Diversity of Butterflies associated with Brassicaceae crops in Basra, Iraq

The study aimed to investigate the seasonal presence and characterization of the group of butterflies (abundance, richness and biodiversity) in the agroecosystem of Brassicaceae plants in the Basra province. Two different ecosystem sites (Karmat Ali at the sedimentary habitat and Al-Zubair region at the desert habitat) were sampled during the growing season of 2020/2021. There are 823 and 507 individuals at the Karmat Ali and Al-Zubair sites, respectively; the specimens consist of 9 butterflies belonging to four families. The most abundant family was Nymphalidae (60%), followed by Lycainidae (28%) and Pieridae (9%), while Hespe-riidae recorded the lowest relative abundance of 3%. The highest butterfly population was recorded for Vanessa Carudi , while Pieris rapae had the lowest density. The results showed differences in abundance, species richness, and Diversity of butterflies at the sites. The highest values of Diversity and richness were at Karmat Ali, compared to the Al-Zubair region. The study of butterflies' abundance and biodiversity indices indicated that environmental factors and the polyculture plantations support the butterfly population in agricultural habitats.


INTRODUCTION
Butterflies are considered adequate ecological representatives for the invertebrates [1][2][3][4] and clear evidence of the changes in the environmental quality.Butterflies also play critical ecological roles in natural and agricultural habitats; they perform basic ecosystem services [5][6][7] by recycling essential nutrients (nitrogen, potassium and phosphorus) which are required by crops; adult butterflies usually suck the nectar, and larvae feed on the leaves of different plants of the agricultural landscapes, then releasing their feces containing some of these nutrients [8][9][10][11] .Also, butterflies exist in the food chain of many vertebrates, such as birds and lizards 12, and they host many parasites, which decrease the pest populations 13,14 .In the last few decades, the population of butterfly species has declined dramatically worldwide due to environmental changes and habitat destruction of 15 .For example, the number of butterflies in the United States has decreased sharply due to global warming and environmental changes 16,17 ; the population of the western monarch is declining at an estimated rate of 1.6% annually; and more than 450 species of butterflies, including the western monarch butterflies, have declined by 99.9% since the 1980s 18 .A declining population of butterfly species was also observed in Europe 19 ; for example, 76% of the 59 species of migratory and endemic butterflies in the United Kingdom between 1976 and 2014 20 .The development of ecological indices is essential in the field of biodiversity conservation.Butterflies quickly respond to ecosystem disturbance.Thus, they have been specified as significant biological indicators for evaluating the biodiversity of natural and agricultural habitats and monitoring the response of the ecosystems to environmental change and degradation 21 .Globally, the decline in the number of butterfly species and habitat losses has led to an increased consciousness of conserving butterflies and their habitat 22 .Due to the critical role of butterflies, which provide essential environmental services to crops and native wild plant species in many ecosystems, extensive research on the habitat requirement of butterflies is essential to promoting conservation efforts 23,24 .Therefore, the conservation and the Diversity of butterfly species (especially the pollinators) requires a broad understanding of their foraging behavior and their spatio-temporal distribution in agricultural habitats 25 ; however, most specialized butterfly species usually depend on a limited set of host plants for their larval stage, or they use a limited number of nectar sources, even when a large number of nectar-producing plants are available 26,27 ; butterflies also tend to use areas within the site where host plants are located near nectar sources or chose the host plants for laying eggs on the host plants close to the nectar sources; thus the correlation of egg laying and feeding on nectar must be studied according to the abundance of the host plants and nectar sources 28 .Despite the Diversity of butterflies in many natural habitats and their importance, especially concerning their ecological, behavioral, and functional role (especially pollination) 5,8 , little research has been done about the role of butterflies on the Biodiversity in Iraq [29][30][31][32] .In agricultural ecosystems, many butterfly species play an essential role as pollinators of several crops that humans depend on for their livelihoods 33,34 ; and no published data describe the Diversity of butterflies present in agricultural habitats in Iraq.The current study aimed to investigate the seasonal presence and characterization of the group of butterflies (abundance, richness and biodiversity) in the agroecosystem of Brassicaceae plants in the Basra province.

Study Sites
Two sites were chosen to study butterflies' seasonal activity and Biodiversity in Basra Province, southern Iraq, during the 2020-2021 growing season.The first site represented the agroecosystem of the sedimentary plain habitat 35 , at the region of Karmat Ali; a field in agricultural station of the College of Agriculture at the University of Basra, close to Shatt Al-Arab river, was chosen as a permanent station No. 1 (30 25 45.1" N, 47 55 52.1" E), Where different crops are grown annually, in addition to the presence of trees such as date palm and Jujube.The second site represented the agroecosystem of the desert habitat 35 , which was designated for the cultivation of the tomato crop and some leafy crops, mainly in Basra province; a field was chosen in Al-Zubair region as a permanent station No. 2 (30 39 5.47" N, 47 42 34.32"E).Each field (12 x 60 m 2 ) was prepared, divided into plots, and planted with seven Brassicaceae crops (White radish Raphanus sativus subsp.acanthiformis, Arugula Eurica Sativa, rapeseed Brassica napus, mustard Brassica carinata, broccoli Brassica oleracea, variety italica, cauliflower Brassica oleracea, variety botrytis, cabbage Brassica oleracea, variety capitata).

