The role of Hymenoptera parasitoids as mortality factors of Silba adipata McAlpine on cayenne pepper plants: parasitism and distribution patterns

Silba adipata (Diptera: Loncaeidae) is a new species that attacks white cayenne pepper in Bali. The research aimed to explore the role of these three types of parasitoids. New variables that have never been used before include spatial and altitudinal distribution patterns, the relationship between the level of parasitism and the level of population density of A. adipata according to plant phenology, and the level of parasitization of parasitoids on hosts at various altitudes in Bali, Indonesia. This research was carried out from April to July 2021 using a survey method in which samples were taken purposively from sample plants. The three parasitoids were distributed in all districts, except F. arisanus and A. japonica which were not found in Denpasar and Jembrana. Three parasitoid species play a role in controlling S. adipata in Bali Indonesia, namely A. japonica, F. arisanus, and D. longicaudata. Among the three parasitoids, A. japonica was most dominant at altitudes >750-1000 MASL, while F. arisanus at altitudes >500 - >1000 MASL and D. longicaudata at altitudes >250-500 MASL. The population densities of the three parasitoids were densely associated with S. adipata populations. The parasitoid that most effectively controls S. adipata in the field is F. arisanus.


Introduction
Cayenne pepper (Capsicum frutescens Linnaeus) is a horticultural commodity widely cultivated in Indonesia.Cayenne pepper production in Indonesia in 2020 was 1.5 million tons, while in 2021, it decreased to 1.39 million tons [1].One of the causes of the decline in cayenne pepper production is the attack of the black fruit fly Silba adipata McAlpine (Diptera: Loncaeidae), a new type of pest in Bali.Farmers assume that this type of pest is the chili fruit fly pest they are familiar with, namely Bactrocera dorsalis Complex (Diptera: Tephritidae) [2].The certainty of the black fruit fly species has been reported by Merta [3] as S. adipata through morphological and molecular analysis.Symptoms of attack by both pests are very similar in the field.However, one characteristic symptom distinguishes black fruit fly attacks, namely the shape and color of the ovipositor puncture marks in the form of brown dots on the surface of immature fruit.
Meanwhile, the symptoms of ovipositor punctures of B. dorsalis flies are black spots around the ovipositor punctures on fruit before it is ripe.Black fly attacks can cause fruit damage and greater losses than fruit flies of the B. dorsalis species.According to Merta notes [3], the percentage of S. adipata attacks can reach 40.31%.The high attack rate was caused by the population composition reaching 62.32% of chilies per plant in the field compared to Bactrocera spp.37.68% [4].
Until now, farmers have relied on the intensive use of synthetic insecticides to control these pests.Intensive use of excessive insecticide concentrations causes adverse side effects on the environment and causes high production costs.Apart from that, using insecticides also causes insect resistance to pests and the loss of natural enemies such as parasitoids [5], which can later affect the distribution, diversity, 1346 (2024) 012013 IOP Publishing doi:10.1088/1755-1315/1346/1/012013 2 abundance, and dominance of species in a community.It is necessary to search for information on the presence of local parasitoids that can potentially control these pests.The alternative strategy of using parasitoids for control purposes is quite promising in suppressing the surge in pest attacks [6].According to Suriani [7], three types of local parasitoids from the Braconidae family can attack S. adipata in the field.Yuliadhi [8] also reported that parasitoids that can attack S. adipata are A. japonica, F. arisanus, and D. laungicaudata.This research aims to conduct a more in-depth study of the presence and role of local parasitoids, especially in relation to the spatial and altitudinal distribution patterns of ad parasitoids, the relationship between the level of parasitization of each parasitoid and the population density of S. adipata according to fruit phenology, and the effectiveness of controlling parasitoids.S. adipata at various altitudes in Bali.The results of this research are a new novelty that can be used as a basis for formulating strategies and technology to control black fruit flies in chili plants.

