The finding matters far beyond one beetle. Ladybirds of the family Coccinellidae are among the most economically important predators on Earth, devouring aphids, scale insects, whiteflies and mealybugs in orchards, forests and croplands. Several species have been shipped around the world as living pesticides, and their fates after release are notoriously hard to track. The Georgian population of Serangium montazerii is historically significant: the country was the first to use this species for biological control of Dialeurodes citri, and populations later introduced into France, continental and Corsican, and into Turkey, all traced back to this Georgian source. Confirming the species still survives where it was first deployed closes a loop that biocontrol scientists have left open since 1975.

The story of the confusion is a textbook case of how taxonomy can go wrong when researchers never compare the specimens in front of them. The beetle released in Adjara in the seventies was identified as Serangium parcesetosum Sicard, 1929, by Timofeyeva and Hoang Duc Nhuan in 1978, who also reassigned it to its original genus after Chapin had moved it to the genus Catana in 1940. Later authors followed that identification, and the 2012 revision of the subfamily Microweiseinae by Escalona and Slipinski did not examine members of either taxon. Then in 1995, Fürsch described a new species, Serangium montazerii, from Iranian specimens in Mazandaran Province. In 1998, Duverger assigned all the introduced Western European populations of Serangium, descendants of the original Georgian introduction, to this newer species. But after examining Corsican specimens, Coutanceau in 2006, and Coutanceau and Malausa in 2014, reassigned the French populations to S. parcesetosum, publishing their conclusions in French in an amateurs’ journal where they remained largely unknown.

Crucially, none of the key players in this debate, neither Fürsch, nor Duverger, nor Coutanceau, ever examined or compared the two taxa directly. The diagnostic characters that finally separate them were noted by Poorani in 1998 and underlined by Bieńkowski in 2020: the shape of the right paramere, a component of the male genitalia, and the inter-ocular distance, the gap between the eyes on the head. There is also a biogeographic clue. The population introduced into Georgia in the 1970s came from North India, Raniket in Uttarakhand, where S. montazerii occurs, while S. parcesetosum is distributed in Central and Southern India. The beetle that arrived in Adjara was almost certainly never S. parcesetosum at all.

The rediscovery itself was modest in scale but precise in method. On 25 June 2019, in a familial orange grove and garden at Chakvis Tskali, coordinates 41.71843 degrees north and 41.73841 degrees east, the researchers used beating trays to collect ladybird beetles by beating and shaking the branches of orange trees, then gathered the dislodged insects with an aspirator. Further orange trees located six kilometers eastward along the Chakvistskali River were also sampled. In the laboratory, specimens were identified to species level using available literature, including works by Gourreau, Iablokoff-Khnzorian, Poorani and Bieńkowski. The single S. montazerii specimen found was female, so genitalia-based determination was impossible, but the shape of the head with an inter-ocular distance equal to twice the size of the eyes allowed confident assignment to S. montazerii.

The location is telling. The site lies close to Batumi and corresponds to the area of the first historical introduction of the species in Georgia, the country of first use of the species against Dialeurodes citri. According to Yigit and Canhilal, the species was still present in Georgia in 1990. It has probably been present in the country since 1975, but was never listed by Merkviladze and Kvavadze in their 2002 national checklist. The species is also present northward in the vicinity of Sochi in Russia, recorded by Orlova-Bienkowskaja and Bieńkowski and by Bieńkowski in subsequent works. A quiet, persistent population has apparently survived on the eastern Black Sea coast for more than forty years, unnoticed by national faunal surveys.

The climate of the region helps explain why. The Batumi area and the Black Sea Georgian coast receive an average of 2515 millimeters of precipitation per year, with mild winters averaging 7 degrees Celsius in January and mild summers averaging 23 degrees Celsius in July, conditions classified as warm temperate, almost subtropical. The natural vegetation is hygrophilous thermophytic mixed deciduous broadleaved forest, and the presence of many citrus orchards, with their specific pests, made Batumi a focus of biocontrol attempts during the Soviet period, with releases of exotic Coccinellidae. The grove where the beetle was found is exactly the kind of habitat where an introduced citrus-pest predator would be expected to persist.

