Silicon-augmented resistance of Kikuyu grass (Cenchrus clandestinus) to invasive forage pest, the twolined spittlebug (Prosapia bicincta), in Hawaii

The twolined spittlebug, Prosapia bicincta (Say) (Hemiptera: Cercopidae), was first detected in rangelands on Hawai’i Island in 2016 and is a major economic pest of forage grass, turfgrass, and sugarcane. Since its arrival, P. bicincta has expanded rapidly, threatening Hawaii’s beef cattle industry by devastating a key forage crop, Kikuyu grass (Cenchrus clandestinus). While elemental silica is not strictly considered an essential nutrient for all plants, it can provide significant benefits, especially under stress conditions. Silica can strengthen counter pest attacks through improving plant structural integrity, posing physical and mechanical barriers, as well as equip and mobilize biochemical/molecular defenses. Under these considerations we investigate the potential for silicon-induced resistance of C. clandestinus to P. bicincta infestations by examining relationships between augmentation quantity, plant health, and pest mortality. In considering economic realities and limitations, we investigate 2 different silica formulations; Redox Bionutrients’ Mainstay Si commercial product and a much less costly hand-mixed formula with calcium silicate. We then imagine the implications of these findings on pest prevention and early management tactics, integrated pest management systems, and agricultural sustainability.