Driving Pest Insect Populations: Agricultural Chemicals Lead to an Adaptive Syndrome in Nilaparvata Lugens Stål (Hemiptera: Delphacidae)

Abstract

The brown planthopper (BPH) is a devastating pest of rice throughout Asia. In this paper we document the BPH biogeographic range expansion in China over the 20-year period, 1992 to 2012. We posed the hypothesis that the range expansion is due to a syndrome of adaptations to the continuous presence of agricultural chemicals (insecticides and a fungicide) over the last 40 years. With respect to biogeography, BPH ranges have expanded by 13% from 1992 to 1997 and by another 3% from 1997 to 2012. In our view, such expansions may follow primarily from the enhancing effects of JGM, among other agricultural chemicals, and from global warming. JGM treatments led to increased thermotolerance, recorded as decreased mortality under heat stress at 40 ± 1 °C (down from 80% to 55%) and increased fecundity (by 49%) at 34 °C. At the molecular level, JGM treatments led to increased abundances of mRNA encoding Acetyl Co-A carboxylase (Acc) (up 25%) and Hsp70 (up 32%) in experimental BPH. RNAi silencing of Hsp70 and Acc eliminated the JGM effects on fecundity and silencing Hsp70 reduced JGM-induced thermotolerance. Integrated with global climate change scenarios, such syndromes in pest insect species have potential for regional- and global-scale agricultural disasters.

Variations in nutrient and trace element composition of rice in an organic rice-frog coculture system

“…Moreover, in the ORF system, the use of organic instead of chemical fertilizer is better for the environment. In China, the overuse of chemical N fertilizers has caused environmental problems due to atmospheric, soil, and water enrichment with reactive N of agricultural origin 4 , 5 , 8 – 10 . The ORF system in this study represhents a feasible strategy to reduce the application of agro-chemicals.…”

“…Improving the yield and quality of rice with minimal chemical fertilizer and pesticide inputs is important for the long-term sustainability of rice production systems over time 1 , 2 . However, low fertilizer-use efficiency 3 – 5 , the greenhouse effect 6 , 7 , water pollution 8 , 9 , and soil acidification 10 are problems that caused by intensive paddy field in China. The introduction of ecologically, friendly animals into paddy fields creates an integrated agro-ecological system.…”

Silencing pyruvate kinase (NlPYK) leads to reduced fecundity in brown planthoppers, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae)

“…We propose a general model in which exposure to agricultural chemicals, including insecticides and fungicides, leads to increased expression of several genes that act in energy metabolism, such as fatty acid synthase (Li et al., ), which increases fatty acid synthesis and acetyl‐CoA carboxylase, which increases availability of malonyl‐CoA substrate, needed in fatty acid synthesis (You et al., ). Taken with increases in sugar and protein synthesis, the enhancing influence of TZP on BPH reproduction and population sizes is conceptualized as an indirect outcome of increased energy metabolism.…”

“…It is responsible for serious crop losses (up to 60%; Prasannakumar, Chander, & Sahoo, ) due to direct feeding and to vectoring plant pathogenic viruses. Its geographic range has expanded in China, likely due to a range of adaptations to constant exposure to agricultural chemicals (You et al, ). For example, exposure to the organophosphate insecticide triazophos (TZP) stimulates increased reproduction in N. lugens (Ge, Chen, Wu, & Jahn, ; Ge et al., ; Zhang et al., ; Zhu et al., ).…”

Intraspecific competition counters the effects of elevated and optimal temperatures on phloem-feeding insects in tropical and temperate rice

“…BPH is often considered as the principal pest of rice throughout the region. Outbreaks of BPH are associated with intensive rice production in irrigated lowlands where farmers apply high concentrations of nitrogenous fertilizers and resurgence insecticides [ 26 , 27 ]. WBPH is a major pest of hybrid rice varieties that has become more prominent throughout Asia in recent decades [ 18 , 25 ].…”