Species Diversity and Composition of Chalcidids Wasps (Chalcidoidea: Hymenoptera) on Tidal Swamp Rice Field in Indragiri Hilir District, Indonesia

Rice harvested area in Riau province is 93.755 ha. Indragiri Hilir Regency has the largest rice harvest area in Riau Province, 23.432 ha and is also the most significant contributor to Riau Province’s rice production, which is 109.921 tons (BPS, 2018). One of the limiting factors in rice production is the pest attack.
       
The application of synthetic pesticides is one of the efforts made to control pests. However, the use of synthetic pesticides will adversely affect the agricultural ecosystem. Therefore, we need to develop natural enemies of rice plant pests, one of which is parasitoid insects. It is a dilemma for the farmers not to rely on insecticides even though their negative impacts are known. For example, the pesticides will also unintentionally eradicating the pest’s natural enemies (Hidrayani et al., 2013).
       
The individuals of the family Chalcididae are parasitoids on Lepidoptera, Coleoptera, Diptera, Neuroptera insects and part of Hymenoptera. Chalcididae is solitary and partly lives in a colony. The distribution of Chalcididae exists throughout the world, but generally, only a few species can live in cold regions. Chalcididae is divided into five subfamilies, including Helticellinae, Epitraninae, Dirhininae, Chalcidinae and Smicromorphinae. At present, in Australia, there are 21 genera, including nine genera from New Guinea and Eastern China. The estimated number of genera globally is about 90 genera, with approximately 1.469 species and mainly in the tropical region (Aguiar et al., 2013). There have been reported about 19 genera and 120 species from Indonesia (Noyes, 2020). Sofyan and Ubaidillah (2017) found six genera consisting of 8 morphospecies of Chalcididae on Eggplant (Solanum melongena) and Bitter Melon (Momordica charantia) in Bogor, West Java.
       
Chalcididae is one of the most exciting and complex hymenopteran families to study taxonomically (Boucek 1988). They show morphological resemblances among genera and species, a phenomenon widely found in other Chalcidoidea families as well and it is not easy to separate them at the species level and often at a generic class. Though many species of Chalcididae look very much alike, they differ widely inhabits (Narendran and Achterberg, 2016). The Chalcididae family has a body character that is easy to recognize compared to other families of the Hymenoptera, including a sturdy body and partly large, black or red with a mark in the form of yellow strokes, has a femur on the enlarged hind legs, has a part serrated abdomen, arched back tibia to support the femur, prepectus smaller than tegula, propodeum mostly areolate, mesepisternum with protruding ventral portions in the anterior epocnemial carina. This character is also found in other families such as Eurytomidae, Leucospidae and Torymidae, but there has never been a combination of these characters (Boucek, 1988; Lotfalizadeh et al., 2012).
       
Conserving and increasing the function of pest’s natural enemies is one of the main components in Integrated Pest Management (IPM) to suppress pest attacks to below the economic profitability threshold of agricultural production.
       
Previous studies showed that the parasitic Hymenoptera has a high diversity index on tidal swamp rice in Indragiri Hilir District (Ikhsan et al., 2020). However, until now, there has been no further information about the presence of Chalcididae in tidal land rice plantations in the Indragiri Hilir Regency. This research aims to study the species diversity of Chalcididae on tidal swamp rice fields in Indragiri Hilir District, Riau Province, Indonesia.

Study area and period
 
The study was conducted in four sub-districts of rice production centers in Indragiri Hilir district from January 2018 until March 2020. The four sub-districts are Batang Tuaka (0°20¢19² S,103°2'53" E), Reteh (0°40'04" S, 103°08'06" E), Tembilahan Hulu (0°24'05" S,103°04'06" E), Keritang (0°42'29" S, 103°0'28" E). Chalcididae was carried out at the Insect Bioecology Laboratory, Faculty of Agriculture, University of Andalas, West Sumatra Province and Pusat Penelitian Biologi LIPI, West Java Province, Indonesia.
 
