Chiriboga Morales Xavier, Tamiru Amanuel, Sobhy Islam S, Bruce Toby J A, Midega Charles A O, Khan Zeyaur
International Centre of Insect Physiology and Ecology (icipe), P.O. Box 30772-00100, Nairobi, Kenya.
Centre for Applied Entomology and Parasitology, School of Life Sciences, Keele University, Keele, Staffordshire ST5 5BG, UK.
Plants (Basel). 2021 Feb 18;10(2):392. doi: 10.3390/plants10020392.
The fall armyworm (FAW) has recently invaded and become an important pest of maize in Africa causing yield losses reaching up to a third of maize annual production. The present study evaluated different aspects of resistance of six maize cultivars, cropped by farmers in Kenya, to FAW larvae feeding under laboratory and field conditions. We assessed the arrestment and feeding of FAW neonate larvae in no-choice and choice experiments, development of larvae-pupae, food assimilation under laboratory conditions and plant damage in a field experiment. We did not find complete resistance to FAW feeding in the evaluated maize cultivars, but we detected differences in acceptance and preference when FAW larvae were given a choice between certain cultivars. Moreover, the smallest pupal weight and the lowest growth index were found on 'SC Duma 43' leaves, which suggests an effect of antibiosis of this maize hybrid against FAW larvae. In contrast, the highest growth index was recorded on 'Rachar' and the greatest pupal weight was found on 'Nyamula' and 'Rachar'. The density of trichomes on the leaves of these maize cultivars seems not to be directly related to the preference of neonates for feeding. Plant damage scores were not statistically different between cultivars in the field neither under natural nor artificial infestation. However, plant damage scores in 'Nyamula' and 'Jowi' tended to be lower in the two last samplings of the season compared to the two initial samplings under artificial infestation. Our study provides insight into FAW larval preferences and performance on some African maize cultivars, showing that there are differences between cultivars in these variables; but high levels of resistance to larvae feeding were not found.
草地贪夜蛾最近侵入非洲，并成为玉米的一种重要害虫，导致产量损失高达玉米年产量的三分之一。本研究评估了肯尼亚农民种植的六个玉米品种在实验室和田间条件下对草地贪夜蛾幼虫取食的不同抗性方面。我们在无选择和选择实验中评估了草地贪夜蛾初孵幼虫的滞留和取食情况、幼虫到蛹的发育情况、实验室条件下的食物同化情况以及田间实验中的植株损伤情况。在评估的玉米品种中，我们未发现对草地贪夜蛾取食的完全抗性，但当给草地贪夜蛾幼虫在某些品种之间进行选择时，我们检测到了它们在接受度和偏好上的差异。此外，在“SC Duma 43”叶片上发现蛹重最小且生长指数最低，这表明该玉米杂交种对草地贪夜蛾幼虫具有抗生作用。相比之下，“Rachar”上记录的生长指数最高，“Nyamula”和“Rachar”上发现的蛹重最大。这些玉米品种叶片上的毛状体密度似乎与初孵幼虫的取食偏好没有直接关系。在田间，无论是自然侵染还是人工侵染，各品种间的植株损伤评分在统计学上没有差异。然而，在人工侵染下，与本季最初两次采样相比，“Nyamula”和“Jowi”在最后两次采样中的植株损伤评分往往较低。我们的研究深入了解了草地贪夜蛾幼虫在一些非洲玉米品种上的偏好和表现，表明这些变量在品种间存在差异；但未发现对幼虫取食的高抗性水平。
