Coccotrypes dactyliperda Fabricius
Taxonomic placing: Insecta, Holometabola, Coleoptera, Curculionidae, Scolytinae.
Common name: Date stone beetle.
Geographical distribution: Wherever date palms grow: the Middle East and North Africa, the Indian subcontinent and North America.
Host plants: Phoenix spp., including the date palm, P. dactylifera Linnaeus and the Canarian palm, P. canariensis Chabaud.
Morphology: The female beetle is 1.5-2.5 mm long, pale to dark brown, its legs and antennae being paler.
Life cycle: The beetle tunnels into the kernels (stones) of green unripe dates where it lays its eggs. The emergent larvae develop and pupate there, each date can support up to 70 individuals. The adults leave the host through a circular hole that they bore and search for new fruit. The pest does not attack ripening fruit. Its adults overwinter within dropped dates and raise 3-4 annual generations. The threshold of development is 12.3ºC. At 28ºC a complete cycle was completed in 3-4 weeks. This beetle is arrhenotokous, a mated female producing an average of 30 eggs, compared to 6-7 progeny for unmated females. The sex ratio in the field is strongly female-biased (only 7-15% males). Due to being sensitive to arid conditions, the pest cannot develop in the very dry environments that prevail in the southern inner valleys of Israel.
Economic importance: The beetle is a primary pest of date palms. It attacks the green unripe fruit during early to mid-summer, bringing about the severe (up to 30-40%) “July drop”. Such drop may start within 1-2 days after the beetles enter the dates, and each beetle can damage several fruit. The dropped and rotting dates then serve as hosts for nitidulid beetles (like Carpophilus spp.) that attack ripe fruit in late summer. More recently the pest invaded Egypt and is causing serious economic damage in the Delta.
Plant resistance: There is some indication that trees of various varieties are more severely infested at different heights.
Cultural control: Dense-mesh netting (0.8 x 0.5 mm holes) that covers the fruit bunches protects the dates from the pest. In addition, collecting and disposing of fallen fruit during winter may reduce the resident beetle population.
Chemical control: Several sprays with an organophosphate, applied during the season onto the green fruit may reduce the damage. However, as these pesticides harm the natural enemis of other date pests, they should be applied only as a last resort.
Blumberg, D. and Kehat, M. 1982. Biological studies of the date stone beetle, Coccotrypes dactyliperda. Phytoparasitica 10: 73-78.
Boraei, H.A. Khodeir, I.a. and El-Hawary, I.S. 1994. On the biology, damage and food preference of date stone palm beetle, Coccotrypes dactyliperda F. (Col., Scolytidae), a newly serious pest of palm trees at the northern regions of the Nile Delta, Egypt. Journal of Agricultural Research, Tanta University 20: 80-90.
Hussein, A.E. 1990. Date varieties and palm height in relation to infestation with date stone beetle, Coccotrypes dactyliperda F. (Coleoptera: Scolytidae). Annals of Agricultural Science 28: 2613-2622.
Kehat, M., Blumberg, D. and Greenberg, S. 1976. Fruit drop and damage in dates: the role of Coccotrypes dactyliperda F. and nitidulid beetles, and prevention by mechanical measures. Phytoparasitica 4: 93-99.