Skip to main content

Soft scale insect, repens scale (Pulvinaria rhododendri), on Rhododendron spp. in Northern Europe

Soft scale insect, repens scale (Pulvinaria rhododendri), on Rhododendron spp. in Northern Europe

NEWS - Repens scale (Pulvinaria rhododendri Kahrer & Hodgson, Hemiptera: Coccomorpha: Coccidae) was discovered in Rhododendron spp. (Ericaceae) in Denmark and Norway which appears taxonomically close to P. camelicola Signoret and P. floccifera Westwood with an uncertain geographic origin, but is likely to have been introduced to northern Europe via imported live plants.

P. rhododendri is distinguished from P. floccifera, P. camelicola and all other Pulvinaria species by a combination of characters-a medial band of large conical spinous setae extending from the anal plate anterior to the head and simple pores with strongly sclerotic margins present in a narrow medial band between the large conical spinous setae.

The new species also differs from P. floccifera by the presence of a type III tubular canal submarginally between the lateral stigmatic clefts (vs. absent). The species is named after the genus of the host plant from which it is most commonly collected, Rhododendron L. P. rhododendri is also found on Vaccinium myrtillus L. (Ericaceae) but only when Rhododendron spp. are present nearby.

In Denmark, the species has been found in gardens on the mainland at Hadsund Syd, Jutland, and at Tyfelse on the island of Zealand, 25 km southwest of Copenhagen. These gardens are probably about 150 km apart. In Norway, P. rhododendri has been collected from Arendal and Grimstad on the south coast, about 250 km north of Jutland, Denmark.

The new species is only known from a small area in northern Europe and was probably first found on Rhododendron spp. in Norway in 2018 causing severe sooty mold infestations. This plant was eradicated but the population appears to have persisted as specimens were collected at the same location in 2022.

It is likely that the first discovery also referred to P. rhododendri and since it is still present, it is clearly growing and overwintering under northern European conditions, having survived two winters in between.

To date, no geographical surveys have been carried out to determine the distribution of the species. This host plant could spread more widely as it is cultivated, is a popular plant and is often moved in the plant trade.

The new species is potentially important as a pest of urban plants, especially Rhododendron spp., based on the distribution mentioned above. In the field, P. rhododendri is somewhat similar to P. camelicola which may have been mistaken for non-entomologists in the past.

P. rhododendri, like other Pulvinaria species, produces abundant honeydew, so the growth of sooty mold is a major problem, forming a thick, unsightly layer covering the leaves. However, so far it does not appear to cause host mortality or other problems.

Original research

Andreas Kahrer & Chris J. Hodgson (2024). A new species of the soft scale insect genus Pulvinaria Targioni Tozzetti (Hemiptera: Coccomorpha: Coccidae) on Rhododendron spp. in Northern Europe. Zootaxa 5512 (2): 233-239, DOI:10.11646/zootaxa.5512.2.7

Dlium theDlium

Popular Posts

Javan broadhead planarian (Bipalium javanum)

Cacing palu or Javan broadhead planarian ( Bipalium javanum ) is a species of animal in Geoplanidae, hermaphrodite, living on the ground, predators, often called only hammerhead or broadhead or shovel worms because of wide heads and simple copulatory organs. B. javanum has a slim stature, up to 20 cm long, up to 0.5 cm wide, head wide up to 1 cm or less, small neck, widening in the middle and the back end is rounded, all black and shiny. Javan broadhead planarians walk above ground level by raising their heads and actively looking left, right and looking up using strong neck muscles. Move swiftly, track meander, climb to get through all obstacles or make a new path if the obstacle is too high. Cacing palu track and prey on earthworms and mollusks. They use muscles and sticky secretions to attach themselves to prey to lock in. The head and ends of the body are wrapped around and continue to close the body to stop prey reactions. They produce tetrodotoxins which are very strong...

Swietenia mahagoni and Swietenia macrophylla, the differences

SPECIES HEAD TO HEAD - To date, mahogany ( Swietenia Jacq.) is recorded as having four species: West Indian mahogany or small-leaved mahogany ( Swietenia mahagoni (L.) Jacq.), big-leaf mahogany ( Swietenia macrophylla King), Honduran mahogany ( Swietenia humilis Zucc.) and Swietenia × aubrevilleana StehlĂ© & Cusin. The debate over the number of taxa in the genus is still not resolved. Some researchers believe that there are only two species: S. mahagoni and S. macrophylla . I agree with that opinion and the two species can only be differentiated by the size of the leaves. All species in this genus have similar morphology except for leaf size. The following is the key to identifying these two species. S. mahagoni has a stalk length of around 37 cm with 5-6 pairs of strands. The strands are about 10 cm long and about 3.5 cm wide. S. macrophylla has a stalk length of up to 45 cm with 4-5 pairs of strands. The strands are up to 31 cm long and up to 8 cm wide. By Aryo Bando...

Black potato (Coleus rotundifolius)

Black potato ( Coleus rotundifolius ) is a species of plant in Lamiaceae, herbaceous, fibrous roots and tubers, erect and slightly creeping stems, quadrangular, thick, and slightly odorous. Single leaves, thick, membranous, opposite and alternate. Leaves are oval, dark green and shiny on the upper side, bright green on the lower side. Up to 5 cm long, up to 4 cm wide, slightly hairy and pinnate leaf veins. Leaf stalks up to 4 cm long. Small, purple flowers. Star-shaped petals, lip-shaped crown, dark to light purple with a slightly curved tube shape. Flowering from February-August. Small tubers, brown and white flesh and tuber length 2-4 cm. Kingdom: Plantae Phylum: Tracheophyta Subphylum: Angiospermae Class: Magnoliopsida Order: Lamiales Family: Lamiaceae Subfamily: Nepetoideae Tribe: Ocimeae Subtribe: Plectranthinae Genus: Coleus Species: Coleus rotundifolius