Agboka, Komi

English

The present research project aimed at
developing and testing different IPM components focusing on i)
habitat management particularly maize-legume intercropping and trap
crops, ii) botanical formulations with special emphasis on neem and
Jatropha curcas and iii) biological control using redistribution or
new association approach for sustainably controlling the maize cob
borer Mussidia nigrivenella Ragonot (Lepidoptera: Pyralidae) in
field and in storage systems. To this end, field and lab
experiments were conducted mainly in different locations in Benin.
Field experiments conducted in four different locations in Benin
using four by two pattern of maize-legumes or cassava planting
indicated that intercrops could reduce the number of eggs and
larvae of M. nigrivenella compared to the monocrop. Maize-
Canavalia ensiformis and maize-Tephrosia vogelii proved to be the
most effective combinations for reducing M. nigrivenella
populations in the different locations. The effect of two
leguminous cover crops, C. ensiformis and Sesbania rostrata and
cowpea planted as border rows on infestations of maize by the
pyralid M. nigrivenella and of other cob-boring lepidopteran pests
was studied in two field trials. Towards harvest of both the main
and minor season trials, M. nigrivenella densities were higher in
the maize alone than the legume treatments, though the effect
depended on the timing of planting of the cover crop in relation to
that of maize. However, pest loads expressed as cumulative number
of feeding-days varied with treatment during the minor season only,
and they were lower on maize with C. ensiformis planted 4 weeks
before maize and maize surrounded by S. rostrata than in the maize
alone treatment. There were no discernable trends for other borers
such as the noctuid Sesamia calamistis Hampson (Lepidoptera:
Noctuidae), the pyralid Eldana saccharina Walker (Lepidoptera: P!
yralidae), and the tortricid Thaumatotibia leuctotreta Meyrick
(Lepidoptera: Tortricidae). Furthermore,M. nigrivenella pest loads
were considerably higher on C. ensiformis than maize. Thus, the
presence of alternative host plant species in the vicinity of maize
fields does not increase M. nigrivenella attack on maize. The
results of laboratory and field experiments using two
concentrations of aqueous extracts of Tephrosia vogelii and Hyptis
suaveolens, and of oils of Azadirachta indica and Jatropha curcas,
as well as the pesticide Furadan 5G showed that oil emulsions of A.
indica and J. curcas oils act not only as oviposition deterrent but
also as ovicides. Overall, treated plants had a strong deterrent
effect on ovipositing M. nigrivenella. In addition, egg hatch was
adversely affected by neem and Jatropha oils. By contrast, larval
survival was not affected by the treatment. In the field, Furadan,
neem and J. curcas oils significantly reduced the number of M.
nigrivenella larvae by 16-49.2%, while aqueous extracts of T.
vogelii and H. suaveolens were similar to the control consisting of
emulsified water. Although M. nigrivenella is mostly described as a
field pest, it can be found feeding on stored maize up to the 4th
month. Survey conducted in Benin in 2006 to assess M. nigrivenella
infestations in different maize storage systems in the Southern
(SGS) and Northern Guinea Savanna (SGS) showed that in SGS and NGS
the percentage of infested stores decreased from 86.7% to 26.7% and
from 51.4% to 14.3%, respectively, during the first 28 weeks of
storage. During the same time, mean numbers of M. nigrivenella per
cob decreased from 0.36 to 0.04 across both zones. All larval
stages, but mostly 3rd to 5th instars, were frequently found even
after more than 12 weeks, showing that M. nigrivenella could
reproduce in storage. Highest M. nigrivenella incidence of 16.8%
and 14.4% were found in the “Ava” and crib stores, respectively.
Infestations were highest in “Ava” and lowest in maize grain stored
in polyethylene bags or in mud silos. In a laborat! ory experiment,
presence of post-harvest beetles negatively affected the bionomics
of the cob borer indicating strong interspecific competition.
Surveys for natural conducted in Malaysia pointed out the presence
of three genera parasitizing Parkia speciosa pod borer: Bracon spp.
(Hymenoptera: Braconidae) accounted for 64%, Eurytoma sp.
(Hymenoptera: Eurytomidae) (32%) and Sphaeripalpus sp.
(Hymenoptera: Pteromalidae) (4%). Overall, mortality caused by
parasitoids could reach <40% hence they were considered a key
mortality factor in the population dynamics of the Mussidia spp./or
pyralid species in Malaysia

Georg-August-University Göttingen

Developing and testing plant health management options against the maize cob borer Mussidia nigrivenella Ragonot (Lepidoptera: Pyralidae) in West Africa

https://ediss.uni-goettingen.de/bitstream/11858/00-1735-0000-000D-F24C-4/1/agboka.pdf

Developing and testing plant health management options against the maize cob borer Mussidia nigrivenella Ragonot (Lepidoptera: Pyralidae) in West Africa

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Georg-August-University Göttingen