Arthropod associates of Kenyan buffelgrass (Cenchrus ciliaris): A field survey for biological control candidates of a globally important invasive grass

Invasive species are the second largest contributor to biodiversity loss and drivers of ecosystem change. Understanding the ecology of insects associated with buffelgrass in its native range may provide an understanding of invasion processes and biocontrol opportunities where buffelgrass has become an invasive challenge. Buffelgrass is a C4 perennial grass native to Africa and Asia that was widely introduced across tropical and subtropical rangelands as livestock forage. Buffelgrass also reduces native biodiversity and ecosystem stability in its introduced range when it escapes pastures. Here, we present the results of a six-year survey of herbivorous insects of a native buffelgrass population from Kenya. Buffelgrass was examined for externally and internally feeding insects of vegetative and reproductive tissues. The samples were photographed and Sanger sequenced to identify them to the lowest possible taxonomic ranking. We collected information on sample abundances, phenologies, tissues consumed, and putative diet breadths. We identified 29 morphospecies representing seven orders and 16 families. We also categorized buffelgrass detritivores and parasitoids that may use buffelgrass herbivores as hosts. The putative host plant specialization was as high as 71% for Diptera. Phenological variation in herbivore presence correlated with seasonal rainfall and provided a guide for when to conduct follow-up biological control agent searches. The most abundant herbivore was a gall midge (Diptera: Cecidomyiidae) that inhabits buffelgrass culms. Additional research should focus on bringing this species into containment where host choice trials can be conducted to determine if it is truly monophagous and to assess its impact on the buffelgrass growth.