Arthropod-Plant Interactions最新文献

Plant-animal interactions and the plant chemical defence systems are a keystone of ecology and of particular interest because they fundamentally shape ecosystem functioning. Despite that, the factors and mechanisms driving the interactions between insectivorous predators and plants, via herbivore-induced plant volatiles—HIPVs remains to be fully understood. Insectivorous birds and arthropods can use chemical cues provided by herbivore-damaged plants, yet the specific chemical defensive traits that are involved in the interactions with predators remain unknown for many plant species. In our experiments, we compared plant volatiles of English oak (Quercus robur) and Sessile oak (Quercus petraea) saplings treated with methyl jasmonate (MeJA). We studied how the MeJA-induced plant volatiles differ between these two closely related plant species, and how it influences higher trophic taxa (e.g., predation, associated arthropod communities). Using plasticine caterpillars, we assessed attractiveness of MeJA-treated oaks (vs. control untreated oaks) for predators. Overall, in both plant species, attack attempts were significantly higher on MeJA-treated saplings compared to control saplings. Birds were responsible for the majority of attack attempts, followed by ants and other arthropods. The mean total amount of volatiles emitted by MeJA-induced saplings differed among the experimental oak species over time and repeated applications of MeJA. MeJA application had no significant effect on the abundance of arthropods. However, the mean body size of individuals of different feeding guilds was affected by MeJA treatment both negatively and positively, depending on the specific feeding guild. Overall, our study concludes that (1) the application of MeJA led to increased attractiveness of oak saplings for insectivorous predators, including invertebrates and birds; (2) MeJA-treated oak saplings emitted eight specific compounds that were not detected in control saplings and two additional compounds that were emitted at 100-fold higher levels in MeJA-treated saplings compared to control saplings; and (3) the predation rate on artificial caterpillars did not significantly differ between oak species.

Poplars establish on alluvial bars within sand and gravel-bed rivers. Alluvial bars also provide particularly suitable habitats for the proliferation of ants. We hypothesized that ants, by modifying substrate structure and resource availability in fluvial habitats, positively influence poplar growth during its establishment stage. We conducted a preliminary nine-month ex situ greenhouse experiment with one ant species (Lasius niger L.) and six different genotypes of poplar cuttings (Populus nigra L.), both collected on the Garonne River, SW France. Three main treatments: ‘P. nigra alone’, ‘P. nigra without ants and with ant food’ and ‘P. nigra with ants and ant food’ were applied. After one growing season, we tested differences in branching length and biomass of stems, roots and leaves. Certain genotypes showed significant differences in growth, but there were no significant differences in stem length, dry mass of stems and roots between the three treatments. The total biomass of poplars after the first growing season was positively affected by the initial size of the cuttings and was modulated by the genotype independently from the treatments. However, an increased poplar growth for the treatment without ants and with ant food was observed according to significant differences in dry weight of leaves and total biomass (i.e. dry mass of stems, roots and leaves) for the pooled genotypes across treatments. We discuss our results with the aim of serving as a reference for future in situ and ex situ experiments and field measurements exploring interactions between ants and poplars, specifically in riparian ecosystems.

Mound-forming ants are important ecosystem engineers as they increase habitat heterogeneity, thus supporting multiple biotic interactions. How these ant-mediated changes in abiotic factors translate into temporal biotic heterogeneity, is a less studied subject. In a case study localized on a Danish heath, we investigated how ant mounds (mineral and organic mounds) affected the phenology and flowering success of five plant species growing on or between ant mounds (Lasius flavus and Formica exsecta). Specifically, we focused on the phenophases’ stem elongation, flowering and seed set. All plant species showed significantly earlier phenophases on the mounds compared to control patches between mounds. These advances resulted in two distinct flowering seasons for one plant species and prolonged continuous flowering seasons for the four other species, when mound and non-mound plant seasons were combined. Likewise, stem elongation and seed set seasons were prolonged, with either two distinct seasons or one continuous season, depending on plant species. Two plant species exhibited increased survival up to the flowering stage when growing on ant mounds, since they flowered before a drought killed a large part of the population. Probable drivers behind these effects, as revealed by a structural equation model, were elevated surface temperature and other soil edaphic factors responsible for plant growth. Furthermore, the direct effects of the ant mounds were nearly twice as high for the organic mounds of F. exsecta compared with the mineral mounds of L. flavus. Possible implications are more resilient ecosystems, as prolonged seasons can mitigate phenological mismatches between interacting species.

