Forest Landscapes Influence Black Coffee Twig Borer, Xylosandrus compactus Eichoff Infestation in Adjacent Robusta Coffee Gardens: Management Implications

The black coffee twig borer, Xylosandrus compactus Eichhoff (Coleoptera: Curculionidae) is one of the major constraints facing the Robusta coffee industry in Uganda since its advent in 1993. Once in a new location, it spreads rapidly within and between coffee gardens. This is mainly driven by favorable climatic conditions, presence of alternate hosts, limited management by farmers and the fact that natural enemies present in the new eco-systems are yet to adapt to it. Its management is difficult due to its cryptic nature of spending almost its entire lifespan is spent inside the host galleries. X. compactus has >200 host plant species worldwide, whereas, >50 plant species have been proven to be hosts in Uganda including: - commercial and ornamental crops as well as shade and forest trees/shrubs. In addition, these trees provide shady conditions that promote infestation of this pest. A study was therefore conducted in central Uganda to elucidate the effects of forest landscapes on the distribution of X. compactus damage in the adjoining Robusta coffee gardens. New alternate host plants of X. compactus within the forests were also documented. This could inform further development of its management strategy Uganda. Results showed that the percentage of coffee suckers and primary branches infested by X. compactus increased significantly (p=0.0171 and p=0.0001 respectively) with increasing distance away from the forest edge towards the center of the forest. The percentage infestation however decreased significantly (p<.0001 and p=0.2367) for suckers and primary branches respectively with increasing distance from forest edge towards the center of the adjoining coffee plantation. These observations are explicable by the fact that the forest acts as a source of X. compactus infestation for the adjoining coffee plantation, commonly referred to as “pull-effect”, the nearer the coffee trees to the forest the greater the initial infestation. Nine alternative host plant species, namely: - charcoal tree Trema orientalis Linn. Blume (Ulmaceae), African celtis, Celtis mildbraedii Engl. (Ulmaceae), bastard-wild-rubber, Funtumia africana Benth. Stapf (Apocynaceae), velvet-leaved combretum, Combretum molle R. Br. Ex. G. Don. Engl & Diels (Combretaceae) and five unidentified tree species were recorded in the forest. These tree/shrub species have been added to the existing inventory of X. compuctus alternate host plants in Uganda. This study clearly demonstrates the influence of natural forest landscapes on incidence and damage of X. compactus infestations in adjoining Robusta coffee gardens. The results suggest that farmers with coffee gardens neighboring forested landscapes should take into account managing the source of X. compactus infestation from natural forests as well as that on coffee and alternate hosts in their gardens. NARO-BCTB traps should therefore be deployed along the forest boundaries in order to intercept the X. compactus from the forests before they enter the coffee gardens. However, there is need to fully elucidate the interactions between the ‘pull-effect’ and landscape and aggregation factors that influence incidence and damage of X.  compactus attacks so as to inform its management

Towards a collaborative research: A case study on linking science to farmers' perceptions and knowledge on Arabica coffee pests and diseases and its management

The scientific community has recognized the importance of integrating farmer's perceptions and knowledge (FPK) for the development of sustainable pest and disease management strategies. However, the knowledge gap between indigenous and scientific knowledge still contributes to misidentification of plant health constraints and poor adoption of management solutions. This is particularly the case in the context of smallholder farming in developing countries. In this paper, we present a case study on coffee production in Uganda, a sector depending mostly on smallholder farming facing a simultaneous and increasing number of socio-ecological pressures. The objectives of this study were (i) to examine and relate FPK on Arabica Coffee Pests and Diseases (CPaD) to altitude and the vegetation structure of the production systems; (ii) to contrast results with perceptions from experts and (iii) to compare results with field observations, in order to identify constraints for improving the information flow between scientists and farmers. Data were acquired by means of interviews and workshops. One hundred and fifty farmer households managing coffee either at sun exposure, under shade trees or inter-cropped with bananas and spread across an altitudinal gradient were selected. Field sampling of the two most important CPaD was conducted on a subset of 34 plots. The study revealed the following findings: (i) Perceptions on CPaD with respect to their distribution across altitudes and perceived impact are partially concordant among farmers, experts and field observations (ii) There are discrepancies among farmers and experts regarding management practices and the development of CPaD issues of the previous years. (iii) Field observations comparing CPaD in different altitudes and production systems indicate ambiguity of the role of shade trees. According to the locality-specific variability in CPaD pressure as well as in FPK, the importance of developing spatially variable and relevant CPaD control practices is proposed. (Résumé d'auteur

Field-based Evidence of the Black Coffee Twig Borer infesting Maesopsis eminii in Coffee Agro-systems in Kiboga District, Uganda

Despite Ugandan coffee farmers’ preference for Maesopsis eminii as a shade tree, the species is an alternate host for the black coffee twig borer, Xylosandrus compactus (Eichhoff)—a major insect pest of coffee in the country. Wilting and drying of leaves and branches of young M. eminii trees (<5 m tall) observed in Kiboga District, Uganda. The branches were trimmed off the trees, separated into primary and secondary branches and then the percentage of those possessing characteristic X. compactus entry holes determined separately. Additionally, the number of entry holes on both primary and secondly branches was established to determine the extent of damage of X. compactus. X. compactus characteristic holes were observed on both primary and secondary branches of M. eminii - percentage of branches having entry holes and the number of entry holes higher on primary than secondary branches. Dissecting the branches at the entry holes revealed various life stages of X.compactus in the gallery, proving that the damage was due to the pest. Presence of this pest on trees that are inter-planted in the coffee agroforestry systems presents a dilemma in managing it. Therefore, research should be geared towards designing management strategies for the pest in the coffee agroforestry systems. In the meantime, farmers should always trim-off and burn all infested parts from coffee and other plants inter-planted in it

Knowledge Gaps between Farmers and Scientists: A Case Study on Perceptions and Knowledge on Arabica Coffee Pests and Diseases of Mount Elgon, Uganda

In this paper, we present a case study on coffee production in Uganda, a sector depending mostly on smallholder farming facing a simultaneous and increasing number of socio-ecological pressures. The objectives of this study were (i) to examine and relate FPK on Arabica Coffee Pests and Diseases (CPaD) to altitude and the vegetation structure of the production systems; (ii) to contrast results with perceptions from experts and (iii) to validate results with field observations, in order to identify constraints for improving information flow from scientists to farmers and back. The presented study was conducted in the framework of the BMZ-funded project entitled “Trade-offs and synergies in climate change adaptation and mitigation in coffee and cocoa systems”. The GOAL of the project is the adaptation of vulnerable coffee/cocoa-based farming systems to climate change that combine improving farmer income and system resilience with contributing to climate change adaptation and mitigation. The PURPOSE is the adoption of new production technologies in cocoa/coffee-based smallholder farming systems that (i) are adapted to climate change, (ii) contribute to climate change mitigation, (iii) sustain the natural resource base, and (iv) respond to livelihoods needs and constraints.</P

Study area.

<p>Location of the study area within the Ugandan Mount Elgon area and the districts of the study area (Bulambuli, Kapchorwa and Sironko) with indicated sub counties and three altitude ranges determined by means of a cluster analysis.</p

CPaD control practices proposed by experts.

<p>CPaD control practices proposed by experts.</p

Comparison of perceived impact scores between altitude ranges.

<p>Comparison of perceived impact scores between altitude ranges.</p

List of questions posed to the farmers.

<p>List of questions posed to the farmers.</p