Shade improves the water status of the soil because

Shade
improves the water status of the soil because of reduced
evapotranspiration in the agro-ecosystem and an increased ground
cover (mulch) and decreased abundance of weeds [61].
In this study we combined entomological assessment of a key
coffee pest with 82 years of climate data, as well as spatial and
demographic data, to assess the impact of GEC on the
economically most important agricultural commodity and to test
the utility of an adaptation strategy that is easy to implement,
hence suitable for the millions of small-scale coffee growers in the
developing world. Our study illustrates the remarkable changes in
human population density, vegetation cover and land-use, local
climate and the interconnections of all these factors in the peri-
urban environment of an East African capital over nearly 100
years. Our study not only demonstrates the urgent need to study
climate-change at regional spatial scales, but also the importance
of local factors. Moreover, we were able to illustrate how these
effects can affect agricultural productivity, mainly through their
impacts on higher trophic levels like insect herbivores. However,
we also showed that a relatively simple strategy, the introduction of
shade trees in coffee plantations, could markedly improve the
resilience of an agroecosystem, providing small-scale farmers in
Africa with a much-needed, easy to adopt, tool to safeguard their
livelihoods in a changing climate.
Materials and Methods
Study site
The study was conducted in a commercial coffee plantation in
Kiambu district (Central province), Kenya (Fig. 2 and Fig. S7). No
specific permits were required for the described field studies. Two
plots of Coffea arabica var. Ruiru 11 (planting density 1.82 6 1.82 m)
were selected; a shaded plot (65% canopy cover) (1 u 11 9 27.15 0 S;
36 u 49 9 23.03 0 E. altitude 1,722 m.a.s.l) with 300 coffee trees and 15
shade trees (two avocado ( Persea Americana L.), 1 mango ( Mangifera
indica L.) and 12 grevillea ( Grevillea robusta (A. Cunn.)), and a sun-
grown plot (10% canopy cover from bananas at one edge of the
plot) (1 u 11 9 24.22 0 S; 36 u 49 9 25.10 0 E. altitude 1,720 m.a.s.l) with
280 coffee trees. Canopy cover (% shade) was estimated visually
four times during the course of the study, both during the rainy
and dry season according to Teodoro et al. [67]. Trees in both
plantations were planted in January 1999, and both plantations
were under the same agronomic management. No H. hampei
control measures were used in either plot during the course of the
study.
Environmental Changes, Coffee and Insect Pests
PLOS ONE | 7 January 2013 | Volume 8 | Issue 1 | e51815

Data collection
Data on H. hampei infestation level were collected every two
weeks from June 2009 to June 2011. In both the shaded and the
sun-grown plots, 15 trees were randomly chosen at each
evaluation date. To assess H. hampei infestation level, two branches
per tree were selected. There, total number of berries and total
number H. hampei infested berries were counted. At each
evaluation date, all the infested berries from both plots were
individually collected and taken to the International Center of
Insect Physiology and Ecology ( icipe ) laboratories in Nairobi,
Kenya, for dissection. In the laboratory, numbers of live, dead and
absent H. hampei colonizing females (i.e., berries that had a
penetration whole in the exocarp but where the insect was not
present), the position of colonizing females inside the berries (see
below) and number of coffee berry borer life stages (i.e., eggs,
larvae, prepupae, pupae and adults) were assessed