Honeydew of HLB vector, Trioza erytreae, increases longevity, egg load and parasitism of its main parasitoid Tamarixia dryi

Trioza erytreae (Del Guercio) (Hemiptera: Triozidae) is one of the vectors of the citrus greening or huanglongbing (HLB) disease, the most devastating citrus disease globally. A classical biological control program has been established to control this vector in Europe, where it has been threatening the citrus industry since its detection in mainland Spain and Portugal. For this, its main parasitoid Tamarixia dryi (Waterson) (Hymenoptera: Eulo-phidae) has been introduced. Here, we evaluated the nutritional value of T. erytreae honeydew as a suitable food source for T. dryi. This solid honeydew is the most abundant food source for the parasitoid in the field. Our results demonstrated that T. erytreae honeydew enhanced the longevity of T. dryi compared to other diets such as water, 'sucrose alone' or 'sucrose + protein'. Females fed on honeydew also oviposited more eggs than those fed on water or 'sucrose alone'. Finally, T. dryi fed on honeydew tended to parasitize more psyllids than those fed on the other diets. Chemical analyses demonstrated that T. erytreae honeydew contains proteins, and this can explain the increase in egg load of honeydew fed parasitoids. Further research is necessary to understand why these females tended to parasitize more than females fed on 'sucrose + protein'. Overall, these results contribute to understanding the successful and rapid establishment of T. dryi in Europe and to the successful rearing and release programs in newly invaded areas.

Automated summary

A biological control program has been established in Europe to control the spread of citrus greening disease, with the introduction of the parasitoid Tamarixia dryi. The main food source of T. dryi is the honeydew produced by its host, Trioza erytreae. Feeding on this honeydew increases the longevity of T. dryi, enhances egg production, and leads to increased parasitism of citrus psyllids.