Hymenoptera diversity on porang (Amarphopallus muelleri) in Sukabumi

Amorphophallus muelleri (porang) is a potential plant as a source of glucomannan. Glucomannan is beneficial as raw material in the sector of food, health, beauty, and industry manufacture so that it has a high economic value. The research objective was to study the diversity of Hymenopteran in the porang plantation. The study conducted at Pakuwon Experimental Garden and Indonesian Industrial and Beverage Crops Research Institute (IIBCRI) Integrated Laboratory from January to July 2020. The insect collection method was installed pitfall trap (PT) and yellow pan trap (YPT) on porang field. There were 12 pitfall traps, and Yellow Pan traps installed on porang plants and set for 24 hours while observed with intervals of 2 weeks. The collected insect was identified into morphospecies. The results showed that Hymenopteran on porang plants consisted of 100 morphospecies. The dominant morphospecies was Anoplolepis gracillepes. The diversity index (H`) of Hymenopteran insect was 2.28 and the evenness (E) was 0.50. Collected Hymenopteran identified as pollinators, predators, and parasitoids. The pollinators were Apidae and Halictidae, the predators were Formicidae and Sphecidae, while the parasitoid insects found were 13 families i.e Braconidae, Scelionidae, and Ceraphronidae, etc.


Introduction
Amorphophallus muelleri, also known by the common name Porang, is a type of plant that produces roots. Porang plants were reported to have been cultivated in Malang, East Java with a distribution of 12 locations in 8 sub-districts [1]. Porang roots contain very high glucomannans (polysaccharides from the Mannan family) with various benefits. One of them is as a raw material in the sector of food, health, beauty, and industry manufacture so that it has a high economic value. In addition, glucomannan reported can improve the digestive system and lowers cholesterol.
The presence of insects cannot be separated from porang cultivation, because of their function as phytophagous, pollinator, decomposer, and natural enemy. The results showed insects on porang plants were found as decomposers, litter transformers, and predators [2]. It was further explained that the number of decomposer insects found in porang plants was sufficient to result in faster decomposition of organic matter, both from animals and plants (litter). The results of this decomposition process will be beneficial for fertility and improve soil structure in Porang plantations.
Insects as natural enemies usually come from the order Hymenoptera, Coleoptera, Diptera, Mantodea, Hemiptera. Natural enemies play a role in suppressing the population of pests or phytophagous insects on agricultural land. Natural enemy insects are divided into predatory insects and parasitoid insects. The insects that worked as predators were found on porang plantation from the  [2]. Ants (Oecophylla smaragdina and Dolichoderus spp.) were reported as predators of pests of the order Hemiptera on cashew crops [3]. In addition, Anoplolepis gracilipes, Solenopsis geminata, and Paratrechina longicornis were also said to have the potential to suppress pest populations [4]. The parasitoid insects found in porang plantations, it was from the Phoridae family [5]. It was reported that phorid parasitoids attack the leaf-cutting ant with a parasitization rate of up to 35% [6].
Hymenopteran has an important role in the cultivation of the crop, such as parasitoids, predators, decomposers, and pollinators. Research on the diversity of phytophagous and terrestrial insects on porang plants has been carried out and several dominant insects have been reported from Hymenoptera [5,7]. It was further explained that the insects found in porang plantations functioned as predators (Anoplolepis sp.) and phytophagous (Gryllus sp and family Aphididae). Therefore, data exploration was carried out to determine the diversity of Hymenoptera insects on porang plants.
The yellow pan trap was a yellow container approximately 10 cm high and 15 cm in diameter. The traps were filled with soap solution up to one-third of the container height and set for 1x24 hours in the field. In each plot, three yellow pan traps were installed in a row by forming a straight line ( Figure 2) so that 12 yellow pan traps were used. The insect sample was put in a plastic bottle filled with 70% ethanol and labeled with the date of the sample collection, the type of trap, and the plot number.
The pitfall trap (PT) used was 9.2 cm in diameter and 10 cm in height. PT was assembled between porang plants filled to a third of their capacity with soapy water and set for 1x24 hours. Soapy water is filled up to a third of the plastic cup. Plastic cups were assembled by making holes between porang plants so that their height is the same as the ground. It aims to record insects that are active on the soil surface. The traps were covered by fiber plastic as a roof to protect them from rainwater. Insect samples were separated from water and put into collection bottles containing 70% alcohol and labeled.  Collected insects were identified as morphospecies and some insects as species in the laboratory. The identification was using identification book, Insects of Australian volume 1 and 2 [9,10], Hymenoptera of the world: An identification guide to families [11], Identification guide to the ant genera of Borneo [12]. The identified insects were tabulated into a database in Excel format. Insect diversity was represented by the number of morphospecies, the diversity index (H), and the evenness index (E) of Hymenoptera. The statistical analysis was using the R statistics software [13].   The Evenness Index is used to assess the evenness of each species in each community [14].

