Interactions between wild flora, crops, aphids (Hemiptera, Aphididae) and their natural enemies in citrus orchards

The survey was carried out in some citrus orchards in the area of Bernalda, in the region of Basilicata, south Italy. Aphids and their natural enemies were monthly sampled from citrus tree canopies and spontaneous plants in four citrus orchards differently managed (organic and conventional with and without herb layer). Four weed species (Rumex crispus, Sonchus oleraceus, Euphorbia peplus and Vicia sp.) were reported as hosts of four non-pest aphids of citrus, which were Myzus persciae, Acyrthosiphon pisum, Hyperomyzus lactucae and Aphis rumicis, serving as preys for natural enemies including coccinellids (Coleoptera, Coccinellidae), lacewings (Neuroptera, Chrysopidae), hoverflies (Diptera, Syrphidae) and various parasitoid species (Hymenoptera, Braconidae) that were recorded on citrus canopies. Statistical analysis of collected data showed a positive correlation between weed management systems and wild plants hosting aphidophagous communities. Furthermore, organic weeding approaches had a positive effect on aphidophagous richness and abundance, whereas the conventional weeding method could cause scarcity of aphid natural enemies, but interactions among strata (entomofaunal diversity on citrus tree canopies & wild plant cover) are still unclear. Overall, this work is a further step towards the investigation of the interaction between plants, crops and arthropods in citrus orchards in the Mediterranean basin to make weed management strategy a key for aphid management in crops.

Keywords:

Citrus , wild flora , aphids , Basilicata , natural enemies , diversity