Abstract:
Maize is an important staple crop widely used in domestic and industrial processes. It is
usually stored in Polypropylene (PP) bags, where it is prone to heavy insect infestations,
resulting in high economic losses. A number of recent interventions to prevent insect
infestations during grain storage include Diatomaceous Earth (DE) and novel bags such
as ZeroFly (ZF) and Purdue Improved Crop Storage (PICS). However, there is paucity
of data on their effectiveness and optimal use in insect pest management. Therefore, this
study was conducted to determine the effectiveness of different storage bags and DE
against stored-insect pests of maize.
The study was conducted between February, 2017 and January, 2018 in a storehouse at
Arisekola Market, Bodija, Ibadan. Pristine 50 kg SWAN 2 maize variety was stored
using eight different bag treatments comprising: PP (control) and ZF, DE admixed in PP
and ZF (PPDE and ZFDE), single and double hermetic liners in PP (PP1L and PICS),
single and double hermetic liners in ZF (ZF1L and ZF2L). A stack of three replicates
for each treatment was placed on separate pallet and arranged one meter apart. In
addition, for each ZF1L, ZF2L, PP1L and PICS, two sets comprising 3 replicates/set
were stored for destructive sampling every four-months using standard procedure. Maize
in ZF, PP, ZFDE and PPDE were sampled monthly. Insect population count, insect
damaged kernel, maize weight loss and insect perforation on bags were determined
through standard procedures. Maize quality was determined through standard seed
germination method, maize Moisture Content (MC) was measured by MC meter and
aflatoxin level by Thin-Layer Chromatography. Data were analysed using descriptive
statistics and ANOVA at α0.05.
Total insect population of 5,945 in all treatment bags comprised predominantly
Sitophilus zeamais (2,593), followed by Tribolium castaneum (1,298), Liposcelis spp.
(1,193) and the least occurring Cryptolestes ferrugineus (861). Percentage of insect
species per bag: ZF2L (0.2) and ZF1L (0.3) were significantly lower than the population
in ZFDE (3.2) and PPDE (7.9), but higher in ZF (51.8) and PP (35.4). Insect damaged
kernel was significantly low in ZF2L (0.4±0.0%), ZF1L (0.5±0.0%) and ZFDE
(0.8±0.3%) compared to ZF (16.9±1.6%) and PP (5.4±0.9%). The maize weight loss
was significantly low in ZF2L (0.1±0.0%), PICS (0.2±0.0%) and ZFDE (0.2±0.1%)
compared to ZF (6.7±0.8%). The number of insect perforations on ZF2L (0.0±0.0), PICS
(1.3±0.4) and ZF (17.0±3.1) were significantly lower compared with the control, PP
(51.5±5.7). Seed germination rate (97.5±0.6%) in ZF2L and PICS were significantly
higher than PP (78.3±0.1%) and ZF (66.0±2.3%). The initial MC of the maize in
treatment bags was 11.4±0.1%, but the final MC in ZF2L (12.2±0.1%) was significantly
lower than in PP (13.5±0.1%). Aflatoxin levels in maize in all treatment bags were
within the recommended limits (4 µg/kg) of Standards Organisation of Nigeria, except
the PP (5.0 µg/kg).
Hermetic storage bags and diatomaceous earth were effective at controlling insect
infestations and preserved stored maize quality. Therefore, they could be used in postharvest storage interventions.