Butterfly community composition and seasonal activity
During the butterfly flight season, Butterflies were monitored and collected for each species at each site biweekly during the sampling period of the growing season of 2020/2021 by using the insect net.Butterflies were sampled between 8:30 and 12:30 am and transferred to the laboratory for identification; specimens were kept in the insect collection box after hardening and recording all the necessary information.Butterfly species Clinical Biotec, Universidad Católica del Oriente (UCO) and Universidad Nacional Autónoma de Honduras (UNAH) were diagnosed using taxonomic keys 36,37 .Butterfly Relative abundance was estimated for each species at both studied sites 38 .
Where Ra= Relative abundance, N = the number of individuals of one species in the sample, Ns = the total number of individuals.

Biodiversity indices
Four ecological indices were used to measure the biodiversity of the butterfly community in the agroecosystems of Brassicaceae plants.The values of the biodiversity indices for the butterflies were calculated during the agricultural season from 1/11/2020 to 1/4/2021:

Shannon Diversity Index (H)
The diversity index values were calculated according to the equation mentioned in 39 .
H=-∑Pi 2) Where H = the value of Diversity, Pi = the ratio of the number of individuals of each species to the total number.The Shannon-Wiener index value usually is between 1.5 and 3.5 for ecological data and rarely exceeds 4.0.

Richness index (D)
The value of the Richness index was calculated according to the equation given in 40 : The reciprocal of the index, 1/d, is often used so that an increase in the index's value is accompanied by an increase in Diversity and a decrease in dominance.

Statistical analysis
The results of Butterflies-seasonal activity were analyzed according to ANOVA; then, the averages were compared using the least significant difference at a probability level 0.05.

Butterfly community composition and seasonal activity
The study of the community composition of butterflies showed that the total numbers of individuals collected were 823 and 507 individuals at the Karmat Ali and Al-Zubair sites, respectively; the specimens consist of 9 species of butterflies belonging to four families of the order Lepidoptera (Table1); the results of Table (2)  indicated that there were significant differences (P < 0.05) among the butterflies populations associated with Brassicaceae plants; butterflies showed highest population of 4.71 individuals/ month at Karmat Ali, compared to 3.28 individuals/ month in the Al-Zubair region.However, the highest butterfly population was recorded for Vanessa crude, which reached 12.73 individuals/ month.At the same time, Belenois aurora had the lowest density, with an average of 0.2 individuals/ month during the growing season.V. carudi recorded the highest rate of 15.55 individuals/ month in the Karmat Ali site, while B. aurora had the lowest rate of 0.2 individuals/ month at both study sites.Also, the results showed significant differences (P < 0.05) in the densities of butterfly species during the growing season in the two study stations (Table 3); the highest population of butterfly species was in March, with an average of 4.21 individuals/month, while the lowest density was found in January, reaching 3,065 individuals/month in both study sites.The highest rate of butterflies was recorded in the Karmat Ali area in March, with an average of 5.73 individuals/month, compared to the lowest number of 2.08 individuals in December.However, in the Al-Zubair area, the highest and lowest populations of 5.58 and 1.37 individuals were found in December and February, respectively.L.S.D. for interaction Months and sites (1.24).

Parnara guttata
The results of Table (4) showed that there were significant (P < 0.05) differences among the populations of butterfly species; the butterfly V. carudi was numerically superior during the growing season; the density was 16.88 individuals in March; however, the species Belenois aurota has not been recorded during the season except in November, with an average of 1.00 individuals/month.L.S.D. for interaction Butterflies and Months (2.78).

Relative abundance
The results of Table (5) showed that the highest relative abundance was recorded for the butterfly V. carudi on the crops of the Brassicaceae during the growing season 2020-2021, at a rate of 38.72%, followed by the butterfly Danaus chrysippus, with the relative abundance of 16.76%; while the lowest relative abundance was recorded for the Pieris rapae, with an average of 1.05%.The results of the study also showed that the family Nymphalidae was the most abundant, reaching 60%, followed by Lycainidae (28%) and Pieridae (9%), while Hesperiidae recorded the lowest relative abundance of 3% (Figure 1).

