Maladera castanea

Status

Potential Invader

Common name(s)

Asian garden beetle, Asiatic garden beetle

Taxonomy

Family: Scarabaeidae Subfamily: Melolonthinae Genus: Maladera Species: Maladera castanea (Arrow, 1913)

DNA barcode

none available

Adult diagnosis

Total body length 7.0–11.0 mm (0.28–0.43). Body shape oblong-oval, widest posteriorly; convex when viewed laterally. Color rusty-brown to orange-brown with iridescent sheen. Clypeusclypeus:
part of the head anterior to the frons; the most anterior portion in dorsal view
with anterioranterior:
the front or forward; opposite of posterior
margin strongly reflexedreflexed:
margin that curves upward
. AntennaeAntennae:
paired sensory organ on head, formed from numerous segments
10-segmented; club 3-segmented. Pronotumpronotum:
the dorsal surface of the thorax
with indistinct, shallow punctationpunctation:
relating to a punctate surface texture
. ElytraElytra:
the hardened and chitinous wing-cover of a beetle that protect and overlie the flight wing
lacking obvious setaesetae:
small, hair-like structure
. Front tibiatibia:
a segment of the leg articulated with the tarsus and femur
of female more robust than in male.

Larval diagnosis

(Ritcher, 1966Ritcher, 1966:
Ritcher P. 1966. White grubs and their allies: a study of North American scarabaeoid larvae. Oregon State University Monographs, Studies in Entomology 4: 1-219.): Grub C-shaped, not hump-backed, cylindrical, whitish. Cardocardo:
basal (first) segment of the maxilla
, maxillary articulating membranemaxillary articulating membrane:
membrane that covers the region where the maxillae articulates with the head
, and many other body parts with numerous black dots. Galeagalea:
outer branch or lobe of the maxilla
and lacinialacinia:
inner portion of the maxilla
fused proximally, but separated distallydistally:
situated away from the point of articulation, thus usually furthest from the body
or tightly fitted together. Maxillamaxilla:
set of paired mouthparts located posterior to the mandibles
with dramatically swollen, bulbous stipesstipes:
lobe-bearing second segment of the maxilla
. Maxillary stridulatory area with row of 17–20 peg-like teeth. Last antennal segment always with a single, large, oblong, dorsaldorsal:
of or relating to the upper surface; opposite of ventral
, sensory spot. Haptomerumhaptomerum:
in larvae, the medio-anterior (middle of upper) portion of the epipharynx, composed of sensory spots
with 3 or 4 heliheli:
in scarab larvae, a coarse spine on or near the haptomerum
. Dorsaldorsal:
of or relating to the upper surface; opposite of ventral
anal lobeanal lobe:
fleshy lobe surrounding anus on the last abdominal segment of larvae
much smaller than the ventralventral:
of or relating to the lower surface; opposite of dorsal
anal lobes. Anal lobes densely setosesetose:
covered in setae
. Rasterraster:
in scarab larvae, a complex of setose, spiny, and bare areas on the ventral surface of the last abdominal segment
with a curved, transversetransverse:
extending horizontally across a surface
row of prominent setaesetae:
small, hair-like structure
anterioranterior:
the front or forward; opposite of posterior
to the ventralventral:
of or relating to the lower surface; opposite of dorsal
anal lobes. Anal opening Y-shaped with base of the Y much more elongate than the arms.

Native range

Northeastern Asia. This species is known from temperate northeastern Asia, occurring in Korea, China, and the Russian Far East (Ahrens, 2007Ahrens, 2007:
Ahrens D. 2007. Taxonomic changes and an updated catalogue for the Palaearctic Sericini (Coleoptera: Scarabaeidae: Melolonthinae). Zootaxa 1504: 1-51. full text (accessed 2015)). In the mainland U.S., this species is known from Maine west to Kansas and south to northernmost Florida (Skelley, 2012Skelley, 2012:
Skelley P. 2012. The Asiatic garden beetle, Maladera castanea (Arrow, 1913) (Coleoptera; Scarabaeidae), a white grub pest new to Florida. Florida Department of Agriculture amp; Consumer Services, Division of Plant Industry Entomology Circular 425: 1-3. full text (accessed 2015)).

