Impact of climate change on biology and management of wheat pests

Highlights

• Climate change is expected to favour most serious wheat pests.

• Climatic changes are opening new windows for pathogens, insects and weeds.

• Management tactics should be revisited and improved in the wake of climate change.

Abstract

Wheat (Triticum aestivum L.) production is vital to global food security. Climate change is threatening sustainable wheat production not only with direct negative effects on crop growth but also with a profound impact on pest biology and management. This review presents a critical analysis of the impact of key climate change elements, including drought, high temperature and increased atmospheric carbon dioxide levels on biology, ecology and behaviour of wheat pests. Climate change is expected to favour the growth, virulence, multiplication, persistence and range expansion of most serious wheat pests. Rapid climatic changes are opening new geographic windows for disease outbreaks, insect attacks and weed infestations in wheat crops across the globe. Wheat–pest interactions are also favourable for pests in most cases where one or more climate change elements come into play. Existing pest management options are not successful under these circumstances. Climate change has a direct negative effect on the efficacy of existing control options, which increases pest virulence and their competitive ability, pest resistance to pesticides and pest–environment interactions, leading to inadequate pest control and substantial crop yield losses. Integrated pest management approaches, based on innovative and traditional pest control strategies, may be more appropriate in the changing climate. Proactive measures, including early detection and eradication by frequent pest-scouting, preventive control, and forecasting of potential outbreaks or new introductions by predictive modelling, could help in this regard. A better understanding of the changing pest biology, interactions and management strategies presented here is inevitable for successful pest management and sustainable wheat production under the changing climate.

Introduction

Wheat (Triticum aestivum L.) is an important grain crop grown on more than 200 million ha worldwide, providing about 21% of the global food requirement (FAO, 2015). Being a staple food in several countries, wheat production is crucial for global food security. However, sustainable wheat production is being challenged by the changing climate. Drastic changes in the global climate will affect wheat production directly and indirectly through its impact on wheat–pest dynamics. The average global combined temperature of land and ocean surfaces increased by 0.85 °C between 1880 and 2012 and is projected to increase further by 0.2 °C per decade (IPCC, 2014). The global atmospheric carbon dioxide (CO₂) concentration increased from 284 ppm to 397 ppm between 1832 and 2013 (Wheeler and von Braun, 2013). Such an increase is likely to affect crop plants and the biology of associated pests (Ziska et al., 2011).

Wheat is affected by hundreds of fungal, bacterial and viral pathogens, which cause diseases of varying severity (Bockus et al., 2010). Wheat pathogens vary in regard to optimal and conducive environmental conditions; some are active at freezing temperatures, while others cause diseases at temperatures above 35 °C (Milus et al., 2006; Sabburg et al., 2015). Continuous monitoring of changes in climate is therefore important when developing management strategies for diseases in the future.

There are more than 100 species of arthropod pests that attack wheat, most of which are occasional or inhabit limited areas of wheat production, with only a few species of major economic importance (Hatchett et al., 1987). The major insect pests of wheat, their seasonal distribution, and mode of damage are presented in Table 1. Current and future climatic variations are expected to significantly affect the biology and behaviour of insect pests, which may change the distribution and severity of their infestation in crops.

Weeds are the most important biological constraint to crop production. Potential yield losses in wheat caused by weeds are reportedly about 23% (Oerke, 2006). Climate change is affecting weed biology, weed dynamics and weed–crop interference, such that changes in management options are needed (Bajwa et al., 2015). Important wheat weeds that threaten wheat productivity are listed in Table 2. Climate change is dictating the invasion of alien weed species across different regions of the world (Bajwa et al., 2016).

In the wake of the changing climate, wheat production is facing serious pest problems globally. There is no comprehensive manuscript covering the effects of climate change on the biology of wheat pests and existing management strategies. Here, we review the changing dynamics of wheat pest biology and management under the changing climate to help researchers and farmers to improve wheat production sustainably.