Arthropod-Plant Interactions最新文献

Plant volatiles play an important role as cues for herbivorous insects in search of resources, mates, and oviposition sites in complex environments. The use of plant volatiles as attractants or repellents can be utilized to monitor and control pest populations. Spodoptera exigua (Lepidoptera: Noctuidae, Hübner, 1808) is a highly destructive pest of cruciferous crops that has developed resistance to a variety of insecticides, making the management challenging. This study aimed to investigate the behavioral response of the pest to volatile organic compounds (VOCs) emitted by Rosmarinus officinalis (Lamiales: Lamiaceae, Linnaeus, 1753). We identified ten compounds from the rosemary using gas chromatography-electroantennographic detection (GC-EAD). We then subjected these compounds to ovipositional and olfactory bioassays. The results revealed that the moths were significantly attracted to seven compounds while being repelled by the others. In oviposition bioassays, linalool showed the greatest attractive effect at 69.97% (P < 0.001) at 15,000 μg·mL⁻¹, while eucalyptol exhibited the highest repellent rate at 47.11% (P < 0.01) at 1500 μg·mL⁻¹. In olfactory bioassays, β-pinene showed high attractiveness at a concentration of 150 μg·mL⁻¹, with the attractive rate of 66.67% (χ² = 8.64, df = 1, P = 0.001). Eucalyptol again displayed strong repellent activity at 42.86% (χ² = 5.14, df = 1, P = 0.023) at a concentration of 1500 μg·mL⁻¹. Furthermore, these compounds elicited a dose–response from the moth in these bioassays. This study demonstrates the theoretical feasibility of using rosemary as an attractive crop in agricultural fields for the environmentally friendly management of beet armyworms. However, when VOCs are applied in the field, they often experience significant dilution, resulting in behaviors much less than those observed in the lab. Therefore, these compounds require testing in field settings to ensure their viability as a management strategy for insects.

Baculoviruses are a group of entomopathogenic viruses that are important natural enemies of insects, particularly lepidopteran larvae. An important component of baculovirus transmission efficiency is the frequency with which hosts encounter patchily distributed virions on plants. Little is known about the ecology and bacterial composition of virus-killed cadavers. We used a baculovirus and host Trichoplusia ni caterpillars to study the effects of virus-killed cadavers on tomato plant defenses and T. ni behavior. We also compared bacterial communities associated with virus-killed and uninfected (freeze-killed) cadavers and found that there was no significant difference in community composition and membership between tomato-fed virus-killed or freeze-killed cadavers. Comparison of virus-killed cadavers from two separate experiments revealed significant differences in bacterial community composition, suggesting that host plant could play a more important role in shaping bacterial communities than virus infection status. Culture-dependent plating indicated that virus-killed cadavers had significantly higher bacterial titers compared with uninfected cadavers. We found that virus-killed cadavers suppressed polyphenol oxidase activity, an important plant defense protein, in mechanically damaged plants, but not in plants damaged by herbivory. Although cadavers did not influence plant defenses induced by feeding damage inflicted by healthy or infected T. ni, this study provides the first evidence that baculoviruses could influence plant defenses through host cadavers. When applied to intact plants, neither virus-killed or freeze-killed cadavers influenced T. ni oviposition, larval choice, or larval consumption, indicating these insects did not discriminate cadaver cues. Virus-killed cadavers could play important roles in mediating interactions between plants, herbivores, and other trophic levels, with potential implications for viral transmission dynamics.

The role of hawkmoths in pollination is surprisingly understudied in tropical Asia and most of the studies related to flower visitation recordings lack a robust assessment. From India, very few research papers could be reviewed on the pollination ecology of hawkmoths. Herein, we analyzed the interactions of 109 individuals in 39 hawkmoth species to study their role as pollen transporters and potential pollinators. 67 individuals (61.47%), accounting for 29 species (74.35%), are found to be pollen carrier moths (PCM). The hawkmoths transported pollen from 16 plant families, with Ericaceae dominating the pollen composition (33.37% of total pollen grains). The pollen spectra (based on pollen abundance and relative pollen frequency) revealed that 44 PCM (18 species) came from Macroglossinae, followed by 16 PCM (7 species) from Smerinthinae, and 7 PCM (4 species) from Sphinginae. Macroglossinae transported pollen of 14 plant families. The value of selectivity (H2’) is 0.77 for the pollen transportation network and 0.36 for the moth-plant visitation network. We followed the refined method of pollen extraction from proboscides, rather than swabbing body parts, which enabled us to assess pollen carrying capacity in a refined way. Considering the scenario of the declining global pollinators, largely affecting crop production, moths are the least concerned insects for conservation and management. The outcome of the present study will help in strengthening the baseline information for expanding plant-moth interaction network-related studies and considering the least concerned groups of insects in the conservation policies.

