Argan (Sapotaceae) trees as reservoirs for Mediterranean fruit fly (Diptera: Tephritidae) in Morocco

Abstract

Argan, Argania spinosa L. (Sapotaceae), forests cover ≃700,000 ha in the Souss region of Morocco and are known as an enormous potential reservoir of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) for nearby citrus orchards. We studied C. capitata population dynamics in a cattle- and insecticide-free domain from 1987 to 1990. Autumnal argan fruiting in 1986 and 1989 highly modified population dynamics by increasing the number of generations breeding in argan. Thus, up to 4 generations can breed in argan, whereas only 2 develop in spring fruiting alone. Most argans contained only a single oviposition. Oviposition was observed with autumnal fruiting from December to late June, just before the last fruit fell. Larval development began in argans still on trees and continued on fallen fruit. Numbers of eggs, larvae per fruit, and adult males captured per Procida trap increased from late May to June or July. Heterogeneity of argan tree phenology permits huge C. capitata populations with a large spread in adult emergences. Each argan produced on average 3 ± 1.3 adult flies. The proportion of aborted ovipositions was high, as was pupal mortality. Only 1 species of endoparasite, Opius concolor Szepligetti, emerged from argans. Parasitism remains constant from March to July but was too low to curb the enormous fly population increase.