Nagham Abdulghani mohammed (1), Fadel Abbas Qader (2)
General Background: Sap-feeding insects consume diets rich in water but poor in essential nutrients, creating major physiological challenges. Specific Background: Many Hemipteran insects possess a specialized digestive modification known as the filter chamber that facilitates sap processing. Knowledge Gap: Although its anatomical presence is well documented, an integrated understanding of its functional mechanisms, molecular basis, and evolutionary diversification remains limited. Aims: This review synthesizes current anatomical, physiological, and molecular findings on the insect filter chamber, with emphasis on digestion, absorption, and evolutionary specialization. Results: Evidence shows that the filter chamber enables rapid osmotic transfer of excess water and sugars from the foregut–midgut directly to the hindgut, supported by aquaporins and sugar transporters, thereby optimizing nutrient retention and metabolic efficiency. Structural complexity varies across taxa, reflecting host-plant adaptation. Novelty: The article integrates classical morphology with recent molecular insights to present the filter chamber as a dynamic regulatory system rather than a passive structure. Implications: Understanding filter chamber function offers prospects for targeted pest management strategies through disruption of specific transport pathways while reducing reliance on broad-spectrum insecticides.Highlights:
The filter chamber regulates water and sugar balance during sap feeding.
Structural variation reflects evolutionary adaptation to host plants.
Transport proteins present potential targets for selective pest control.
Keywords:Filter Chamber; Sap-Feeding Insects; Osmotic Regulation; Aquaporins; Digestive Adaptation
[1] Z.-Q. Zhang, “Phylum Arthropoda,” in Animal Biodiversity: An Outline of Higher-Level Classification and Survey of Taxonomic Richness (Addenda 2013), Z.-Q. Zhang, Ed. Auckland, New Zealand: Magnolia Press, 2013, pp. 1–82.
[2] N. E. Stork, “How Many Species of Insects and Other Terrestrial Arthropods Are There on Earth?” Annual Review of Entomology, vol. 63, pp. 31–45, 2018.
[3] D. Grimaldi and M. S. Engel, Evolution of the Insects. Cambridge, UK: Cambridge University Press, 2005.
[4] P. J. Gullan and P. S. Cranston, The Insects: An Outline of Entomology, 5th ed. Oxford, UK: Wiley-Blackwell, 2014.
[5] R. F. Chapman, The Insects: Structure and Function, 5th ed. Cambridge, UK: Cambridge University Press, 2013.
[6] F. Karolyi, J. F. Colville, S. Handschuh, B. D. Metscher, and H. W. Krenn, “One Proboscis, Two Tasks: Adaptations to Blood-Feeding and Nectar-Extracting in Long-Proboscid Horse Flies,” Arthropod Structure & Development, vol. 41, no. 3, pp. 275–281, 2012.
[7] L. M. Schoonhoven, J. J. A. van Loon, and M. Dicke, Insect-Plant Biology, 2nd ed. Oxford, UK: Oxford University Press, 2005.
[8] A. R. War, G. K. Taggar, M. Y. War, and B. Hussain, “Impact of Climate Change on Insect Pests, Plant Chemical Ecology, and Tritrophic Interactions,” in Sustainability in Plant and Crop Protection. Cham, Switzerland: Springer, 2016.
[9] A. E. Douglas, “Phloem-Sap Feeding by Animals: Problems and Solutions,” Journal of Experimental Botany, vol. 57, no. 4, pp. 747–754, 2006.
[10] M. A. Jervis, Insects as Natural Enemies: A Practical Perspective. Dordrecht, The Netherlands: Springer, 2005.
[11] L. I. Gilbert and S. S. Gill, Eds., Insect Control: Biological and Synthetic Agents. London, UK: Academic Press, 2010.
[12] M. Coll and M. Guershon, “Omnivory in Terrestrial Arthropods: Mixing Plant and Prey Diets,” Annual Review of Entomology, vol. 47, pp. 267–297, 2002.
[13] W. R. Terra and C. Ferreira, “Basic Biology of Insect Midgut and Its Associated Microbiota,” in Insect Gut Microbiome and Its Applications. Cham, Switzerland: Springer, 2020.
[14] M. E. Benbow, J. K. Tomberlin, and A. M. Tarone, Eds., Carrion Ecology, Evolution, and Their Applications. Boca Raton, FL, USA: CRC Press, 2015.
[15] P. Engel and N. A. Moran, “The Gut Microbiota of Insects: Diversity in Structure and Function,” FEMS Microbiology Reviews, vol. 37, no. 5, pp. 699–735, 2013.
[16] A. E. Douglas, “Multi-Organismal Insects: Diversity and Function of Resident Microorganisms,” Annual Review of Entomology, vol. 60, pp. 17–34, 2015.
[17] J. L. Nation, Insect Physiology and Biochemistry, 3rd ed. Boca Raton, FL, USA: CRC Press, 2016.
