Laboratory and Field Trials to Identify Sustainable Chemical Control Strategies for Trioza erytreae in European Citrus Orchards

Trioza erytreae (Del Guercio) is one of the psyllid insect vectors of the causal agents of huanglongbing. This paper proposes an assessment of the effectiveness of several pesticides with and without a pine oil-based organic adjuvant, in order to contain the spread and population of this pest and reduce the side effects on the Tamarixia dryi parasitoid. Five insecticides and their combinations with pine oil were sprayed against T. erytreae on citrus trees under semi-field and field conditions. The effect of the same treatments was assessed on T. dryi under laboratory conditions. All insecticides, except for acetamiprid, increased their effectiveness when combined with pine oil under both conditions. Cyantraniliprole, dimethoate, and their respective combinations with the organic adjuvant showed the highest efficacies against T. erytreae. Under laboratory conditions, dimethoate reported the most negative effect on T. dryi activity whereas cyantraniliprole and its combination with pine oil yielded a low toxicity effect on this parasitoid. Our results recommend the development of an integrated control approach for citrus growers based on an insecticide rotation program, preventing the emergence of pest resistance to one substance. In this sense, other insecticides, such as lambda-cyhalothrin with pine oil adjuvant or acetamiprid, could be considered.