Research implementation
This research was carried out in nine districts/cities in Bali.In each district/city, 10 m 2 of land were taken, consisting of 11 beds, which had been planted with 64 chili plants/beds, totaling 660 plants.In each bed, 10 sample plants were taken systematically in a U-shape at intervals of 6 plants.Fruit sampling was done to look for infected fruit on each plant sample (Fig. 1).Samples of infected fruit were collected in clear plastic bags with a volume of 1 liter and then taken to the laboratory for culture.Cultivation in the laboratory is carried out by preparing plastic cups (diameter = 8, height = 10.5 cm).Plastic cups were filled with 20 g of sand; the sand was moist using water; one plastic cup was filled with one infected chili, covered with gauze, and labeled with the sampling date.It is then maintained until adult flies and parasitoids emerge from the pupa.Observations of the number of flies and adult parasitoids emerging from the pupae were carried out every day, starting two weeks after rearing was carried out.Data on the number of adult flies and parasitoids were recorded for each observation and then tabulated and analyzed according to the analysis guidelines.To determine the spatial and altitudinal distribution patterns of parasitoids it is calculated using the following formula [9]: Information: S 2 = Distribution pattern, Xi = Number of individuals of the ith species, X = Total individual average, N = Total sampling. Criteria: Meanwhile, evaluating the relationship between the level of parasitoid parasitization and the density of S. adipata according to fruit phenology was carried out on a special land covering an area of 10 acres located in Banua Village, Kintamani District, Bangli districts.The land already contains chili plants, which are starting to bear fruit.Plant samples were taken using the diagonal method of as many as 21 plants.Samples of infected fruit were taken from each plant and then placed in a transparent plastic bag with a volume of 1 liter.The number of infected fruits collected is then taken to the laboratory for further cultivation until adult flies and parasitoids emerge from the pupae.To calculate the level of parasitization of parasitoids, use the Magurran formula [10] as follows: Data analysis Spatial and altitudinal distribution data were analyzed using the Fowler and Cohen [10] formula, while data on the relationship between parasitoid parasitization levels and S. adipata density according to fruit phenology were depicted in graphs and histograms.The effectiveness of parasitoids in controlling S. adipata at various heights using the Magurran [10] method is presented as a histogram.

Spatial and Altitudinal Distribution Patterns 3.1.1 Spatial distribution pattern
The types of parasitoids found interacting with S. adipata flies in the field were Asobara japonica, Fopius arisanus, and Diachasmimorpha longicaudata (Figure 1).The distribution pattern of parasitoid populations varies between parasitoid species and between districts.The results of data analysis for parasitoid distribution patterns, according to Fowler and Cohen [9], are presented in Table 1.The parasitoid distribution index value ranges from 0.28 to 1.43 between locations, which means that the spatial distribution pattern of parasitoids ranges between random (< 1) and clustered (> 1).The spatial distribution pattern of the parasitoid F. arisanus is mostly clustered in the Badung, Bangli Buleleng, Gianyar, Tabanan, and Karangasem districts.Meanwhile, other parasitoid distribution patterns spread randomly throughout the districts/cities in Bali.This incident occurred because F. arisanus has the highest population abundance in almost all districts/cities in Bali.Meanwhile, the abundance of the other two types of parasitoids is relatively low in all districts/cities in Bali.The results of this study confirm Untung's statement [11] that most insects in low-population conditions have a random population distribution pattern, while insects in high-population conditions tend to have a clustered distribution.The results of this study also corroborate Supartha's [12] findings that the availability of host plants in the field greatly affects the abundance of host insect and parasitoid populations.Notes: S 2 < 1 = Random, S 2 = 1 = Regular, S 2 > 1 = Clustered

