Spent coffee grounds do not control cycad aulacaspis scale

Abstract

Cycad aulacaspis scale [CAS (Aulacaspis yasumatsui)] is a highly destructive pest insect worldwide. CAS feeds on cycad (Cycas sp.) plantings and is also posing a problem for the foliage industry. The use of spent coffee grounds to prevent or control CAS has received increased popularity in the last few years. This study assesses whether the application of spent coffee grounds is a realistic control method against CAS, and whether spent coffee grounds can be successfully used as a natural alternative to chemical pesticides. Two tests were performed during Summer 2010 and 2011. The first experiment assessed seven treatments: five coffee treatments, neem oil, and orange oil to control CAS on the debao cycad (Cycas debaoensis). In the second experiment, only coffee mulch was tested against the control on the debao cycad and fadang (Cycas micronesica). There was no statistical evidence of a difference between the control and the coffee mulch treatment with regard to infestation (insects per square centimeter). Soil pH differences were confirmed between control and coffee treatments, with the application of coffee mulch lowering pH by an average of 0.48. Spent coffee grounds did not have an effect on cycad mortality, but neem oil and orange oil increased cycad mortality.