Author : Abdul Razak B. Hj Mohd. Nordin

Summary : Harumanis mango in Perlis suffered from the outbreak of leafhoppers, Idioscopus nitidulus Walk. in 1986 and 1987. The laboratory and field experiments were conducted to investigate some aspects of the biology of mango leafhoppers, I. nitidulus Walk., an important pest of mango flowers and shoots in South East Asia. The synchrony of insect population with the phenology of the plant was also studied. The adults were found to survive on mature leaves in the absence of flowers and shoots. However, reproduction occurred during the onset of flowering and young shoot development. The fluctuating patterns in the abundance of hoppers coincided with the availability of flower panicles and developing shoots. The number of hoppers appeared unaffected by the heights and positions of flower panicles in the tree. The developmental period of male and female hopper on flower panicle were found to be 13.77 +/- 0.25 days and 13.50 +/- 0.60 days, respectively. The developmental periods of male and female hopper reared on shoot of Harumanis were 15.07 +/- 0.81 days and 17.10 +/- 0.77 days, respectively. The mean incubation periods on flower panicles and shoots were 3.85 +/- 2.00 days and 3.76 +/- 2.00 days, respectively. The hoppers were able to survive on all mango varieties but had varying developmental periods. The shortest developmental time was found with the hoppers reared on Dam Dork Mai; 12.10 +/- 0.42 days and 12.71 +/- 0.75 days for male and female, respectively. There were four instars when reared on harumanis and Nam Dork Mai, whereas five instars were found with those reared on Sala and Apple mango. Hoppers reared on the flower panicles of Harumanis mangoes produced an average of 277.1 +/- 109.6 eggs with percentage hatchability of 90.2 +/- 8.4 percent, while those on vegetable shoots had an average of 149.5 +/- 56.6 eggs and percentage hatchability of 54.8 +/- 21.8 percentage. Studies on the hopper's mating behaviour showed that single mated females produced an average of 175.9 +/- 71.7 eggs.