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Euwallacea spp. (Coleoptera: Scolytidae) are polyphagous globally distributed invasive ambrosia beetles. One of the species was recently detected attacking Ricinus communis growing in Coffea canephora gardens in Uganda. This study was undertaken to: (a) determine the distribution, incidence, and relative abundance of Euwallacea sp. on R. communis in Uganda; (b) determine the influence of the presence of C. canephora on the incidence and abundance of Euwallacea sp. on R. communis; and (c) identify ambrosia fungus of Euwallacea sp. on R. communis. Five C. canephora farms with R. communis and five others with R. communis but without C. canephora were sampled in each of the six districts surveyed. Incidence of Euwallacea sp. on R. communis was measured, by inspecting the host trees in each farm for the presence or absence of the pest. Abundance of Euwallacea sp. on R. communis was estimated, by counting holes of Euwallacea sp. at the lower 1.7 m of R. communis stems. A fungus was isolated from galleries of Euwallacea sp. on R. communis and identified. Results show that Euwallacea sp. was present on R. communis in all districts surveyed, with 30–70% of the farms infested in each district and 5–28 holes of Euwallacea sp. found on each sampled stem of R. communis. Coffea canephora appeared to facilitate the infestation of R. communis by Euwallacea sp., although it did not seem to influence the multiplication of the insect inside the host. Cunninghamella echinulata appeared to be the ambrosia fungus associated with Euwallacea sp. Therefore, Euwallacea sp. is a threat to many economically important plants in Uganda that are known to be hosts of this pest. [ABSTRACT FROM AUTHOR]

We studied the seasonal population dynamics ofXylosandrus compactusonCoffea canephorafor 24 months from June 2013 to May 2015 at the National Coffee Research Institute, Mukono, Uganda. Every month, we randomly sampled 20 infested twigs from different coffee trees on each of three experimental blocks, and dissected them to count different stages ofX. compactus per twig. We recorded monthly mean temperature and total rainfall. Seasonal fluctuations in numbers of different life stages ofX. compactusinsideC. canephoratwigs over time were analysed with a general linear model. Ambient temperature and rainfall were used to predict changes in monthly mean counts by means of a multiple linear regression. The population ofX. compactusvaried significantly across months and its major peak occurred from May to August. This variability was poorly explained by prevailing weather conditions with only the number of dead females correlated negatively with mean monthly temperature. Therefore, it may be suitable to apply management interventions againstX. compactusonC. canephorain Uganda prior to May–August of each year to prevent the pest from attaining damaging levels. Further research is necessary to better understand the effect of weather variables on population dynamics of this insect pest. [ABSTRACT FROM PUBLISHER]

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 , s tudies on the biology of Plagiolepis sp., its mass rearing protocols and factors favoring its proliferation in the field are highly recommended . [ABSTRACT FROM AUTHOR]