Songklanakarin J. Sci. Technol. 43 (2), 414-421, Mar. - Apr. 2021 Original Article Diversity of arthropods and decreased seed weight for various cocoa plantation systems Flora Pasaru1*, Alam Anshary1, Mahfudz1, Shahabuddin Saleh1, Mohammad Yunus1, Burhanuddin Nasir1, and Effendy2 1 Department of Agrotechnology, Faculty of Agriculture, Tadulako University, Palu, Central Sulawesi, 94118, Indonesia 2 Department of Agriculture Economics, Faculty of Agriculture, Tadulako University, Palu, Central Sulawesi, 94118, Indonesia Received: 25 May 2019; Revised: 3 October 2019; Accepted: 25 February 2020 Abstract Cocoa farmers in Palolo sub-district conducted cocoa cultivation by implementing three cocoa cropping systems, including the cocoa cropping system without using shade trees (A1), using a number of permanent shade trees (A2), and using natural forests as the shade trees (A3). The aim of the study was to determine the diversity of arthropods and decreased seed weight in the three cocoa cultivation systems. The sampling of arthropods used pitfall traps, light trap, and Yellow Fan Trap. The found 2684 arthropod individuals represented 12 orders, 47 families and 106 species. Diversity index and abundance index were the highest for cocoa crop ecosystem A2 (2.9 and 13.1). The largest decrease in weight of cocoa seeds was found in the A1 locations (8.34%) and the lowest in the A3 locations (3.61%). We recommend that cocoa cultivation should use protective trees. Keywords: cocoa cultivation, diversity of arthropods, seed weight 1. Introduction Greenberg, 2000). Cocoa has been traditionally cropped in primary or secondary forests (Rice & Greenberg, 2000). In One of the main causes of tropical forest loss is their Central Sulawesi (a part of Sulawesi), where the study was conversion to agricultural cultivation systems (Achard et al., conducted, there was a traditional planting system that was 2002; Margono et al., 2012; Margono, Potapov, Turubanova, changed by removing shading native forest trees and replacing Stolle, & Hansen, 2014; Wilcove, Giam, Edwards, Fisher, & them with shade trees, such as Gliricidia sepium (G. sepium) Koh, 2013), especially of palm oil, cocoa, and rubber. or Cassia sp., or with trees that provide edible fruits, wood or Because the world demand for chocolate continues to increase other valuable products. (Rice & Greenberg, 2000; Bisseleua, Missoup, & Vidal, In general, young cocoa crops are still cultivated 2009), cocoa has become the most important commercial crop under shade trees, but after adulthood the shade trees are often in the world. Cocoa is mostly grown by small farmers in completely eliminated, because farmers want to increase the Indonesia (Effendy, 2018). yield of cocoa seeds (Belsky & Siebert, 2003; Bisseleua et al., Of the cocoa production in Indonesia, around 65% 2009; Rice & Greenberg, 2000; Siebert, 2002; Steffan- is produced in Sulawesi (Clough, Faust, & Tscharntke, 2009; Dewenter et al., 2007; Tscharntke et al., 2011). The Leuschner et al., 2013), where about 50% of the cocoa motivation was to reduce competition for sunlight, water and cultivation area was located on ex-forest land (Rice & nutrition between cocoa and shade trees (Belsky & Siebert, 2003; Rice & Greenberg, 2000; Schwendenmann et al., 2010). Changes in cocoa cultivation have had a number of negative *Corresponding author consequences, especially loss of biodiversity, increased soil Email address: [email protected] erosion due to reduced protection from heavy rain, and F. Pasaru et al. / Songklanakarin J. Sci. Technol. 43 (2), 414-421, 2021 415 reduced carbon storage in biomass (Montagnini & Nair, 2004; Muhardi & Effendy, 2017; Rice & Greenberg, 2000;). In addition, various primary or secondary forest ecosystem services provided by the trees were no longer available to local communities, including wood supply, fuel, and fruit production (Tscharntke et al., 2011). Although recent studies in tropical agroforests have discussed these benefits, little is a b c known about the cocoa cultivation system effects on the diversity of arthropods and the decrease in weight of cocoa Figure 1. (a) cocoa crop without shade trees (A1) seeds. (b) cocoa crop using several shade trees (A2) Arthropoda as one of the important components in (c) cocoa crop using natural forest shade trees (A3) the ecosystem could be used as an indicator of the quality of the forest environment and in the agricultural environment. leaves and other impurities, a zinc cover of 20 cm was Besides that, arthropods could be used as consideration installed on top with wooden supports of 20 cm height. Such material for pest management. Arthropods also play a role in trap was placed on each observation plot in each sampling reshaping organic matter to maintain soil fertility, thus also site. It was used to sample the species and populations of maintaining the ongoing nutrient cycle in agricultural active moving arthropods above the ground level in cocoa agroecosystems (Parzanini, Parrish, Hamel, & Mercier, 2018; plantations. For each observation plot, 5 traps were used, with Vaes-Petignat & Nentwig, 