Journal of Pest Science
Are GrainPro Cocoons™ an eective alternative to conventional
phosphine fumigation in large‑scale control of stored‑maize insect
A. A. Chigoverah
· B. M. Mvumi
· C. Muchechemera
· J. V. Dator
Received: 6 September 2017 / Revised: 3 April 2018 / Accepted: 26 May 2018
© Springer-Verlag GmbH Germany, part of Springer Nature 2018
There is a dearth of comprehensive data regarding the performance of large-scale hermetic maize storage in sub-Saharan
Africa (SSA) as an alternative to the sole and widely used phosphine fumigant. Trials were therefore conducted at three sites
in Zimbabwe for up to 12 months to evaluate the performance of 20 tonne-capacity GrainPro Cocoons™ compared with
conventional phosphine fumigation practice. A split-plot experimental design was used consisting of two main plots, namely:
the cocoon and fumigated stack with three sub-plots being depth positions: top, middle and bottom. At each site, sampling
was conducted at setting-up and at termination. Samples were assessed for insect population, grain damage, weight loss,
germination and moisture content. There were no signiﬁcant diﬀerences between the main plots for grain damage, weight
loss, insect pest population/kg and germination after 4 months of storage. Hermetic storage was signiﬁcantly more eﬀective
than fumigation practice in preserving germination after 8 and 12 months; and in reducing grain damage, weight loss, and
insect population after 12 months of storage (P < 0.05). An economic analysis using the cocoon instead of conventional
fumigation, based on an incremental beneﬁt-cost ratio (BCR), showed no beneﬁt of the alternative when considering the local
retail price. However, the alternative was beneﬁcial with a BCR of 1.11 when import tariﬀs were removed from the initial
cost. These ﬁndings show that with supporting national policies, cocoons can be a cost-eﬀective alternative to phosphine
fumigation. Other environmental and human safety gains of using cocoons are priceless.
Keywords Strategic grain reserves · Hermetic storage · Prostephanus truncatus · Sitophilus zeamais · Cryptolestes
ferrugineus · Incremental beneﬁt-cost ratio · Environmental and human safety
Commercial storage pest control is dependent on phos-
phine despite human and environmental safety concerns
and pest resistance problems.
Performance evidence of large-scale hermetic cocoon
maize storage in sub-Saharan Africa is scarce.
Eﬃcacy of cocoons was evaluated compared with the
conventional phosphine fumigation practice.
The two pest control methods were equally eﬀective
for ≤ 8 months with cocoons showing superiority at
Live adult Cryptolestes ferrugineus were observed in
Cost-eﬀectiveness of cocoons can be enhanced through
import duty concessions.
Maize is the major staple crop grown in sub-Saharan Africa
(SSA) accounting for up to 34% of the total area under cereal
production (Smale et al. 2013). It constitutes 30% of the
Communicated by C.G. Athanassiou.
* B. M. Mvumi
Department of Soil Science and Agricultural Engineering,
Faculty of Agriculture, University of Zimbabwe, P.O. Box
MP167, Mount Pleasant, Harare, Zimbabwe
Grain Marketing Board, Dura House, P.O. Box CY77,
Causeway, Harare, Zimbabwe
GrainPro Inc., Subic Gateway Park Phase 1,
Subic Bay Freeport Zone, Philippines