Scymnus nubilus explained

Scymnus (Scymnus) nubilus, is a species of lady beetle found in Pakistan, India, Bangladesh, Sri Lanka, Nepal, Myanmar, China, and Asia Minor.^[1]

Description

Body length is 1.5 to 2.0 mm. Maximum body weight is about 1.5 mg.^{[2] [3]} Body small, elongate, and moderately convex. Body dark brown ventrally, and densely covered with fine, short, transparent, yellowish hairs. Head light brown to dark brown in color. Eyes are large and brown. Antennae small, and segmented. Pronotum dark brown, in which middle part is much darker and posterior, anterior margins are lighter reddish brown. Elytra mainly yellowish to reddish brown, and punctate. There is a dark brown to black sutural stripe from basal margin of elytra.^{[4] [5]}

Biology

Primarily an aphidophagous species, it is also a predator of several mealybugs and scale insects. The diet include: Aphis craccivora, Aphis fabae, Brevicoryne brassicae, Lipaphis erysimi, Myzus persicae, Aphis gossypii, Aphis spiraecola, Aphis frangulae, Cinara juniperi, Hyadaphis coriandri, Hysteroneura setariae, Rhopalosiphum maidis, Therioaphis trifolii, Macrosiphum granarium, Schizaphis graminum, Phenacoccus solenopsis, Ferrisia virgata, Drosicha mangiferae, Amrasca devastans, Amrasca biguttula, Bemisia tabaci, Tetranychus atlanticus, Toxoptera aurantii, Adelges joshii, Aonidiella auranti, Aonidiella citrina, Aonidiella orientalis, Aspidiotus destructor, Hemiberiesia latanias, Rhopalosiphum padi, Leucaspis coniferarum, Parlatoria, Pentalonia nigronervosa, Pinnaspis strachani, Quadraspidiotus perniciosus, Maconellicoccus hirsutus and Tecaspis.^{[6] [7] [8] [9]}

Host plants of the beetle include: mustard, lucerne, cabbage, cauliflower, potato, turnip, bottle gourd, brinjal, okra, wheat, cotton and rose. Mating occurs about 4 to 5 days after emergence of the adult. Then oviposition followed after 6 days. Eggs are laid singly during an oviposition period of more than a month, where the female lays about 9 eggs each.^[10] Larva produces a wax layer by dorsal epidermal cells, which is an effective defensive mechanism.^[11]

Notes and References

1. Ali M, Ahmed K, Ali S, Raza G, Hussain I, Nafees MA, Anjum SI . An annotated checklist of Coccinellidae with four new records from Pakistan (Coleoptera, Coccinellidae) . ZooKeys . 803 . 93–120 . 2018-12-06 . 30643484 . 6292984 . 10.3897/zookeys.803.22543 . free .
2. Pacheco P, Borges I, Branco B, Lucas E, Soares AO . Costs and Benefits of Wax Production in the Larvae of the Ladybeetle Scymnus nubilus . Insects . 12 . 5 . 458 . May 2021 . 34065731 . 8156663 . 10.3390/insects12050458 . free .
3. Mayadunnage S, Wijayagunasekara HN, Hemachandra KS, Nugaliyadde L . Predatory Coccinellids (Coleoptera: Cocinellidae) of vegetable insect pests: a survey in mid country of Sri Lanka. . Tropical Agricultural Research . 19 . 69–77 . 2007 .
4. Ashfaque M, Ullah F, Rafi MA, Naz F . Taxonomic study of subfamily Scymninae (Coleoptera: Coccinellidae) with one new record from Gilgit-Baltistan, Pakistan. . Turkish Journal of Zoology . November 2015 . 39 . 6 . 1034–40 . 10.3906/zoo-1401-17 .
5. Ali M, Perveen R, Naqvi AU, Ahmed K, Raza G, Hussain I . The tribe Scymnini (Coccinellidae: Coleoptera) from Sindh Province, Pakistan . Journal of Insect Science . 15 . 146 . 2015 . 26454480 . 4664943 . 10.1093/jisesa/iev105 .
6. Rosagro RM, Borges I, Vieira V, Solé GP, Soares AO . Evaluation of Scymnus nubilus (Coleoptera: Coccinellidae) as a biological control agent against Aphis spiraecola and Cinara juniperi (Hemiptera: Aphididae) . Pest Management Science . 76 . 2 . 818–826 . February 2020 . 31414715 . 10.1002/ps.5585 .
7. Kumar MV, Chakraborty N . Biology of Scymnus nubilus Mulsant (Coleoptera: Coccinellidae), a native predator of pink mealy bug, Maconellicoccus hirsutus (Green)(Hemiptera: Pseudococcidae). . Journal of Entomological Research . 1997 . 21 . 4 . 329–34 .
8. Borges I, Hemptinne JL, Soares AO . Contrasting population growth parameters of the aphidophagous Scymnus nubilus and the coccidophagous Nephus reunioni. . BioControl . June 2013 . 58 . 3 . 351–7 . 10.1007/s10526-012-9490-y . 17771318 .
9. Meseguer R, Borges I, Vieira V, Pons G, Soares AO . Ecosystem services provided by the native predator Scymnus nubilus Mulsant (Coleoptera: Coccinellidae) against aphids on forestry nurseries. Ponta Delgadam . Benefits and Risks of Exotic Biological Control Agents IOBC-WPRS Bulletin . Azores (Portugal) . September 2018 . 145 . 62–3 .
10. Johnson J . Biology of Scymnus nubilus Muls.(Coccinellidae: Coleoptera) an insect predator. . Agricultural Research Journal of Kerala . 1972 . 10 . 2 . 183–5 .
11. Pacheco PA . Cost and benefits of the morphological defences in larvae of Scymnus nubilus Mulsant (Coleoptera: Coccinellidae) . Ph.D. . Universidade dos Açores . 19 January 2012 .