Geographic variation of diapause in Laodelphax striatellus Fallén (Hemiptera: Delphacidae)

• 1、College of Plant Protection, Nanjing Agricultural University, Nanjing, 210095

Abstract：The small brown planthopper, Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae) occurs seriously in temperate regions, causing severe losses in rice, wheat and other crops. The planthoppers enters diapause in the 3rd or 4th instar nymphs induced by short day-length and low temperature. To investigate the geographic variation in L. striatellus diapause, we compared the incidence of nymphal diapause under various constant temperatures (20 C and 27 C) and photoperiods (LD4:20, LD8:16, LD10:14, LD12:12, LD14:10 and LD16:8) regimes among three populations collected from Hanoi (21.02 N, 105.85 E, northern Vietnam), Jiangyan (32.51 N, 120.15 E, eastern China), and Changchun (43.89 N, 125.32 E, northeastern China). Our results indicated there were significant geographic variations in diapause of L. striatellus. With the original latitude of the populations increased, higher diapause incidence and longer critical photoperiod were exhibited. The critical photoperiod of Jiangyan and Changchun populations were approximately 12h 30min and 13h at 20 C, and 11h and 11h 20min at 27 C, respectively. The considerable geographic variations in nymphal diapause of L. striatellus reflect the adaptation in response to a variable environment.

Keywords： Laodelphax striatellus diapause geographic variation