Journal of Experimental Agriculture International

Aims: In this study we tested four Catambra commercial formulates (hydroalcoholic extracts) used as insecticides in Italy, against Meloidogyne incognita and Meloidogyne javanica.

Catambra plant (Ambrogios, Catalpa) a European patent belonging to Ambrogio srl, rich in an iridoid glycoside catalpol, is used to date as a mosquito deterrent, but no data exist on its biological activity against soil parasites as Meloidogyne sp. Catalpa species demonstrate various biological properties of pharmaceutical and agronomical interest, mainly due to their contents in glycosides.

Place and Duration of Study: All paralysis bioassays were performed in Pesticide Science Laboratory, of Aristotle University Thessaloniki, Greece, while chemical analysis in Department of Life and Environmental Sciences, University of Cagliari.

Materials and Methods: The activity was tested in paralysis bioassays with freshly hatched second-stage juveniles (J2) immersed in test solutions for four time periods (12, 24, 48 and 96 hours). Catalpol contents of the extracts were measured by means of HPLC/MS and its activity was also tested against J2. The effect of exhaustive evaporation of hydroalcoholic extracts prior use in bioassays was also studied for nematicidal activity.

Results: Out of the four extracts tested without being evaporated first, two extracts (C-2 and C-4) exhibited activity and the EC_50/48h on M. incognita were calculated at 640 and 728 μg/ml. On the other hand, M. javanica was proven sensitive only to the C-4 extract and the activity had an EC_50/48h value at 500 μg/ml. When extracts were exhaustively evaporated before use, only the C-4 paralysed J2 and the EC_50/48h values were 728 and 500 μg/ml against M. incognita and M. javanica, respectively. Interestingly, catalpol was not found to be nematicidal at the concentration range of 100 to 1000 μg/ml. The nematicidal activity of the extracts was therefore not correlated with their content in catalpol. This was confirmed by the chemical composition study, since the C-4 extract, exhibiting activity against both species, was of low contents in catalpol (21 μg/ml), and the C-3 extract that had the highest contents in catalpol (358 μg/ml) did not paralyse J2.

Conclusion: Catambra nematicidal activity is not based in its contents in catalpol, and further studies are conducted to delineate for activity among other constituent components.