Elucidation of the whole carotenoid biosynthetic pathway of aphids at the gene level and arthropodal food chain involving aphids and the red dragonfly

Background Aphids can be positioned as robust pest insects in farming and as ones of the model organisms for arthropods in molecular biology. Carotenoids are pigments that protect organisms from photooxidative damage caused by excessive light. Aphids were shown to possess genes of fungal origin for carotenoid biosynthesis, whereas a little knowledge was available about the functions of the genes and the biosynthetic pathway. Even carotenoid species contained in aphids were not enough understood. Main purpose of this study is to clarify these insufficient findings. Results The whole carotenoid biosynthetic pathway of the pea aphid (Acyrthosiphon pisum) was elucidated at the gene level, through comprehensive functional analysis of its carotenogenic genes, using Escherichia coli that synthesized carotenoid substrates, along with structural and quantitative analysis of carotenoids from various aphid species. Four genes were needed to synthesize all carotenoids accumulated in aphids from geranylgeranyl diphosphate. The tor gene mediated desaturation reaction from phytoene to 3,4-didehydrolycopene. It was revealed that a gene designated ApCrtYB3, which was considered to have functionally evolved in aphids, can convert lycopene into uncommon carotenoids with the γ-ring such as (6′S)-β,γ-carotene and γ,γ-carotene. We further demonstrated that the atypical carotenoids work as ecological indicators for estimating the food chain from aphids to predatory arthropods, and showed that aphids contributed with significant levels to the food chain from insect herbivores to several predatory arthropods, i.e., the red dragonfly (Sympetrum frequens; adults), seven-spotted ladybird (Coccinella septempunctata), and two spiders, Oxyopes sertatus and Nephila clavata. Gut microflora of the dragonfly (mature adults) was also found to include endosymbiotic bacteria such as Serratia symbiotica specific to the black bean aphid (Aphis fabae). Conclusions We revealed the whole carotenoid biosynthetic pathway of aphids, including functional identification of the corresponding genes. Subsequently, we showed that arthropodal food chain can be estimated using the uncommon carotenoids of aphids as ecological indicators. This result indicated that aphids made significant contributions to the food chain of several predatory arthropods including the red-dragonfly adults. Aphids are likely to be positioned as an important “phytochemicals” source for some predatory insects and arachnids, which are often active under bright sunlight.

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.

Kelimpahan Relatif Artropoda Predator Penghuni Tajuk Tanaman Padi Galur Padi Rakitan Politeknik Negeri Lampung

The abundance of predatory arthropods in the rice field ecosystem acts as a biological agent that suppresses pest populations. This study aims to analyze the types of species, individuals, and abundance of predatory arthropods. The research was conducted at the Lampung State Polytechnic Seed Teaching Farm in August-December 2020. The rice plant lines planted by Lampung State Polytechnic were 14 New Type Rice (PTB) lines, namely Pandan Wangi (PW, B1, B2, B3, B4, B7, D2, D3, F3, F4, H1, H4, K, and L2 with 2 and comparable superior varieties namely Ciherang (CH) and Gilirang (Gil)). Rice cultivation is carried out conventionally. Observations of predatory arthropods that inhabit rice canopy were carried out using 3 double swings of insect nets / sweepnets per treatment plot. Insect collection was carried out at 06.00-09.00 WIB then identified in the Food Crops Laboratory II, counting the number of species, number of individuals and relative abundance. The results showed that predatory arthropods that inhabit the canopy of rice plants in several rice plant lines were obtained from the Oxyopidae, Tetragnathidae, Lycosidae, Coenagrionidae, Correidae, Coccinellidae, Chrysomelidae, and Staphylinidae families. The Tetragnathidae and Coenagrionidae families have the highest proportion of species and are found in each rice plant line.

