Species composition and larval instar population structure of Scarabaeids in forestry in the Natal Midlands

Abstract

White grub is the common name of most scarabaeid larvae and some are considered ! as grubs of economic importance to agricultural crops. Expansion of forestry into previous croplands has resulted in some pests of previous agricultural crops becoming important in forestry. Field trials planted over three seasons, determined the mortality factors influencing the establishment of commercial eucalypt and black wattle plantations in the Natal Midlands. White grubs had the highest pest status. I Characteristic raster pattern was used to identify larvae as a particular morphospecies with the aid of the dissecting microscope. Head I capsule width pattern was used to determine the larval instars responsible for the damage. High incidences of seedling damage was recorded from December to April. Several morphospecies were found I damaging seedlings simultaneously. Morphospecies 1, 2, 3, 4, 5 and 6 were responsible for the damage but morphospecies 1, 2, 4 and 5 were the most predominant. First, second and third instar larvae were found damaging seedlings and ! they sometimes occurred simultaneously. Second and third instar larvae were the predominant larval instars.