(Hemiptera: Aphididae) and ladybirds (Coleoptera: Coccinellidae)
Transcription
(Hemiptera: Aphididae) and ladybirds (Coleoptera: Coccinellidae)
BIHAREAN BIOLOGIST 9 (1): 63-65 Article No.: 141134 ©Biharean Biologist, Oradea, Romania, 2015 http://biozoojournals.ro/bihbiol/index.html Abundance and diversity of aphids (Hemiptera: Aphididae) and ladybirds (Coleoptera: Coccinellidae) population in wheat fields of Urmia, northwestern of Iran Nouraddin SHAYESTEH1, Hossein RANJI2 and Masumeh ZIAEE3,* 1. Department of Plant Protection, Faculty of Agriculture and Natural Science, Mahabad Branch, Islamic Azad University, Mahabad, Iran. 2. Department of Plant Protection, Faculty of Agriculture, Urmia University, West Azerbaijan, Iran. 3. Department of Plant Protection, Faculty of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Iran. * Corresponding author, M. Ziaee, E-mail: [email protected] Received: 31. July 2014 / Accepted: 27. October 2014 / Available online: 24. April 2015 / Printed: June 2015 Abstract. Abundance and species diversity of aphids and ladybirds in three wheat fields located in Urmia city were studied in 2010 and 2011. Samplings were conducted with 120 plants in the wheat fields from mid-April to late July. Species richness was measured using Shannon and Simpson indices. Six aphid species (Aphididae) and five coccinellids (Coccinellidae) were identified in the fields. Among the collected aphid species, Schizaphis gramimun (Rondanii) and Metopolophium dirhodum (Walker) were most abundant in the fields. For coccinellids, Coccinella septempunctata L. was the most abundant species. Highest aphid species diversity was observed on 17 April 2010. No aphid species was found after 15 July of both years. Key words: Aphids, Coccinellida, diversity, population, Urmia, wheat. Introduction Cereals are one of the major dietary crops for human. Among them, wheat is highly consumed by human and known as a strategic product (Shewry 2009); because most governments using direct protection instruments to safeguard local production of wheat. Iran is a traditionally selfsufficient country, with about 47% of daily caloric intake from wheat (Ahmed et al. 2013). In 2000, one of the important goals of Jihad-e- keshavarzi Ministry of Iran was to reach self-sufficiency in crop production and in 2004 wheat self-sufficiency was happened (Farhadian et al. 2012). Several species of aphids have been reported in Iran. Schizaphis gramimun (Rondanii) and Sitobion avenae (Fabricius) are the most abundant species in the wheat fields (Afshari and Dastranj 2010; Kamangar & Malkeshi 2010). Aphids are the major pest insects in the wheat fields; for example, they reduce the grain protein by feeding on wheats and inject toxic enzymes into plants during feeding (Rakhshani et al. 2008). Coccinellids are major natural enemies of cereal aphids and control numerous species of wheat aphids. The larvae and adults of coccinellids consume aphids and reduce the rate of increase of aphid's colony (Caballero-López et al. 2012). The simplest way to measure species biodiversity is to count the number of species present in a designated area (Okpiliya 2012). Kamangar and Malkeshi (2010) reported the species and abundance of wheat aphids and coccinellids in Kurdistan province. There were 7 aphid and 6 coccinellid species in the fields. The most abundant aphid and ladybird species were S. avenae (66.5%) and S. gramimun (30%), Hippodamia variegata Goeze (60%) and C. septempunctata (37%). Diversity indices provide information about community composition. Diversity indices are measured by species richness (the total number of species present) and species evenness (the distribution of the individuals within species designations); therefore, it could give us more ecological information rather than a simple species list in the fields (Okpiliya 2012). Although there are numerous studies on the diversity of cereal aphids in Iran, no studies have been conducted in the wheat fields of West Azerbaijan. West Azerbaijan has fewer limitations for wheat production and also it can be suggested as rainfed cultivation because of its low stress. Therefore, West Azerbaijan has the high level of rainfed wheat production in Iran (Ghadiryanfar et al. 2009; Shahbazi & Rosa 2010). The aim of this study was to investigate the abundance and species diversity of cereal aphids and their predatory ladybirds using the Shannon's (H) and Simpson’s Indices of diversity at various time intervals throughout two years in Urmia-West Azerbaijan. Materials