[18] W. R. Terra and C. Ferreira, “Biochemistry and Molecular Biology of Digestion,” in Insect Molecular Biology and Biochemistry. London, UK: Academic Press, 2012, pp. 365–418.
[19] J. A. Dow, “The Essential Roles of Metal Ions in Insect Homeostasis and Physiology,” Current Opinion in Insect Science, vol. 23, pp. 43–50, 2017.
[20] M. K. Fischer and A. W. Shingleton, “Host Plant and Ants Influence the Honeydew Sugar Composition of Aphids,” Functional Ecology, vol. 15, no. 4, pp. 544–550, 2001.
[21] B. Stadler and A. F. Dixon, “Ecology and Evolution of Aphid-Ant Interactions,” Annual Review of Ecology, Evolution, and Systematics, vol. 36, pp. 345–372, 2005.
[22] A. J. P. Goodchild, “Evolution of the Alimentary Canal in the Hemiptera,” Biological Reviews, vol. 41, no. 1, pp. 97–140, 1966.
[23] J. Pompon, D. Quiring, C. Goyer, P. Giordanengo, and Y. Pelletier, “A Phloem-Sap Feeder Mixes Phloem and Xylem Sap to Regulate Osmotic Potential,” Journal of Insect Physiology, vol. 57, no. 9, pp. 1317–1322, 2011.
[24] D. E. Ullman and D. L. McLean, “The Alimentary Canal of Frankliniella occidentalis,” International Journal of Insect Morphology and Embryology, vol. 17, no. 2, pp. 125–134, 1988.
[25] S. Caccia, M. Casartelli, and G. Tettamanti, “The Amazing Complexity of Insect Midgut Cells,” Cell and Tissue Research, vol. 377, no. 3, pp. 505–525, 2019.
[26] D. R. Price and J. A. Gatehouse, “RNAi-Mediated Crop Protection Against Insects,” Trends in Biotechnology, vol. 26, no. 7, pp. 393–400, 2014.
[27] D. A. Ashford, W. A. Smith, and A. E. Douglas, “Living on a High Sugar Diet,” Journal of Insect Physiology, vol. 46, no. 3, pp. 335–341, 2000.
[28] T. L. Wilkinson and A. E. Douglas, “Phloem Amino Acids and Host Plant Range,” Entomologia Experimentalis et Applicata, vol. 106, no. 2, pp. 103–113, 2003.
[29] G. D. Ewart and A. J. Howells, “ABC Transporters Involved in Transport of Eye Pigment Precursors,” Methods in Enzymology, vol. 292, pp. 213–224, 1998.
[30] S. Kikuta et al., “Aquaporin Water Channel AgAQP1,” Journal of Insect Physiology, vol. 58, no. 6, pp. 829–835, 2012.
[31] M. B. Ponsen, The Digestive System of Subsaltusaphis ornata. Wageningen, The Netherlands: Agricultural University Wageningen, 1979.
[32] J. M. Cicero, J. K. Brown, and P. D. Roberts, “The Digestive System of the Whitefly Bemisia tabaci,” International Journal of Insect Morphology and Embryology, vol. 24, no. 3, pp. 295–306, 1995.
[33] I. Foldi, “The Scale Cover,” in Soft Scale Insects: Their Biology, Natural Enemies and Control, vol. 7A. Amsterdam, The Netherlands: Elsevier, 1997.
[34] I. K. Singh and S. Singh, “RNA Interference: A Novel Source of Resistance to Combat Whitefly,” in RNAi for Plant Improvement and Protection. Wallingford, UK: CABI, 2021.
[35] D. A. Ashford, W. A. Smith, and A. E. Douglas, “Living on a High Sugar Diet,” Journal of Insect Physiology, vol. 46, no. 3, pp. 335–341, 2000.
[36] A. M. Jamal, A. A. Haidar, and M. O. Mohammed, “Extraction and Evaluation of the Effectiveness of Chitosan as Insecticides,” International Journal of Agriculture and Animal Production, vol. 4, no. 6, pp. 16–24, 2024.
[37] T. S. A. Al-Hayali, O. T. H. A. Alhadithy, and F. A. Qader, “Toxic Efficiency of Fumigation Using Two Essential Oils,” Indian Journal of Agricultural Research, vol. 59, no. 6, pp. 988–992, 2025.
[38] S. H. A. K. Al-Hamawandy and S. M. Shahraban, “Integrated Management of the Oriental Citrus Mite,” Kirkuk University Journal for Agricultural Sciences, vol. 15, no. 1, pp. 47–53, 2024.
[39] A. M. Mahmoud and S. S. Hamad, “Molecular Study of Head Lice Among Primary School Children,” Kirkuk Journal of Science, vol. 20, pp. 43–47, 2025.
[40] A. D. Yates and A. Michel, “Mechanisms of Aphid Adaptation to Host Plant Resistance,” Current Opinion in Insect Science, vol. 26, pp. 41–49, 2018.