Arboreal arthropod assemblages in chili pepper with different mulches and pest managements in freshwater swamps of South Sumatra, Indonesia

Herlinda S, Tricahyati T, Irsan C, Karenina T, Hasbi, Suparman, Lakitan B, Anggraini E, Arsi. 2021. Arboreal arthropod assemblages in chili pepper with different mulches and pest managements in freshwater swamps of South Sumatra, Indonesia. Biodiversitas 22: 3057-3066. In the center of freshwater swamps in South Sumatra, three different chili cultivation practices are generally found, namely differences in mulch and pest management that can affect arthropod assemblages. The effect of mulches and pest management on arboreal arthropod assemblages specific to chili production centers in the freshwater swamps of South Sumatra has never been investigated. This study aimed to observe arboreal arthropod assemblages in chili with different mulches and pest management. Arboreal arthropods were sampled using sweep nets in three locations with plots treated with leaf litter mulch and bioinsecticide, plastic mulch and synthetic insecticide, and weedy plot without mulch with synthetic insecticide. The species number of arboreal arthropods found was 28 species of Arachnids and 23 species of Insects, and consisting of 6 families of the Arachnids and 25 families of Insects. The abundance of arboreal arthropods was 65.60 individuals/5 nets per observation. In the chili field without mulch but with the insecticide, the species biodiversity and abundance of arboreal predatory arthropods were the highest. In contrast, in the chili field, that applied with synthetic insecticides and plastic mulch, the abundance of arboreal predatory arthropods was the lowest. The herbivorous insect populations in chili with plastic mulch and synthetic insecticides and the chili with the leaf litter mulch were higher than those in the chili without mulch. In the chili with the leaf litter mulch and bioinsecticide, the species number and abundance of the spiders were the highest compared to the other chili fields. The weedy chili field without mulch and chili with the leaf litter mulch has proved ideal habitats for the arboreal predatory arthropods.

The abundance of canopy arthropods in South Sumatra (Indonesia) freshwater swamp main and ratooned rice applied with bioinsecticides and synthetic insecticide

Prabawati G, Herlinda S, Pujiastuti Y. 2019. A comparative study on the arboreal arthropod abundance of rice fields between applied with fungal bioinsecticides and abamectin in the freshwater swamp of South Sumatra, Indonesia (Study case in the main and ratoon rice fields). Biodiversitas 20: 2921-2930. Ratoon rice has been cultivated by local farmers in South Sumatra and can be a source of habitat and niches for the main rice arthropods. The study aimed to compare the abundance of arthropods between main and rationed rice field applied with fungal bioinsecticides and abamectin. This study used bioinsecticides from fungi of Beauveria bassiana, Metarhizium anisopliae, and Cordyceps militaris and control using abamectin. Arboreal arthropods sampled using a sweep net. The abundance of arthropods in the main rice tends to be higher than in ratoon. Spiders found during the two rice seasons were Araneidae, Linyphiidae, Lycosidae, Oxyopidae, Salticidae, Theridiidae, Tetragnathidae, Theridiosomatidae, while predatory insects found were Mantidae, Coenagrionidae, Staphylinidae, Anthicidae, Latridiidae, Formicidae, Coccinellidae, Coccinellidae, Tettigoniidae, Miridae, Carabidae. The fungal bioinsecticides did not reduce the predatory arthropod abundance but the abamectin caused a decrease in the abundance of all guilds. The most drastic decrease was found in web-building spiders. The movement of hunting spiders and the predatory insects of the main to ratoon rice was faster than that of web-building spiders. The existence of ratoon rice could become habitats and niches for arthropods from the main rice. For this reason, controlling the herbivore insects could use bioinsecticides derived from entomopathogenic fungi.

Prey capture in a mantid (Gonatista grisea): does geotropy promote success?

Gonatista grisea (Fabricius) is one of many arboreal arthropods and reptiles that orient downwards to ambush prey. To investigate if orienting downwards increases hunting success, a 2 × 2 factorial experiment was performed using mantid orientation (upwards, downwards) and direction of prey approach (posterior, anterior) as factors and prey capture success as the response variable. The results indicated that the mantid captures prey equally well when oriented upwards or downwards but that it is less effective when the prey approaches posteriorly. Because prey likely climb upwards more frequently than downwards, these findings suggest that G. grisea increases its hunting success with its downwards orientation.

Bird predation affects canopy-living arthropods in city parks

Earlier studies suggest a significant top-down impact of vertebrate predators on arboreal arthropods. However, the general importance of such predator-prey interactions is not yet established. The impact of bird predation on macro-arthropods living in canopies of birch (Betula pendula) and oak (Quercus robur) was studied at six sites in four city parks in Göteborg, southwestern Sweden. In a 17-week field experiment we manipulated the bird-predation pressure on arthropods on birch and oak branches. Passerine numbers differed significantly between birch sites but not between oak sites. Bird predation significantly reduced the abundance on both birch and oak branches of seven out of nine arthropod taxa examined: Araneae, Opiliones, Dermaptera, Psocoptera, Heteroptera (oak only), Coleoptera, and Lepidoptera (birch only). For birch, arthropods were of larger average body size on experimental than on control branches at two sites. At the third site, however, arthropods were larger on control branches. For oak, arthropods were significantly larger on experimental than on control branches at two sites. At the remaining site, in the same park as the deviating birch site, there was no difference between size distributions. Thus, in one of the parks, experimental effects on size distributions at birch and oak sites contradicted the results from the other parks. Site effects on arthropod abundance were found for three insect taxa on birch and one insect taxon on oak. There were significant interactions between experimental treatment and site for Dermaptera on birch and for Araneae on oak. Although one of the parks (the central one) differed from the others in certain aspects, the results suggest that overall, bird predation was not seriously affected by the urban environment. We conclude that bird predation on arthropods is an important link in canopy food webs of temperate-zone forests.