Spatio-Temporal Interactions Between Maize Lepidopteran Stemborer Communities and Possible Implications From the Recent Invasion of Spodoptera frugiperda (Lepidoptera: Noctuidae) in Sub-Saharan Africa

Abstract

Spatio-temporal dynamics of multi-species pest communities and the interactions between them influence the structure of pest complex that attack crops. In East and Southern Africa, cereal crops, especially maize, is attacked by a complex of lepidopteran stemborer species made up of Busseola fusca (Fuller) and Sesamia calamistis Hampson (Lepidoptera: Noctuidae), and Chilo partellus (Swinhoe) (Lepidoptera: Crambidae). There is inadequate information on the extent of single-and multi-species infestations by this pest complex, their current spatio-temporal variations, and the primary abiotic factors that influence these. Furthermore, the recent invasion of the fall armyworm, Spodoptera frugiperda J.E. Smith, in sub-Saharan Africa will likely influence this stemborer community structure. Sampling was conducted in maize fields to record stemborer species and larval numbers from infested plants, in 28 localities found in six agro-ecological zones (AEZs) of Kenya and parts of Tanzania, as well as in one locality in the mid-altitudes where the three stemborer species occurred together. Both single-and multi-species stemborer communities characterized infestation of maize at field and plant levels, but varied in proportions between the AEZs. Infestation patterns and larval densities varied between seasons at mid-locality stemborer communities followed a clustered distribution pattern. Temperature was the most significant abiotic factor influencing the composition of stemborer communities at all spatial scales. Rainfall was significant only at the local scale. Results are discussed in relation to current stemborer community structures in maize fields and what the likely potential implications are, in the light of climate change and the recent establishment of the fall armyworm in Africa.

Molasses Grass Induces Direct and Indirect Defense Responses in Neighbouring Maize Plants

“…The stemborer C. partellus is one of the most injurious pests of maize, Zea mays L. (Poaceae), in sub-Saharan Africa, causing yield losses ranging between 20 and 80% depending on age of the crop at time of infestation and pest pressure (Kfir et al 2002). It is furthermore predicted that the relative importance of C. partellus in the Lepidoptera pest complex of maize will increase in future due to the changing climate (Ntiri et al 2016(Ntiri et al , 2019Tamiru et al 2007). Plant-plant signalling could be exploited to develop novel and ecologically sustainable crop protection strategies against the devastating stemborer pest and hence enhance smallholder maize production in the region.…”

Spatio‐temporal partitioning and sharing of parasitoids by fall armyworm and maize stemborers in Cameroon

“…The absence of stemborers at vegetative maize in both seasons in our study provides evidence (in part) for a competitive (temporal) displacement of stemborers by FAW. Such temporal displacement, while reducing the economic importance of stemborers, when taken in isolation, is expected to exacerbate total lepidopteran damage to maize now occupying each, a section of the development of the crop (Ntiri et al., 2019). During this study, FAW and stemborers–FAW population dynamic curve displayed opposite trend, with that of FAW being above that of stemborers at the early stage of maize growth and start decreasing while that stemborers increased, clearly suggesting a process of mutual exclusion.…”

A system dynamics model for pests and natural enemies interactions

“…The three stemborers frequently occur as single or mixed species communities 11,12 whose structure varies with agroecological zones. Busseola fusca is generally the dominant species in the highlands, while C. partellus dominates in the lowlands 6,26 , and S. calamistis occurs at all altitudes 27 . These stemborer species often occur as a mixed community of the three species in the mid-altitudinal regions 7,12 .…”