Studies On The Interaction Of Arthropods Fungi And Mycotoxin On Stored Maize Grain In Ethiopia.

In Ethiopia, maize (Zea mays L.) is the most important cereal crop produced and consumed by the majorityrnof the population. High productivity and adaptability to a wide range of environment made the maize croprnone of the national commodity crops to meet the food self-sufficiency program of the country. However,rncurrently food safety issue related to postharvest arthropod infestation and associated problems put this croprnunder pressure. These studies were designed to know the species composition, frequency of occurrence, andrnabundance of stored maize grain inhabiting arthropods with particular reference to mold feeder arthropodsrn(Sap beetles, Staphylinids and others) for designing management options for the pest and to understand therneffects of their damage on potentially mycotoxin producing fungal infection and Aflatoxin contamination ofrnstored maize grain. The studies were conducted in purposively selected Woreda of Amhara and Oromiarnregion, Ethiopia, from August 2013 to August 2017. Random sampling method was employed forrnArthropods survey. Completely Randomized Design was used for sample collection from selected Woredarnof the two regions to determine the effects of insect and mold damaged maize cob on status of sap beetlesrnand other mold feeder insects, corn ear rot types, development of detection methods for sap beetles andrnStaphylinids and best detection time, and the effects of arthropods on potentially mycotoxin producingrnfungal infection and Aflatoxin contamination. LC/MS/MS method was used to detect aflatoxinrncontamination in stored maize grain. It was known from the results obtained that 81 arthropods; belongingrnto class Insecta (87.65%), Arachnida (8.64%), and Crustaceans (3.70%) were identified. In all selectedrnWoreda from both regions and in both years, Sitophilus spp., and Sitotroga cerealella from grain feeders;rnNitidulidae spp., Mycetophagidae spp., and Drosophillidae spp., from mold feeders; Lepinotus fromrnpsocids; Tyrophagus putrescentiae from mites; Staphylinidae spp., and Dactylosternum abdominal fromrnnatural enemies associated with mold feeder arthropods and parasitic Hymenoptera from natural enemiesrnassociated with grain and grain product feeders were found to be the most frequently and abundantlyrnencountered arthropods. In the current study, 27 species were recorded for the first time as occurring inrnEthiopia. In the study on status of sap beetles and other mold feeder arthropods on pre-harvest maize cobrndamage types, 19 species of mold feeder arthropod occurred in association with insect and mold damagedrncobs. However, only Carpophilus sp., Brachypeplus sp., Litargus balteatus LeConte, Carpophilusrndimidiatus (F.), Carpophilus hemipterus (L.), and Entomobrya spp., appeared in more than 30% of insectrnand mold damaged cobs. Occurrence of corn ear rot types per 120 mold damaged cobs varied significantlyrnvirn(P0.05). In both regions (years), abundance of selected sap beetles and other mold feeder insects werernsignificantly higher on insect and mold damaged cob than undamaged cob (P0.05). Moreover, in bothrnregions (years), the mean number of selected sap beetles and other mold feeder insect per insect and moldrndamaged cobs were significantly (P0.05) higher for Carpophilus hemipterus (L.) and Litargus balteatusrnLeConte than Carpophillus dimidiatus, Typhae stercorea and Brachypeplus spp. More than four speciesrnwere detected from each of the sap beetles and staphylinids using fermented maize cob and maize cobrntreated with fruit juice, in the study on how to detect these insect in stored maize grain ecosystem.rnCarpophillus hemipterus (100%, 42.11%) and Brachypeplus spp., (100%, 34.75%) were found to be therntwo most frequently and abundantly detected sap beetles during this experiment. Among the four identifiedrngenera of staphylinids, Atheta spp., were found to be the most frequently and abundantly detected generarn(92.5%, 15.64%). Total mean number of Carpophilus hemipterus and Brachypeplus spp., per trap capturedrnindicated that fermented maize cob and fermented banana juice mixed with fermented pineapple juice werernsignificantly (P0.05) more effective than fermented banana and pineapple juice in detecting these insects.rnHowever, no significant difference (P˃0.05) was observed among these attractant in detecting staphylinids.rnSignificantly (P0.05), more Carpophillus hemipterus was detected in the first two weeks. However,rnsignificantly (P0.05) more Brachypeplus spp., and Staphylinids were detected in the last two weeks. Thernresult obtained from the effects of insects on potentially mycotoxin producing fungal infection and aflatoxinrncontamination in stored maize indicated that the incidence of potentially toxigenic fungi and aflatoxinrncontamination were significantly (P0.05) higher on insect damaged maize kernels than undamaged maizernkernels and mold feeder arthropods than grain feeder arthropods (P0.05). The mean number of arthropods,rngrain temperature and moisture content and number of arthropod and mold damaged maize kernels werernsignificantly (P0.05) higher on untreated seeds than Malathion treated seeds. Pearson correlation showedrnsignificant (P0.05) positive correlation between arthropod infestation and grain temperature and moisturerncontent and number of arthropod and mold damaged maize kernels in stored maize grain. The present studyrnconcluded that the role of arthropod infestation in stored maize grain ecosystem. The role of arthropod inrnstored maize ecosystem include, exposing maize kernels to potentially mycotoxin producing fungalrninfection, providing suitable condition for the growth of fungi and vectoring fungal spores in stored maize.rnThe present study also concluded that condition of stored grain could determine species composition ofrnarthropods in stored maize grain ecosystem.

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