Insect collection
 
The individuals of the Chalcididae family were collected at two planting periods at each location. In each planting period, the collections were done three times at different stages of rice cultivation: before planting, vegetative stage and generative stage in every location. The condition before planting was referred to as the stage before the land was cultivated and there was still vegetation. In the vegetative stage, Chalcididae was collected when the rice plants were about one month old. In the generative phase, the Chalcidids were collected when the ice plants were about two months old. In every sub-district, one area of peatland rice with a minimum size of 1.000 × 500 m was assigned as a sampling location. Two transect lines (1.000 m length each) were made in every area with a minimum distance between transect lines of 300 m. There were ten sampling plots (1×1 m) in each line with a space between sample plots of 100 m. So, in each transect line, there were ten sampling plots. In each plot, the sample plant was determined systematically by making a diagonal line of sub-samples of 1×1 m. Chalcididae was collected using the malaise trap, sweep net and yellow pan trap (Darnaedi and Noerdjito 2007).
 
(i) Malaise trap
 
Malaise trap was installed at each research location, each with one malaise trap. The installation of the malaise trap was based on the direction of the wind, which was facing north or south. Generally, insects that are actively flying and foraging prefer light like sunlight. If these insects fly and pass through these traps, the insect is more easily trapped when compared to mounting according to the sun’s rise because this trap is designed for insects from the side, not from the front. Trapped insects were collected in a bottle that was filled with 96% alcohol. This trap was installed for one week in each phase of rice cultivation. Then the trapped sample was transferred to the sample bottle and labeled.
 
(ii) Sweep net
 
A sweep net was set up on each sample. We did ten double swings. Insects that were caught immediately put into a film bottle containing 96% alcohol. In the laboratory, the pest’s natural enemies (i.e., parasitoids and predators) were separated from other insects. Each morphospecies was separated, then inserted into 2 ml Eppendorf, which contained 96% alcohol for identification purposes.
 
(iii) Yellow pan trap
 
Yellow pan trap was used to catch insects interested in yellow. Collecting insects with a yellow pan trap was done by placing one yellow pan trap on each sample bed. The yellow pan trap was filled with detergent water to reduce the surface pressure of the water so that the insects that enter will sink and die. Installation of a yellow trap was done in the morning before 09.00 A.M., then taken back in the afternoon. The trapped insects were filtered and taken using a brush not to damage parts of the insect. Then the insects were inserted into a film bottle that has been filled with 96% alcohol to be identified in the laboratory.
 
Identification of chalcididae
 
Insects were carried to the Insect Bioecology Laboratory, Faculty of Agriculture, University of Andalas, West Sumatra Province. All insects obtained were separated by order. Identification of the Chalcididae family was carried out at the Entomology Laboratory, Zoology Division of the Biology Research Center, Indonesian Institute of Sciences, Bogor, West Java. Insect identification was based on the main morphological characteristics of the mouth, antennae, wings, legs and skin color. The identification used various references, namely Hymenoptera of The World by Goulet and Huber (1993), Australasian Chalcidoidea (Hymenoptera) by Zdenek Boucek (1988), Oriental Brachymeria identification books written by Narendran (1989) and official websites http://www.bugguide.net. Also, identification was confirmed with the help of Hymenoptera experts and was supported by basic books from the Entomology Laboratory of the Indonesian Institute of Sciences (LIPI).
 
Data analysis
 
Several parameters were calculated in data analysis. The diversity index (H’) was calculated using the Shannon-Wiener formula. Species richness index (d) was using the Margalef formula. Species Evenness Index was calculated using the Pielou’s Evenness (J’) formula, which measured the proportion of each species in a population at a certain place and time according to the formula by Krebs (2000). Species Similarity Index was calculated to determine the proportion of species similarity between two communities using the Jaccard species similarity index. Benchmark values use the evenness index Krebs (2000).

The abundance of the Chalcididae family in the studied areas of Indragiri Hilir Regency is shown in Table 1. Most number of an individual that was collected belongs to Brachymeria excarinata (25 individuals). This species was reported from all studied areas. From an abundance aspect, Reteh (10 individuals), Batang Tuaka (7 individuals), Keritang (4 individuals), Tembilahan Hulu (4 individuals). Brachymeria excarinata and Anthrocephalus sp. were collected from all of the studied areas.
 

