Increased temperature induces leaffolder outbreak in rice field

Abstract

The rice leaffolder, Cnaphalocrosis medinalis Güenée (Lepidoptera: Crambidae), has emerged as a serious pest with significant outbreaks over the last decade in several rice‐growing countries, including China and Bangladesh and resulting in heavy rice yield losses. Climate changes (particularly high temperatures in late winter in Bangladesh) coincide with upsurge in outbreaks of this pest. We generated a statistical model using more than two decades of data to show that increased temperatures associate with this upsurge. Over the 22‐year model period, leaffolder populations in November increased significantly, corresponding to significant monthly temperature trends (but not rainfall) over the same period. Utilizing a linear model, we find that increasing temperature interacts with the amount of rainfall. With the variable month as a proxy for all seasonal effects affecting leaffolder abundance, the model reveals a significant correspondence with climate variations compared to average conditions; specifically, the model predicts that increasing maximum temperatures will lead to more leaffolder, while more rain will decrease their abundance. This study suggests that warmer environment contributed to recent outbreaks of leaffolder in rice‐growing countries; thus, climate change increases rice yield losses by increasing pest population in the field.

Elevated temperatures diminish the effects of a highly resistant rice variety on the brown planthopper

“…For example, researchers have documented a northward shift in distribution of the green shield bug, Nezara viridula , in Japan that may be related to warmer winter temperatures 12 . Furthermore, planthoppers and leaffolders exhibit outbreak dynamics related to extreme weather events, and some research suggests that recent increases in pest population densities could be associated with increasingly warm local weather conditions 9 , 10 . Despite such observations of direct climate effects on rice pest populations, it is the interactions between climate and rice crop management that are likely to have the greatest effects on rice herbivores.…”

Temperature-dependent oviposition and nymph performance reveal distinct thermal niches of coexisting planthoppers with similar thresholds for development

“…However, rice may be affected by increased levels of insect herbivory as the climate warms. For example, an increase in the abundance of planthoppers (Homoptera: Delphacidae) and leaffolders (Lepidoptera: Pyralidae) since the beginning of the millennium has been associated with increasing temperatures in Asia [25][26][27]. Furthermore, planthopper and leaffolder migrations in East Asia have occurred progressively earlier in recent decades and herbivore overwintering ranges in southern Asia have expanded poleward, and are predicted to expand even further in coming decades [28][29][30].…”

Comparative transcriptome analysis of the rice leaf folder (Cnaphalocrocis medinalis) to heat acclimation

“…The rice leaf folder Cnaphalocrocis medinalis (Lepidoptera: Pyralidae) is an important pest of rice and other gramineous crops in Asia, often causing serious losses [26]. This pest is sensitive to temperature changes [27][28][29]. The upper and lower threshold temperatures of this pest are 36.4°C and 11.2°C, respectively [30].…”