Incidence of Erythrina gall wasp (Quadrastichus erythrinae Kim), an invasive insect pest on Erythrina spp., in major black pepper (Piper nigrum L.) growing areas of Kerala and Karnataka,

Abstract

Surveys were conducted to determine the incidence of Erythrina gall wasp (Quadrastichus erythrinae, EGW), an invasive insect pest on Erythrina spp., in major black pepper (Piper nigrum) areas of Kerala and Karnataka, India. From each garden, 15 trees were selected and the number of trees with symptoms of damage was recorded. The total number of branches available and numbers infested was also recorded to calculate the percentage of trees/twigs infested in each garden. The percentage of trees/twigs infested was also calculated for each taluk and district. The surveys indicated that the EGW was present in all the districts and taluks surveyed in Kerala and Karnataka. The pest infestation affected the growth of Erythrina standards resulting in the reduction in foliage and available shade for black pepper vines. In many gardens, the pest infestation led to Erythrina mortality resulting in the collapse of the entire canopy of black pepper vines. However, there were significant differences in the percentages of trees/twigs infested by the pest in various districts/taluks. The incidence and severity of damage caused by EGW significantly varied on various Erythrina spp. and also on various types of E. variegata. The rating of resistance/susceptibility of various species/types of Erythrina to EGW based on percentage of damaged twigs indicated that E. variegata (dense-thorn type) was moderately resistant and E. variegata (white-thorn type) was highly susceptible in the field. E. variegata (black-thorn type) and E. subumbrans were moderately susceptible to the pest in the field.