Thrips (Thysanoptera: Thripidae) feed on leaf and flower tissue and some of them can be facultative predators. Caliothrips phaseoli Hood causes severe damage to different species of the Fabaceae family, mainly to Phaseolus vulgaris L. crops. The purpose of this research is to assess the change in feeding damage due to predation on Tetranychus merganser (Acari: Tetranychidae) eggs by the first and second larval stages of C. phaseoli on bean leaf discs, under laboratory conditions. Predation and damage were assessed through functional response and ordinal scale, respectively. The first and second larval stages of C. phaseoli exhibited a type II functional response. The second larval stage of C. phaseoli displayed shorter handling time and higher attack rate in comparison to the first instar. The first and second larval stages of C. phaseoli consumed 3.8 and 4.9 eggs of T. merganser per day, respectively. The second larval stage caused the highest damage (median = 3). The feeding damage of C. phaseoli was negatively associated to the number of eggs offered. The C. phaseoli larvae became more predatory than herbivorous when the number of eggs offered increased; therefore, C. phaseoli can be considered a facultative predator.

The behavioral phenotypes of hosts may be altered during parasitism, which could favor either the host or the parasite. Pea aphid Acyrthosiphon pisum hosts parasitized by the primary parasitoid wasp Aphidius ervi leave the stems or lower leaf surfaces where they are most commonly found and move to upper leaf surfaces before they die and mummify. In order to test whether the change of microhabitat benefits the host or the parasitoid, we transplanted pea aphid mummies reared in the laboratory to three different microhabitats on alfalfa plants in the field: the upper leaf surfaces, the lower leaf surfaces, and the stems. Survival analysis revealed no significant differences in mummy survival to emergence across the microhabitat treatments before an alfalfa harvest, when predation pressure was very high, and 2 weeks after an alfalfa harvest, when predation pressure was very low. In contrast, 5 weeks after an alfalfa harvest, when predation pressure was intermediate differences in predation risk were apparent: mummies transplanted to the upper leaf surface had the lowest mortality rates, mummies transplanted to the lower surface of leaves had intermediate mortality rates, and mummies transplanted to the stems had the highest mortality rates. Furthermore, a laboratory study suggested that, compared to other plant substrates, mummies on stems were more likely to be preyed upon by the ladybeetle, Hippodamia convergens, which concentrated its search on stems. Our results support the adaptive manipulation hypothesis, in that parasitized aphids appear to induce their host to move to a region of reduced predator foraging, where their risk of attack is reduced.

Mexico is the center of maize Zea mays L. domestication with a large diversity of landrace genotypes that are of great economic, cultural and social importance. Landrace maize genotypes are mainly cultivated by smallholder farmers for local and specialized markets of culinary dishes, However, all maize genotypes are subject to insect herbivory among which the Fall Armyworm (Spodoptera frugiperda Smith and the White grub larvae (Phyllophaga vetula Horn cause serious yield losses, by feeding on leaves and roots, respectively. Here we investigated the response of landrace and hybrid maize genotypes to herbivory from foliar (S. frugiperda) and root feeding (P. vetula) insects with five maize landrace and five hybrid maize genotypes. The main results showed that landrace maize genotypes suffered from a higher level of herbivory by S. frugiperda than hybrid maize genotypes. For root herbivory, no clear differences between landrace and hybrid maize were observed and overall, only one out of the five maize genotypes for each type of maize were negatively affected from the presence of P. vetula. In conclusion, maize genotypes respond differently to root and foliar herbivory, which should be considered when developing pest management strategies in maize agroecosystems.

Using knowledge about plant–insect interactions in a crop protection perspective is a pre-requisite to promote the development of novel pest management strategies. Enhancing plant natural defenses has been described as a promising way to improve the management of pests. In cotton, plant topping (cutting off the top of the plant) for inducing such defenses has been proposed as a promising tool for integrated pest management. The main objective of this study was to explore the effect of cotton topping on the performance of the cotton aphid, Aphis gosypii, under greenhouse conditions. The effect of plant topping was evaluated on topped and on neighbor non-topped plants. Results showed that cotton topping disturbed A. gossypii aphids not only on the topped plant but also on neighbor non-topped plants. The population of aphids grew slower in the topped compared to the control treatment and lower abundances of aphids were found in the topped treatment up to a distance of 100 cm to the topped plant. When an individual nymph was confined in a clip-cage, the production of winged adults after 15 days of confinement was higher in the topped compared to the control treatment. This difference decreased as the distance to the topped plant increased. In conclusion, our study proves that cotton topping mediates plant-pest interactions on the focal and neighbor plants. We discuss how cotton topping is a promising technique that could be used as part of an integrated pest management program, particularly for smallholders in West Africa, for controlling aphid infestations.

