Variations in species diversity and the role of butterflies in oil palm agroecosystems at PT BSM South Sumatra

Reducing the use of chemical fertilizers and controlling pests/chemical diseases is one of the prerequisites for the realization of sustainable oil palm plantation management. In line with that, the paradigm of green economic development requires optimizing the utilization of biodiversity in various aspects of managing oil palm plantations in Indonesia. Therefore, research is needed that can describe the variation and role of biodiversity (one of which is butterfly taxa) in the agro-ecosystem of oil palm plantations. This study aims to identify variations in species diversity and the role of butterflies in the agro-ecosystem of oil palm plantations. Observation of butterfly species diversity was carried out on seven types of oil palm plantation land cover at PT BSM. The method used is pollard transect (2 km with a width of 10 m) and trapping. The role of various types of butterflies is carried out through a literature search. The results showed that there were 163 individuals from 30 species and consisted of 4 families namely Papilionidae, Pieridae and Lycaenidae. The highest diversity and richness index values were found in smallholder plantations 1 (H′=2.42) and (Dmg=4.01), while the lowest were found in young oil palm areas (H′=0.87) and (Dmg=0. 99). The highest evenness index value was found in shrubs (E=1) while the lowest was in young oil palm land cover (E=0.54). Butterfly species that have potential as environmental bioindicators are Tanaecia pelea, Neptis hylas, Cupha erymantis, Neptis ida, Danaus affinis, Junonia atlites, Leptosia nina, Catopsilia pyranthe, Rapala iarbus, Papilio memnon, Losaria coon, Papilio polytes, Spindiasis lohita and Eurema hecabe. While the pollinators are Ypthima baldus, Catopsilia pyranthe, Hypolimnas bolina, Papilio polytes, and Neptis hylas.


Introduction
The increase in national income in almost all countries has an impact on the depletion of natural resources and environmental damage [1].Initially, the trend of global economic development adhered to the red economy paradigm in the form of an abundance of natural resources.In line with population growth and food needs as well as the development of science and knowledge, the economic development paradigm then changed to a green economy [2].Efficient use of natural resources, minimizing environmental damage, reducing green house gas (GHG) emissions, developing and implementing clean products and technologies is referred to as green economic development.Knowledge and technology-based green economy aims to see the relationship between humanresources and natural ecosystems and minimize human economic activity against climate change and global warming.
The plantation sub-sector, one of which is oil palm plantations (Elaeis guinensis Jacq) plays an 1243 (2023) 012014 IOP Publishing doi:10.1088/1755-1315/1243/1/012014 2 important role for the Indonesian economy.Plantations are a source of foreign exchange, investment and employment opportunities.The rapid development of oil palm is one of them in the province of South Sumatra.South Sumatra is one of the provinces in Sumatra with the third largest oil palm plantation after Riau and North Sumatra.In 2011 oil palm plantations had reached 2.2 million hectares [3,4] The area of oil palm plantations from 2013 to 2019 in Indonesia has expanded from 10.47 million Ha to 14.59 million Ha [5].The existence of clearing and conversion of land into oil palm plantations is suspected of eliminating or reducing biodiversity.Research by [6] stated that the conversion of primary and secondary forests to oil palm plantations resulted in a decrease in species richness, one of which was butterflies, by 79-83%.
Reducing the use of chemical fertilizers and chemical pest/disease control is one of the prerequisites for the realization of sustainable oil palm plantation management.Agricultural practices that use chemical fertilizers and pesticides and massive land cultivation have contributed to environmental degradation.The IPCC reports that currently agriculture contributes 13% of total global carbon emissions [7].In addition, agricultural practices also cause health problems due to the use of pesticides which cause the death of more than 40,000 people each year in the world [8].Therefore, agricultural practices that are not ecologically friendly must be stopped and replaced with green agriculture which is more prosperous for farmers, ecologically friendly (agroecology) and sustainable.
The green economy development paradigm demands optimizing the utilization of biodiversity in various aspects of oil palm plantation management in Indonesia.Butterflies have a role in maintaining the balance of the ecosystem, helping to pollinate plants and as a bioindicator of environmental quality [9].The existence of butterflies also determines the continuity of plant regeneration and the ecological balance of an ecosystem because of their role as pollinators and part of the food chain [10].[11] stated that butterflies have high specificity and sensitivity to certain environmental conditions and also like an unpolluted environment.This makes butterflies potential as bioindicators of environmental conditions [12].
Butterflies are one of the highest biodiversity in Indonesia.Butterflies are one type of insect belonging to the order Lepidoptera [13] which has a wide distribution area from lowlands to high mountain forests, from 0-2,000 meters above sea level [14].Butterflies are easily recognizable biotic components in the ecosystem, because they look attractive both in shape and in various colors.The ecological role of butterflies in the ecosystem is not only as herbivores, but also as an important component in pollination, ecological indicators in the environment, and maintaining the balance of the ecosystem [15].Therefore, to optimize the role of biodiversity, research is needed to identify variations species diversity and the role of butterflies in the oil palm agroecosystem.

