Abstract
The invasion and wide spread of Spodoptera frugiperda represent real impediments to food security and the livelihood of the millions of maize and sorghum farming communities in the sub-Saharan and Sahel regions of Africa. Current management efforts for the pest are focused on the use of synthetic pesticides, which are often economically unviable and are extremely hazardous to the environment. The use of biological control offers a more economically and environmentally safer alternative. In this study, the performance of the recently described parasitoid, Cotesia icipe, against the pest was elucidated. We assessed the host stage acceptability by and suitability for C. icipe, as well as its ovigenic status. Furthermore, the habitat suitability for the parasitoid in the present and future climatic conditions was established using Maximum Entropy (MaxEnt) algorithm and the Genetic Algorithm for Rule‐set Prediction (GARP). Cotesia icipe differentially accepted the immature stages of the pest. The female acceptance of 1st and 2nd instar larvae for oviposition was significantly higher with more than 60% parasitism. No oviposition on the egg, 5th and 6th larval instars, and pupal stages was observed. Percentage of cocoons formed, and the number of emerged wasps also varied among the larval stages. At initial parasitism, parasitoid progenies, time to cocoon formation and overall developmental time were significantly affected by the larval stage. Egg-load varied significantly with wasp age, with six-day-old wasps having the highest number of mature eggs. Ovigeny index of C. icipe was 0.53. Based on the models, there is collinearity in the ecological niche of the parasitoid and the pest under current and future climate scenarios. Eastern, Central and parts of coastal areas of western Africa are highly suitable for the establishment of the parasitoid. The geographic distribution of the parasitoid would remain similar under future climatic conditions. In light of the findings of this study, we discuss the prospects for augmentative and classical biological control of S. frugiperda with C. icipe in Africa.
Highlights
Cereal crops, such as maize, Zea mays L. (Poaceae) and sorghum, Sorghum bicolor (L) (Poaceae) are the major staple food and source of income for millions of peoples in sub-Saharan and Sahel regions of Africa [1]
Cotesia icipe differentially accepted the immature stages of S. frugiperda for oviposition (F3,16 = 19.98, P < 0.0001)
Most if not all importing countries require information regarding indigenous parasitoid diversity and their potential role on the invasive pest before considering introducing any exotic natural enemy. In this regard, following the detection and widespread occurrence of fall armyworm (FAW) in East Africa, and in an attempt to identify an indigenous parasitoid that could form a new association with this pest, we evaluated the performance of the newly described species, C. icipe against all the immature stages of S. frugiperda
Summary
Cereal crops, such as maize, Zea mays L. (Poaceae) and sorghum, Sorghum bicolor (L) (Poaceae) are the major staple food and source of income for millions of peoples in sub-Saharan and Sahel regions of Africa [1]. (Poaceae) and sorghum, Sorghum bicolor (L) (Poaceae) are the major staple food and source of income for millions of peoples in sub-Saharan and Sahel regions of Africa [1]. The production of these crops in Africa is hindered by several biotic and abiotic factors, chief among them is the infestation by insect pests [2,3,4]. The pest was first detected in Africa in the rainforest zones of Nigeria in 2016 [7] It has spread across sub-Saharan Africa [8], Egypt, Sudan, Mauritania, South and Southeast Asia, China [9] and recently in Australia [10]. The FAW is on the European and Mediterranean Plant Protection Organization (EPPO) A1 list and its spread northwards in Africa poses an eminent threat of invasion to Europe, the Middle East and beyond [11]
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