While most ground beetles (Coleoptera: Carabidae) include seeds in their diet, preferences for seed feeding vary among carabid species and range from facultative diet supplementation to obligate seed feeding. DNA-based diet analyses have been used to study their regulatory effect on soil seedbanks. It is unknown whether specialized granivores digest seed species they are adapted to (‘essential seeds’) faster, and whether this affects food web construction based on molecular data. We hypothesized that specialized granivores digest their essential seed faster than other seeds, and at faster rates than generalist granivores or carnivores. Further, we assumed that generalist granivores digest different seeds equally fast, while carnivorous carabids digest seeds slower than granivores. In feeding experiments, three carabid species—Amara similata (specialized granivore), Harpalus affinis (generalist granivore), and Poecilus cupreus (generalist carnivore)—were fed either a broadly accepted seed or the specialist's essential seed. Gut content samples were collected 0, 6, 12, 24, 48, and 72 h after feeding and screened with plant-primers to trace seed DNA. Time until 50% detection probability in the specialists was shorter for its essential than the broadly accepted seed and shorter than in the generalist granivore, which digested both seed species equally fast. The carnivore was reluctant to feed on the seed species offered, and detection probabilities did not significantly decrease with digestion time. Our findings suggest that the strength of specialized granivores’ feeding interactions and their role in weed seed regulation might be underestimated when assessed with DNA-based diet analysis, due to their more efficient seed digestion.

The frequency of intraguild predation (IGP) in coccinellids (Coleoptera: Coccinellidae) in the extraguild prey habitats affects the dynamics of prey-predator and predator-predator interactions. Higher incidences of IGP among the coexisting coccinellids plausibly threaten the biocontrol strategies and the biodiversity of the indigenous species. It is imperative to present the issue of IGP in predaceous coccinellids in terms of molecular evidence. Hence, we reviewed the existing literature on molecular methods such as PCR-based gut content analysis, DNA barcoding analysis, metagenomics, High-throughput sequencing, and Next generation sequencing, to better understand the incidences of IGP, and their impact on biological control and the decline of native species. The molecular studies have corroborated field and laboratory studies, providing realistic estimations of IGP, the dominance of an IG predator, and its impact on biocontrol and native coccinellids. Limitations and future directions have also been discussed. This is the first review on molecular techniques used to study IGP in coccinellids.

The growth of functional plants that support beneficial arthropods within citrus, Citrus sinensis L., orchards may significantly improve the management of the Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann). This research conducted over three years (2020–2023) evaluated the consequences of sowing alfalfa, Medicago sativa L., as a cover crop (Cp plots) compared with bare ground (Bp) in a citrus orchard on the medfly populations and their tree- and ground-dwelling predators. Each year, the study was conducted from October 16th to December 11th. The number of medfly adults/trap/week decreased in the Cp plots compared to the Bp plots during 2021 and 2022. A significant reduction in the number of larvae/fruit and the percentage of infested fruits was seen in Cp plots compared with Bp plots in 2021 and 2022. The total abundance of tree- or ground-dwelling predators was higher in Cp plots than in Bp plots. In addition, Cp plots enhanced the Shannon diversity index for tree-dwelling predators and ground-dwelling predators compared with Bp plots. Therefore, planting alfalfa as a functional cover crop in citrus orchards offers a practicable strategy for reducing medfly populations in integrated pest management.

Salinization stands out as a harsh environmental stress element that hinders the productivity of crops. Climatic changes, alterations in land utilization, and changes in the salinity levels of irrigation water are the main reasons of rising salinization of soil. Enhanced soil salinity modifies the plant quality, potentially leading to cascading impacts on phytophagous insects. On the other hand, virus infection of host plants can have notable effects on the demographic characteristics of the herbivorous insects including virus vectors. So, in our study we investigated how salinity stress affects the demographic characteristics of Frankliniella occidentalis (WFT) through cherry tomato plant infected with tomato yellow ring virus (TYRV). Despite significant enhancement of adult longevity, oviposition period, and fecundity of WFT on virus-infected plants under no-stress conditions, these parameters were adversely affected by salinity stress, leading to a decline in overall fitness of the WFT. The salinity interfered the development duration of nymphs, adult longevity, and oviposition of WFT. Remarkable differences detected in the intrinsic and finite increase rates as well as the net reproduction rate of WFT under high level of salinity. Salinity had a negative impact on WFT development; nonetheless, population projection forecasted a clear but slower growth trend in WFT population particularly under moderate level of salinity (2.8 dS/m of NaCl), while high level of salinity (4.7 dS/m) led to notable fitness costs in WFT populations. The results imply that WFT may pose a growing threat in both virus-free and virus-infected environments characterized by low to moderate salinity levels, potentially exacerbating the negative impacts of salinity on tomato yields. This study will provide insights into the life table characteristics of WFT in tomato fields infected with tomato yellow ring orthotospovirus, aiding in environmentally friendly management strategies.

