Invasive Stink Bugs and Related Species (Pentatomoidea)

482 Invasive Stink Bugs and Related Species (Pentatomoidea)

10.6.2.2.3 Chemical Insecticides

In Cameroon and Kenya, first attempts to control Antestia bugs with synthetic insecticides were car-
ried out in the middle of the 1940s, by using broad spectrum dichlorodiphenyltrichloroethane (DDT)
(Thelu 1946, Le Pelley 1968). This insecticide quickly proved to be very efficient, but after a few
years, some problems emerged, particularly secondary population outbreaks of other coffee pests,
such as leaf-miners and mealybugs, which had been, until then, limited by high levels of parasit-
ism. In Cameroon, DDT was quickly abandoned in favor of hexachlorocyclohexane (HCH) and lin-
dane, its gamma isomer. Lindane was not used in Kenya because it was thought to taint coffee (Le
Pelley 1968). From the middle of the 1950s, organochlorine insecticides were replaced progressively
by organophosphates. Those organophosphates that were allegedly moderately toxic to humans were
recommended widely in Africa for decades for the control of Antestia bugs (McNutt 1979, Crowe and
Gebremedhin 1984). Some organophosphates, such as chlorpyrifos-ethyl, malathion, fenthion, and
fenitrothion, still are recommended and/or in use today for Antestia bug control. For example, a survey
conducted in the early 2010s in Kenya showed that the four most commonly used insecticides in cof-
fee farms were organophosphates, namely chlorpyrifos-ethyl, fenitrothion, diazinon, and dimethoate
(Mugo et al. 2011). The toxicity of organophosphates to humans and adverse effects on the environ-
ment are well known, and the use of most of them largely has been restricted, if not totally prohibited,
in temperate regions.
New molecules have been tested and recommended since the early 1990s. In Ethiopia, Chichaybelu
(1993) screened different insecticides for Antestia bug control and reported that two synthetic pyre-
throids, cypermethrin and lambda-cyhalothrin gave good results. Today, these two molecules also are
considered to be highly toxic for the environment, primarily because of toxicity to fishes. In Cameroon,
Mbondji Mbondji and Ngollo Dina (1992) conducted large field experiments to compare efficacy of
various insecticides. This study showed good ability of pyrethroids to control Antestiopsis intricata on
coffee (Table 10.3).
New neonicotinoid insecticides were recommended recently for pest control on coffee. In Rwanda,
for example, imidacloprid, a systemic insecticide was recommended for the control of Antestia bugs
starting in 2013 and showed a 3-month persistence and effectiveness in the field. An optimal timing of
spraying well ahead of harvest is recommended to avoid pesticide residues in coffee berries (N. D. T. M.
Rukazambuga, unpublished data).

TABLE 10.3

Comparison of Field Efficacy (in % of the Total Antestia Bug Population Killed) of Different Insecticides for

the Control of Antestiopsis intricata on Coffee in Cameroon (from Mbondji Mbondji and Ngollo Dina 1992)

Active Ingredient Group Dose (g/ha) Field Efficacy (%)

Lindane Organochlorine 320.0 95.3

Isoprocarb Carbamate 184.5 67.5

Propoxur Carbamate 184.5 94.8

Diazinon Organophosphate 455.0 41.3

Fenthion Organophosphate 1000.0 40.9

Chlorpyriphos-ethyl Organophosphate 750.0 94.3

Deltamethrin Pyrethroid 8.0 94.5

Alpha-cypermethrin Pyrethroid 24.0 97.4

Fenobucarb

+ Fenvalerate

Carbamate

+ Pyrethroid

375.0

+ 25.0

92.5

Fenitrothion

+ Cypermethrin

Organophosphate + Pyrethroid 360.0

+ 6.0

92.2

Fenitrothion

+ Lambda-cyhalothrin

Organophosphate + Pyrethroid 360.0

+ 5.0

98.0