Boric acid for suppression of the ant Anoplolepis tenella and effects on an associated scale insect pest Stictococcus vayssierei in cassava fields in the Congo Basin

The scale insect, Stictococcus vayssierei, is one of the major pests and constraints to cassava production in
the Congo Basin. It is frequently found associated with the ground nesting ant, Anoplolepis tenella, under
cassava plant. Amdro fire ant bait granules (contains 7.3 g/kg Hydramethylnon), borax and boric acid
solution were evaluated in the laboratory for toxicity against A. tenella colonies.Workers were exposed to
bait for ten days during primary screening and colonies for six weeks during secondary screening.
Mortality was recorded daily for each toxicant. In a field experiment, the effect of a 1% boric acid-sucrose
solution was evaluated on A. tenella and its impact on the density of S. vayssierei on cassava. Each of the
three toxicants displayed delayed toxicity with less than 15% mortality after the first day. In comparison
to Amdro and borax, the 1% boric acid-sucrose solution was more effective in killing ant workers. The
boric acid-sucrose solution reduced the numbers of workers and brood by 90% within 6 weeks. In the
field experiment, monthly ant and scale sampling showed significant reductions in ant density in treated
fields which resulted in a reduction of scale infestation on cassava. We recorded a 16% yield increase in
treated plots compared to control plots. These results outline the dependence of S. vayssierei survival on
A. tenella attendance and demonstrate that control of the ant in cassava fields can help in developing
control options for the scale insect pest in the Congo Basin.The scale insect, Stictococcus vayssierei, is one of the major pests and constraints to cassava production in
the Congo Basin. It is frequently found associated with the ground nesting ant, Anoplolepis tenella, under
cassava plant. Amdro fire ant bait granules (contains 7.3 g/kg Hydramethylnon), borax and boric acid
solution were evaluated in the laboratory for toxicity against A. tenella colonies.Workers were exposed to
bait for ten days during primary screening and colonies for six weeks during secondary screening.
Mortality was recorded daily for each toxicant. In a field experiment, the effect of a 1% boric acid-sucrose
solution was evaluated on A. tenella and its impact on the density of S. vayssierei on cassava. Each of the
three toxicants displayed delayed toxicity with less than 15% mortality after the first day. In comparison
to Amdro and borax, the 1% boric acid-sucrose solution was more effective in killing ant workers. The
boric acid-sucrose solution reduced the numbers of workers and brood by 90% within 6 weeks. In the
field experiment, monthly ant and scale sampling showed significant reductions in ant density in treated
fields which resulted in a reduction of scale infestation on cassava. We recorded a 16% yield increase in
treated plots compared to control plots. These results outline the dependence of S. vayssierei survival on
A. tenella attendance and demonstrate that control of the ant in cassava fields can help in developing
control options for the scale insect pest in the Congo Basin.The scale insect, Stictococcus vayssierei, is one of the major pests and constraints to cassava production in
the Congo Basin. It is frequently found associated with the ground nesting ant, Anoplolepis tenella, under
cassava plant. Amdro fire ant bait granules (contains 7.3 g/kg Hydramethylnon), borax and boric acid
solution were evaluated in the laboratory for toxicity against A. tenella colonies.Workers were exposed to
bait for ten days during primary screening and colonies for six weeks during secondary screening.
Mortality was recorded daily for each toxicant. In a field experiment, the effect of a 1% boric acid-sucrose
solution was evaluated on A. tenella and its impact on the density of S. vayssierei on cassava. Each of the
three toxicants displayed delayed toxicity with less than 15% mortality after the first day. In comparison
to Amdro and borax, the 1% boric acid-sucrose solution was more effective in killing ant workers. The
boric acid-sucrose solution reduced the numbers of workers and brood by 90% within 6 weeks. In the
field experiment, monthly ant and scale sampling showed significant reductions in ant density in treated
fields which resulted in a reduction of scale infestation on cassava. We recorded a 16% yield increase in
treated plots compared to control plots. These results outline the dependence of S. vayssierei survival on
A. tenella attendance and demonstrate that control of the ant in cassava fields can help in developing
control options for the scale insect pest in the Congo Basin.