431
through in cashew pest management strategies. The use of weaver ants was found
to be comparatively as effective as insecticides, yet cheaper in cost and very sustainable. Detailed below are insights into the application of weaver ant technology
on cashew pests based on the experiences in Tanzania.
2 Insect Pests as Cashew Production Constraints
Yield statistics suggest Africa to contribute half of the world production of cashew
(FAOSTAT 2018). But comparatively, the yield per unit area attained in Asian countries is ten times that of Africa. The low production per unit area in SSA is attributed
to damage and losses caused by insect pests and diseases at different growth stages
(Maruthadurai et al. 2012). The compensatory value attained in the African continent is attributed to the extensiveness of the areas under production of the crop.
Biotic constraints, particularly saps sucking insect pests and the fungal diseases
(powdery mildew disease), Oidium anacardii (Noack), have largely contributed to
the low yields (NARI 2010). These pests can lead to 60% to 100% yield losses,
depending on the variety, location and season (Agboton et al. 2013; ICIPE 2011).
Insect pests that attack cashew nut crops in SSA are varied with complex ecologies (Hammed et al. 2008). The crop is attacked by more than 60 different insect
species throughout its growth period (Dwomoh et al. 2008). Although there are different species of cashew pests in different SSA countries, variations are limited due
to similarities in ecology and weather parameters. Thus, common pests in any
cashew-growing country in Africa would be the same. The most important insect
pests in SSA include the coreid coconut bug, Pseudotheraptus wayi Brown
(Hemiptera: Coreidae); the mirid bugs, Helopeltis anacardii Miller and H. schoutedeni Reuter (Hemiptera: Miridae) and thrips, Selenothrips rubrocinctus (Giard).
These are often the dominant species which suck and feed on new tender shoots,
flower panicles and young developing fruits (NARI 2010). The extent of damage
caused by these pests varies with location, variety and management practices
(Dwomoh et al. 2009).
3 Management of Cashew Pests
The high devastation level and the knowledge that existed before 2016 necessitated
a total reliance on calendar spray of insecticides to control cashew pests. Lambda
cyhalothrin and its generics as well as endosulfan have been the lone tool that
cashew growers depend on (CABI 2005; Martin et al. 1997; Mitchell 2000; NARI
2010). Chemical control remains one of the well-known control measures among
growers, but the recently confirmed effectiveness of O. longinoda on cashew pests
provides the best alternative (NARI 2010). Smallholder farmers are seeking alternative technologies like the use of weaver ants that reduce production costs and/or
increase yields. The negative effects associated with irrational use of insecticides
Economic Rationale of Using African Weaver Ants, Oecophylla longinoda…
through in cashew pest management strategies. The use of weaver ants was found
to be comparatively as effective as insecticides, yet cheaper in cost and very sustainable. Detailed below are insights into the application of weaver ant technology
on cashew pests based on the experiences in Tanzania.
2 Insect Pests as Cashew Production Constraints
Yield statistics suggest Africa to contribute half of the world production of cashew
(FAOSTAT 2018). But comparatively, the yield per unit area attained in Asian countries is ten times that of Africa. The low production per unit area in SSA is attributed
to damage and losses caused by insect pests and diseases at different growth stages
(Maruthadurai et al. 2012). The compensatory value attained in the African continent is attributed to the extensiveness of the areas under production of the crop.
Biotic constraints, particularly saps sucking insect pests and the fungal diseases
(powdery mildew disease), Oidium anacardii (Noack), have largely contributed to
the low yields (NARI 2010). These pests can lead to 60% to 100% yield losses,
depending on the variety, location and season (Agboton et al. 2013; ICIPE 2011).
Insect pests that attack cashew nut crops in SSA are varied with complex ecologies (Hammed et al. 2008). The crop is attacked by more than 60 different insect
species throughout its growth period (Dwomoh et al. 2008). Although there are different species of cashew pests in different SSA countries, variations are limited due
to similarities in ecology and weather parameters. Thus, common pests in any
cashew-growing country in Africa would be the same. The most important insect
pests in SSA include the coreid coconut bug, Pseudotheraptus wayi Brown
(Hemiptera: Coreidae); the mirid bugs, Helopeltis anacardii Miller and H. schoutedeni Reuter (Hemiptera: Miridae) and thrips, Selenothrips rubrocinctus (Giard).
These are often the dominant species which suck and feed on new tender shoots,
flower panicles and young developing fruits (NARI 2010). The extent of damage
caused by these pests varies with location, variety and management practices
(Dwomoh et al. 2009).
3 Management of Cashew Pests
The high devastation level and the knowledge that existed before 2016 necessitated
a total reliance on calendar spray of insecticides to control cashew pests. Lambda
cyhalothrin and its generics as well as endosulfan have been the lone tool that
cashew growers depend on (CABI 2005; Martin et al. 1997; Mitchell 2000; NARI
2010). Chemical control remains one of the well-known control measures among
growers, but the recently confirmed effectiveness of O. longinoda on cashew pests
provides the best alternative (NARI 2010). Smallholder farmers are seeking alternative technologies like the use of weaver ants that reduce production costs and/or
increase yields. The negative effects associated with irrational use of insecticides
Economic Rationale of Using African Weaver Ants, Oecophylla longinoda…