​​Identification of Insect Pests of Maize (Zea mays L.) in Girar Jarso and Hidebu Abote Districts, North Shewa Zone, Oromia, Central Ethiopia

Maize (Zea mays L.) is an important crop and widely grown by commercial and small-scale farmers (Midingoy et al., 2016). Maize ranked the second in area covered having an area of 17.68% (about 2,274,305.93 hectares) and found the first ranks in yield contributed 28.75% (96,357,345.00 quintals) in production in Ethiopia (CSA, 2020). In Sub-Saharan Africa, 77% of maize is using as food and only 12% serves as feed (Inuwa, 2018). 

Due to changing global climatic patterns and due to change in host range of pests, many new pests previously not known on maize has been reported to feed on maize and a latitudinal shift in the distribution of insect pests has been observed (David and Ramamurthy, 2017). Stem borers belong to a group of moths whose larval stages are the most destructive, as they initiate their feeding on the plant, thereby inflicting physically and economically important damage on crops. Stem borers caused important lossesof maize ranging from 11% in the highlands to 21% was lost in the dry areas in Ethiopia (Odendo et al., 2003).

In the study area, the socio-economic conditions are very poor and maize production is highly limited due to lack of insect pests’ awareness, identification and prevalence of pestsand insufficient of agricultural extension expert in the characteristics and identification of insect pests. Thus, the current investigation was aimed to identify theinsect pests’ infestation level of maize, the types of species/orders and infestation status at different maize growth stages.

The survey was conducted in the year of 2019 to 2020 cropping season in North Shewa Zone, Oromia, Ethiopia. The Zone is found 112 km away from Addis Ababa on the northern direction.The study was carried out in Girar Jarso and Hidebu Abote District of the Zone. The average annual temperatureand average annual rainfall of Girar Jarso and Hidebu Abote varies from 15^oC - 26^oC and1200-1400 mm and 20-4oC and 800-1100 mm respectively (Fig 1).



The sample size was determined according to the formula:
 

 

Where
n= Sample size; N= Number population; e is confidence level (95%) (Yemane, 1967). The survey was purposively selected to get ease access of resources to elicit the views of persons who have expertise and knowledge about specific domain (Tongco, 2007). The pest assessment was carried out at all crops growth stages. Ten crops were taken from each diagonalfrom 10 m2 area and assessed. Pest assessment was done along the two diagonals (in an “X” pattern) of the field from three points quadrants. The major data collected were the species/orders of insect pests and nature of pests’ damage to maize at different growth stages. Morphological identification of pest was done using hand lens and utilizing identification keys (Zim and Cottam, 2000). The pests status were determined based on the degree of damage caused to plant and were named in a scale of 1-3, where 1 = little or not important; 2 = cause little and occasional damage and 3 = common and causes serious damage (Adamu et al., 2000). The data were analyzed using SPSS (Version 20.00) and descriptive statistics was used to get the variation of the surveyed insect pests in percentage.  

Major constraints of maize production
 
The survey indicated that the majority of respondents ranked (50.00%) as yield loss by insect pests, (37.00%) yield loss by lack of improved maize varieties, (33.00%) yield loss by diseases, (18.12%) yield loss by lack of inorganic fertilizer and (11.10%) yield losses by weed infestation in Girar Jarso District (Table 1). Likewise, maize production was affected as the respondents mentioned (48.00%) due to lack of improved maize seed variety, (47.00%) due to attacked by insects, (29.00%) loses due to diseases infestation, (28.20%) due to lack of inorganic fertilizer and (8.88%) by weeds in the surveyed kebeles of Hidebu Abote District (Fig 2). Early et al. (2016) reported that the spread of insect pests, plant diseases and invasive alien plant species to new regions, as the world’s climate changes, is a threat to farmers globally, especially in Africa where climate change effects are projected to be the most severe in the world and anticipated that the spread of diseases, insect pests and weeds were potentially cause the loss of more than 40% of the world’s food supply. As reported by (Bhandari et al., 2015), Survey report revealed that 42% respondents ranked for insects as a main problem followed by 32% for weed and 17% for disease.


