Chinese rose beetle, Chinese rose chafer
Family: Scarabaeidae Subfamily: Rutelinae Genus: Adoretus Species: Adoretus sinicus Burmeister, 1855
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Total body length 10.0–12.0 mm (0.39–0.47 in). Body elongate oval. Color brownish with numerous distinctive, cream-white setae; setae sometimes missing in worn specimens. Front tibia with 3 teeth on external margin; male teeth pointed; female teeth comparatively rounded; teeth may be worn in older specimens. Front tarsomere with length of segments 2–4 (combined) more than 1.5 times that of segment 1 in male; front tarsomere with length of segments 2–4 (combined) less than 1.2 times that of segment 1 in female. Last sternite of female with apex rounded posteriorly; apex weakly quadrate in male.
(Habeck, 1962): Grub C-shaped, not hump-backed, cylindrical, whitish. Maxilla with galea and lacinia fused. Lacinia of maxilla with 3 well-developed terminal unci. Mandible with a ventral, elongate, oval, stridulatory area consisting of a numerous transverse, granular ridges; left mandible with outer scissorial tooth wider than inner tooth; right mandible with teeth equal in width but outer tooth projects farther than inner. Maxillary stridulatory teeth with apical points anteriorly projecting. Plegmatia present. Haptomerum of epipharynx with a dense, transverse row of 5–8 (usually 6) heli. Last antennal segment with single dorsal sensory spot. Respiratory plate C-shaped with numerous oval to round openings surrounding a prominent oval bulla. Raster with a subtriangular teges of hamate setae; palidia absent. Anal opening slightly curved, transverse. Lower anal lip with 8 stout setae, 10 long slender setae and 10 short slender setae.
Japan and Taiwan. Although this species is native to Japan and Taiwan (Mau and Kessing, 1991), it has spread widely and is now established in a great number of locations including Cambodia, the Caroline Islands, China, Guam, Hawaii, Indonesia, Singapore, Thailand, and Vietnam (McQuate and Jameson, 2011).
This species has been recorded feeding on over 500 species of plants (Hession et al., 1994), including such economically important species as broccoli (Brassica oleracea), cabbage (Brassica oleracea), cacao (Theobroma cacao), Chinese broccoli (Brassica oleracea), Chinese cabbage (Brassica rapa), chiso (Perilla frutescens), corn (Zea mays), cotton (Gossypium barbadense), cucumber (Cucumis sativus), eggplant (Solanum melongena), ginger (Zingiber officinale), grape (Vitis labrusca), green beans (Phaseolus vulgaris), jack fruit (Artocarpus heterophyllus), okra (Hibiscus esculentus), peanuts (Arachis hypogaea), Oriental persimmon (Diospyros kaki), raspberry (Rubus niveus), roses (Rosa spp.), salak palm (Salacca zalacca), soybean (Glycine max), star fruit (Averrhoa carambola), strawberry (Fragaria chiloensis), sweet potato (Ipomoea batatas), taro (Colocasia esculenta), and tea (Camellia sinensis) (McQuate and Jameson, 2011). In Hawaii, this species is also known to damage several endangered native plants including kauila (Colubrina oppositifolia), hau kuahiwi (Hibiscadelphus distans), and ko’oloa’ula (Abutilon menziesii) (Howarth, 1985).
Adults are active year-round and emerge after dusk to feed, with large numbers often congregating on the same plant (McQuate and Jameson, 2011). During the day, adults hide in soil at the base of their food plant (Williams, 1931). Host plants can easily be identified by the distinctive lace-like damage inflicted upon the leaves (Arrow, 1917). Developmental time was examined by Habeck (1964) in laboratory-reared specimens. He found that females deposited eggs 4 cm (1.6 in) in soil, with larvae emerging after 7–16 days. Warmer temperatures resulted in shorter emergence times. The first instar lasted 19.6–22.8 days, the second lasted 14.5–16.8 days, and the final lasted 34.3–44.4 days. The pupal stage lasts 11–17 days. Interestingly, larvae appear to develop more rapidly in the field, with the egg to adult cycle lasting 6–7 weeks (Mau and Kessing, 1991). Larvae are detritivores and do not appear to feed on living plant tissues (Mau and Kessing, 1991).
Severe. This species is a known biosecurity threat with a long history of biological invasion. It has spread continuously over the past 120 years with recent records coming from specimens intercepted in India (Bhawane et al., 2012) and Australia (Stanway et al., 2001). It is officially recognized by the USDA as a class B pest (USDA APHIS, 2012), and it is officially regarded as a pest with high risk of introduction in California (Cosner, 2013). It damages a great range of economically important plants, causing severe and economically significant damage (McQuate and Jameson, 2011).
Established. This species is found on all the major islands of Hawaii (Nishida, 2002). It became established in the late 19th century, with the earliest record dating to 1891 (Riley and Howard, 1893). By 1893, it was “rapidly becoming a most serious pest” (Riley and Howard, 1893). Across its range, Adoretus sinicus may be found in many habitats including urban, agricultural, and wilderness areas (García-Moll, 2013).
Established. This species has long been established in Guam, with the first report dating to 1949 (Pemberton, 1954).
It is thought that Adoretus sinicus first arrived to Hawaii as larvae or eggs transported in soil associated with plants imported from Asia (Ohaus, 1935; Pemberton, 1964). Adults are attracted to dim lights at night (though oddly may be deterred by bright lights), and it is possible that they would be attracted to artificialy lit docks or airports and hitchhike aboard freight and cargo. Indeed, this species has been intercepted in Australia on maritime containers (Stanway et al., 2001). This beetle is very common in Hawaii (pers. observation), and it should be regarded as having a very high likelihood of spreading to the southern U.S. and U.S. territories, including Puerto Rico and the U.S. Virgin Islands.
This species is extremely similar to the closely related Adoretus compressus. The two species cannot reliably be separated based on external morphology. Identification requires dissection and examination of the male genitalia.
Adoroleptus sinicus (Burmeister)
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