Biological control of diaspidid scales Aspidiotus nerii Bouché andAonidiella aurantii (Maskell) by means of commercial Aphytis melinus DeBach(Hym., Aphelinidae) releases: basis for an IPM strategy in Spanish citrus

Abstract: The California red scale, Aonidiella aurantii (Maskel) (Hemiptera: Diaspididae),and the Oleander scale, Aspidiotus nerii Bouche (Hemiptera: Diaspididae) are consideredkey pests of mandarin and lemon trees in Spanish citrus orchards, respectively. These pestsare typically controlled throughout the application of broad spectrum pesticides such usorganophosphates and insect growth regulators which result harmful for other naturalenemies principally coccinellids. To develop a feasible and reliable IPM strategy in thesecrops, the control of these scales must be afforded without disturbing the natural control ofseveral secondary pests, avoiding the use of the above-mentioned pesticides. Since 2008,Koppert Biological Systems is mass rearing the parasitic wasp Aphytis melinus DeBach(Hym., Aphelinidae) in Spain. This availability has made possible the realization ofcommercial scale trials aimed in the implementation of this parasitic wasp as a biologicalcontrol agent for controlling A. aurantii and A. nerii by means of inoculative-augmentativereleases. These trials have been carried out together with the Agriculture Consejería ofMurcia. The tested strategy is similar to other existing in other countries where this parasiticwasp is widely implemented such as Australia, USA and South Africa. However, theagronomic, climatic conditions, pest incidence and natural enemies are different to those inthe Mediterranean countries.In this work we describe the strategy used for the implementation of A. melinus, showing thetiming and rates for the releases in several commercial orchards which were determinedunder the criteria of professional crop advisors and growers based on the initial infestationsand the management of the crop.The results have revealed that A. melinus can be used as the base of biological control-basedIPM programs for A. aurantii and A. nerii control in citrus orchards. Its implementationcould increase the use of this control method in Spain and would likely have the same effectin other production areas.