Status of antestia bug (Antestiopsis spp.) (Hemiptera: Pentatomidae) in Arabica Coffee under smallholder farming inTanzania
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Date
2024
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Publisher
Sokoine University of Agriculture
Abstract
Coffee is an imperative cash crop grown in Tanzania for beverage
and household income generating activity. The crop is grown in the
vast and varying landscape of Tanzania. Around 17 out of 26
Regions in Tanzania mainland grow coffee. Both Arabica and
Robusta coffee are grown in Tanzania. Tanzania is the third largest
producer of coffee in Africa after Ethiopia and Uganda, contributing
about one percent of the world`s coffee and ranking the 15th largest
coffee producing country in the world. Close to 90 percent of
Tanzanian coffee is produced by some 450 000 small families
operations on 265 000 hectares of land of which 120 000 are in the
Robusta growing areas of Kagera. The remaining ten percent of
coffee is grown by larger producers (Estates). The production and
trade in coffee contributes indirectly to the incomes of roughly seven
percent of Tanzania`s 60 million population. Arabica coffee
production in Tanzania accounts for 70% of the total coffee
produced in the country. The giant Arabica coffee producing
Regions in Tanzania are Kilimanjaro, Ruvuma and Songwe.
Coffee is Tanzania`s second largest export cash crop, accounting
for 24% of the country's total foreign exchange earnings after
Tobacco. Coffee export has generated about USD 100 million per
year over the past 15 years. In the 2018/2019 coffee season,
Tanzania exported a total of 68,147 MT of green coffee beans, with
Japan accounting for 34% of this volume, Italy 18%, Germany 11%,
Belgium 10% and the USA 10%. Despite these admirable facts
coffee production is constrained by abiotic and biotic factors.
Recently smallholder Arabica coffee farmers reported the presence
of pentatomid, variegated bugs which destructs all the vegetative
and fruiting part of coffee tree, likewise, Tanzania Coffee Board
reported about stagnated coffee production. These problems were
allied with the presence of the Antestia bug in coffee fields. The
Antestia bug (Antestiopsis spp.) has been mentioned among the
major pests of coffee in Tanzania. The pest has not been
extensively studied creating a huge knowledge gap about status. Knowledge on the Antestia bugs abundance and their species is
lacking. This study aimed at bridging that gap by establishing the
Antestia bug status to enable farmers, extension officers and
decision makers to have appropriate knowledge for developing
suitable management strategies and options for managing the pest.
The studies were carried out in three major Arabica coffee producing
regions namely; Kilimanjaro, Ruvuma and Songwe. Diagnostic
surveys were conducted through a multistage sampling method
used to select Districts and farms to be studied. In each Region; two
Districts were selected in which three villages were selected. Twenty
smallholder coffee farms were subsequently randomly selected in
each Village for the study. In each farm numbers of coffee trees
were selected according to specific objectives. A total of 360 farms
(120 from each region) were selected each with 64 coffee trees that
were visited for data collection in 12 months. Thus, a total of 23,040
coffee trees were used for the study. To determine the Antestia bug
species and abundance in the three Regions visual physical counts
were adopted coupled with sampling of Antestia bug specimens
every month. Using the available identification key, the collected
Antestia bugs (Antestiopsis spp.) were identified in the field based
on morphological features. Specimens (nymphs) that were difficult to
identify up to species level were collected in perforated bottles and
reared at Tanzania Coffee Research Institute (TaCRI) to allow full
development of their colors and strips on the pronotum and
scutellum. Aided by literature, the identification of reared Antestia
bug was made possible coupled with confirmation of the species
expert at SUA and TPHPA in Arusha.
Obtained results established the existence of only one species of
Antestiopsis orbitalis Westwood with two subspecies namely
Antestiopsis orbitalis bechuana Kirkaldy and Antestiopsis orbitalis
ghesquiere Carayon exist. Of the 748.96 total number of specimens
collected 637.39 (85.10%) were A. orbitalis bechuana and 111.57
(14.90%) were A. orbitalis ghesquiere. The region-wise discretion of
pest abundance suggested contribution of 62.44%, 26.90% and
10.65% by Kilimanjaro, Ruvuma and Songwe Regions respectively. The canopy shade intensity played a significant role on the
abundance of Antestia bugs. A statistically highly significant
(P<0.001) difference was established on the Antestia bugs, with the
dense shade canopy having higher pest population than the
sparsely shaded ones. Pearson's linear correlation analysis of
Antestia bug damage indices suggested a positive relationship
between dense shade canopy and Antestia bug damage on foliage,
flowers and fruits incidences and severities.
Likewise, the coffee fruiting phenology had a significant (p<0.001)
effect on bug density. The finding provided insights into the species,
abundance and distribution of Antestia bugs on Arabica coffee in
Tanzania. Furthermore, the incidence and severity of Antestia bug
(Antestiopsis spp.) was determined. Manifestation of Antestia bug
damage through symptoms and signs were used to gauge the pest
incidences and severity based on the established scales. Results
suggested that all Regions were infested by Antestia bugs albeit at
varied intensities with the highest incidence and severity being in
Kilimanjaro both in dense and sparse shade locations, where the
average bugs number per tree was 4.29, 3.25, average incidence of
foliage (39.95%, 31.3%), flowers (45.03%, 33.15%), and fruits
(56.78%, 43.08%) and average severity was foliage (1.99, 1.55),
flower (2.26, 1.66) and fruits severity (2.96, 2.06) respectively. In
Kilimanjaro, the maximum number of Antestia bugs, incidence and
severity recorded was 12.4, 100%, and 5 respectively. The two other
regions; Ruvuma and Songwe had relatively low numbers, incidence
and severity of Antestia bug. The lowest counts were established in
Songwe Region at Ileje District with abundance, incidence and
severity of 0.01, 0, 0 score respectively. Dense shade had the
highest Antestia bug damage incidence than sparse shade canopy
(p<0.05).
Conclusively, the current study shaded insights into the species,
incidence and severity of Antestia bugs on Arabica coffee fields as
well as the influence of canopy shades and fruiting phenology on the
pest in Tanzania. The study possibly escalates the necessity to
understand the effects of shade, and fruit phenology in the buildup of Antestia bug population in the coffee field for development of
effective management options. Furthermore, the study provides a
clear picture of critical time for controlling Antestia bugs through
intervention on the fruit phenology during which increase of the
Antestia bugs to damage the crop is stimulated. Although the pest is
omnipresent in all surveyed regions, Kilimanjaro was the worst
affected while Songwe was the least affected.
Concerted efforts to manage the pests are highly advised to
minimize the losses caused by the alarming population density of
the pest on coffee crops. Education to smallholder coffee farmers on
pest monitoring, canopy shade management, use of pest resistant
improved varieties and rational spray of insecticides in the IPM-
based approach is advised. Further studies on naturally existing
natural enemies that may be used for biological control may be over-
emphasized.
Description
Dissertation
Keywords
Antestia bug (Antestiopsis spp.), Hemiptera: Pentatomidae, Arabica Coffee, Smallholder farming, Tanzania