Study of the associations of aphids-entomophagous in Foeniculum vulgare (Umbelliferae) and Conyza bonariensis (Asteraceae) in the central region of Santa Fe, Argentina

The objective of this work was to study the aphids-entomophagous associations in Foeniculum vulgare (Miller) and Conyza bonariensis L. in order to implement Conservative Biological Control (CBC) in agroecosystems of the central region of Santa Fe Province. Direct observation on plants was conducted on a weekly basis, from February to May 2008. The identification of species was carried out in the greenhouse when it was not possible to do it in the field. The aphid species identified on F. vulgare was Hyadaphis foeniculi (Passerini) (Hemiptera: Aphididae), and on C. bonariensis predominated Uroleucon ( Lambersius ) sp. (Hemiptera: Aphididae). Parasitoids and predators were also important. The relationships between aphids and natural enemies were estimated by correlation analysis. These coefficients indicated a relationship between H. foeniculi and Diaeretiella rapae (M’Intosh) (Hymenoptera: Braconidae) (0.63) and between U . ( Lambersius ) sp. and coccinellids (Coleoptera: Coccinellidae) (0.43). It was concluded that these plants are very important in order to keep different groups of entomophagous in agroecosystems, and their use in CBC aphid pest programs is possible, helping to reduce insecticide applications in crops.