Alongside S. montazerii, the orange trees harbored a cosmopolitan cast of introduced ladybirds: many Harmonia axyridis, the harlequin ladybird, in both succinea and axyridis color forms, Novius cardinalis, the vedalia beetle famous for conquering cottony cushion scale worldwide, and Rhyzobius lophanthae, established in a large number of countries in Europe and around the world. Among the native species found on the same trees were Hyperaspis campestris, Scymnus haemorrhoidalis, Scymnus subvillosus, Scymnus interruptus, Scymnus rubromaculatus and Nephus quadrimaculatus. In addition, the team reported one observation of Hippodamia undecimnotata in Chalaubani, in the Gurjaani district of Kakheti, on 21 June 2019 on Carduaceae plants, a new district and a new province not recorded in the 2002 checklist.

The updated species list is more than a tally. It is a full nomenclatural renovation, following the actual phylogeny and modern supra-generic classification based on works by Kovář, Seago and colleagues, Escalona and Slipinski, Che and colleagues, and Zhang and colleagues, with genus-level updates for Chnootriba, Novius, Rhyzobius, Anisocalvia and Hippodamia. When a taxon’s name has changed since the 2002 publication, the original indication is reported. Many species were not listed by Kovář in the Catalogue of Palearctic Coleoptera, and the authors add indications for these. The list runs alphabetically through the tribes: six species of Chilochorini, three of Coccidulini, thirty-six of Coccinellini, one of Diomini, three of Epilachnini, five of Hyperaspidini, one of Noviini, one of Platynaspini, twenty of Scymnini, two of Stethorini, two of Sticholotidini, three of Tetrabrachini, and one introduced species of Serangiini in the subfamily Microweiseinae.

The bottom line is that the Georgian fauna of Coccinellidae contains 84 species. Two species, Scymniscus biflammulatus and Serangium montazerii, have been added to the Merkviladze and Kvavadze list, but one species, Tetrabrachys connatus, is dubious for the country, since Kovář records it only in central Europe, ranging from Austria to Ukraine and from Montenegro to Bulgaria, and the Georgian records reported by Schneider and Leder in 1878 in Racha-Lechkhumi and by Savenko in 1953 in Kutaisi need specific investigations to confirm or refute its presence. A further two species are now considered synonyms. Thirty species were not listed in the Catalogue of Palearctic Coleoptera. Among the biocontrol agents introduced into Georgia, Cryptolaemus montrouzieri, an important predator of mealybugs, is reported from Sochi in high numbers and could still be present in Georgia, while eight other species released between 1935 and 1990 have not been reported since their introduction, either in Georgia or along the Russian Black Sea Caucasus coast. Genetic studies would also be necessary to assess the origin of the actual Georgian populations of Harmonia axyridis, perhaps resulting from spreading from the admixed Western European population. For a country that pioneered the use of S. montazerii against citrus blackfly, the rediscovery confirms that a beetle released as a living pesticide in 1975 is still quietly patrolling the orange groves of Adjara, a survivor of one of the world’s earliest and least documented biocontrol campaigns.

Subject of Research: Rediscovery of the ladybird beetle Serangium montazerii in Georgia and an updated checklist of 84 Coccinellidae species for the country.

Article Title: Rediscovery of Serangium montazerii Fürsch in Georgia and updated list of the Coccinellidae of Georgia

Article References: Migeon, A., & Arabuli, T. (2022). Rediscovery of Serangium montazerii Fürsch in Georgia and updated list of the Coccinellidae of Georgia. Caucasiana, 1, 1-6. https://doi.org/10.3897/caucasiana.1.e60966

Image Credits: AI Generated

DOI: 10.3897/caucasiana.1.e60966

Keywords: ladybird beetles, Coccinellidae, Georgia, biological control, Serangium montazerii, taxonomy, invasive species, Caucasus biodiversity, Rediscovery, Serangium, montazerii, rsch