Management of Blue Gum Chalcid (Leptocybe invasa Fisher & La Salle (Hymenoptera: Eulophidae) infestation on different species of Eucalyptus trees in Kalu district, Eastern Amhara, Ethiopia

Abstract

The recently introduced chalcid pest known as the Blue Gum Chalcid (BGC) (L. invasa) is currently one of the major insect pests of Eucalyptus tree species in Ethiopia. A research was conducted in Kalu district, South Wollo, Eastern Amhara, Ethiopia, the main objective of which was to evaluate the effectiveness of synthetic insecticides, hoeing and water showering options against BGC. Two parallel experiments were conducted in the nursery and in the field. Eucalyptus camaldulensis, E. saligna, E. viminalis, E. citrodora and E. globulus were considered in the nursery at Chorisa. One to three-year old E. camaldulensis plantations were considered at Tikuro plantation site. At the nursery, seven treatments and at the field 10 treatments were tested in a Randomized Complete Block Design (RCBD) with three replications from January to February 2019, where treatments were applied 3 times at 15-day intervals. Results from the 1-year old plantation revealed that application of Dimethoate 40%, Carbofuran 3G and Dimethoate 40% + hoeing followed by Carbofuran 3G + hoeing and Thiamethoxam 25WG were effective in checking the BGC insect pest infestation. In the 3-year old plantation, Carbofuran 3G significantly reduced the infestation followed by Dimethoate 40%. At the nursery, Dimethoate 40% and Carbofuran 3G reduced the infestation followed by Carbofuran 3G + Dimethoate 40% and thiamethoxam 25WG. Water showering and hoeing did not reduce BGC infestation in all cases at the field plantations. Treatments that received synthetic insecticides and hoeing had low infestation, the reason for which was the insecticide rather than the hoeing, because the hoeing alone didn’t differ from the control. Application of Dimethoate 40% and Carbofuran 3G with hoeing and weeding activities were recommended to manage and limit BGC insect pest infestations.