The biological control of Opuntia stricta var. dillenii (balas) in the Jizan Emirate of Saudi Arabia

Experiments on the host-specificity of the cochineal, Dactylopius opuntiae biotype “stricta” were carried out under semi-quarantine conditions established in the Ministry of Agriculture and Water, Riyadh, Saudi Arabia. The objective was to release this biological control agent onto Opuntia stricta var. dillenii infestations in Jizan Emirate of the Kingdom. Results indicated that the cochineal prefers Opuntia stricta (Balas) as compared to the two cultivars of Opuntia ficus-indica  (Berchumi Abha and Berchumi Asir) that are cultivated in Saudi Arabia.  Male and female survival was considerably lower on Berchumi than on Balas. Also, the weight of the cochineal females and their progeny were considerably lower on Berchumi than on the normal Balas host.  The results confirm earlier research from South Africa which shows that Berchumi is a sub-optimal host and that survival of cochineal on this host in the field is highly unlikely. The threat of any serious non-target effects on Berchumi is minimal, and is thus recommended that the cochineal be released for the biological control of invasive Balas in the Kingdom of Saudi Arabia.  The benefits of biological control far outweigh any possible risks to Berchumi.