Method
The research was conducted at PT Bina Sawit Makmur (BSM) South Sumatra, on 7 types of land cover including young oil palm (SM), medium oil palm (SS), old oil palm (ST), high conservation value (NKT), shrubs (SB), smallholder plantation 1 (KR 1) and smallholder plantation 2 (KR 2).The data collected is species classification data including the number of species and the number of individuals.Data collection was carried out using the pollard transect method.Observations were made along a transect line measuring 10 meters wide and 2 km long (Figure 1) for each of the 7 types of land cover with 3 repetitions.Catching using insect nets with a diameter of 50 cm.Observations were made in sunny conditions when the butterflies were active at 09.00-12.00.Observation of butterflies using the trapping method using an insect net with a diameter of 50 cm using fruit bait (mango, pineapple, banana, jackfruit and durian).The number of butterfly traps used was 5 traps for each observation path (2,000 m) and installed for 3 x 24 hours.Trap locations on each transect line were chosen in places visited by butterflies, such as near food sources for butterflies and near water sources.The data is recorded in a tally sheet and then identified using a butterfly field guide.

Variations in species diversity
The total number of butterflies found in the seven land cover types was 163 individuals from 30 butterfly species consisting of four families, namely Lycaenidae (1 species), Papilionidae (4 species), Pieridae (10 species) and Nymphalidae (15 species) as presented in table 1.The family with the most species composition is the Nymphalidae family, namely 15 species out of a total of 30 species.The highest number of species was found in type 1 smallholder plantations with 13 species while the lowest number of species was found in young oil palm with 5 species.The highest number of individuals was found in young oil palm of 56 individuals while the lowest were found in medium oil palm of 9 individuals.Ypthima baldus Tanaecia pelea Melanitis leda Mycalesis horsfieldi 0 0 0 2 0 1 0 3 The Nymphalidae family dominates because it has the largest members and the distribution.In accordance with [16,17,18,19] stated that the Nymphalidae family is the family with the most species in various habitat types, is cosmopolitan spread in various regions of the world and tends to be polyphagous (having more than one type of food) so that it has a higher survival ability.In addition, the Nymphalidae family prefer bright places, gardens and woodland areas, and some like foul smelling places [20].
Comparison of species diversity, species richness and evenness of butterfly species in each land cover type can be seen in Figure 2. Smallholder plantation land cover type 1 had the highest species diversity and species richness values (H'=2.42Dmg=4.01), while young oil palm land cover had the lowest species diversity and species richness values (H'=0.87Dmg=0.99).The highest evenness index value was found in shrubs with an evenness index value E = 1, while the lowest evenness index value was found in young oil palm land cover with an evenness index E = 0.54.Eurema hecabe Eurema brigitta 0 0 0 0 0 4 0 4 3.
Catopsilia pyranthe Appias lyncida Rapala iarbus Papilio memnon Losaria coon The high value of the butterfly species diversity index in the KR1 land cover type was due to the abundance of understorey plants and the presence of flowering plants that served as food for the butterflies.Flowering undergrowth found in KR1 included Asystasia gangetica, Clidemia hirta, Mikania micrantha, and Passiflora foetida.These flowers have bright colors that are able to attract the attention of butterflies and are easily responded to by the senses of butterflies, and have nectar which is a source of food for butterflies.In addition, the existence of a small ditch in the middle of the garden and a river on the edge of the site is also the reason for the high species diversity in KR1.In accordance with the of [21] and [22] stated that the availability of forage plant vegetation and the presence of water sources are factors that support the high diversity of butterflies.
In addition to the presence of quite a lot of undergrowth, flowering plants that feed butterflies, a small ditch in the middle of the garden and a river on the edge of the location.Temperature is a support for butterfly life.Based on the results of observations, the average temperature in people's garden 1 is 27.3ºC.[23,24] stated that the temperature that supports the life of butterflies and their activities is between 21ºC -34ºC and 20ºC -40ºC.Evenness is a value that shows the distribution of the number of individuals per each species at a location.In the bushland cover type, there is no dominant butterfly species.The results showed that the evenness index value in the shrubs was 1.A high evenness index indicates a habitat has an almost equal or even abundance of individual species [25].The level of evenness can affect the stability of the species because stability has the opportunity to maintain the sustainability of the existing species.Stability causes the breeding of each type of butterfly to produce new individuals.Air humidity is one of the factors that affect reproduction [26].[10] stated that to reproduce, butterflies need higher humidity, which is in the range of 84-92%.The highest air humidity was found in scrub land cover with a value of 91%.

