The mirid bugs Stenotus rubrovittatus and Trigonotylus caelestialium,
which cause pecky rice, have become a threat to rice cultivation in
Asia. Damage caused by these pests has rapidly become frequent since
around 2000 in Japan. Their expansion pattern is not simple, making it
difficult to manage them by prediction. Some insects with wide
distributions have locally adapted variations in life-history traits. We
performed laboratory rearing experiments to assess the geographical
scale of intraspecific variations in life-history traits of S.
rubrovittatus and T. caelestialium. These were aimed at increasing the
accuracy of occurrence estimates and the number of generations per year.
These results were compared with previous research, and differences in
development rates were observed between populations of different
latitudes, but not of the same latitude. Finally, plotting the timing of
adult emergence and the potential number of generations per year on maps
with a 5-km grid revealed that they differed greatly locally at the same
latitude. These maps can be used for developing more efficient methods
of managing mirid bugs in integrated pest management.
Estimation of the Annual Number of Generations of the Rice Bug, Leptocorisa chinensis Dallas (Hemiptera: Alydidae), Using the Development of Gonads and Formation of Endocuticle Layers after Adult Emergence