Graphical Abstract

Salinity stress affects western flower thrips, Frankliniella occidentalis (Pergande), by affecting food sources, physiology, and behavior, leading to reduced fitness and increased mortality rates.

The specific interaction of fig (Ficus) and its fig wasp pollinator (Agaonidae) is sustained by the olfactory signal in combination with morphological co-adaptations. Ficus deltoidea complex is a dioecious fig tree that is regularly pollinated by the fig wasp Blastophaga spp. This complex includes 13 varieties, seven of which are native to Peninsular Malaysia. The classification relies exclusively on leaf characterisation, without considering gene flow across sympatric taxa. Additionally, it remains unexplored whether different varieties support distinct fig wasp pollinators, or to what extent the floral scents emitted by receptive phase figs of these varieties differ. An experiment was conducted to determine the host specificity of Blastophaga sp. from var. trengganuensis in the germplasm of UniSZA by placing a donor male tree from var. trengganuensis surrounded by other varieties. To see the correlation between the varieties entered by the fig wasps and the volatile odour compound (VOC) releases from the receptive figs, a headspace solid-phase microextraction and gas chromatography–mass spectrometry analysis were used. The breakdown of one-to-one specificity in fig and fig wasp mutualism occurs when Blastophaga sp. from var. trengganuensis enters another variety (var. kunstleri) apart from its own variety. Monoterpenes, sesquiterpenes, and aliphatic compounds were detected in the odours of five sympatric fig varieties of F. deltoidea with varying compositions. Multivariate data analysis using PLS revealed the existence of three distinct groups based on differences in VOC content. Females of both var. kunstleri and var. trengganuensis were clustered together, with 12 compounds identified as potentially correlated with the number of fig wasps that entered. Our findings imply that pollinator specificity in figs was potentially mediated by chemical signals in the fig odour where the overlapping of compounds between two varieties caused the pollinators from one variety to reach their non-host plants. Pollinator sharing between two varieties revealed the breakdown of pollinator specificity in var. trengganuensis, showing gene flow is happening in the closely related trees that differ in appearance.

Flower mites are often assumed to negatively impact plant reproductive fitness by depleting floral resources for pollinators. However, there is a lack of studies directly investigating the effects of mites on pollination. This study explores the potential role of Hattena rhizophorae mites in the pollination of the anemophilous species Rhizophora mangle. We hypothesized that H. rhizophorae mites might contribute to the pollination of R. mangle if they (1) are prevalent on flowers, (2) can easily disperse through means other than phoresy, and (3) contribute to pollen transport and deposition.

We examined the spatiotemporal variability of H. rhizophorae mites on R. mangle flowers in relation to the season, the R. mangle patch size, and the abundance of insect visitors that may act as their dispersal vectors We also investigated whether mites could alternatively disperse among flowers via air currents and running water, quantified the pollen grains on the mites’ bodies, and observed whether they made contact with the flower stigmas. We found that mites might serve as pollinators of R. mangle as they were relatively common on flowers, with an average infestation frequency of 40% ± 7% of flowers and an abundance of 68.4 ± 15.5 mites per flower. Their numbers increased with patch size, insect visitor abundance, and during the rainy season. Mites were transported by wind, though there was no evidence of transportation by running water. They appeared to contribute to pollen transport and deposition, as we observed pollen grains attached to their bodies and mites walking on flower stigmas.

Insect damage to a plant activates induced defenses, which include releases of herbivore induced plant volatiles (HIPVs) that attract natural enemies and usually repel generalist herbivores. Oppositely, most herbivore specialists have evolved responses against these defenses, and in many cases are attracted to host HIPVs. However, it is not clear if a specialist is able to discriminate HIPVs released by conspecifics, other specialists, or generalist damage. Dioscorea bulbifera is an invasive vine native to Asia and Africa with infestations in the southeastern United States, Hawai’i, and Puerto Rico. A host specific biological control agent, Lilioceris cheni (Coleoptera: Chrysomelidae) was introduced in 2011 to control D. bulbifera. Recently, a new host specific biological control agent, Lilioceris egena, has been released to improve the biological control program for D. bulbifera. In this study, attraction of L. cheni to HIPVs from generalist, Spodoptera frugiperda (Lepidoptera: Noctuidae); specialist, L. egena; and conspecific damage were investigated. Behavioral assays indicated L. cheni had preference for any type of herbivore damaged plants compared to undamaged plants and discriminated between conspecific damaged plants in the presence of generalist damaged plants, favoring conspecific damaged plants. Differently damaged D. bulbifera plants were then evaluated using gas chromatography coupled with mass spectroscopy which revealed significant quantitative differences between both the specialists’ herbivore damage compared to the generalist volatile profiles with induction of 11 volatiles and suppression of four. This study highlights the importance of understanding an invasive plant’s response to specialist and generalist damage for better management of the invasive species.