Arthropod-Plant Interactions最新文献

Root herbivory by insects can significantly impact plant performance and yield, particularly in crop production. Our understanding of the impact of chronic root herbivory by the rice water weevil, Lissorhoptrus oryzophilus, remains limited. Using an insecticidal seed treatment to manipulate levels of herbivory in small plots under natural field conditions, this study investigated the differences in rice water weevil infestation, plant growth, nutrient uptake, and phytohormone production in two rice cultivars. Two separate trials were established at different planting dates. For each trial, field plots were laid out following a randomized block design with six blocks and each block contained a factorial arrangement of cultivar (a hybrid and an inbred) and insecticidal seed treatment (seed-treated and nontreated). Rice water weevil densities were measured through root-soil core sampling at various time points after permanent flood establishment. Additionally, plant samples were collected at several timepoints for analyses of plant biomass, nutrient concentration, and phytohormones. Results showed that weevil densities varied over time with peak densities occurring around four weeks after permanent flood. The hybrid cultivar supported higher weevil densities but exhibited greater root and shoot biomass compared to the inbred cultivar. Weevil infestations negatively affected shoot biomass and nutrient concentrations, with significant reductions in several macronutrients and micronutrients over time. In addition, OPDA levels, a precursor of JA biosynthesis, were higher in the shoots of weevil-infested rice plants. Yield losses due to weevil infestations ranged from 8 to 35% with inbred cultivar experiencing greater yield losses than hybrid cultivar. Overall, our findings indicate that chronic root herbivory in rice was associated with reduced plant growth, yields, and nutrient uptake.

Two species of death-camas (Toxicoscordion, formerly Zigadenus) from the western USA imbue their pollen and nectar with steroidal alkaloids, including zygacine. The toxins are tolerated by the plants’ ubiquitous pollinator, Andrena astragali. This bee is monolectic, visiting no other flowers for pollen. However, 20 years of additional surveys revealed a few foragers of another bee, A. amphibola, plus two Eristalis hover flies (Syrphidae) that occasionally forage from death-camas flowers at some locations. The hover flies likely detoxify the ingested alkaloids, but the apparent tolerance of zygacine by this other Andrena is enigmatic.

Ant–plant mutualisms are widespread, with over 4000 angiosperm species worldwide bearing extra-floral nectaries where sugar is secreted in exchange for protection against herbivores. Turnera velutina, an endemic Mexican shrub, has facultative mutualist interactions with different ant species, and these interactions have variable effects on its fitness. Specifically, the presence of Camponotus ants have been linked to the highest T. velutina’s fruit production, in comparison with the presence of other patrolling ant species. Whether this outcome is because Camponotus ants are the most aggressive, the largest, the fastest at locating herbivores, and/or more gregarious with many workers patrolling/attacking herbivores, has not yet been formally investigated. In this study, we assessed the defensive behavior and repelling capacity of six ant species against larvae of Euptoieta hegesia (Lepidoptera), the main herbivore of T. velutina in the studied population. Contrary to our expectations, Camponotus ants were not the most effective defenders, and they were only better than Cephalotes ants, a genus that has been found to be opportunistic in other plant systems. Surprisingly, the two smallest ants, Dorymyrmex bicolor and Brachymyrmex sp., were the best defenders and the fastest at repelling herbivores, partly because many workers simultaneously attacked the larvae. We discuss how different ants may impact various aspects of a species’ fitness, highlighting the dynamic and complex outcomes of ant–plant interactions, as a function of species identity and their impacts on herbivores.