E = H'/ln S
Annotation: E = Evenness index H' = diversity index ln = logaritma natural S = Number of morphospecies Hymenoptera. Indicator of Evenness Index: E > 1: high level Evenness; While E < 1: low level Evenness

The diversity and abundance of Hymenoptera insects
A total of 831 Hymenoptera individuals from 17 families and 99 morphospecies were collected from porang plantations in the Pakuwon experimental garden from January to March 2020. In general, the Hymenoptera families found in this study can be grouped into three functional groups, namely the parasitoid group consisting of 13 families, 65 morphospecies and 127 individuals, predators of two families, 23 morphospecies, and 679 individuals, as well as pollinators of two families, 11 morphospecies and 25 individuals ( Table 1).
The results of the analysis showed that the diversity index (H`) of Hymenoptera insects on porang plants was 2.28. The value of H` is medium-level diversity due to it ranges between 1.35 and 3.5. The high value of species diversity is an indicator of the stability of a habitat. High stability indicates a high level of complexity which causes the habitat to have a high level of tolerance for disturbances that will occur within the habitat component. The high and low diversity of insects in agricultural land is affected by various factors such as plant vegetation [2,15], shade trees, [16], presence of natural habitats [17], landscape structures [18]. In the porang plantation, there is a kemiri sunan as a shade tree that will affect the temperature and light intensity. It will also affect the microclimate in porang plantations which are thought to affect the optimum conditions for insect life, according to research that shade plants with wide canopies, flat branches, and many leaves allow some insects to prefer the habitat [19].
The abundance of the Hymenoptera insect family with a high number of individuals from a family can cause a family to dominate the habitat. The Hymenoptera insect's Evenness value (E) of 0.50 shows that the value is less than 1, indicating that there are only one or two dominating species in porang plantations. The results showed that the family Formicidae that had a high relative abundance was Anopolepis gracillipes. The high population of A. gracillipes is due to the fact that insects are sociable insects that reside in groups, making them easier to catch. In addition, human activities will increase the population of ants that is A. gracillipes [20].

Functions of Hymenoptera insects in porang plantations
Hymenoptera insects found in porang plantations consisted of 17 families and 99 morphospecies were divided into three groups, namely parasitoids, predators, and pollinators. Parasitoid insects are insects that, in the larval stage, live and eat from other insects, usually plant-eating insects [24]. Parasitoids can prey on eggs, pupae, and adult insects (imago). In porang plantations, it found that families preyed on the eggs and larvae of phytophagous insects, such as Braconidae, Ichneumonidae, Ceraphronidae [25] ( Figure 3). In addition, the families, Scelionidae, Platygastriidae, Eulophidae are egg parasitoids [26] (figure 2). One of the parasitoids that can be identified up to the genus is Apanteles sp. which is a larval parasitoid of caterpillar pests whose imago is either a butterfly or a moth [25].
Predatory insects are insects that eat smaller or herbivores insect so that they are beneficial to control pests that can harm plants. Predatory insects found on porang plants consisted of families Formicidae and Spechidae. The Formicidae insects found on porang plants were A. gracillipes reported as predators for smaller insects such as thrips and mealybugs, while Paratrechina sp. includes in the predators of predators fruit borer pests [16,27]. Pest control using predators can reduce crop damage, based on Pollinator insects are insects that support the pollinating process of plants. The results showed that two families of pollinator insects found were Apidae and Halictidae families in porang plantations. The abundance of pollinator insects in porang plantations was still low due to the observations were made in the vegetative phase, because porang plantations were three months old. While the flowering period of porang plants is 3-4 years old [30]. The use of seeds in porang plant propagation results in more uniform roots, faster harvesting ages, and easier seed handling [31].

Conclusion
Insect of Hymenopteran found on porang plants was consisted of 100 morphospecies and 17 families. The dominant morphospecies was Anoplolepis gracillepes. The diversity index (H`) of Hymenopteran insects was 2.28, while the evenness (E) was 0.50. Collected Hymenopteran identified as pollinators, predators, and parasitoids. The pollinators were Apidae and Halictidae while the predators were Formicidae and Sphecidae, the parasitoid insects were 13 families i.e. Braconidae, Scelionidae, and Ceraphronidae, etc.