Cacopsylla bidens (Šulc)
Taxonomic placing: Insecta, Hemimetabola, Hemiptera, Psylloidea, Psyllidae.
Common name: Pear psylla
Geographical distribution: Mediterranean basin, Moldova, Romania, France, and Italy.
Host plants: Various pome-fruit trees and ornamentals, such as rose and privet.
Morphology: The body is about 3-4 mm in length, brown-black in winter turning pale brown in summer. The eyes are red. The young nymph is yellowish, becoming brown in later stages, when it also produces some wax
Life cycle: The pest overwinters as fifth-stage nymphs or adults, beginning to lay eggs in early spring. They prefer to feed on young leaves, but may also suck from lignified branches. In the Middle East the pest has 8-9 annual generations, and each female produces about 70-80 progeny. The pear psylla shows seasonal dimorphism, the summer forms being lighter and smaller than members of the winter phenotype, which are darker and larger.
Economic importance: Damage to pear trees is due to excreting large amounts of honeydew on which dark sootymold fungi settle, making the fruit unsaleable and interfering with photosynthesis. The pest also injects toxic saliva into the infested plant parts, which causes leaf wilt and drop. Some species of Cacopsylla transmit fire blight and pear decline diseases to pears, but not C. bidens.
Management
Monitoring: In late winter buds should be checked for pest eggs. Buds, flowers and fruit clusters are to be examined in the spring, and leaf bases and fruits should be checked for eggs and nymphs in summer.
Horticultural methods: Pear psylla populations infesting pear trees were reduced by using lower levels of nitrogen fertilizers, and the application of plant growth regulators may possibly reduce pear psylla populations.
Plant resistance: Some pear selections are relatively resistant to the pest, apparently due to antibiosis mechanisms that affect nymph survival. Such accessions may be used as rootstocks or as sources for resistant genes in breeding programs.
Chemical control: Although the pest rapidly develops pesticide resistance to many plant-protection chemicals, avermectins and kaolin dust are still in use.
Biological control: The anthocorid predator Anthocoris nemoralis has some effect on pest numbers, although it often arrives on pear trees after most of the damage has already been inflicted.
References
Blomquist, C.L. and Kirkpatrick B.C. 2002. Frequency and seasonal distribution of pear psylla infected with the pear decline phytoplasma in California pear orchards. Phytopathology 92: 1218-1226.
Mohamed, G.H., Ouvrad, D. and Fatma, A.M. 2013. Pear psylla, Cacopsylla bidens (Šulc, 1907): a new pest on pear trees in Egypt (Hemiptera: Psylloidea). Egyptian Academic Journal of Biological Sciences 6: 49-52.
Reuveny, H. 2005. Improving the control of pear psylla (Cacopsylla bidens) in Israel. Alon Hanotea 59: 350-353 (in Hebrew with English summary).
Shaltiel, L. and Coll, M. 2004. Reduction of pear psylla damage by the predatory bug Anthocoris nemoralis (Heteroptera: Anthocoridae): the importance of orchard colonization time and neighboring vegetation. Biocontrol Science and Technology 14: 811-821.
Shaltiel-Harpaz, L., Kedoshim, R., Openhiem, D., Stern, R. and Coll, M. 2010. Effect of host plant makeup through nitrogen fertilization and growth regulators on the pear psylla population. Israel Journal of Plant Protection 58: 149-156.
Shaltiel-Harpaz, L. (and 7 co-authors). 2014. Two pear accessions evaluated for susceptibility to pear psylla Cacopsylla bidens (Šulc) in Israel. Pest Management Science 70: 234-239.
Soroker, V., Alchanatis, V. (and 4 co-authors) 2013. Phenotypic plasticity in the pear psyllid, Cacopsylla bidens (Šulc) (Hemiptera, Psylloidea, Psyllidae) in Israel. Israel Journal of Entomology 43: 21-31.
Soroker V., Anshelevich L., Talebaev S., Gordon D., Reneh S., Caspi I., and Harari A.R. 2003. Reproductive biology as a key to the management of pear psylla (Cacopsylla bidens). IOBC-WPRS Bulletin 26 (11): 83-89.
Website http://www.psyllidkey.com/steckbrief/pdf/cacopsylla_bidens_engl.pdf