The occurrence of the native ragwort Jacobaea vulgaris and its relatives is a problem for grassland owners, due to the pyrrolizidine alkaloids being poisonous for livestock. Besides J. vulgaris, the invasive Senecio inaequidens is challenging and control measures in line with nature conservation goals are needed. To evaluate prospects of using the native and herbivorous Tyria jacobaeae as a biological control agent, we studied its performance on S. inaequidens in comparison to the native J. vulgaris and J. aquatica. We compared the egg-laying decision of 106 females (number and placement of eggs on the plant, in the surrounding or not laid at all) and performance of 50 larvae, reared in five treatments with different food supply (only leaves or leaves and flowers) of the three ragwort species. We found that females oviposited preferably on the plant when J. vulgaris and J. aquatica were available, whereas in the presence of S. inaequidens most eggs were retained and not laid. No differences were observed in larval weight, weight gain, or leaf area consumed when larvae were fed with J. vulgaris (leaves, leaves and flowers) or J. aquatica leaves. Furthermore, 90% of the larvae provided with these treatments pupated successfully. In contrast, larvae developed slowly when provided with S. inaequidens and none survived to pupation. Our results show that J. aquatica is a suitable alternative host for T. jacobaeae, whereas S. inaequidens is not. We therefore argue that T. jacobaeae has no biological control potential against S. inaequidens.

Pollinator-dependent crops are typically uniform habitats but the presence of an interplanted cover crop can increase field heterogeneity, potentially affecting pollinator foraging patterns. Particularly, tall grass species like rye can act as physical barriers, constraining movement between crop rows and reducing flower visitation. In this study, we investigated the effects of rye cover crop on pollinator foraging behavior in seedless watermelon. We used 27 commercial fields between 2022 and 2025, which had either no rye (0% rye), one rye strip to every three watermelon rows (25% rye) or one rye strip every other watermelon row (50% rye). Across years, we conducted 20 observational surveys per rye level during watermelon bloom, recording multiple aspects of foraging behavior. We categorized bees in four guilds: honey bees, bumble bees, large solitary bees and small solitary bees. Overall, the number of flower visits per watermelon row was greatest with higher rye level (0% rye: 1.8, 25% rye: 2.0, 50% rye: 3.3). Rye level affected the number of row changes differently for each pollinator guild. Honey bees and small solitary bees were more affected by rye compared to bumble bees and large solitary bees; they visited more flowers per row but moved between rows less frequently. Large solitary bees exhibited the highest probability of crossing over rye. Our study shows that rye created a barrier effect by funneling bee movement, which may lead to uneven yields. To minimize potential nonuniform pollination, we recommend practices that enhance pollinator distribution and biodiversity for more resilient pollination services.

Alfalfa (Medicago sativa L.) improvement under arid conditions increasingly requires integrating biotic stress tolerance with forage quality. This study evaluated six alfalfa genotypes—comprising native, exotic, and synthetic origins—for their response to infestation by the alfalfa weevil (Hypera postica), the primary insect pest affecting alfalfa productivity worldwide, under open-field conditions. Five genotypes consisted of half-sib progenies derived from either native (GAB) or exotic parental sources (AME, ABT, SAR, ETS), whereas the synthetic genotype (SYN) corresponded to a Syn-1 population obtained by mixing seeds of superior S₁ progenies selected from a polycross, with 60% originating from the native GAB background and the remaining 40% equally contributed by the four exotic families (10% each). Genotypic differences in infestation severity were substantial, ranging from 3.03% in the synthetic line SYN to 9.00% in AME and SAR, both half-sib progenies of exotic parents. The native-derived GAB exhibited intermediate infestation (6.58%) but maintained high crude protein − CP (23.65%) and moderate resilience in plant structure, marking it as a valuable contributor from local germplasm. The synthetic line SYN displayed the best integrated performance, combining the lowest infestation with sustained growth (internode length − LEN = 2.62 cm), pigment retention (SPAD = 44.1), and thermal stability (leaf temperature = 15.9 °C). In contrast, exotic-derived ABT, ETS, AME, and SAR showed sharper declines in structural and physiological traits under pest pressure. Across genotypes, infestation significantly increased fiber fractions (Neutral Detergent Fiber − NDF: + 7.2%; Acid Detergent Lignin − ADL: + 0.85%) while reducing digestibility (Dry Matter Digestibility − DMD declined to 62.3% in ETS) and SPAD index. Multivariate analysis (81.8% variance explained) revealed strong integration of morpho-physiological and nutritional traits. These findings underscore the breeding potential of native-derived progeny (GAB) and the synthetic line (SYN) for generating cultivars that jointly express pest resilience and forage value, offering strategic assets for sustainable alfalfa production in arid, pest-prone systems.

