Abstract
In a study about the impact of natural enemies of Phyllocnistis citrella Stainton conducted in Spain, predation appeared as the most important mortality factor. Predators responded to changes in flushing, and this was attributed to continuous availability of preferential prey feeding on tender flushes. In this paper the role of aphid-mutualists and generalist predators feeding on aphids as well as on P. citrella (ants and lacewings, respectively), has been investigated. In the laboratory, Chrysoperla carnea Stephens could complete its development when fed on P. citrella third instars only. In the field, highly statistically significant regressions were obtained between prey indicators (aphid density and flush) and C. carnea densities. Nevertheless, using P. citrella density resulted in a negative relationship. In another field trial, predation rates did not change when ants were excluded from P. citrella-infested trees. Therefore, neither ants, nor lacewings could be identified as key-predators of P. citrella. Although we could not prove the efficiency of these predators, these studies have given us the chance to become aware of the existence of an important guild of unidentified generalist natural enemies.
Highlights
The citrus leafminer, Phyllocnistis citrella Stainton, (Lepidoptera: Gracillariidae) is a pest native to SouthernAsia which spread to all citrus-growing areas worldwide during the last decade of the XX century (Urbaneja et al, 2003)
It appeared that predators responded to changes in flushing when this was regular, and this was attributed to continuous availability of preferential prey feeding on tender flushes, such as aphids
It was suggested from that study that generalist predators feeding on aphids, such as green lacewings, Chrysoperla carnea Stephens (Neuroptera: Chrysopidae), and aphid-mutualists, such as ants, which feed on P. citrella (Pomerinke, 1999), and were very commonly seen in P. citrella-infested orchards, were probably responsible for the high predation rates observed
Summary
The citrus leafminer, Phyllocnistis citrella Stainton, (Lepidoptera: Gracillariidae) is a pest native to SouthernAsia which spread to all citrus-growing areas worldwide during the last decade of the XX century (Urbaneja et al, 2003). Flushing patterns and incidence of aphids, P. citrella and C. carnea were followed from spring to fall 1999 at 15-day intervals at two different locations: Elx (38o 16’ N, 0o 41’ W, 86 m altitude) and Montcada (39o 35’N, 0o 23’ W, 33 m altitude).
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