doi:10.14720/aas.2020.115.2.1280 Original research article / izvirni znanstveni članek Relationship between Aphis spiraecola Patch, 1914 (Hemiptera: Aphidi-dae) and citrus foliar minerals Salim LEBBAL 1 2 3 Received September 27, 2019; accepted May 3, 2020. Delo je prispelo 27. septembra 2019, sprejeto 03. maja 2020. Relationship between Aphis spiraecola Patch, 1914 (Hemiptera: Aphididae) and citrus foliar minerals Abstract: Spring and autumn flushes are generally the most infested periods by citrus aphids. Nevertheless, the role of citrus foliar minerals on aphids is not clear. Thus, this paper aims to study the correlation between certain minerals and the infestation degree of citrus varieties by Aphis spiraecola. Aphid counting was carried out on 12 leaves for each of the six species retained (clementine, lemon, grapefruit and three varieties of mandarin), during autumn (October 2014) and spring (April 2015) flushes. In addition, mineral contents of the leaves in P, K, Na, Ca and Li were measured for the same periods. The results showed that the infestation levels of the studied varieties were higher in the spring flush than in the autumn one. Moreover, analyzes of young leaves showed an important intraspecific (mandarin varieties) and interspecific differences in the mineral composition between the examined citrus trees. The study of the relationship between infestation levels by A. spiraecola and mineral content of the six examined species showed no significant correlation, suggesting a marginal role of the five analyzed minerals in the relation citrus - A. spiraecola. Key words: citrus aphid; clementine; lemon; grapefruit; mandarin; flushes Razmerje med pojavljanjem jabolčne uši Aphis spiraecola Patch, 1914 (Hemiptera: Aphididae) in mineralno sestavo listov citrusov Izvleček: Spomladanski in jesenski viški rasti citrusov so navadno obdobja njihove največje okužbe z listnimi ušmi, vendar je znano zelo malo o pomenu mineralne sestave listov na njihovo pojavljanje. Namen prispevka je bil preučiti korelacijo med nekaterimi minerali v listih različnih citrusov in stopnjo okužbe z listno ušjo Aphis spiraecola. Štetje listnih uši je bilo izvedeno na 12 listih vsake od preučevanih vrst (klementine, limone, grenivke in treh sort mandarine), v jesenski (oktober 2014) in spomladanski (april 2015) rasti. Dodatno so bile v istem obdobju v listih izmerjene vsebnosti P, K, Na, Ca in Li. Rezultati so pokazali, da je bila stopnja okužbe pri vseh sadnih vrstah večja v obdobju spomladanske kot jesenske rasti. Analize mladih listov so še pokazale pomembne znotrajvrstne razlike (med sortami mandarin) in medvrstne razlike v mineralni sestavi pregledanih citrusov. Raziskava odvisnosti med velikostjo okužbe z vrsto A. spiraecola in mineralno sestavo analiziranih vrst citrusov ni pokazala značilne korelacije, kar kaže na mar-ginalno vlogo petih analiziranih mineralov v razmerju citrusov in preučevane listne uši. Ključne besede: listne uši citrusov; klementina; limona; grenivka, mandarina; viški rasti 1 Abbas Laghrour University, Faculty of Nature and Life Sciences, Department of Agronomy, Khenchela, Algeria 2 Hadj Lakhdar University, Department of Agronomy, Batna, Algeria 3 Corresponding author, e-mail: salim-leb@hotmail.com Acta agriculturae Slovenica, 115/2, 429-436, Ljubljana 2020 115-2 vsebina.indd 449 23. 06. 2020 07:25:36 S. LEBBAL 1 INTRODUCTION Herbivorous insects identify their host plants through the morphological aspect, chemical signals and sometimes by the combined action of all these factors (Stadler & Reifenrath, 2009). Upon herbivore attack, plants produce and emit volatile organic compounds, and some of them may be used in defensive strategy namely the attraction of the herbivores natural enemies (Laznik & Trdan, 2018). In addition, the performance of insects is determined directly by the quality of host plants (Sun & Ge, 2011). The main nutritional needs of insects are amino acids, vitamins, minerals, carbohydrates, lipids and sterols (Silva et al., 2005). There is much evidence in the literature about the importance of minerals in plant resistance (Hedin