In Brazil, genetically modified cotton is increasing in most cultivated areas to manage insects, mainly Lepidoptera. Pests associated with cotton crops are diverse. Aphis gossypii Glover, 1877 (Hemiptera: Aphididae), one of the most important cotton pests, sucks photoassimilates from the phloem sap causing mold growth and damage to plant tissues. The interactions between Bt plants and non-target organisms and the impact of A. gossypii damage on these plants need further studies. Therefore, the objective was to evaluate the physiological stress caused by A. gossypii on Bt cotton and its isohybrid (same genetic background but not transgenic). The Bt cotton (Cotton Event 281-24-236/3006-210-23) and the isohybrid of this plant were planted in pots in a completely randomized design, as the treatments, with 30 replications in a greenhouse. The chlorophyll fluorescence parameters of the plants were evaluated by using a fluorometer. Regression models were adjusted for Bt cotton and the isohybrid, and the differences between treatments were evaluated through the model identity test. The photosynthetic parameters of Bt cotton and its isohybrid infested by this insect were similar.

Solanaceae is a large plant family whose center of diversity is in South America, it includes important crop plants and various weeds. Several species of Tephritid fruit flies have been reported in association with Solanaceous plants, particularly those in the genus Rhagoletis. However, many of these reports are on commercial crops such as tomato, and there is still little knowledge on use of wild native plants. Here, we report results of a 3-year survey of Solanaceous fruit in North-Western Argentina. Fruit of 22 species of Solanaceae were collected over 3 years in the Yungas, Dry Chaco, and Monte biomes. Fourteen of these plants were infested with dipteran, coleopteran, and lepidopteran larvae. Lycium sp. represents a new host plant record for Haywardina cuculi, Solanum aligerum is a new host plant record for Anastrepha fraterculus, Drosophila suzukii, and Rhagoletis blanchardi. Solanum argenteum, Solanum confusum, Solanum delitescens, Solanum pseudocapsicum, Solanum stukertii, and Solanum tenuispinum are new host plant records for Rhagoletis blanchardi. Solanum trichoneuron is a new host plant record for Anastrepha fraterculus. Two unidentified species of Lonchaeidae were found infesting nine species of Solanaceae. Hymenopteran parasitoids in the genus Utetes, Doryctobracon, and Ganaspis were found in association with Solanaceae infesting tephritids. We also report notes on the life cycle and behavior of the tephritids recovered during this sampling effort.

Plants are frequently exposed to heat stress as a result of global warming. Heat stress leads to a series of physiological responses including stress volatile elicitation, but how heat stress-induced volatile cues affect the behavior of herbivores is poorly understood. In this study, the polyphagous herbivore Spodoptera litura (tobacco cutworm, TCW) and Chrysanthemum nankingense were selected as the model to elucidate the interactions between herbivore behavior and heat stress-induced plant physiological changes. Photosynthetic characteristics and volatile emissions were measured in C. nankingense control plants (25 °C for 3 h), in C. nankingense exposed to moderate (35 °C for 3 h), and severe (45 °C for 3 h) heat stresses. Net photosynthetic rate (A_n) decreased by more than two-fold after exposure to 45 °C due to non-stomatal inhibition of photosynthesis. 45 °C treatment induced emissions of the camphor and (E)-β-caryophyllene. Exposure to 35 °C had minor effects on photosynthetic characteristics and did not induce terpene emissions. Using dual-choice olfactometer bioassays, we found that 45 °C treatment enhanced the attractiveness of the plants to TCW. Moreover, the leaf concentrations of nine sesquiterpenes were increased and the feeding of TCW was strongly inhibited after 45 °C treatment compared with control plants. Taken together, our study highlights the impact of heat stress on the behavior of the herbivore mediated by the accumulation and emission of sesquiterpenes and suggests altered pest-host interactions under future warmer climates. Modulation of terpenoid emissions and contents should be considered in developing future ecological pest control strategies in agricultural fields.