Consumer-Ready Insect Hotels: An Assessment of Arthropod Visitation and Nesting Success

Insect nesting boxes and hotels have the potential to provide shelter and overwintering sites for beneficial insect communities such as pollinating bees, wasps, earwigs, and other predatory arthropods. This study evaluated beneficial arthropod visitation to consumer-ready, commercially available nesting boxes over a 2-yr period. Insect hotels were placed on mature river birch (Betula nigra L.) and crape myrtle (Lagerstroemia indica L.) in garden plots established with floral resources for pollinators and other beneficial insects. Paper and thread-waisted wasps, soldier flies, predatory ants, and spiders were observed visiting the boxes. Boxes located in garden plot treatments (with floral resources) had the greatest numbers and diversity of pollinator and beneficial insect taxa compared to control plot treatments (naturalized areas away from floral resources) in 2016. Insect hotels placed on B. nigra had a higher number of thread-waisted wasps in 2016 and spiders and total beneficial insects in 2017. Higher numbers of predatory ants and total beneficial arthropods were found in boxes placed on L. indica in 2016. During the study, bamboo stems and drilled tunnels in the insect boxes were evaluated for arthropod inhabitance. Largest counts of occupied stems and tunnels were observed in boxes placed in proximity to floral resources and on L. indica trees.

Phytophagous insects and predatory arthropods in soybean and zinnia

Anggraini E, Anisa WN, Herlinda S, Irsan C, Suparman S, Suwandi S, Harun MU, Gunawan B. 2021. Phytophagous insects and predatory arthropods in soybean and zinnia. Biodiversitas 22: 1405-1414. In Indonesia, soybean is the third most important commodity after rice and corn. Cultivation technique such as planting hedgerows was expected to attract and retain natural enemies of pest predators. This study was conducted to determine the phytophagous insects and predatory arthropods species in soybean (Glycine max L.) and zinnia (Zinnia sp., hybrids) plants as refugia. This study utilized three methods i.e., visual observation, pitfall trap, net-trap in both soybean and zinnia planting areas. All collected insects were carried to the laboratory for observation and identification using insect determination key book. Insect identification was based on their morphological characteristics. The results study showed that phytophagous and predatory arthropods were found in both soybean and zinnia plantations in Agro-Techno Center (ATC), Sriwijaya University, Indonesia. There were 11 species of phytophagous and 5 species of entomophagous insects identified at soybean cultivation. Meanwhile, 5 species of phytophagous and 9 species of predatory arthropods including five spider species found, namely Pardosa distincta, Oxyopes javanus, Lycosa pseudomonas, Pardosa sp. and Drapetisca socialis at zinnia cultivation area. However, chi-square analysis (at alpha 0.05), confirmed that there was no significant difference between predatory arthropods in soybean and Zinnia the results indicate that soybean is might be suitable to be planted as refugia for predatory arthropods.

Predicting Damage to Hop Cones by Tetranychus urticae (Acari: Tetranychidae)

Twospotted spider mite (Tetranychus urticae Koch) is a cosmopolitan pest of numerous plants, including hop (Humulus lupulus L.). The most costly damage from the pest on hop results from infestation of cones, which are the harvested product, which can render crops unsalable if cones become discolored. We analyzed 14 yr of historical data from 312 individual experimental plots in western Oregon to identify risk factors associated with visual damage to hop cones from T. urticae. Logistic regression models were fit to estimate the probability of cone damage. The most predictive model was based on T. urticae-days during mid-July to harvest, which correctly predicted occurrence and nonoccurrence of cone damage in 91 and 93% of data sets, respectively, based on Youden’s index. A second model based on the ratio of T. urticae to predatory arthropods late in the season correctly predicted cone damage in 92% of data sets and nonoccurrence of damage in 77% of data sets. The model based on T. urticae abundance performed similarly when validated in 23 commercial hop yards, whereas the model based on the predator:prey ratio was relatively conservative and yielded false-positive predictions in 11 of the 23 yards. Antecedents of these risk factors were explored and quantified by structural equation modeling. A simple path diagram was constructed that conceptualizes T. urticae invasion of hop cones as dependent on prior density of the pest on leaves in early spring and summer, which in turn influences the development of predatory arthropods that mediate late-season density of the pest. In summary, the biological insights and models developed here provide guidance to pest managers on the likelihood of visual cone damage from T. urticae that can inform late-season management based on both abundance of the pest and its important predators. This is critically important because a formal economic threshold for T. urticae on hop does not exist and current management efforts may be mistimed to influence the pest when crop damage is most probable. More broadly, this research suggests that current management practices that target T. urticae early in the season may in fact predispose yards to later outbreaks of the pest.