Cucurbit beetle

Scientific name

Diabrotica speciosa (Coleoptera: Chrysomelidae)

Similar species

Diabrotica viridula

banded cucumber beetle, Diabrotica balteata
The cucurbit beetle (Diabrotica speciosa) is nearly identical to a species common in the southeastern United States, the banded cucumber beetle (Diabrotica balteata). The larvae of the banded cucumber beetle can cause extensive damage to tuber-bearing crops.

Distribution

United States: not known to occur in the United States.

Worldwide: South America.

Native to South America.

Diagnostic characteristics

Adults

• 5.5 - 7.3 mm (0.22 - 0.29 in.) in length.
• Body is grass-green with yellow spots. Headhead:
  one of the three main body segments in insects; the anterior-most segment containing the many sensory structures including the eyes, antennae, and mouthparts
  is reddish-brown to black.
• Oblong and oval in shape.
• In females, the rear of the abdomenabdomen:
  one of the three body segments in insects; the most posterior segment containing the heart, reproductive organs, and digestive organs
  is more pointed than in males.
• Males have longer antennae and an extra abdominal segment (sclerite) causing the abdomenabdomen:
  one of the three body segments in insects; the most posterior segment containing the heart, reproductive organs, and digestive organs
  to look more blunt.
• Hardened forewings (elytra) have three large, oval, transverse spots on each elytra segment.
• Antennae are 4 - 5 mm (0.16 - 0.2 in.) in length.
• First three antennal segments closest to the headhead:
  one of the three main body segments in insects; the anterior-most segment containing the many sensory structures including the eyes, antennae, and mouthparts
  are lighter in color.

Pupae

• 5.8 - 7.1 mm (0.23 - 0.28 in.) long contained within an 8 mm (0.31 in.) by 4 mm (0.16 in.) oval cell in the soil.

Larvae

• Three larval instars.
• 8.5 mm (0.33 in.) in length.
• Chalky white body; dirty-yellow to light brown headhead:
  one of the three main body segments in insects; the anterior-most segment containing the many sensory structures including the eyes, antennae, and mouthparts
  capsule.
• Sub-cylindrical in shape.

Eggs

• 0.74 (0.03 in.) in length and 0.36 mm (0.01 in.) in width.
• Clear white to pale yellow.
• Ovoid.

Hosts

Citrus hosts

All Citrus species and their hybrids.

Non-citrus hosts

The adults are highly polyphagous, recorded on over 60 species. Feed mainly on vegetables, but are particularly associated with Cucurbitaceae. A partial list includes:

• apple, Malus spp.
• bean, Phaseolus vulgaris
• cabbage, Brassica oleracea, var. capitata
• canola, Brassica napus
• cherry, Prunus spp.
• corn, Zea mays
• peanut or groundnut, Arachis hypogaea
• potato, Solanum tuberosum
• soybean, Glycine max
• squash,Cucurbita spp.
• sweet Potato, Ipomoea batatas
• tomato, Solanum lycopersicum
• wheat, Triticum aestivum

Host damage

Flowers

Flowers are preferred by adults; reduces yield.

Fruits

General damage by adult feeding.

Leaves

Adults will feed on foliage when flowers are not available. Damage by adult feeding can cause defoliation.

Roots

Larvae infest and eat roots resulting in stunted growth.

Biology

The cucurbit beetle is cold-tolerant and overwinters as an adult. They hide in the crown or rosettes of winter-growing plants. In the spring, adults emerge to feed on the host planthost plant:
the plant the provides sustenance for an insect
. Adults like to feed on pollen-rich flowers such as cucurbits, thistle, and sunflower. Eggs are oviposited on the soil close to a host planthost plant:
the plant the provides sustenance for an insect
. Larvae complete three instars while feeding on the roots of the host planthost plant:
the plant the provides sustenance for an insect
and pupate in the soil. Multiple generations are possible. In tropical areas, the cucurbit beetle reproduces continuously.

Comments

The cucurbit beetle is reported to semi-persistently vector Passionfruit yellow mosaic virus, Mimosa mosaic virus, and Purple granadilla mosaic virus. However, none of these viruses are reported to infect Citrus spp.

References

Germain, J.F. 2000. EPPO Pest risk assessment area: Europe (01/8504) - Diabrotica speciosa (Germar). (http://pest.ceris.purdue.edu/services/napisquery/pam_detail.php?id=INAMFQA).

Jackson, L. 2010. Cooperative Agricultural Pest Survey - Approved methods: Cucurbit Beetle - Diabrotica speciosa. (http://pest.ceris.purdue.edu/services/napisquery/query.php?code=cam).

(OEPP/EPPO). 2005. EPPO data sheets on quarantine pests Diabrotica speciosa. OEPP/EPPO Bull. 35: 374-376.(http://www.eppo.org/QUARANTINE/insects/Diabrotica_speciosa/DS_Diabrotica_speciosa.pdf).

Authors

Weeks, J.A., K. W. Martin, A.C. Hodges, and N.C. Leppla