and methods General information of sampling Sampling of cereal aphid and ladybirds populations were conducted every two weeks during the growing season of 2010 and 2011 in three half-acre fields of wheat, Triticum aestivum L., (Var. Zarin) located in Urmia city. The sampling wheat fields were in Saatloo station (37°44'18"N 45°10'53"E), Nazloo (37°39'35"N 44°58'48"E) and Tizkharab village (37°38'45"N 45°27'7"E). Wheat was planted in November (both 2010 and 2011 year) and sampling was conducted from mid-April in tillering stage of wheat till late July in heading and flowering stage. Sampling was performed from a corner of the field and continued throughout the field in a “Z” pattern (MacRae 1998). A total of 120 plants were selected randomly from each field. Each plant was uprooted by hand and put in a mesh covered semitransparent plastic bag. Each bag was labeled with the information of the sampling date and location. In the laboratory, a cotton-pad soaked in chloroform and placed in each plastic bag for 5 min until the insects were died. Subsequently, aphids and ladybirds were identified and their number was counted. Equations The Shannon-Wiener’s (equation 1) (Magurran 1988) and Simpson’s (equation 2) (Simpson 1949) diversity indices were used to calculate the diversity. The Pielou’s (equation 3) (Price 1997) and Simpson’s (equation 4) indices were used to calculate evenness of aphids and coccinellids communities. Equation 1: Shanon’s diversity indices: No H ′ = −∑ [ pi log pi ] i =1 where, pi is the proportion of ith species among all collected samples, and s is the total number of species in the community. Equation 2: Simpson’s diversity indices: N 1− D = 1− ∑ i =1 ni (ni − 1) N ( N − 1) where, 1-D: Simpson’s index, ni: number of individuals in ith N. Shayesteh et al. 64 species, N: total number of individuals in all collected species. The highest Shanon’s (H’) diversity index of aphids was obtained on 17 April (1.251) followed by 1 June (1.158) with equitability indices of 0.698 and 0.646, respectively (Table 3). where, s is the total number of species in the community (rich- The highest Simpson’s index (0.686) was also calculated on 17 April (Table 3). In 2011, the highest Shanon’s index of ness) and H’ is Shanon’s diversity index. aphids was calculated on 30 May (0.881) followed by 15 Equation 4: Simpson’s equitability (evenness): April (0.868); however, for Simpson’s index, the highest D 1 1 ED = * = s 2 aphids diversity index was reported on 15 June (Table 4). Dmax ∑ Pi S i =1 Generally, diversity indices of aphids in 2010 were higher than 2011. Results Coccinella septempunctata was more abundant compared to the other species (Table 5). Diversity indices of ladybirds Six species of wheat aphids belonging to Aphididae family were higher in 2011 than 2010. Simpson’s diversity index of were identified including Schizaphis gramimun (Rondani), ladybirds in 2010 and 2011 were 0.33 and 0.37, respectively Metopolophium dirhodum (Walker), Sitobion avenae (Fabricius), indicating that the possibility of selecting two different speRhopalosiphum padi L., Diuraphis noxia (Mordvilko) and Rho- cies of coccinellids is 33% in 2010 and 37% for 2011. palosiphum maidis Fitch. Also, five species of coccinellids were identified including Coccinella septempunctata, Hippodamia variegata Goeze, Adalia bipunctata L., Psyllobora vigin- Discussion tiduopunctata L., Scymnus sp. and Brumus octosignatus Gebler. Table 1 and 2 showed the number and the frequency of oc- In this study six aphid and five coccinellid species were currence of aphid species in 2010 and 2011, respectively. identified. Aphid numbers increased throughout the season Schizaphis gramimun and M. dirhodum were the most abun- from 90 aphids on 17 April 2010 to a maximum of 456 aphids dant aphid species in the fields (Table 1 and 2). on 17 June 2010 after time which they began to decline again. H′ Equation 3: Pielou’s evenness: J= Ln(S ) Table 1. Frequency of occurrence of aphid species at different time intervals in wheat fields of Urmia in 2010. Species 17.April 1. May 17. May 1. June 17. June 1. July 17. July 1. August Number Relative frequency (%) S. granirum 42 138 260 360 248 98 0 0 1146 44.84 S. avena 22 40 65 170 120 20 0 0 438 17.14 M. dirhodum 16 192 380 230 78 0 0 0 896 35.05 D. noxia 0 0 0 25 10 0 0 0 35 1.37 R. padi 10 5 18 0 0 0 0 0 33 1.29 R. madidis 0 8 0 0 0 0 0 0 8 0.31 Total 90 383 723 785 456 118 0 0 2556 100 Table 2. Frequency of occurrence of aphid species at different time intervals in wheat fields of