Hiding in plain sight: Cryptic enemies are found on cochineal (Hemiptera: Dactylopiidae), a scale insect of economic and cultural significance

Abstract

Abstract Cochineal is the common name for cactus‐feeding scale insects in the Dactylopiidae. These ruby‐red insects include the domesticated dye insect Dactylopius coccus. Dactylopius coccus and congeners have been introduced around the world, some accidentally, to become pests of prickly pear cactus species (Opuntia), and some intentionally, for dye production or biological control of pest Opuntia. In the northern Sonoran Desert (Tucson, AZ, USA), we studied the enemy complex of D. opuntiae and D. confusus on Opuntia and characterized two cryptic enemies, a coccinellid beetle predator and a parasitoid wasp. (1) Hyperaspis sp. The coccinellid predator Hyperaspis trifurcata shares a niche with a similar, typically all‐black beetle. Morphological data, crossing tests, and phylogenetic results showed the black beetle to be a distinct, undescribed species in the genus Hyperaspis, with a rare spotted phenotype that is similar in appearance to H. trifurcata. Crossing tests among black and spotted forms showed the spotted morph is inherited as a single‐locus dominant allele. (2) Formicencyrtus thoreauini. Rearing of this ant‐like parasitoid wasp (Encyrtidae) in pure culture of D. opuntiae showed it to be a semi‐gregarious primary parasitoid of cochineal. To our knowledge, this is the first confirmed instance of a cochineal parasitoid. Observations of development show early instar larvae keep their posterior end within the egg chorion, attached to an aeroscopic plate with a connection to the cochineal body wall. Late instar larvae are eventually surrounded by a membrane, likely of larval origin. Wasps then pupate in a dry air‐filled chamber within the desiccated scale remains before chewing out as an adult. Both Hyperaspis sp. and F. thoreauini may have restricted distributions. Hyperaspis sp. does not appear to be a member of the cochineal community in Mexico or Texas, and scant records suggest F. thoreauini may also be restricted to the Southwestern USA.

Keywords

• biological control
• cactus pest
• Chalcidoidea
• Coccinellidae
• parasitic wasp
• pest cactus