Soil pollution with metals is a worldwide problem with negative effects on ecosystem health. Metals are persistent and can accumulate in the food web, with potential toxic effects for most organisms. Some metal-tolerant plants can accumulate metals in their aboveground parts, including the pollen and nectar of their flowers. Therefore, insects visiting these flowers are exposed to these toxic elements. They can also be influenced by the plant species turnover observed along pollution gradients. Surprisingly, the impact of soil metal contamination on pollinating insect diversity has rarely been studied. To fill in this gap, we carried out a study in a former mining valley in the French Pyrenees with metal contamination by Zn, Pb and Cd. We estimated the richness and community composition of insects visiting the flowers of metal-tolerant and metal-intolerant plant species in 96 plots along metal pollution gradients. Insect richness did not change along the pollution gradient and was similar between metal-tolerant and metal-intolerant plant species. On the contrary, insect community composition changed along the gradient and differed between plant types. We also found that insect species richness increased with the flower abundance of the focal plant. This study showed that flowers of metal-tolerant plants, including hyper-accumulator species, are visited by several insect species and harbour a distinct pollinator community. The ingestion of metal-rich nectar or pollen may have lethal or sub-lethal effects for these flower-visiting insects. Further experimental studies are needed to determine if metal-rich floral resources act as an ecological trap for some of these species.

Agricultural habitat and landscape factors influence arthropod community structure in urban agroecosystems, thereby influencing the crucial role that arthropods play in supporting ecosystem services, such as biological pest control. Top-down regulation can be enhanced or diminished by shifts in arthropod communities, thus, understanding which factors alter abundance and richness of herbivores and natural enemies in agroecosystems can guide approaches to habitat management and pest control strategies. We examined which local habitat factors (e.g., ground cover, floral abundance, vegetation height) and landscape factors (e.g., urban cover) drive changes in herbivore and natural enemy abundance, richness, and composition on squash (Cucurbita pepo) plants in urban agroecosystems. We collected and identified arthropods from foliage, stems, and flowers using visual surveys on C. pepo plants across 21 urban agroecosystems in the central coast of California. Both local and landscape factors were associated with shifts in abundance and richness of specific herbivore and natural enemy taxa. Specifically, squash area was associated with higher abundance of leaf beetles and herbivore Hemiptera and herbaceous plant richness tended to predict lower herbivore, aphid and leaf beetle abundance. Squash area was associated with higher natural enemy abundance and richness, higher spider and ladybeetle richness, and higher predator Hemiptera abundance. Garden size boosted natural enemy and ladybeetle abundance and ladybeetle richness. Tree and shrub abundance was associated with higher spider, ladybeetle, and predator Hempitera abundance. Herbaceous plant richness was associated with lower ladybeetle abundance and richness. Finally, urban cover boosted predator Hemiptera abundance and richness. No local or landscape factors predicted shifts in herbivore or natural enemy composition. We examine why and how specific local and landscape habitat factors shape the arthropod community structure in a common garden crop and consider implications for garden management practices.

Ancient interactions between plants and insect herbivores are primarily understood through investigations of insect feeding damage on fossil leaves. Such damage is assigned to a damage type on the basis of its morphology. The damage type system is a valuable tool for comparing insect herbivory between different sites; however, for such comparisons to be quantitatively robust requires that the fossilization process does not significantly alter the morphology of herbivore damage on leaves. Here we test the effect of decay in water on leaves with simulated hole or margin feeding damage through controlled laboratory experiments. Crataegus intricata leaves were artificially damaged with hole punches and then left to decay in river water for 50 days. The morphology of the damage was checked on days 0, 3, 5, 7, 10, 12, 14, 17, 21, 24, 27, 31, 34, 37, 44, and 50, and each leaf was assigned to a damage type. Although the leaves underwent many decay-related changes, the damage did not change in any noticeable way in any experimental replicate, and the assigned DTs did not change. These results indicate that decay in standing water does not alter the morphology of damage on leaves. Further studies are needed to assess if other components of the fossilization process, such as transport, decay in sediment, or diagenetic alteration can alter herbivore damage on leaves.