et al., 1977). For instance, Khattab (2007) reported that potassium may play a role in the defense mechanism of aphid-infested plants. Several authors have mentioned that low K levels have a positive effect on aphids (Myers et al., 2005; Myers & Gratton, 2006; Hayes et al., 2009), because a lack of potassium in plants favors the accumulation of amino acids in tissues (Amtmann & Armengaud, 2009; Soetan et al., 2010). Mineral ions are important to insect's physiology in at least three major processes: enzyme activation (K, Mg, Fe, Co, Mn), trigger and control mechanisms (Na, Ca, K), and structure formation (Mg) (Silva et al., 2005). Moreover, pests need adequate quantities of several minerals to grow and reproduce (Wigglesworth, 1966). Components such as carbon and nitrogen act directly on the fertility of the pest (Awmack & Leather, 2002). Shoot growth occurs in most types of citrus in well-defined waves (flushes). The spring flush is the most important one, containing both vegetative and reproductive shoots (Spiegel-Roy & Goldschmidt, 1996). According to Lotmani et al. (2008), the chemical composition of the leaves formed during the different flushes is generally different. Previous studies (Lebbal & Laamari, 2015; Lebbal & Laamari, 2016) have shown that spring and autumn flushes are the most infested by aphids. Nevertheless, research on the effect of the mineral composition of citrus leaves on aphids is almost absent. Therefore, this paper aims to study the correlation between certain leaf minerals of some citrus varieties and their infestation level by Aphis spiraecola Patch, 1914. 2 MATERIALS AND METHODS In order to show the effect of the leaf chemical composition on the infestation of six citrus species (clem- entine clone 63, lemon 'Eureka', grapefruit 'Shambar' and three varieties of mandarin: 'Ortanique', 'Carvalhal' and 'Commune'), aphid counting was carried out on 12 randomly chosen young leaves belonging to 4 trees for each of the retained varieties, at the rate of 3 leaves / tree, distributed over the different cardinal directions. These leaves were collected during autumn (october 2014) and spring (April 2015) flushes. Moreover, a foliar analysis of healthy young leaves of these same periods was realized. In total, five minerals were quantified: phosphorus (P) using colorimetry, and sodium (Na), potassium (K), calcium (Ca) and lithium (Li) using flame photometry (Jenway, model PFP7). This latter offers interesting possibilities for the study of the mineral composition of plants (Gueguen & Rombauts, 1961). The location of the young leaves taken was at the periphery of the foliage of the analyzed varieties (Martin-Prevel et al., 1965), at about the height of a person. These leaves were dried and then they were crushed for later use in the determination of mineral elements. The studied orchard (36° 42' N ; 6° 47' E ; 200 m above sea level) is situated in Skikda province (northeast of Algeria) characterized by a sub-humid climate. Its trees were planted in 2001. They were subject to almost the same technical itinerary. The used stock for graft is Troyer citrange (Citrus sinensis L. x Poncirus trifoliata Raf.) except for lemon which is grafted on volkamer lemon (Citrus volkameriana Pasquale). The studied orchard has been managed with limited spraying of pesticides. Weeding was performed mechanically and irrigation was applied during the dry season. Whereas, the fertilization was carried out using 46 % urea. A correlation analysis was carried out between the level of citrus infestation and mineral content of leaves during the autumn and spring flushes. These analyzes were performed using SPSS software for Windows 10.0.5 (SPSS, Inc.). 3 RESULTS AND DISCUSSION It was noticed that the infestation levels of these varieties were higher in the spring flush than in the autumn one (Table 1). In addition, analyzes of young leaves taken during the two flushes showed remarkable intraspecific and interspecific differences in the mineral composition. Plants do not have the same mineral requirements. Their contents in these elements affect their physiology and consequently the herbivorous insects feeding on them (Silva et al., 2005). Several authors, among others, Mar-chal et al. (1974), Roversi et al. (2008) and Paskovic et al. (2013), indicated differences in leaf composition in nutrients for different fruit trees. 