Long-term seasonal forecasting of a major migrant insect pest: the brown planthopper in the Lower Yangtze River Valley

Abstract

Rice planthoppers and associated virus diseases have become the most important pests threatening food security in China and other Asian countries, incurring costs of hundreds of millions of US dollars annually in rice losses, and in expensive, environmentally harmful, and often futile control efforts. The most economically damaging species, the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae), cannot overwinter in temperate East Asia, and infestations there are initiated by several waves of windborne spring or summer migrants originating from tropical areas in Indochina. The interaction of these waves of migrants and synoptic weather patterns, driven by the semi-permanent western Pacific subtropical high-pressure (WPSH) system, is of critical importance in forecasting the timing and intensity of immigration events and determining the seriousness of subsequent planthopper build-up in the rice crop. We analysed a 26-year data set from a standardised light trap network in Southern China, showing that planthopper aerial transport and concentration processes are associated with the characteristics (strength and position) of the WPSH in the year concerned. Then, using N. lugens abundance in source areas and indices of WPSH intensity or related sea surface temperature anomalies, we developed a model to predict planthopper numbers immigrating into the key rice-growing area of the Lower Yangtze Valley. We also demonstrate that these WPSH-related climatic indices combined with early-season planthopper catches can be used to forecast, several months in advance, the severity of that season's N. lugens infestations (the correlation between model predictions and outcomes was 0.59), thus allowing time for effective control measures to be implemented.Keywords Nilaparvata lugens · Windborne insect migration · Atmospheric circulation · Rice pests · Planthopper risk prediction · Western Pacific subtropical high-pressure system Key message• East Asia has experienced a resurgence of serious rice planthopper outbreaks in recent years. In one of the worst-affected areas, the Lower Yangtze Valley of China, the number and timing of brown planthopper immigrants from further south has a major influence on the risk of local outbreaks.• Here we show how seasonal outbreak risk can be predicted from indices of the intensity of the western Pacific subtropical high-pressure system, a major atmospheric circulation system that drives the synoptic weather patterns affecting planthopper immigration.Communicated by V. Gagic. Electronic supplementary materialThe online version of this article (https ://doi

Analysis of atmospheric circulation situation and source areas for brown planthopper immigration to Korea: a case study

“…, Hu et al. ). However, the latter may not be able to satisfy the stringent requirements of overseas migration, due to its short duration and small range of influence (e.g., the immigrants moving into Japan mainly rely on southwesterly low‐level jet; Seino et al.…”

“…The characteristic of long‐range migration, relying on suitable atmospheric conditions, is one of the root causes for N. lugens to spread in Asian countries (Kishimoto , Otuka , Hu et al. ). From spring, planthopper populations migrate northward from the tropical Indochina Peninsula with summer monsoon to East Asia.…”

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“…30, 47 This persistent large-scale weather system produces frequent winds from the southwest in the spring and summer, and then switches to frequent winds from the north in the autumn, over the entire East Asian migration arena, thus providing suitable transporting flows for insect migrants over the whole flight season. 43, 47 Our study of likely FAW migration trajectories is entirely consistent with this situation, and our modelling suggests that FAW only need to take-off and climb to a few hundred meters above ground to achieve rapid, long-distance transport towards eastern China during the spring. The migration system can therefore evolve without any further specialised behaviours, simply due to the high frequency of seasonally-favourable tailwinds.…”

Quantifying flight aptitude variation in wildA. gambiaes.l. in order to identify long-distance migrants

“…The long-distance migration (LDM) of insects (Dingle 2014;Dingle and Drake 2007;Chapman, Reynolds and Wilson 2015;Chapman and Drake 2019) produces numerous services and disservices relevant to human agriculture, economy and health (Bauer et al 2017), e.g. in terms of food security (Rainey 1989;Leskinen et al 2011;Hu et al 2019;Glick 1939;Dingle 2014;Cheke et al 1990;Chapman, Reynolds, and Smith 2004), public health (Garms, Walsh and Davies, 1979;Ritchie & Rochester, 2001;Sellers, 1980) and even the transfer of nutrients by migrating insects (Hu et al 2016;Landry and Parrott, 2016;Wotton et al 2019). Here, we follow the definition of migration as persistent movements of individuals that are not affected by immediate cues for food, reproduction, or shelter (i.e.…”