       
The structure of species composition and the relative abundance of the Chalcididae family (all the collected samples using Sweep net, Yellow pan trap and Malaise traps) in Indragiri Hilir Regency are shown Table 2. According to collected data (Table 2), Brachymeria excarinata (19.69%) has the highest relative abundance in Indragiri Hilir District, followed by Anthrocephalus lugubris (15.75%) and Anthrocephalus sp. (11.02%). According to the table, in Batang Tuaka, the highest abundance value was for Brachymeria excarinata (5.51%), followed by Anthrocephalus lugubris (2.36%). In Keritang, the highest value was for Antrocephalus maculipennis (5.51%), followed by Brachymeria lasus (3.94%). In Reteh, the highest value was for Brachymeria excarinata (7.87%), followed by Anthrocephalus sp. (4.72%). In Tembilahan Hulu, the highest value was for Anthrocephalus lugubris (10,24%), followed by Antrocephalus phaeospilus (8.66%).
 

       
The diversity index and species evenness index in the studied localities were calculated and are presented in Table 3. According to the Shannon-Wiener index, Species richness Margalef index (d) and Simpson index (D), it was indicated that Keritang had a higher species diversity than the other studied localities. In the same way, Batang Tuaka had the least species diversity. Based on the Shannon-Wiener index, Keritang had the most species diversity, followed by Tembilahan Hulu, Reteh and Batang Tuaka, respectively. The Species Evenness Pielou’s index (J) showed that Keritang had the most amount of numerical, followed by Reteh, Batang Tuaka and Tembilahan Hulu, respectively.
 

       
Similarity levels of species of Chalcididae on tidal swamp rice in the four studied areas were classified as low until high. The similarity of species is highest in the Keritang and Tembilahan Hulu (0.64) and followed by the similarity of species in the Keritang and Batang Tuaka (0.56), Keritang and Reteh (0.50), Tembilahan Hulu and Batang Tuaka (0.50), Tembilahan Hulu and Reteh (0.50), Batang Tuaka and Reteh (0.38). It means that the composition of Chalcididae is relatively varied between one sub-district and another in Indragiri Hilir District. Then, several species of Chalcididae only exist in one location and several species exist in various locations (Table 4).
 

       
The diversity of Chalcididae in this study showed a higher diversity at the generative phase than before the planting and vegetative phases (Table 5). This was likely caused by the many types of weeds and pests that existed before the planting and generative stage. Our finding is in line with the result of the previous study that Hymenoptera diversity has a high diversity at the time before planting, then decreases in the vegetative phase and increases in the generative phase (Ikhsan et al., 2020).
 

       
We found 127 individuals of Family Chalcididae consisting of 5 genera and 11 species were collected using Sweep net, Yellow pan trap and Malaise traps. Among them are reported as a new record to Indonesia, namely A. Lugubris, A. maculipennis, B. excarinata, B. minuta and Dirhinus anthracia. Vegetation around rice plants has a significant influence on the presence of Chalcididae. Therefore, the landscape of an area is one of the main factors in the distribution of Chalcididae. Tembilahan Hulu and Keritang Districts have a higher diversity index than Batang Tuaka and Reteh Districts (Table 3). Keritang Sub-district and Tembilahan Hulu Sub-district have the highest number of morphospecies and individuals compared to Batang Tuaka and Reteh. This is likely due to the Keritang Sub-district implemented a polyculture planting system while the other two applied monoculture farming.
       
Consequently, each study site has a different chalcidoid wasp species composition. Chalcididae species richness can be a predictor of rice management systems. Our finding strengthens the statement by Yaherwandi et al., (2008) reported that Nyalindung, which has a more complex structure and consists of rice, pulses and vegetable ecosystems, has a higher number of individuals, species and Hymenoptera families to Gasol and Selajambe, which consists monoculture rice farming.
       