Altitudinal distribution pattern
The results of analyzing the altitudinal distribution pattern of parasitoids according to Fowler and Cohen [9] are presented in (Table 2).The parasitoid distribution index value ranges from 0.41-2.09between locations, meaning that the altitudinal distribution pattern of parasitoids is random (< 1) and clustered (> 1).The altitudinal distribution pattern of the parasitoid F. arisanus is mostly clustered at altitudes >500-750, >750-1000 and >1000.Meanwhile, the distribution pattern of other parasitoids is random at all altitudes in Bali.This event occurred because F. arisanus has the highest population abundance at altitudes >500-750, >750-1000 and >1000.Meanwhile, the abundance of the other two types of parasitoids is relatively low at all altitudes in Bali.The results of this study also confirm Untung's statement [11] that most insects in low populations have a random distribution, while in high populations, they tend to change towards a clustered distribution.
Each insect species has a unique distribution pattern due to the influence of insect biology, habitat type, and other environmental factors [13].Often, the distribution patterns of these insect species change due to many influencing factors, including population density.Insects in low-population conditions mostly spread randomly, whereas in high-population conditions, they tend to turn into clustering (11).
The distribution pattern of parasitoid populations is also greatly influenced by biotic factors (Table 3) such as genetic resistance, sex ratio, and the ability of parasitoids to adapt to the environment and abiotic factors such as food availability, climate, temperature, and humidity) in each area planted with cayenne pepper in the field.The host plant factor as a food source for host insects that spread in the field greatly influences the distribution of parasitoids [14].Apart from food availability factors, altitude and temperature also play an important role and are limiting factors for the spread of insects [15].Chemical compounds released by plants (kairomone) can guide parasitoids in the process of finding host insects in the field.Kairomones are chemical substances released by host plant species that can attract other species, namely host larvae and parasitoids [16].S. adipata is a new pest species that attacks chili plants in Bali.One natural enemy that can control the population is parasitoids.According to Suriani [8], three species of parasitoids can control this new pest species in the field.The three parasitoid species are A. japonica, F. arisanus, and D. longicaudata, which spread in Gianyar district, Bali.This study also found these three types of parasitoids in all districts/cities except A. japonica and F. arisanus, which were not found in the Jembrana district and Denpasar City (Figure 2).However, the population of F. arisanus is very dominant in Bangli, Gianyar, Tabanan, and Karangsem.Meanwhile, D. longicaudata is very dominant in Klungkung (Figure 3).This data confirms that when the parasitoid population is high, it spreads in clusters; when the population is low, it tends to spread randomly.

parasitization rate of parasitoids on S. adipata based on plant phenology
This relationship was monitored from when the plants started to bear fruit 13 weeks after planting (WAP) until 18 WAP.The results showed that black fruit fly infestation had occurred since the plants were 13 WAP and reached its peak when they were 15 WAP.The attack lasted until 18 WAP.The level of black fruit fly population density developed in line with the level of black fruit fly infestation by plant phenology.Figure 3 shows that the parasitization level of parasitoids has a close relationship with the population density of host insects based on plant phenology.Parasitoid parasitism incidence occurs on the host when the plants are 13 WAP and peaks when the host reaches peak density at 15 WAP.Parasitoid parasitism lasted until the plants were 18 WAP.Figure 4 also shows the dominance of the parasitoid species F. arisanus, which strongly attacks S. adipata from the beginning to the end according to the stage of plant development in the field.Another parasitoid species that also played an important role after F. arisanus was A. japonica from the beginning of the observation until the plants were 16 WAP.Meanwhile, the parasitoid D. longicaudata, which has the lowest relative population density, also showed an important role after F. arisanus at 17 -18 WAP.adipata according to the phenology of cayenne pepper plants in the field