450 Acta agriculturae Slovenica, 115/2 - 2020 115-2 vsebina.indd 450 23. 06. 2020 07:25:39 Relationship between Aphis spiraecola Patch, 1914 (Hemiptera: Aphididae) and citrus foliar minerals In general, concentrations of lithium and phosphorus are higher during the spring flush than in the autumn one. The study of the relationship between degrees of aphid infestation and foliar content of the six examined cultivars showed no significant correlation (Table 2). Similarly, Harrewijn (1970) found that difference in longevity and reproduction rate of Myzus persicae (Sulzer, 1776) was not correlated with the total N or soluble N-content of the potato leaves. Silva et al. (2005) revealed that variation in aphid abundance along different sampling times is correlated to C : N ratio, N, Mg, P and S, but correlations vary with cultivar and aphid species. For instance, they found no significant correlations between aphid population variation and minerals for an alfalfa resistant cultivar, except for C : N ratio. Likewise, Myers et al. (2005) observed no significant difference in mean generation time between soybean aphids feeding on the K-deficient and non-deficient soybean leaves. Nevertheless, they indicated that aphids in the K-deficient treatment exhibited significantly greater intrinsic rate of increase, finite rate of increase, and net reproductive rate relative to aphids feeding on non-deficient leaves. The yellowing associated with po- tassium deficient soybean leaves may preferentially attract migrating soybean aphids, placing potassium deficient fields at a further disadvantage (Hogg & Gratton, 2010). Many correlations have been reported between some minerals and biotic parameters of aphids in subsequent studies (Douglas & van Emdeen, 2007; Djazouli, 2010; Agarwala & Das, 2012; Helfenstein et al., 2015). Miyasaka et al. (2007) mentioned that increased reproduction by Sipha flava (Forbes, S.A., 1885) aphids on kikuyu (Pennisetum clandestinum Hochst) was accompanied by high foliar N. Moreover, short development times of Macrosiphum euphorbiae Thomas, 1878 were associated with high P and K content in Petunia leaves (Jansson & Ekbom, 2002). In the present study, aphid colonies may be affected much more by other factors (climate, primary and secondary metabolites) than by the leaf composition in these mineral elements. According to Jansson and Ek-bom (2002), the complexity of plant nutrient content on aphid performance suggests that not only nutrient levels but also ratios of nutrients should be considered. In addition, interactions between nutrients and al-lochemicals may be key factors in plant susceptibility to Table 1: Variation in infestation levels (mean number ± standard error of A. spiraecola aphids/leaf) and mineral content (in |ig g-1 of dry matter) of citrus leaves during the autumn and spring flushes Flush Parameters Clementine Clone 63 Lemon Eureka Grapefruit Shambar Mandarin Ortanique Mandarin Carvalhal Mandarin Commune Autumn Infestation 13.75 ± 10.10 5.92 ± 4.91 1.58 ± 0.92 5 ± 1.51 12.83 ± 3.36 8.67 ± 4.23 Na 0.5 0.58 0.54 0.55 0.56 0.66 P 3.4 5.7 5.7 4.7 5.2 61.8 Li 38 38 43.1 32.2 32.2 26.5 K 29.4 63.4 41.8 56.4 71.8 199.9 Ca 23071.4 9137.1 18507.9 8785.7 3428.5 1642.8 Spring Infestation 71.08 ± 14.84 33 ± 18.98 50.17 ± 25.80 48 ± 9.90 20.83 ± 11.45 12.08 ± 5.83 Na 0.56 0.55 0.57 0.61 0.56 0.57 P 11.2 13.3 14.1 14.9 5.7 5.5 Li 43.8 38 49.5 95.6 112.9 107.2 K 52.4 60.2 62.7 92.9 71.4 73.9 Ca 15928.5 8785.7 7000 17714.2 17714.2 12357.1 Table 2: Coefficients of correlation between the level of infestation of six citrus varieties by A. spiraecola and the mineral contents of their leaves Analyzed elements Infestation degree Na P Li K Ca Correlation of Pearson 0.042 - 0.011 0.153 - 0.129 0.181 P 0.896 0.974 0.635 0.690 0.573 Acta agriculturae Slovenica, 115/2 - 2020 451 115-2 vsebina.indd 451 23. 