Inductions of reproduction and population growth in the generalist predator Cyrtorhinus lividipennis (Hemiptera: Miridae) exposed to sub‐lethal concentrations of insecticides

BACKGROUND The miridbug, Cyrtorhinus lividipennis, is a significant predacious enemy of rice planthoppers. The effects of sub‐lethal concentrations of triazophos, deltamethrin and imidacloprid on fecundity, egg hatchability, expression levels of genes associated with reproduction, and population growth in C. lividipennis were investigated. RESULTS The fecundities for three pair combinations (♀c × ♂t, ♀t × ♂c and ♀t × ♂t) treated with sub‐lethal concentrations of the insecticides triazophos, deltamethrin and imidacloprid (LC10 and LC20) showed a significant increase compared to the untreated pairs (♀c × ♂c). However, sub‐lethal concentration treatments did not affect the egg hatchability. The ClVg expression levels of female adults exposed to triazophos, deltamethrin and imidacloprid (LC20) increased by 52.6, 48.9 and 91.2%, respectively. The ClSPATA13 expression level of adult males exposed to triazophos, deltamethrim and imidacloprid (LC20) increased by 80.7, 41.3 and 48.3%, respectively. Furthermore, sub‐lethal concentrations of insecticides (LC20) caused increased population numbers in C. lividipennis. CONCLUSION Sub‐lethal concentrations of triazophos, deltamethrin and imidacloprid stimulated reproduction and enhanced population growth of C. lividipennis. The reproductive stimulation might result from the up‐regulation of ClVg or ClSPATA13. These findings may be useful in mediating populations of planthoppers. © 2017 Society of Chemical Industry