Evaluation of the effectiveness of parasitoids as a mortality factor for S. adipata at various altitudes
The performance of parasitoids as a mortality factor for S. adipata at several altitudes in Bali shows different variations (Figure 5).The parasitoid of F. arisanus showed the best performance in controlling S. adipata, as indicated by a higher parasitization level than other species.According to [17], the parasitoid F. arisanus has a long ovipositor, making laying eggs on host larvae inside the fruit easier.The length of the ovipositor of the female parasitoid F. arisanus is the same or longer than its body [18].Thus, the parasitoid F. arisanus has the highest level of parasitization at an altitude of 1,000 meters above sea level (MASL), with a parasitization rate of 9.11%.Yuliadhi [19] also found that the parasitoid F. arisanus was the most dominant parasitoid parasitizing fruit fly (B.dorsalis), with parasitization rates between 8.22-9.30% in the field.Meanwhile, the parasitoid A. japonica has the highest level of parasitization at altitudes above 750-1000 meters above sea level with a parasitization rate of 4.11%, while the parasitoid D. longicaudata has the highest level of parasitization at altitudes above 250-500 meters above sea level with an average parasitization rate of 7.63%.In contrast to D. longicaudata, which was found to parasitize B. dorsalis on star fruit, it had a low level of parasitization, namely 0.75-1.09% in lowland areas of Denpasar City [18].The parasitoid D. longicaudata can carry out the parasitization process from 0 meters above sea level to 500 meters above sea level.The parasitoid F. arisanus can dominate areas at altitudes >500 meters above sea level to >1,000 meters above sea level.This event shows that the parasitization ability of parasitoids in the field is greatly influenced by physical environmental conditions such as changes in climate, temperature, and humidity, which can directly affect the life of parasitoids.Apart from these factors, food availability and altitude also play an important role and are limiting factors for the growth and development of insects because they have a very close influence on the physiological condition of insects, their population abundance, and their distribution patterns in the field.[20] reported the parasitoid G. micromorpha as a potential biocontrol agent.L. huidobrensis can spread slowly due to the barrier influence of these physical factors.a result of the support of food sources from chili host plants in the field.The qualitative and quantitative availability of chili plants and chili fruit in the field greatly determines the abundance and distribution pattern of the host insect, S. adipata, shown in Figure 3. Apart from that, the influence of physical factors such as temperature, air humidity, and rainfall also greatly determine the survival of parasitoids.Not all parasitoids can adapt to temperature, humidity, and rainfall variations in each location.This event is demonstrated by the adaptability of each parasitoid species to these physical factors.The parasitoid F. arisanus was not found in the Jembrana district and Denpasar City.This incident is related to the developmental tolerance of F. arisanus larvae to temperatures ranging between (22-25°C) [21].This research shows that the Jembrana district and Denpasar City altitude ranges from 0 to 250 meters above sea level with a temperature of around 32oC.This temperature is less than optimal for developing the parasitoid F. arisanus (Table 3).In general, it can be concluded that the factors that influence insects' spatial and altitudinal distribution are the availability of the number of host plants for S. adipata host populations for parasitoids.This event can be seen in Figure 3, namely that the fluctuation of the host insect population largely determines the fluctuation of the parasitoid population.In addition, competition between species within the same host can also influence the survival of other types of parasitoids [22].

Conclusions
Three parasitoid species play a role in controlling S. adipata on white cayenne pepper in Bali Indonesia, namely A. japonica, F. arisanus, and D. longicaudata.The three parasitoids were distributed in all districts, except F. arisanus and A. japonica which were not found in Denpasar and Jembrana.Among the three parasitoids, A. japonica was most dominant at altitudes >750-1000 MASL, while F. arisanus at altitudes >500 ->1000 MASL and D. longicaudata at altitudes >250-500 MASL.The population densities of the three parasitoids were densely associated with S. adipata populations.Parasitoid F. arisanus had the highest population density at plant age 13 -18 WAP, while A. japonica, F. arisanus, and D. longicaudata population density increased from 13 -15 WAP, then decreased until plant age 18 WAP.Parasitoid F. arisanus showed the highest population density from 13 to 18 weeks of planting.It was followed by A. japonica at 13-16 weeks, and D. longicaudata at 17-18 weeks.The parasitoid that most effectively controls S. adipata in the field is F. arisanus.

Figure 1 .
Figure 1.Symptoms of ovipositor puncture of S. adipata (A) and B. dorsalis (B) on the surface of cayenne pepper fruit (arrow)

Figure 3 .
Figure 3. Abundance and dominance of parasitoid species in all districts/cities in Bali, Indonesia

Figure 4 .
Figure 4. Relationship between the level of parasitoid parasitization and the population density of S. adipata according to the phenology of cayenne pepper plants in the field

Figure 5 .
Figure 5. Level of parasitization of the parasitoid S. adipata at high altitudes in Bali, Indonesia

Table 1 .
Index value of spatial distribution pattern of the parasitoid pest S. adipata in cayenne pepper plantations in all districts in Bali Province

Table 2 .
Distribution pattern of the altitudinal parasitoid pest S. adipata in cayenne pepper plantations in all districts in Bali Province

Table 3 .
Temperature and humidity at each altitude Thanks to the Chancellor of Udayana University, Head of the Institute for Research and Community Service of Udayana University, and Dean of the Faculty of Agriculture of Udayana University for providing support through Udayana Excellent Research with number B/99-60/UN 14.4.A/PT.01.05/2021.Head of the Integrated Pest Management Laboratory (IPMLab) for guidance and providing facilities and infrastructure related to this research.