A barcode database for insects associated with the spread of the Cocoa Swollen Shoot Virus Disease in Côte d'Ivoire.

Abstract

Swollen Shoot is a viral disease affecting cocoa trees, transmitted by several species of mealybugs (Insecta, Hemiptera, Sternorrhyncha, Pseudococcidae). These insects maintain trophobiotic relationships with a complex and species-rich assemblage of ants protecting them and natural enemies controlling their populations. Here, we provide a curated DNA barcode database to characterise this insect community. Systematic observation of 7,500 cocoa trees was conducted, coupled with the collection of mealybug colonies and associated insect communities (parasitoids, predators and ants). Natural enemies were reared from mealybug colonies collected from 1,430 cocoa trees. Specimens were identified morphologically and sequenced for fragments of the standard DNA barcode region of the COI. We recovered 17 species of mealybugs from the family Pseudococcidae. Amongst these species, eight are new to the Ivorian cocoa orchard: Dysmicoccusneobrevipes Beardsley, Ferrisiadasylirii (Cockerell), Maconellicoccusugandae (Laing), Paracoccusmarginatus Williams & Granara de Willink, Phenacoccussolenopsis Tinsley, Planococcusminor (Maskell), Pseudococcusconcavocerarii James and Pseudococcusocciduus De Lotto. Three of these species were identified for the first time in cocoa orchards in Africa: D.neobrevipes, Fe.dasylirii and Ph.solenopsis. A total of 54 ant species were identified and represented the first record of these species associated with mealybug colonies in cocoa in Côte d'Ivoire. Amongst the species associated with the mealybugs, 22 primary parasitoids, eight hyperparasitoids, 11 ladybirds beetles (Coccinellidae), seven gall midges (Cecidomyidae), one predatory lepidopteran species and four spider species were identified. Nine species of mealybugs parasitoids are newly recorded in the African cocoa orchards: Acerophagusaff.dysmicocci, Aloencyrtus sp., Anagyruskamali, Anagyrusaff.pseudococci, Aenasiusadvena, Clauseniaaff.corrugata, Gyranusoideaaff.tebygi, Zaplatycerusaff.natalensis (Encyrtidae) and Coccophaguspulvinariae (Aphelinidae) and one hyperparasitoid, Pachyneuronmuscarum (Pteromalidae). For Côte d'Ivoire in particular, besides the previously mentioned nine parasitoids and one hyperparasitoid, five additional species are recorded for the first time, including four primary parasitoids, Blepyrusinsularis (Encyrtidae), Clauseniacorrugata (Encyrtidae), Clausenia sp. (Encyrtidae), and Coccidoctonuspseudococci (Encyrtidae) and one hyperparasitoid, Cheiloneuruscyanonotus (Encyrtidae). These results significantly enhance the knowledge of the diversity of the entomofauna associated with Swollen Shoot disease and pave the way for developing control methods based on the natural regulation of its mealybug (Pseudococcidae) vectors.