Aulacophora fauveli Beenen, 2008 ; Candezea semiviolacea (Fauvel, 1862) ; Candezea palustris (Perroud, 1864)

New Caledonian cucurbit beetles

General 

• Three species are observed in New Caledonia which look very similar. They are called "yellow beasts" by New Caledonian farmers without any particular distinction.
• However, a few distinctive signs allow them to be differentiated:
  • Candezea semiviolacea has an orange colored head and yellowish to olive-green elytra.
  • Candezea palustris and Aulacophora fauveli have an orange-red head, thorax and abdomen. C. palustris is distinguished from A. fauveli by the apex of its abdomen which is black in color.
• These insects belong to the Chrysomelidae family and the Galerucinae subfamily . Note that the two beetles of the genus Candezea were associated only a short time ago with the genus Monolepta.
• Their size varies between 6 and 10 mm, Aulacophora fauveli being slightly larger than the 2 other species.
• Observed mainly in the open field.
  
  

• Sensitive botanical family (s)

• Affected production areas * :

*TO. fauveli is present in some islands of the Pacific. C . palustris occurs in the Solomons, Australia, New Caledonia, Papua New Guinea and Vanuatu. C. s emiviolacea is endemic to New Caledonia. C. pa lustris and C. s emiviolacea are polyphagous. A. fauveli appears to be more specific to cucurbits.

• Organs attacked

 Symptoms, damage

• Symptoms :
  • Leaves eaten mainly by adults which feed on the blade. This one is cut, holed more or less regularly
  • The damage can be very severe on young plants. Apart from zucchini and Chinese cabbage, the impact on other vegetable species is moderate as long as the vegetative development of the plant is sufficient.
  • Flowers and fruits are also eaten and cut.
  • The larvae that live in the soil feed on the roots.

• Signs : Presence of adult insects on plants and in the crop (figures).

 Biology 

• Development cycle : There is no information on the development cycle of these species.
  
  • The larvae present in the soil consume the roots and they need water to develop.
  • The metamorphosis takes place in the soil.
• The most severe attacks are often observed during rains occurring after a dry period.

 Protection

• Produce the plants in an nursery insect-proof (instead of sowing in the open field) and check their sanitary quality before and during their introduction into the crop or shelter. Otherwise, carry out the culture under net during the vegetative development. The most critical phase lasts until the 6-8 leaf stage.
• Check the sanitary quality of the plants before and during their introduction into the crop or shelter.
• Mulch the crop (plastic or canvas) to limit the emergence of adults from the ground. However, these species are very mobile and attacks can still be caused by adults from adjacent plots.
• The  chemical protection is not very effective in this use. Due to their high mobility, it is difficult to touch these insects during spraying.