06. 2020 07:25:39 S. LEBBAL insect attack (Reese, 1983). Some allochemicals may even make certain nutrients not assimilable (Reese, 1977). 4 CONCLUSION This study revealed that, compared with the autumn flush, the six citrus species tested had a higher aphid's infestation rate during the spring period. Furthermore, clear differences were shown in mineral composition between the examined varieties. However, statistical analysis showed no significant correlation between aphid infestation levels during these two periods and young leaf content in mineral elements (P, K, Na, Ca and Li). Further studies are desirable in this field, in order to clarify the direct and indirect contribution of each mineral element in the resistance or sensitivity of citrus to aphid attacks. 5 REFERENCES Agarwala, B. K., & Das, J. (2012). Weed host specificity of the aphid, Aphis spiraecola: Developmental and reproductive performance of aphids in relation to plant growth and leaf chemicals of the Siam weed, Chromolaena odo-rata. Journal of Insect Science, 12 (24), 1-13. https://doi. org/10.1673/031.012.2401 Amtmann, A., & Armengaud, P. (2009). Effects of N, P, K and S on metabolism: New knowledge gained from multi-level analysis. Current Opinion in Plant Biology, 12, 275-83. htt-ps://doi.org/10.1016/j.pbi.2009.04.014 Awmack, C. S., & Leather, S. R. (2002). Host plant quality and fecundity in herbivorous insects. Annual Review of Entomology, 47, 817-844. https://doi.org/10.1146/annurev. ento.47.091201.145300 Djazouli, Z.-E. (2010). Ecophysiologie et perspectives de lutte contre les pucerons du peuplier noir dans quelques localités Algériennes : Cas de Chaitophorus leucomelas et Phloeomy-zus passerinii (Homoptera, Aphididae). Doctorate Thesis, ENSA El Harrach (Algeria). Douglas, A. E., & van Emden, H. F. (2007). Nutrition and Symbiosis. In H.F. van Emden & R. Harrington (eds.), Aphids as crop pests (115-134), United Kingdom, CAB International. https://doi.org/10.1079/9780851998190.0115 Gueguen, L., & Rombauts, P. (1961). Dosage du sodium, du potassium, du calcium et du magnésium par spectropho-tométrie de flamme dans les aliments, le lait et les excréta. Annales de Biologie Animale, 1(1), 80-97. https://doi. org/10.1051/rnd/19611080 Hayes, R. C., Li, G. D., Dear, B. S., Humphries, A. W., & Tidd, J. R. (2009). Persistence, productivity, nutrient composition, and aphid tolerance of Cullen spp. Crop & Pasture Science, 60, 1184-1192. https://doi.org/10.1071/CP09095 Hedin, P. A., Jenkins, J. N., & Maxwell, F. G. (1977). Behavioral and Developmental Factors Affecting Host Plant Resistance to Insects. In P.A. Hedin (ed.), Host plant resistance to pests (231-275), United States of America, American Chemical Society. https://doi.org/10.1021/bk-1977-0062.ch016 Helfenstein, J., Pawlowski, M. L., Hill, C. B., Stewart, J., La-gos-Kutz, D., Bowen, C. R., Frossard, E., & Hartman, G. L. (2015). Zinc deficiency alters soybean susceptibility to pathogens and pests. Journal of Plant Nutrition and Soil Science, 178, 896-903. https://doi.org/10.1002/jpln.201500146 Hogg, D. B., & Gratton, C. (2010). The soybean aphid/potassium relationship. Proceeding of the 2010 Wisconsin Crop Management Conference, 49, 7-8. Jansson, J., & Ekbom, B. (2002). The effect of different plant nutrient regimes on the aphid Macrosiphum euphorbiae growing on petunia. Entomologia Experimentalis et Ap-plicata, 104, 109-116. https://doi.org/10.1046Zj.1570-7458.2002.00997.x Khattab, H. (2007). The defense mechanism of cabbage plant against phloem-sucking aphid (Brevicoryne brassicae L.). Australian Journal of Basic and Applied Sciences, 1, 56-62. Laznik Z. & Trdan, S. (2018). Are synthetic volatiles, typically emitted by insect-damaged peach cultivars, navigation signals for two-spotted lady beetle (Adalia bipunctata L.) and green lacewing (Chrysoperla carnea Stephens) larvae? Journal of plant diseases and protection, 125(6), 529-538. https://doi.org/10.1007/s41348-018-0172-6 Lebbal, S., & Laamari, M. (2015). Seasonal dynamics of aphids on lemon (Citrus limon (L.) Burm. f.), orange (C. sinensis (L.) Osb.) and clementine (C. clementina