MST-Department of Agribusiness Management and Trade (AMT)

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Browsing MST-Department of Agribusiness Management and Trade (AMT) by Author "Anyanda, Geoffrey Nyapom"

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    Maize Variety Performance Under Fall Armyworm Infestation and Associated Natural Enemies un Machakos, Kilifi, Makueni, Embu, Kakamega and Trans-Nzoia Counties, Kenya
    (Kenyatta University, 2024-05) Anyanda, Geoffrey Nyapom
    Fall armyworm (FAW) Spodoptera frugiperda (J.E. Smith) is a polyphagous pest native to America, causing crop losses and food insecurity in Sub Saharan Africa (SSA). The identification of maize genotypes resources with FAW resistance is therefore crucial. This study therefore assessed bionomic parameters of resistance to FAW on six maize genotypes under laboratory conditions, evaluated the extent of damage and yield loss caused by FAW on the same genotypes under artificial and natural infestation and finally determined the associated natural enemies to FAW. The study was conducted in Kenya between 2019- 2020 cropping periods. The genotypes used included two FAW-tolerant hybrids (CKHFAW180294 and CKH191221), two commercial hybrids (WE2115 and CKH10717), and two open-pollinated varieties (ZM523 and KDV4). For bionomic parameters of resistance, larval development time and reproductive potential were assessed in response to leaves from each of the genotypes in the laboratory. FAW life table was then constructed based on laboratory bioassays. A split plot design was used to estimate the extent of damage and yield loss in artificial infestation. The six genotypes were artificially infested with FAW neonates at two vegetative stages (V5, V7) and a reproductive (R1) stage in a nethouse. Natural infestation experiments were conducted in split plot design laid out in RCBD. Leaf and ear damage scores were recorded on a 1-9 scale as well rotten ears (%), tunnel length (%), stem exit holes and grain yield were also recorded. Larval development time was significantly higher in CKH19121 maize genotypes and the lowest on KDV4. The intrinsic rate of natural increase for FAW life tables varied from 0.24 on CKH191221 to 0.41 on KDV4. The mean generation time of FAW ranged from 17.6 days on KDV4 to 22.8 days on CKH191221. In artificial infestation, foliar damage was lowest on CKH191221 and highest on KDV4 at V7 infestation stage in week 1. CKH191221 had the lowest ear damage score, whereas ZM523 had the highest scores at V5 infestation stage. The highest and lowest yield reductions were observed on ZM523 (64%) at V7 infestation stage and CKHFAW180294 (6%) at R1 infestation stage, respectively. Natural infestation trial was conducted in six major maize growing areas. The lowest mean leaf damage caused by FAW ranged from 3.2 and 3.6 in CKH191221 and CKHFAW180294, respectively. Similarly, the lowest ear damage score was reported in CKH191221. In addition, tolerant genotypes had the lowest number of stem exit holes, % rotten ears and cumulative stem tunneling. These results also revealed an 8-10%- negative loss in yield on the tolerant genotypes and 38 to 45% between the commercials and OPVs across locations. two of egg- larval parasitoid, five larval parasitoid and one pupal parasitoid species were recovered from the families Braconidae (3), Tachinidae (1) and Ichneumanidae (2). Coccygidium luteum was the most dominant parasitoid with a relative abundance of 18.9% while the least dominant parasitoid was Palexorista zonata at 6.95%. Genotypes, CKH191221 and CKHFAW180294 displayed the highest potential as promising genotypes hence baseline for further examination and deployment in SSA maize breeding populations with partial FAW resistance and yield gains.