   


Insect pest Infestation at different growth stages
 
The highest and lowest Average yield loss of maize due to insects stated by respondents (46.68%) and (30.95%) were infested at Shebele Fati and Sherer Genet kebele of GirarJarso Districts whereas the highest and the lowest average that respondents ranked (52.93%) and (20.50%) yield loss of maize were reduced by insect at Gidabo Jama and Dabala Bokolo kebeles of Hidebu Abote district at different growth stages.At district level, the total average yield loss of maize emphasized by respondents were (48.00%) by lack of improved variety and (8.88%) by weed infestation in Hidebu Abote District (Table 2) . The maximum and minimum infested maize by insects were (64.38%) and (63.34%) and 9.20% to 13.00% in Girar Jarso and Hidebu Abote Districts at late seedling and seedling growth stage (Fig 3). The samples of photos of infested maize and sorghum by insects at different crops growth stages at the two districts were taken during field observation (Fig 4).






 
Major identified insect pests of maize at Hidebu Abote district
 
The survey result indicated that lepidopterans, orthopterans, coleopterans, hemipterans and thysonepterans were identified in the district. From the fifteen identified insects, grass hopper (Hieroglyphus nigrorepletus), maize leaf hopper (Cicadulinambila), maize pod borers (Helicoverpa armigera, Etiella), maize stem borers (Chilopartellus Swinhoe), Hairy caterpillar (Amsacta albistriga Walker), black cut worm (Agrotisipsilon Hufnagal), Maize leaf Aphid (Rhopalosiphum maidis Fitch), army worm (Mythimna separata Walker), fall armyworm (Spodoptera frugiperda), pink stem borer (Sesamia inferens Walker), Thrips (Megaluro thripsusitatus) and corn ear worm (Helicoverpa zea Boddias) were identified as a major pests causing serious losses of maize (Table 3).The research reported by (Fenta et al., 2019), More than 40 species of insects has been recorded on maize in the field.
 


Major identified insects at Girar Jarso district
 
Grass hopper (Hieroglyphus nigrorepletus), thrips (Megaluro thripsusitatus), maize stem borer (Chilopartellus Swinhoe), corn leaf aphid (Rhopalosiphum maidis Fitch) and pink stem borer (Sesamia inferens Walker) were the major insect pests infested maize at different growth stages. Whereas, maize leaf hoppers (Empoasca kraemeri), hairy caterpillar (Amsacta albistriga Walker), army worm (Mythimna separata Walker), chafer beetle (Chiloloba acuta Wiedmann) and corn ear worm (Helicoverpa zea Boddi) were the minor insectsinfested maize medium to lower at different growth stages. In other ways, pod borers (Helicoverpa armigera Etiella), black cut worm (Agrotis ipsilon Hufnagal), fall army worm (Spodoptera frugiperda) and shoot bug (Peregrinus maidis Ashamed) were the lowest available insects cause little or not important to loss of maize at kebeles of Girar Jarso district (Table 4). The total average number of insect pests emerged were (124) at late seedling stage, (94) at seedling stage and (78) at maturity stage. Homoptera, Lepidoptera, Thysnoptera, dipthera and Orthoptera were the major insect orders infested maize at seedling, late seedling and maturity stages.  

The maximum and minimum yield loss of maize recorded by insect pests and weed infestationwere (50.00%) and (11.10%) in GirarJarso district and (48.00%) due to lack of improved maize seed variety and (8.88%) due to weeds infestation in Hidebu Abote district. Lepidopterans, orthopterans, coleopterans, hemipterans and thysonepterans were the identified orders. Grass hopper (Hieroglyphus nigrorepletus), maize leaf aphid (Rhopalosiphum maidis Fitch) and maize stem borer (Chilopartellus Swinhoe) were the serious identified insects in the two districts.

Strong pest monitoring, identifying, characterizing and taking measure has to be given especially for major pests, insect pest management, giving training for farmers reduce the infestation of maize by insects.