The role and the potential of butterflies in palm oil agro-ecosystem
Based on observations of 7 types of land cover, 163 individuals were found consisting of four families, namely Lycaenidae (1 species), Papilionidae (4 species), Pieridae (10 species) and Nymphalidae (15 species).The distribution of butterflies in various land covers varied as presented in table 2. The types of butterflies Junonia orithya and Appias libythea were scattered in 6 land covers while Tanaecia pelea, Neptis ida, Danaus affinis, Elymnias hypermenestra, Spindasis lohita, Gandaca harina, Appias lyncida, Rapala iarbus, Papilio polytes, Neptis hylas, Cupha erymantis, Eurema brigitta, Losaria coon, Leptosia nina, Catopsilia pyranthe, Amanthusia phidippus, Papilio memnon and Junonia atlites are species that only spread in 1 land cover.Junonia orithya from the Nymphalidae family and Appias libythea from the Pieridae family were the most common species, namely 69 individuals and 22 individuals spread over 6 types of land cover.while the species Tanaecia Pelea, Neptis hylas, Cupha erymantis, Neptis ida, Danaus affinis, Junonia atlites, Leptosia nina, Catopsilia pyranthe, Rapala iarbus, Papilio memnon, Losaria coon, Papilio polytes, and Spindasis lohita are the fewest species found, namely 1 individual found spread over 1 type of land cover.[27] states that the presence of butterfly species in the observation area with high abundance indicates the successful adaptation of generalist species.Generalist species do not have a strong association with certain environmental factors, so they can be found in various types of habitats.While the type of specialist is a type that has a strong relationship and requires specific environmental factors.Specialist types can be used as a basis for determining butterfly species that have the potential to be used as environmental bioindicators [28].[27].Several previous studies have shown that Eurema hecabe can adapt in logged-over forest areas [6], ex-mining forest areas [28], and fragmented urban forest habitats [29].Eurema hecabe is a cosmopolitan, polyphagus, multivoltine butterfly species, and can adapt to high environmental temperatures [30,31].In certain habitats, if butterflies are threatened with extinction, plants, insects and other animals that live in those habitats are also at risk because some butterfly species are very sensitive to changes in their habitat, therefore butterflies can be used as bioindicators of environmental change [32].
Insects have many roles in the environment, one of which is the interaction between plants and insects which act as pollinators [33].Butterflies have an important role in the ecosystem as natural pollinators, where butterflies have the ability to fly far and actively move to visit flowers.The staple food source for adult butterflies (imago) is flower nectar.When sucking the nectar, the pollen will meet the pistil with the help of a butterfly [34].This also plays a role in maintaining the balance of the ecosystem, enriching and preserving biodiversity [35].Several types of butterflies found as pollinators are Ypthima baldus, Catopsilia pyranthe, Hypolimnas bolina, Papilio polytes, and Neptis hylas [36].Butterflies aside from being pollinating agents also have other roles such as being able to add genetic variation to plants.Butterflies visit flowers to suck nectar as a food source and meet nutritional needs.When sucking flower nectar, pollen or what is commonly called pollen will stick to the proboscis and legs of the butterfly, then when moving to another flower the pollen will stick to the stigma, resulting in pollination [37].Butterflies have the lowest position in the food chain, namely acting as first-level consumers who will be preyed upon by larger predators such as birds, rats, monkeys, bats, snakes, frogs, beetles and spiders [37].

Conclusion
Butterfly diversity at PT BSM consists of 163 individuals from 30 species belonging to 4 families.The total diversity of butterfly species in six types of cover at PT BSM South Sumatra, namely 13 types of community gardens, 10 types of shrubs, 9 types of smallholder plantations, 8 types of old oil palm, 7 types of medium oil palm, 6 high conservation areas types and 5 types of young oil palm.
Variations in land cover types respond differently to the level of diversity of butterfly species in oil palm plantations.The highest diversity index and richness index were found in type 1 community garden land cover (H'=2.42,Dmg=4.01) and the highest evenness index was found in shrubs (E=1) while the diversity index, richness index and the lowest evenness index was found in young palms (H'=0.87,Dmg=0.99,E=0.54).

Figure 2 .
Figure 2. Diversity, richness and evenness of butterfly species in the seven land cover types

Table 1 .
List of butterfly species found in various types of land cover

Table 2 .
Types and distribution of butterflies found at PT BSM