Spatial Diversity
The results of Table (6)

Temporal Diversity
The results of the temporal Diversity of butterfly species in the Karmat Ali region (

DISCUSSION
The community composition of butterflies associated with Brassicaceae plants was very similar depending on the butterfly species at the Karmat Ali and Al-Zubair sites; nine species of butterflies were recorded belonging to four families of the order Lepidoptera; the results of the study indicated that the family Nymphalidae was the highest relative abundant, followed by Lycainidae and Pieridae; while Hesperiidae was lower abundant (Figure 1); Nymphalidae is represented by two important species, V. carudi and Danaus chrysippus, which prefer open field cultivations compared to greenhouses 43 ; in this study, V. carudi which is one of the relative generalist species 43 had the highest butterfly population and was the most abundant throughout the sites, while P. rapae was less abundant and had low density during the growing season.The current study's findings indicated that a small number of butterfly species occurred in Brassicas fields in both sites of the sedimentary and desert habitats.Several investigations indicated that agroecosystem habitats usually supported poor communities of butterfly species 44, 45 , 46 explained that the agroecosystem usually supported very few butterfly species (generally 5-50), which is characterized by a high population of butterflies.However, another study about the butterflies in Dohuk Province, northern Iraq, showed the presence of 49 species belonging to seven families: Papilionidae, Pieridae, Libytheidae, Nymphalidae, Satyridae, Lycaenidae and Hesperiidae 32 .
The seasonality results indicated that the highest rate of butterflies was recorded in the Karmat Ali area in March, and the lowest number was found in December.In contrast to the Al-Zubair site, the highest and lowest populations of butterflies were observed in December, and the lowest populations were recorded in February (Table 3-5).Depending on field observation, the most abundant butterfly, V. carudi (Nymphlidae), a generalist species, was regularly recorded collecting floral resources on several weeds in the blooming stage; they were observed making extended visits to flowers of Malow Malva parviflora in December in Al-Zubair.The results of this study confirmed that the 1st site (Karmat Ali), cultivated with different plantations and located at the river edge, had high Diversity and population densities.In contrast, the 2nd site (Al-Zubair), which had an enormous monoculture plantation, stressed fewer species of butterfly community 47,48 .However, the seasonal variation of butterfly species populations at these two different sites could be attributed to the cyclic changes in climate elements of temperature and precipitation monthly [49][50][51] .The butterflies' seasonal activity usually coincides with the peak of the flowering stage of host plants [52][53][54] .
Overall, butterflies' Diversity and richness varied between the study sites; the Karmat Ali site hosted a higher diversity and richness of butterfly species than the Al-Zubair site.The differences in butterflies' richness and Diversity were attributed to the differences in region characteristics (agricultural landscape, plantations, and river vicinity of Brassica plants), in addition to the influence of environmental factors 55 .
) Where D = the value of Richness, S = number of species, N = total number of individuals in the sampleEvenness index (J)The Evenness index was determined according to41 : J=H/log(S) … … … … … … … … .(4) Where J = the Evenness value, H = value of the index of Diversity, S = number of species Dominance index (d) This index was calculated according to the equation in 42 : d=N max / N … … … … … … … … .(5) Since d = the value of Dominance, N max = number of individuals of the dominant species, N = total individuals in the sample.

Figure 1 :
Figure 1: Relative abundance of butterflies' families associated with the Brassicaceae crops in Basra during the growing season of 2020-2021.

Table 2 . Population density of butterfly species in the two study sites during the growing season 2020-2021.
L.S.D. for interaction butterflies and regions (1.759).

Table 6 . Butterflies Biodiversity in Karmat Ali and Al-Zubair regions, 2020-2021.
indicated that the ecological indices had a slight variation between the study stations; the highest values of Diversity and richness were 1.79 and 1.19 at Karmat Ali, compared to the values of 1.65 and 0.96 in the Al-Zubair region.The highest values of dominance and Evenness were 0.40 and 0.75 in the Al-Zubair region, and the lowest values of 0.38 and 0.66, respectively, were in Karmat Ali.

Table 7 )
indicated that the butterflies' highest value of Diversity was 1.80 in November; however, the lowest value was 1.45 in February.The highest value of richness (1.47) was recorded in March, and the lowest (1.19) was in November.The results revealed butterflies' lowest degree of dominance (0.29) and highest evenness value (0.86) in February.In contrast, the highest value of dominance (0.53) and lowest value of Evenness of species (0.54) was found in November.

Table 7 . Butterflies biodiversity during the growing season at Karmat Ali region, 2020-2021.
At the Al-Zubair region (Table8), the temporal Diversity of butterfly species differed from that of the Karmat Ali site; the highest and lowest values of Diversity were 1.80 and 1.21 in January and February, respectively.The lowest value of richness was recorded in January (1.32), while the lowest was found in November (0.52).In December, the highest degree of dominance (0.46) and lowest Evenness (0.72) of butterflies were recorded.However, the lowest value of dominance (0.28) and highest Evenness (0.96) was found in November and January, respectively.