Natural mortality factors acting on citrus leafminer, Phyllocnistis citrella, in lime orchards in South Florida

Seasonal mortality of the citrus leafminer, Phyllocnistis citrella Stainton, was studied from 1994 through 1998 in `Tahiti' lime, Citrus aurantifolia (Christm.) Swingle, in Homestead, Florida. Survival of each developmental host stage and the proportion attacked by indigenous and introduced natural enemies were determined. Before the recovery of the introduced parasitoid, Ageniaspis citricola Logvinovskaya, in 1995, the third-instar host had the highest average proportion of parasitized individuals (0.14) followed by the prepupa (0.11) while the first instar had the lowest proportion parasitized (0.02). After the first recovery and establishment of A. citricola, the proportion of pupae parasitized increased to 0.56 followed by the prepupa (0.14) and the third instar (0.11). Before the introduction of A. citricola, the highest proportion of hosts killed by predation was observed in second instar (0.17) and third instar (0.15). After the establishment of the introduced species, the proportion of dead individuals due to predation was greater for second instar (0.31) and third instar (0.21) larvae. Mortality caused by indigenous natural enemies was significantly correlated with increases of P. citrella density. Parasitism of P. citrella by the exotic parasitoid, A. citricola, correlated less well to host density over the season (r(2) = 0.12) than did mortality caused by indigenous natural enemies (r(2) = 0.76). Moreover, a higher percent mortality in population of P. citrella was obtained from predation by the indigenous natural enemies than the introduced parasitoid as shown in the mortality estimates from 1995 to 1998.