429
© Springer Nature Switzerland AG 2020
B. R. Singh et al. (eds.), Climate Impacts on Agricultural and Natural Resource
Sustainability in Africa, https://doi.org/10.1007/978-3-030-37537-9_25
Economic Rationale of Using African
Weaver Ants, Oecophylla longinoda
Latreille (Hymenoptera: Formicidae)
for Sustainable Management of Cashew
Pests in Tanzania
Gration M. Rwegasira, Maulid M. Mwatawala, Rozalia G. Rwegasira,
Abdullah N. Rashidi, Nene Wilson, and William George
Abstract Cashew nut, Anacardium occidentale Linnaeus, is an important crop to
the African economy, contributing to livelihood of many families. It is among the
top foreign-currency-earning crops in East and West African countries. The crop is
attacked by several sucking pests that survive on multiple host plants. These
include: Pseudotheraptus wayi, Helopeltis anacardii, H. schoutedeni, and
Selenothrips rubrocinctus. Management of these pests is usually a challenge which
triggers irrational use of synthetic pesticides. Excessive use of pesticides concerns
human health and pollution in the environment. The use of African weaver ants,
Oecophylla longinoda, has presented an alternative to pesticides for sustainable
cashew pest management. The predator was found to be as highly effective
(P < 0.0001) as the recommended insecticide (Lambda cyhalothrin) (P < 0.0001)
in controlling cashew pests. The several economic analyses on the profitability of
the technology over the recommended pesticides by partial budgeting, marginal
rate of returns, benefit-cost ratio and net present value proved O. longionda to be
superior to pesticides. The partial budgeting indicated a net benefit of US$7.72 per
cashew tree by changing from insecticides to O. longinoda within two seasons.
G. M. Rwegasira (*) · M. M. Mwatawala
Department of Crop Science and Horticulture, Sokoine University of Agriculture,
Morogoro, Tanzania
e-mail: grwegasira@sua.ac.tz; mwatawala@sua.ac.tz
R. G. Rwegasira
Morogoro Region Administrative Secretariat, Morogoro Regional Secretariat, Morogoro,
Tanzania
A. N. Rashidi
Research Ministry of Agriculture, Natural Resources, Livestock and Fisheries,
Pemba, Tanzania
N. Wilson
TARI Naliendele, Mtwara, Tanzania
W. George
University of Dodoma (UDOM), Dodoma, Tanzania
© Springer Nature Switzerland AG 2020
B. R. Singh et al. (eds.), Climate Impacts on Agricultural and Natural Resource
Sustainability in Africa, https://doi.org/10.1007/978-3-030-37537-9_25
Economic Rationale of Using African
Weaver Ants, Oecophylla longinoda
Latreille (Hymenoptera: Formicidae)
for Sustainable Management of Cashew
Pests in Tanzania
Gration M. Rwegasira, Maulid M. Mwatawala, Rozalia G. Rwegasira,
Abdullah N. Rashidi, Nene Wilson, and William George
Abstract Cashew nut, Anacardium occidentale Linnaeus, is an important crop to
the African economy, contributing to livelihood of many families. It is among the
top foreign-currency-earning crops in East and West African countries. The crop is
attacked by several sucking pests that survive on multiple host plants. These
include: Pseudotheraptus wayi, Helopeltis anacardii, H. schoutedeni, and
Selenothrips rubrocinctus. Management of these pests is usually a challenge which
triggers irrational use of synthetic pesticides. Excessive use of pesticides concerns
human health and pollution in the environment. The use of African weaver ants,
Oecophylla longinoda, has presented an alternative to pesticides for sustainable
cashew pest management. The predator was found to be as highly effective
(P < 0.0001) as the recommended insecticide (Lambda cyhalothrin) (P < 0.0001)
in controlling cashew pests. The several economic analyses on the profitability of
the technology over the recommended pesticides by partial budgeting, marginal
rate of returns, benefit-cost ratio and net present value proved O. longionda to be
superior to pesticides. The partial budgeting indicated a net benefit of US$7.72 per
cashew tree by changing from insecticides to O. longinoda within two seasons.
G. M. Rwegasira (*) · M. M. Mwatawala
Department of Crop Science and Horticulture, Sokoine University of Agriculture,
Morogoro, Tanzania
e-mail: grwegasira@sua.ac.tz; mwatawala@sua.ac.tz
R. G. Rwegasira
Morogoro Region Administrative Secretariat, Morogoro Regional Secretariat, Morogoro,
Tanzania
A. N. Rashidi
Research Ministry of Agriculture, Natural Resources, Livestock and Fisheries,
Pemba, Tanzania
N. Wilson
TARI Naliendele, Mtwara, Tanzania
W. George
University of Dodoma (UDOM), Dodoma, Tanzania