Urmia in 2011. Species S. granirum S. avena M. dirhodum D. noxia R. padi R. madidis Total 15. April 14 5 48 0 2 0 69 30. April 28 10 188 0 6 0 232 15. May 45 4 210 0 1 0 260 30. May 134 25 230 0 2 0 391 15. June 142 72 102 2 2 0 320 30. June 155 68 0 10 0 0 233 15. July 28 48 0 3 0 0 79 30. July 0 0 0 0 0 0 0 Number 546 232 788 15 13 0 1594 Relative frequency (%) 34.25 14.55 49.43 0.95 0.82 0 100 Table 3. Diversity indices of aphid’s community at different time intervals in wheat fields of Urmia in 2010. Diversity indices 17. April 1. May 17. May 1. June 17. June 1. July Total H 1.251 1.087 1.014 1.158 1.068 0.455 1.088 EH 0.698 0.606 0.566 0.646 0.596 0.253 0.607 1-D 0.686 0.608 0.586 0.656 0.606 0.283 0.6466 ED 0.518 0.424 0.402 0.484 0.422 0.231 0.471 Table 4. Diversity indices of aphid’s community at different time intervals in wheat fields of Urmia in 2011. Diversity indices H EH 1-D ED 15. April 0.868 0.484 0.475 0.313 30. April 0.655 0.365 0.327 0.247 15. May 0.561 0.3134 0.318 0.244 30. May 0.881 0.492 0.533 0.356 15. June 0.124 0.627 0.652 0.477 H: Shanon’s Index, EH: Shannon's equitability, 1-D: Simpson’s index, ED: Simpson’s equitability 30. June 0.765 0.427 0.472 0.314 15. July 0.794 0.443 0.510 0.335 Total 1.0396 0.580 0.617 0.435 Abundance and diversity of aphids and ladybirds population in wheat fields of Urmia Table 5. Frequency of occurrence and relative frequencies of ladybird’s community in wheat fields of Urmia during 2010 and 2011. 2010 2011 Species No. C. septempunctata 100 79.36 91 77.12 H. varigata 24 19.04 22 18.64 A. bipunctata 0 0 2 1.69 P. vigintiduopunctata 0 0 1 0.85 B. octosignatus 2 1.58 2 1.69 126 100 118 100 Total Relative frequency (%) No. Relative frequency (%) Table 6. Diversity indices of ladybird’s community at different time intervals in wheat fields of Urmia during 2010 and 2011. 2010 2011 H 0.565 0.645 EH 0.351 0.400 1-D 0.336 0.373 ED 0.100 0.102 H: Shanon’s Index, EH: Shannon's equitability, 1-D: Simpson’s index, ED: Simpson’s equitability. On 1 July 2010, only two S. granirum and S. avena species were observed in the region and their population ceased and reached to zero on 17 July. A similar trend was observed in 2011. Parry et al. (2004) expressed biotic factors such as high temperature and continuous rainfall can also reduce aphid's populations. Wheat fields are sprayed by pesticides in urgent cases only when Sunn pest (Eurygaster integriceps Puton) populations become above the economic level. In Iran, the main infestation areas of sunn pest are in the provinces of Teheran, Markaz, Esfahan, Fars, Bakhtaran, Kurdistan, Lorestan, Zanjan, Ealam and Khorasan (Rassipour et al. n.d.). Our findings indicated that there was a large population of C. septempunctata in the fields. It seems the presence of high ladybird species in the wheat fields is because the fields are not sprayed by pesticides. However, the results showed that at the end of the sampling period in both years ladybird populations was decreased significantly. The population decline coincided with ripening wheat suggest migration of coccinellids to other shelters, especially for summer aestivation. Grez et al. (2013) stated that coccinellids were more abundant when surrounding landscapes had more native shrublands and semi-urban areas than in those with more annual crops. Therefore, the presence of regular patches around the fields and landscape composition and heterogeneity affects not only the composition of coccinellids but also the efficacy of these biological control agents. Zhao et al. (2013) stated that abundance, species richness and diversity increased with increasing plant diversity and landscape complexity. In our study, small and simple structure of the landscapes were examined that expected to decrease the richness of the aphids and ladybirds. Diversity indices depend not only on species richness but also on the evenness, or equitability, with which individuals are distributed among the different species (Okpiliya 2012). In our study, maximum and minimum value of Simpson's index for coccinellids community was 0.686 on 17 April 2010 and 0.283 on 1 July 2010. The Simpson's index of aphids in 2010 and 65 2011 were 0. 0.647 and 0.617, respectively. This suggests that the possibility of selecting two different species of aphids randomly in the checked fields in 2010 was 64% while for the year 2011 the possibility was 61%. For coccinellids, Simpson's index was 0.336 and 0.373 for 2010 and 2011, respectively. 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