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Egonyu J.P.,National Coffee Research Institute | Kucel P.,National Coffee Research Institute | Kagezi G.,National Coffee Research Institute | Kovach J.,Ohio State University | And 4 more authors.
African Entomology | Year: 2015

The white coffee stemborer, Monochamus leuconotus (Pascoe, 1869) (Coleoptera: Cerambycidae), is a key insect pest of Arabica coffee, Coffea arabica in Africa. We tested the effect of C. arabica varieties and stem treatment by wrapping, smoothening and insecticidebanding on the incidence of this pest and yield of the crop. The pest incidence was consistently lower on C. arabica variety KP423 than on two other varieties KP162 and SL28, suggesting that KP423 is less susceptible to M. leuconotus. Correspondingly, KP423 yielded almost five-fold more coffee cherries than the other two varieties. Stem-smoothening and insecticide-banding did not significantly influence the incidence of M. leuconotus, while stemwrapping occasionally increased the incidence of the pest. None of the stem treatments influenced the yield of coffee cherries. These results support cultivation of KP423 in areas prone to M. leuconotus, and offer prospects for identification of resistance genes against the pest. The results, however, contradict previous reports that stem-smoothening and stem-wrapping can suppress M. leuconotus.

Egonyu J.P.,National Coffee Research Institute | Baguma J.,National Coffee Research Institute | Ogari I.,National Coffee Research Institute | Ahumuza G.,National Coffee Research Institute | And 7 more authors.
Biological Control | Year: 2015

The coffee twig borer (Xylosandrus compactus Eichhoff) is an economically important pest of Robusta coffee in Uganda. In this study, a formicid ant, Plagiolepis sp., found in X. compactus galleries at the National Coffee Research Institute in 2014, was evaluated for potential to provide biological control of the twig borer. In a Petri dish feeding bioassay, Plagiolepis sp. preyed on all stages of X. compactus except adults within 24 h. In field bioassays where Plagiolepis sp. was caged over X. compactus-infested twigs for one month in muslin sleeves, the predator colonized pest galleries and eliminated all life stages of X. compactus as opposed to the untreated control. In a survey of Plagiolepis sp. in 11 districts of eastern, central and western Uganda, the ant was present in nine of the districts with highest levels of colonization (over 18%) of X. compactus galleries in Luwero district in the central Lake Victoria crescent agroecological zone. These results appear to confirm that Plagiolepis sp. is an indigenous predator of X. compactus which invades pest galleries and feeds on the pest in the field. For prospective utilization of Plagiolepis sp. as a biological control agent of X. compactus, studies on the biology of Plagiolepis sp., its mass rearing protocols and factors favoring its proliferation in the field are highly recommended. © 2015 Elsevier Inc.

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