In this study, we found eleven species within five genera of chalcidids waps from the tidal swamp rice field in Indragiri Hilir (Table 1). Among those eleven species, five species, namely A. lugubris, A. japonicus, A. maculipennis, B. excarinata and B. minuta, are reported as the first time recorded from Indonesia. There was not much information on the biology and parasitization of Chalcidids wasp in Indonesia that makes it challenging to know the host. However, the wasps are so far known to be parasitoids of a wide range of insect pests, mainly the order of Lepidoptera, however some as hyperparasitoids of Tachinidae (Diptera), Braconidae and Ichneumonidae (Boucek, 1988; Narendran, 1989; Noyes, 2020).
       
The parasitoid species Brachymeria excarinata Gahan, 1925 (Hymenoptera: Chalcididae), is recorded for the first time from Rawalpindi and Islamabad, Punjab (Pakistan) as hyper-parasitoid of Cotesia plutella (Khaliq et al., 2016).
       
Also, Moningka et al., (2012) reported that there was found Brachymeria sp. that parasitized pests on Paddy rice in South Minahasa District. Besides Brachymeria sp., other rice pest parasitoids such as Telenomus sp.; Ooencyrtus sp.; Tetrastichus sp.; Trichogramma sp.; Compsilura sp.; Brachymeria sp.; Apanteles sp. and Amauromorpha sp. In another study by Daniel and Ramaraju (2018) reported 12 species within nine genera of Chalcididae were collected from the rice ecosystem in the Cauvery delta zone in India.

Brachymeria excarinata and Antrocephalus sp. are species found in all study sites and Brachymeria excarinata has the highest individual abundance (Table 1 and Table 2). This reflects that B. excarinata can be spread well and comprehensively in all tidal rice planting locations in Indragiri Hilir Regency. That means B. excarinata is a potential parasitoid that can be developed for pest control in rice cultivation. B. excarinata has been reported from Cameron, Egypt, Iran, India, China, Japan, Taiwan, Vietnam, Philippines, Papua New Guinea (Noyes, 2020) and the first record to Indonesia in this paper. The species has a very wide range of host, mainly the order of Lepidoptera at about 23 species within eight families and one species of Coleoptera (Noyes, 2020). The species was recorded for the first time from Rawalpindi and Islamabad, Punjab (Pakistan), as hyper-parasitoid of Cotesia plutellae. Besides, B. excarinata was also found as a pupa parasitoid from Craspedonta leayana (Coleoptera: Chrysomelidae) in North-East India (Singh et al., 2006). Although Brachymeria is pretty well known and easily recognizable on the generic level, this cannot be said about the species within this genus, which are very numerous in all warmer parts of the world (Ubaidillah, 1996).
       
Similarity levels of species of Chalcididae on tidal swamp rice in the four studied areas were classified as low to high (Table 4). Tembilahan Hulu Sub-district with Keritang Sub-district has the highest similarity index (0.64). This high similarity can be caused by the landscape of rice plantations in the Tembilahan Hulu and Keritang districts, which are both diverse, not a monoculture.
       
Diversity index, species abundance and Chalcididae individual abundance in rice plantations in the tidal land of Indragiri Hilir Regency showed the same up and down pattern in the two planting periods (Table 5). Diversity index, species abundance and Chalcididae individual abundance in the vegetative phase were lower than in the pre-planting phase and then the diversity index increased in the generative phase. This happened at all research locations in the tidal land rice plantations of Indragiri Hilir Regency. This was likely caused by the many types of weeds that existed before the planting stage. Our finding is in line with the results of previous studies that complex agricultural landscapes can increase parasitoid diversity (Yaherwandi et al., 2008). Parasitoid diversity and parasitism depend on many factors; those are location, season, host feeding niche and host diversity (Hamid et al., 2003).

The authors are grateful to the Indonesian Ministry of Research Technology and Higher Education and LPDP for giving the scholarship and financial support for this research. We are grateful too to the student and lecturer of the Agriculture Faculty, the Islamic University of Indragiri, for support in our study.