Predatory gall midges on mealybug pests – Diversity, life history, and feeding behavior in diverse agricultural settings

• Five gall-midge species occurred in mealybug colonies exposed in five crops.
• Each was reared from at least two mealybug species belonging to different genera.
• Larvae feed on all mealybug stages and may subsist on a single individual.
• The predators are multivoltine and complete twice as many generations as their prey.
• No preference for distinct prey genera was found in laboratory trials.

Predatory gall midges (Diptera: Cecidomyiidae) are some of the most common natural enemies associated with mealybugs. However, the generally poor knowledge on their life history and taxonomy has obscured their role in the biological-control of these pests. A comprehensive survey in vineyards and in banana, citrus, persimmon and pomegranate orchards throughout Israel, using more than 670 sentinel baits, revealed five species of gall midges. All species fed in the laboratory on Planococcus citri (Risso) and Phenacoccus solani Ferris, and in trials with Diadiplosis multifila (Felt) no preference for either of these mealybug species was found. Larvae fed on all stages of the mealybugs, and the gall midges completed their life cycle within 10–20 days. Adult peak activity of the five studied species was in summer, with low numbers obtained from baits in winter and fall. No difference in overall numbers of gall midges was found among crops, and differences in species composition among sites are attributed to geographic and climatic conditions.

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