Coffee Berry Borer Joins Bark Beetles in Coffee Klatch

Unanswered key questions in bark beetle-plant interactions concern host finding in species attacking angiosperms in tropical zones and whether management strategies based on chemical signaling used for their conifer-attacking temperate relatives may also be applied in the tropics. We hypothesized that there should be a common link in chemical signaling mediating host location by these Scolytids. Using laboratory behavioral assays and chemical analysis we demonstrate that the yellow-orange exocarp stage of coffee berries, which attracts the coffee berry borer, releases relatively high amounts of volatiles including conophthorin, chalcogran, frontalin and sulcatone that are typically associated with Scolytinae chemical ecology. The green stage of the berry produces a much less complex bouquet containing small amounts of conophthorin but no other compounds known as bark beetle semiochemicals. In behavioral assays, the coffee berry borer was attracted to the spiroacetals conophthorin and chalcogran, but avoided the monoterpenes verbenone and a-pinene, demonstrating that, as in their conifer-attacking relatives in temperate zones, the use of host and non-host volatiles is also critical in host finding by tropical species. We speculate that microorganisms formed a common basis for the establishment of crucial chemical signals comprising inter-and intraspecific communication systems in both temperate-and tropical-occurring bark beetles attacking gymnosperms and angiosperms.

Climate Change or Urbanization? Impacts on a Traditional Coffee Production System in East Africa over the Last 80 Years

Global environmental changes (GEC) such as climate change (CC) and climate variability have serious impacts in the tropics, particularly in Africa. These are compounded by changes in land use/land cover, which in turn are driven mainly by economic and population growth, and urbanization. These factors create a feedback loop, which affects ecosystems and particularly ecosystem services, for example plant-insect interactions, and by consequence agricultural productivity. We studied effects of GEC at a local level, using a traditional coffee production area in greater Nairobi, Kenya. We chose coffee, the most valuable agricultural commodity worldwide, as it generates income for 100 million people, mainly in the developing world. Using the coffee berry borer, the most serious biotic threat to global coffee production, we show how environmental changes and different production systems (shaded and sun-grown coffee) can affect the crop. We combined detailed entomological assessments with historic climate records (from 1929-2011), and spatial and demographic data, to assess GEC's impact on coffee at a local scale. Additionally, we tested the utility of an adaptation strategy that is simple and easy to implement. Our results show that while interactions between CC and migration/urbanization, with its resultant landscape modifications, create a feedback loop whereby agroecosystems such as coffee are adversely affected, bio-diverse shaded coffee proved far more resilient and productive than coffee grown in monoculture, and was significantly less harmed by its insect pest. Thus, a relatively simple strategy such as shading coffee can tremendously improve resilience of agro-ecosystems, providing small-scale farmers in Africa with an easily implemented tool to safeguard their livelihoods in a changing climate.

Thermal Tolerance of the Coffee Berry Borer Hypothenemus hampei: Predictions of Climate Change Impact on a Tropical Insect Pest

Coffee is predicted to be severely affected by climate change. We determined the thermal tolerance of the coffee berry borer, Hypothenemus hampei, the most devastating pest of coffee worldwide, and make inferences on the possible effects of climate change using climatic data from Colombia, Kenya, Tanzania, and Ethiopia. For this, the effect of eight temperature regimes (15, 20, 23, 25, 27, 30, 33 and 35 degrees C) on the bionomics of H. hampei was studied. Successful egg to adult development occurred between 20-30 degrees C. Using linear regression and a modified Logan model, the lower and upper thresholds for development were estimated at 14.9 and 32 degrees C, respectively. In Kenya and Colombia, the number of pest generations per year was considerably and positively correlated with the warming tolerance. Analysing 32 years of climatic data from Jimma (Ethiopia) revealed that before 1984 it was too cold for H. hampei to complete even one generation per year, but thereafter, because of rising temperatures in the area, 1-2 generations per year/coffee season could be completed. Calculated data on warming tolerance and thermal safety margins of H. hampei for the three East African locations showed considerably high variability compared to the Colombian site. The model indicates that for every 1 degrees C rise in thermal optimum (T(opt)), the maximum intrinsic rate of increase (r(max)) will increase by an average of 8.5%. The effects of climate change on the further range of H. hampei distribution and possible adaption strategies are discussed. Abstracts in Spanish and French are provided as supplementary material Abstract S1 and Abstract S2.