, also the social sciences and humanities. Furthermore, over the last couple of years, the need for the integration of other kinds of knowledge (experience based or indigenous knowledge) is increasingly acknowledged. For instance, the incorporation of such knowledge is indispensable for place-based approaches to sustainable land management, which require that the specific ecological and social context is addressed. However, desirable as it may be, such an engagement of the holders of tacit knowledge is not easy to achieve. It demands reconciling well-established scientific procedural standards with the implicit or explicit criteria of relevance that apply in civil society — a process that typically causes severe tensions and comes up against both habitual as well as institutional constraints. The difficulty of managing such tensions is amplified particularly in large integrated projects and represents a major challenge to project management. At the Helmholtz Centre for Environmental Research — UFZ, several integrated research projects have been conducted over the past years in which experience has been gained with these specific challenges. This paper presents some of the lessons learned from large integrated projects, with an emphasis on project design and management structure. At the centre of the present contribution are experiences gained in the coordination and management of LEGATO (LEGATO stands for Land-use intensity and Ecological EnGineering — Assessment Tools for risks and Opportunities in irrigated rice based production systems, see www.legato-project.net), an ongoing, large-scale, inter- and transdisciplinary research project dealing with the management of irrigated rice landscapes in Southeast Asia. In this project, local expertise on traditional production systems is absolutely crucial but needs to be integrated with natural and social science research to identify future-proof land management systems.

Rice Pest Management by Ecological Engineering: A Pioneering Attempt in China

Ecological engineering is a relatively new concept of environmental manipulation for the benefit of man and the environment. Recently, a pioneering attempt was made in China to see if rice insect pest problems could be solved through ecological engineering. Five years of experimentation at Jinhua, Zhejiang Province in eastern China involved habitat manipulation based on growing nectar producing flowering plants (preferably sesame) combined with trap plants on the rice bounds, reducing the intensity of pesticide use and nitrogenous fertilizers, and managing the vegetation in non-rice habitats including the rice-free season. These practices increased biodiversity in the ecosystem, significantly increased biological control of rice pests, and provided biological stability in the ecosystem. Experimentation with ecological engineering in China indicated that it offers immense opportunities to rice pest management using non-chemical methods leading to economic and environmental benefits. Ecological engineering is not a “high-tech” approach so is simple and practical for rice farmers to implement. Having witnessed the benefits and utility of ecological engineering, the National Agriculture Technology Extension and Service Centre (NATESC) of Ministry of Agriculture has recommended it as the national rice pest management strategy in China.