Pollen feeding habits of Chrysoperla carnea s.l. adults in the olive grove agroecosystem

Abstract

Chrysoperla carnea s.l. (Stephens) larvae are important natural enemies in agroecosystems. However, adults feed on honeydew excreted by hemipterans, and pollen and nectar from flowering plants. Pollen is essential for egg production, but to our knowledge, the pollen diet of C. carnea in perennial crops has never been addressed. In this work, the objective was to study the diversity and potential selection of pollen types consumed by C. carnea in the olive grove agroecosystem. For this study, C. carnea adults were captured from April to December of 2012 and 2013, and simultaneously, inventories of the plant diversity were obtained in olive orchards and adjacent scrubland and herbaceous patches. The pollen types contained in C. carnea guts were identified by microscopy and compared with the pollen types in the environment using Jacobs`s second selection index. The results indicated that (i) C. carnea females and males captured in the olive tree canopy visited scrub and herbaceous vegetation patches; (ii) they fed on different anemophilous and entomophilous pollen types from tree and scrub (Olea europaea, Fabaceae, Pinaceae, Cistaceae or Ericaceae) and herbaceous (Asteraceae, Apicaceae, Brassicaceae, Poaceae, Rumex type or Plantago type) strata; and (iii) adults fed not only on flowers but also on pollen settled on vegetation surfaces. Here, we demonstrated that C. carnea could benefit not only from the diversity of entomophilous pollen during the plant flowering periods but also from other pollens that could remain in the environment in different periods. This has important implications for the management of the floral diversity adjacent to the crop.