The Antestia Bug Complex in Africa and Asia 483
10.6.2.2.4 Organization of Chemical Control
Insecticide sprayings may be the only efficient control measure to stop an Antestia bug outbreak that
could lead to high crop loss. However, chemical control has some disadvantages, besides cost and human
and environment health issues. Ideal insecticide use requires sophistication in rational use that may be
absent is some locations. Economic thresholds have been fixed for Antestia bug infestations by research
institutions to help coffee farmers and private companies organize chemical sprayings. Economic thresh-
old is that pest density (given in number of insects per tree) that likely will cause crop loss that exceeds
the cost of chemical control. The bugs can cause considerable damage even when present in relatively
small numbers, and economic thresholds usually are low for Antestia bugs. They vary from a country
to country and sometimes between regions of the same country. For example, in Kenya, in East of Rift
Valley, a mean of 2 bugs per coffee tree is considered to have attained the economic injury level. In West
of Rift, which is a wetter area, economic thresholds are exceeded when more than 1 bug per tree is pres-
ent (Mugo et al. 2011). In Uganda, Rwanda and Burundi, sprayings are recommended if mean density
exceeds 1 bug per tree (McNutt 1979, Leblanc 1993). In Ethiopia, 5 bugs per tree is the current economic
threshold for chemical control (Crowe and Gebremedhin 1984).
A method for a quick and cheap monitoring of Antestia bug populations on coffee has been available
since the 1930s and used for decades, with some improvements. The method, commonly referred to as
“pyrethrum test,” consists of spraying a determined number of coffee trees with pyrethrum and counting
the Antestia bugs that fall on plastic sheets that were spread on the ground around the trees before spray-
ing (Le Pelley 1968). The number of trees to be sprayed and the spraying frequency for a good population
assessment were controversial. A study conducted in the 1990s in Burundi statistically confirmed that 10
trees per plantation was the good sampling size for optimal results (Bouyjou and Cilas 1992).
10.6.2.3 Biological Control
10.6.2.3.1 Parasitism Rate and Parasitoid Value
As discussed in Section 10.4, Antestia bugs are hosts for a wide range of parasitoids, especially egg para-
sitoids. Good parasitism rates indicate these species are promising agents for biological control. Greathead
(1966b) reviewed the literature on Antestia bug parasitoids in Africa and obtained information on parasit-
oid life history and their potential value in biological control. His main points are summarized as follows:
(1) egg parasitism was always high regardless of the area studied, with rates ranging from 40 to 95%;
the predominant egg parasitoid species was Telenomus (= Asolcus) sechellensis; (2) nymphal parasitism
reached 50% and was due to Aridelus spp., with promising perspectives in some areas; and (3) adult para-
sitism due to Bogosia spp. (Tachinidae) and Corioxenos antestiae (Strepsiptera) usually did not exceed
10%, and, therefore, these parasitoids were not considered to be good candidates for biological control.
In Rwanda and Burundi, parasitoids have been found to reduce the Antestia population by 68%
(Foucart and Brion 1959, Brion 1963). In these countries, egg parasitism was due mainly to Telenomus
sechellensis, Gryon fulviventre, and Trissolcus mopsus, and, to a lesser extent Anastatus antestiae and
Acroclisoides africanus. The adult tachinid parasitoid Bogosia rubens also was present, but had a lim-
ited impact (11.5% parasitism rate) (Foucart and Brion 1959, Brion 1963).
A recent study conducted in Ethiopia by Abebe (1999) reported 45-50% egg parasitism by three spe-
cies, namely Trissolcus (= Asolcus) suranus, Gryon fulviventre (= Hadronotus antestiae) and Anastatus
antestiae, with T. suranus being the most abundant. On the other hand, Corioxenos antestiae and
Bogosia rubens contributed only 5% of Antestia bug parasitism in this study.
10.6.2.3.2 Parasitism Seasonality
In Cameroon, a study conducted in the main area of Arabica coffee production showed high rates of
egg parasitism of Antestiopsis intricata due to five parasitoid species Telenomus sechellensis, Trissolcus
mopsus, Gryon fulviventre, Pediobius sp., and Anastatus antestiae (Mbondji Mbondji 2001). In the
Foumbot location in the West region of Cameroon, a large monthly collection and laboratory rearing of