Surrounding landscape influences the abundance of insect predators in rice field

Abstract

Background Natural enemy abundance in a crop plot depends on its prey presence and also influenced by habitats close to field. Landscape changes are also important factors driving pest and natural enemy population abundance in a specific crop field. Examining these kinds of effects on insect pests or biocontrol agents, as well as analysis of their functional food webs, would be asset to make a fruitful pest management programme at local scales. Therefore, this study was undertaken to evaluate the impact of surrounding landscape on the abundance insect predators in rice field. Results This study revealed a dependency on rice bund margin width, with spider populations increasing with increased bund widths. Conversely, population abundance did not rely on the number of weed species observed on earthen ridge around the rice field. In general, relative abundances of predator populations differed significantly across the three landscapes tested. Among the four predators of rice insect pest, the green mirid bug showed highest number irrespective of landscape. Comparatively, higher predator diversity (Shanon diversity) was observed in landscape I followed by landscape III and landscape II. All landscapes showed different diversity indices indicating heterozygosity existed in each study site. These landscape diversity influences the predator’s abundances at a local scale. Variogram derived from this study also indicated the landscape heterozygosity existed in studied locations which can also explain the predator’s abundances in rice field at locale scale. Conclusion These findings suggest that predators of rice insect pests are landscape specific. Therefore, characterization of each local landscape in Bangladesh rice production landscapes are necessary before planning and implementation of integrated pest management. Geospatial analysis of local landscape would be more effective to analyze such unique characteristics. As a step in this direction, preliminary variography analyses using the RED spectral band of December 2016 LANDSAT 8 imagery propose an initial learning suite of methods for describing useful local characteristics affecting rice pest predators.

Following the outbreak: preliminary findings on the landscape effect on Dasineura oleae and its parasitoids in Central Italy

“…Perennial non-crop habitats could provide nectar, pollen and alternative resources such as overwintering sites and refugees for antagonists. Speci cally, the proportion of non-crop area in the landscape has been positively related to species richness (Schmidt et al 2005), predators' abundance (Ali et al 2020;Gardiner et al 2009a) and subsequent suppression of pests as demonstrated in soybean (Gardiner, et al 2009b) and oilseed rape (Thies and Tscharntke 2010). Further case studies should provide a reliable conclusion about this issue.…”

Indigenous farmers’ perceptions of problems in the rice field agroecosystems in the upper Baram, Malaysia

“…Similarly, local women in Coatitilán, Mexico, perceive that forests and trees prevent soil erosion and that vegetation plays an important role in soil water retention and landscape structure maintenance, thereby protecting agricultural land and productivity [ 89 ]. For the mitigation of problems and to compensate for ecosystem service losses, a diverse complex landscape with natural habitats [ 88 ] can benefit farmers, such as in a form of pest control [ 44 ], or by receiving water for the rice fields from woodlots [ 12 ].…”

“…In general, landscape configuration and composition affect the ecological processes that occur in landscapes and landscape elements, such as hydrological flows and variation within catchments [ 42 ] or on the RAE’s arthropod population [ 43 ]. According to Ali et al (2020), the landscape around rice fields influences the insect pest population, indicating that landscape structure should be considered when implementing integrated pest management [ 44 ]. Similar effects have been reported in Sungai Semanok, Sarawak, where rice farmers lack access to the same high-quality pesticides as nearby oil palm plantations, resulting in pest migration to rice fields and thus negatively affecting agricultural productivity [ 34 ].…”

Land use alters the abundance of herbivore and predatory insects on crops: the case of alfalfa

“…In recent decades, agriculture has intensified at local and regional scales worldwide, increasing the proportion of monocultures, field sizes, and the degrees of fragmentation of natural and seminatural habitats, causing fundamental changes in agricultural landscapes (Tscharntke et al 2005;Baessler and Klotz 2006). These landscape changes are considered to be important factors modifying the abundances of both insect pest and natural enemy populations in agroecosystems (Ali et al 2020). However, a metaanalysis showed that crop pests and predators can also exhibit inconsistent responses to the composition of landscapes and that these responses might result from variations in how habitat and biocontrol are measured (Karp et al 2018).…”