Plant host(s)

The adults of this scarab have been recorded feeding on the foliage, stems, and flowers of over 100 plant species (Skelley, 2012Skelley, 2012:
Skelley P. 2012. The Asiatic garden beetle, Maladera castanea (Arrow, 1913) (Coleoptera; Scarabaeidae), a white grub pest new to Florida. Florida Department of Agriculture amp; Consumer Services, Division of Plant Industry Entomology Circular 425: 1-3. full text (accessed 2015)). Economically important host plants damaged by adults include Aster spp., basil (Ocimum basilicum), beans (Phaseolus spp.), beet (Beta vulgaris), Begonia spp., blackberry (Rubus spp.), blueberry (Vaccinium spp.), broccoli (Brassica oleracea), cabbage (Brassica oleracea), carrot (Daucus carota), cherry (Prunus spp.), Chrysanthemum spp., currant (Ribes spp.), Dahlia spp., eggplant (Solanum melongena), foxglove (Digitalis spp.), Geranium spp., hemp (Cannabis spp.), lettuce (Lactuca sativa), morning-glory (Ipomoea spp.), pea (Pisum sativum), peach (Prunus persica), plum (Prunus spp.), bell pepper (Capsicum annuum), rose (Rosa spp.), spinach (Spinacia oleracea), strawberry (Fragaria × ananassa), sunflower (Helianthus annuus), turnip (Brassica rapa), Viburnum spp., and willow (Salix spp.) (Eckman, 2015Eckman, 2015:
Eckman L. 2015. Host plant feeding preferences of the adult Asiatic garden beetle, Maladera castanea Arrow (Coleoptera: Scarabaeidae). MS thesis, University of Connecticut. full text (accessed 2015)). LarvaeLarvae:
the immature form of an insect; in scarabs, also called grub or white grub; preceded by the egg stage, followed by the pupal stage
, too, are generalist herbivores and have been recorded feeding on the roots of such economically important plants as blueberries (Vaccinium spp.), corn (Zea mays), soy beans (Glycine max), sweet potato (Ipomoea batatas), and turf grasses (Skelley, 2012Skelley, 2012:
Skelley P. 2012. The Asiatic garden beetle, Maladera castanea (Arrow, 1913) (Coleoptera; Scarabaeidae), a white grub pest new to Florida. Florida Department of Agriculture amp; Consumer Services, Division of Plant Industry Entomology Circular 425: 1-3. full text (accessed 2015)).

Life history

(Eckman, 2015Eckman, 2015:
Eckman L. 2015. Host plant feeding preferences of the adult Asiatic garden beetle, Maladera castanea Arrow (Coleoptera: Scarabaeidae). MS thesis, University of Connecticut. full text (accessed 2015)): In New York, females of this species deposit eggs in soil between July and October, showing a preference for shady, moist, overgrown, and weedy areas. After emerging, the larvaelarvae:
the immature form of an insect; in scarabs, also called grub or white grub; preceded by the egg stage, followed by the pupal stage
burrow to a depth of 15–30 cm (5.9-11.8 in) and begin feeding of plant roots. Winter is passed in the second or third larval instarinstar:
in scarabs, one of the three larval growth phases (i.e., first instar, second instar, third instar), each ending with the larvae molting to the next phase
and feeding usually resumes by mid-April. Roughly ten months are spent in the larval stage, with pupation lasting 14 days. Adult emergence begins in July, but likely begins earlier in warmer climates. Adults can live for more than 100 days, although the average lifespan is closer to 30 days. Adults are nocturnal and fly only when temperatures exceed 16°C (70°F). During the day, adults are inactive and remain near or on host plants.

