Occurrence and population dynamics of small brown planthopper, Laodelphax striatellus (Homoptera: Delphacidae) on spring sown maize in Punjab

The insect pest incidence on spring maize was studied on two hybrids under three plant protection conditions in three separate crop sets sown in end January, mid and end February during 2011 and 2012 at Ludhiana. Apart from shoot fly, Atherigona naqvii a key pest of spring sown maize, the high incidence of delphacid, the small brown planthopper, Laodelphax striatellus (Fallén) was observed for the first time in spring sown maize in the Punjab during spring 2011. The L. striatellus appeared in the 2^nd week of April and its population started declining in the 2^nd week of May. During 2011, the counts per sweep in end January, mid and end February sown crops varied from 0.86–131.06, 1.20–186.08 and 0.28–145.70 per sweep in comparison to 0.11–0.44, 0.06–1.15 and 0.06–1.49 per plant during the corresponding sown crop during 2012. The counts on hybrids and in different plant protection conditions did not differ significantly. The correlations of population counts of L. striatellus were negative with maximum (r = -0.14 to -0.52) and mean air temperature (r = -0.13 to -0.57). The coccinellids were also observed in correspondence to the higher population of L. striatellus. The sporadic incidence of L. striatellus on spring maize laid the emphasis on regular monitoring of insect biodiversity and its interaction with environmental factors in new cropping systems as the coccinellids coupled with high temperature were able to manage the L. striatellus without any insecticidal application.