Predation of Florida red scale Chrysomphalus aonidum (L.) by the metallic blue ladybeetle Curinus coeruleus (Mulsant)

Florida red scale, Chrysomphalus aonidum (L.) is a species of armored scales, which attacks citrus crops. Biological control, particularly ladybeetles, are critical for its management in citrus production systems. We evaluated predation of C. aonidum by adult and larvae (3rd–4th instar) of the metallic blue ladybeetle, Curinus coeruleus. C. coeruleus were tested against C. aonidum in three separate treatments on Valencia orange leaves in Petri-dish arenas (1) individuals with armor intact, (2) individuals with armor removed, and (3) mix of individuals with armor intact or removed, to determine if armor inflicts distraction to predator consumption of scale and impact. Within 24 h of exposure to C. aonidum, adult beetle consumption rate averaged 64–68% in the two treatments containing all or half of the individuals with armor, compared to 100% in the treatment with armor removed. The consumption rate in the former two treatments increased to 83–89% within 72 h. Larval consumption of C. aonidum with armor intact was 25% at 24 h and 41% at 72 h, compared to 92–100% in the treatment with armor removed. The adults resulting from the larvae developed on C. aonidum with the armor intact or between the diets of armor intact or removed consumed more scales without armor than with armor. Significant consumption of C. aonidum by adults and larvae of C. coeruleus indicates that it is an efficient predator of this pest species. These novel findings suggest that this predator could be useful for suppressing C. aonidum populations in citrus production systems, particularly in habitats where both species are established such as Florida.

Chrysomphalus aonidumas pest of citrus in Greece

The presence of the scale insect Chrysomphalus aonidum (Linnaeus) (Hemiptera: Diaspididae), (the Florida red scale) is recorded in Greece and some data on its morphology are given. The coccid was found on the ornamental plant Dracaena sp. in Athens in the year 2000 and its rearing on potato tubes (Solanum tuberosum) and Cucurbita maxima is possible in the insectary. In January 2007 C. aonidum was found on heavily infested Citrus limon and Citrus sinensis, as well as on the less infested ornamental bushes Ficus benjamina and Ligustrum japonicum in outdoor conditions in the city of Kalamata (Peloponnese-southern Greece). In the past the presence of C. aonidum was recorded in Greece, but it was considered an occasional pest of citrus due to its difficulty to become acclimatized.

Effects of the malathion-bait mixture used on citrus to control Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) on the Florida red scale, Chrysomphalus aonidum (L.) (Hemiptera: Diaspididae), and its parasitoid Aphytis holoxanthus DeBach (Hymenoptera: Aphelinidae)

Examples of Chrysomphalus aonidum (L.) from which the scale covers had been removed, were about six times as sensitive to malathion as intact insects (LC50s of 0·09% and 0·55%, respectively). These results indicate that the scale cover probably absorbed part of the insecticide. Immature stages of the external parasitoid Aphytis holoxanthus DeBach on C. aonidum were not affected by 0·13% malathion applied to the host. However, adults of the parasitoid, which were extremely susceptible, were exposed before or during emergence to lethal levels of the insecticide present in the host scale cover. The findings are discussed in the light of the adverse effects of malathion-bait sprays applied against Ceratitis capitata (Wiedemann) on beneficial insects, and failures of biological control of scale pests on citrus in Israel.