2014; Watanasit, Chaiyathape, & the distance between the traps 10 m, and collection at 1 x 24 Permkam, 2002). hours. The aim of this study was to compare the alternative The "Light Trap" tool consisted of a pulling or lure cocoa cultivation systems with respect to the diversity of lamp, with part of the lamp in a plastic container (basin), as a arthropods and the decrease in weight of cocoa seeds. In place to store insects that came because they were attracted to Central Sulawesi, shady and non-shady cocoa cultivation the light. Insects that are attracted to light would fall into a systems occur together, adjacent to each other in the reservoir containing detergent and salt solution. This tool was environment, and we compared three widespread cocoa installed for 1x24 hours to catch insects that are attracted to cultivation systems (cocoa without shade trees; the shade of light. One piece was put in the middle of the observation site legumes G. sepium, Cassia sp., trees that provided edible in each observation plot. fruits; and natural forest shade). Yellow fan trap is made of a yellow plastic container with a diameter of 25 cm, placed on a table (size 30 2. Materials and Methods cm x 30 cm x 1 m), and is placed between crops (installed in an open place to be easily seen by predatory insects ) in each 2.1 Study site description observation plot. This tool was used to trap insects that flew and were carried away by the wind. It was filled with a This study was conducted in Pangana Sejahtera solution of soap and salt water so that insects were trapped, village, Palolo sub-district, Sigi regency. Sigi regency is and was used for 1 x 24 hours before collection of located at an altitude of 600 meters above sea level. The study accumulated samples. sites were cocoa farms owned by farmers. The selection and The sampling of active arthropods on the ground determination of location were conducted using a survey and arthropods that actively flew above the surface using method and purposive sampling, namely the regions based on pitfall trap, light trap, and yellow fan trap followed the their potential as cocoa production centers. The study sites methods of Price & Sherpard (1980) and Whitcomb (1980). were divided into three types based on the cocoa cultivation All catches from the traps at 6 observation times of system, namely cocoa crop without shade trees (A1), cocoa each site were collected, with the observations conducted crop by using some shade trees species (A2), and cocoa crop every 14 days. Observation of arthropods was conducted in using natural forest shade trees (A3) (Figures 1a, 1b, and 1c). the morning from 07.00 until 10.00 local time (wita). Trapped arthropods were separated by using a tea filter and rinsed with 2.2 Sampling of arthropods clean water, then they were put in a collection bottle containing 70% alcohol. Each arthropod from each type of Arthropod samples at each study site (Figure 1a, 1b, trap tool was separated and labeled according to the time of 1c) were collected from 3 sample plots, and each sample plot observation and the site, and was taken to the Laboratory of had 5 sampling points for pitfall trap, 2 points for yellow fan Pest and Plant Disease of the Faculty of Agriculture, Tadulako trap, and 1 point for light trap. Thus each plot required 8 University, for identification of species, and tallying the arthropod traps. Each sample plot was determined randomly numbers of individuals. and the installation of the trap devices was systematic, so that the number of Arthropod traps needed at each study site was 2.3 Identification of arthropods based on 24 (consisting of 15 pitfall traps, 6 yellow fan traps, and 3 morphological characteristics light traps). The pitfall trap was made of plastic beaker (size Identification of arthropods was conducted in 200 ml), 15 cm high and 10 cm wide. It was filled with clean orders, families, genera. The classification of arthropods was water having added detergent and salt to 1/3 level. This was based on taxonomy and trophic structure. Identification could inserted into the ground so that the mouth was level with the be done with the CPC 2002 program and the key book of ground surface. To protect the trap from rainwater or fallen determination Borror, Triplehorn, & Johnson, (1992). 416 F. Pasaru et al. / Songklanakarin J. Sci. Technol. 43 (2), 414-421, 2021 Morphological observations were conducted using an electron where n1i and n2i are the numbers of the ith species in the two microscope. samples A and B, respectively. The percentage decrease in the weight of cocoa 2.4 Arthropoda based on its functional role seeds was calculated using the equations in Pedigo & Buntin (2003) as follows: The study samples were arthropods trapped in cocoa U.Nd D.Nu plantation ecosystems. The variables observed were diversity P .100% composition according to the roles in ecology (phytophagus, U.(Nd Nu) parasitoid, predator, or decomposer) and we focused more on where: natural enemies while regarding pollination there are several P = percentage of weight loss of cocoa seeds (%) prior studies, such as Frimpong et al.