Hort. ex Tan.) in Skikda (Algeria). Journal of Entomology and Zoology Studies, 3(5), 321-24. Lebbal, S., & Laamari, M. (2016). Population dynamics of aphids (Aphididae) on orange (Citrus sinensis 'Thomson Navel') and mandarin (Citrus reticulata 'Blanco'). Acta agricultu-rae Slovenica, 107(1), 137-145. https://doi.org/10.14720/ aas.2016.107.1.14 Lotmani, B., Kolaï, N., Berkani, A., & Bouzouina, M. (2008). Contribution à l'étude de l'influence des composés phé-noliques des feuilles de Citrus sur l'activité des adultes de Phyllocnistis citrella Stainton (Lepidoptera ; Gracillariidae). Recherche Agronomique, 22, 59-66. Marchal, J., Martin-Prével, P., Blonde, L., Cassin, J., & Lossois, P. (1974). Influence des porte greffe sur la composition foliaire du clémentinier et d'autres espèces d'agrumes sous différents climats. Fruits, 29(2), 131-148. Martin-Prével, P., Del Brassine, J., Lossois, P., & Lacoeuilhe, J.-J. (1965). Echantillonnage des agrumes pour le diagnostic foliaire. Fruits, 20(11), 595-603. Miyasaka, S. C., Hansen, J. D., McDonald, T. G., & Fukumoto, G. K. (2007). Effects of nitrogen and potassium in kikuyu grass on feeding by yellow sugarcane aphid. Crop Protection, 26, 511-517. https://doi.org/10.1016/jxropro.2006.04.023 Myers, S. W., & Gratton, C. (2006) Influence of potassium fertility on soybean aphid, Aphis glycines Matsumura (He-miptera: Aphididae), population dynamics at a field and regional scale. Environmental Entomology, 35(2), 219-227. https://doi.org/10.1603/0046-225X-35.2.219 Myers, S. W., Gratton, C., Wolkowski, R. P., Hogg, D. B., & Wedberg, J. L. (2005). Effect of soil potassium availability on soybean aphid, Aphis glycines (Hemiptera: Aphididae) population dynamics and soybean yield. Journal of Eco- 452 452 Acta agriculturae Slovenica, 115/2 - 2020 115-2 vsebina.indd 450 23. 06. 2020 07:25:39 Relationship between Aphis spiraecola Patch, 1914 (Hemiptera: Aphididae) and citrus foliar minerals nomic Entomology, 98, 113-120. https://doi.org/10.1093/ jee/98.1.113 Paskovic, I., Perica, S., Pecina, M., Hancevic, K., Paskovic, P. M., & Custic, H. M. (2013). Leaf mineral concentration of five olive cultivars grown on calcareous soil. Journal of Central European Agriculture, 14(4), 1471-1478. https://doi. org/10.5513/JCEA01/14.4.1380 Reese, J. C., 1977: The Effects of Plant Biochemicals on Insect Growth and Nutritional Physiology. In P.A. Hedin (ed.), Host plant resistance to pests (129-152), United States of America, American Chemical society. https://doi. org/10.1021/bk-1977-0062.ch009 Reese, J. C. (1983) Nutrient-Allelochemical Interactions in Host Plant Resistance. In P.A. Hedin (ed.), Host Plant resistance to insects (231-243), United States of America, American Chemical Society. https://doi.org/10.1021/bk-1983-0208. ch013 Roversi, A., Ughini, V., & Monteforte, A. (2008). Influence of genotype, year and soil composition on sweet cherry leaf mineral composition. Acta Horticulturae, 795, 739-746. https://doi.org/10.17660/ActaHortic.2008.795.119 Silva, A. D. A. E, Varanda, E. M., & Primavesi, A. C. (2005). Effect of the inherent variation in the mineral concentration of alfalfa cultivars on aphid populations. Bragantia, 64(2), 233239. https://doi.org/10.1590/S0006-87052005000200010 Soetan, K. O., Olaiya, C. O., & Oyewole, O. E. (2010). The importance of mineral elements for humans, domestic animals and plants: A review. African Journal of Food Science, 4(5), 200-222. Spiegel-Roy, P., & Goldschmidt E. E. (1996). Biology of Citrus. United States of America, Cambridge University Press. htt-ps://doi.org/10.1017/CB09780511600548 Städler, E., & Reifenrath, K. (2009) Glucosinolates on the leaf surface perceived by insect herbivores: Review of ambiguous results and new investigations. Phytochemistry Review, 8, 207-225. Sun, Y., & Ge, F. (2011). How do aphids respond to elevated CO2? Journal of Asia-Pacific Entomology, 14(2), 217-220. https://doi.org/10.1016Zj.aspen.2010.08.001 Wigglesworth, V. B. (1966). Insect Physiology. United Kingdom, John Wiley & Sons. Acta agriculturae Slovenica, 115/2 - 2020 453 453 115-2 vsebina.indd 451 23. 06. 2020 07:25:39