Pest potential

Major. This species is a known biosecurity threat with a history of biological invasion (Ahrens, 2007Ahrens, 2007:
Ahrens D. 2007. Taxonomic changes and an updated catalogue for the Palaearctic Sericini (Coleoptera: Scarabaeidae: Melolonthinae). Zootaxa 1504: 1-51. full text (accessed 2015)). Invasiveinvasive:
a species that has recently arrived to a new location, usually via human activity, causing notable economic and/or ecological damage
populations have become established in Canada (Cutler and Rogers, 1990Cutler and Rogers, 1990:
Cutler G and Rogers R. 1990. New record of the Asiatic garden beetle, Maladera castanea (Arrow), in Atlantic Canada. Journal of the Entomological Society of Ontario 140: 40-45. full text (accessed 2015)), Turkey, the Republic of Georgia, and the US (Ahrens, 2007Ahrens, 2007:
Ahrens D. 2007. Taxonomic changes and an updated catalogue for the Palaearctic Sericini (Coleoptera: Scarabaeidae: Melolonthinae). Zootaxa 1504: 1-51. full text (accessed 2015)). In the US, the range of this species has expanded slowly but steadily since its 1921 introduction (Skelly, 2012). Adults cause severe leaf damage to a wide range of plant species important for agriculture, horticulture, and forestry (Eckman, 2015Eckman, 2015:
Eckman L. 2015. Host plant feeding preferences of the adult Asiatic garden beetle, Maladera castanea Arrow (Coleoptera: Scarabaeidae). MS thesis, University of Connecticut. full text (accessed 2015)). LarvaeLarvae:
the immature form of an insect; in scarabs, also called grub or white grub; preceded by the egg stage, followed by the pupal stage
feed on plant roots and can cause significant damage, particularly to turf grass (Held and Ray, 2009Held and Ray, 2009:
Held D and Ray C. 2009. Asiatic garden beetle Maladera castanea (Coleoptera: Scarabaeidae) grubs found in damaged turf in Alabama. Florida Entomologist 92: 670-672. full text (accessed 2015)). The pest potential of larvaelarvae:
the immature form of an insect; in scarabs, also called grub or white grub; preceded by the egg stage, followed by the pupal stage
is reduced somewhat by their tendency to burrow deep into soils, and their preference for weedy, unkempt habitats (Skelley, 2012Skelley, 2012:
Skelley P. 2012. The Asiatic garden beetle, Maladera castanea (Arrow, 1913) (Coleoptera; Scarabaeidae), a white grub pest new to Florida. Florida Department of Agriculture amp; Consumer Services, Division of Plant Industry Entomology Circular 425: 1-3. full text (accessed 2015)).

Status in Hawaii

New record, not established. We recorded a single specimen of Maladera castanea from Oahu (deposited at the Bernice Pauahi Bishop Museum). The specimen label indicates it was discovered at Hickham Air Force Base in a spider's web in 1977.

Status in Guam

Not established or recorded. This species has not been recorded from Guam.

Potential distribution and dispersal pathway

This species is strongly attracted to lights at night (Held and Ray, 2009Held and Ray, 2009:
Held D and Ray C. 2009. Asiatic garden beetle Maladera castanea (Coleoptera: Scarabaeidae) grubs found in damaged turf in Alabama. Florida Entomologist 92: 670-672. full text (accessed 2015)), and it is likely attracted to well-lit ports and airports. This would allow for hitchhiking on marine or air cargo. Indeed, the Oahu record may represent an individual that hitchhiked aboard military aircraft. Adults hide on or near food plants by day (Eckman, 2015Eckman, 2015:
Eckman L. 2015. Host plant feeding preferences of the adult Asiatic garden beetle, Maladera castanea Arrow (Coleoptera: Scarabaeidae). MS thesis, University of Connecticut. full text (accessed 2015)) and could be moved during transportation of nursery plants. Further, it is possible that larvaelarvae:
the immature form of an insect; in scarabs, also called grub or white grub; preceded by the egg stage, followed by the pupal stage
or eggs could be transported in shipments of commercial turf or potted plants.

Similar species

This species is very similar to the closely related Maladera japonica. These species can be separated by comparison of the male genitalia, examination of pronotal punctationpunctation:
relating to a punctate surface texture
(punctures shallow and indistinct in M. castanea versus moderately deep and distinct in M. japonica), and more superficially by color (color rusty-brown to orange-brown with iridescent sheen in M. castanea versus dark brown without iridescent sheen in M. japonica).

Other names (synonyms)

Aserica castanea (Hallock), Autoserica castanea (Hallock), Maladera verticalis (Fairmaire), Serica korgei Petrovitz, Serica verticalis Fairmaire

Report your observation

In Hawaii, this species represents a new invasiveinvasive:
a species that has recently arrived to a new location, usually via human activity, causing notable economic and/or ecological damage
species. Prevent the spread of this species by reporting your observation at our iNaturalist project.