Arthropod-Plant Interactions最新文献

Screen house experiments were conducted under free-choice conditions to determine the antixenosis mechanism of host plant resistance in nineteen cotton test entries against whitefly, Bemisia tabaci (Gennadius). They were assessed for settling behavior and oviposition preference. The study revealed that introgression line D-12-7-4-P-2 was most preferred for whitefly settling and oviposition and categorized as highly susceptible, whereas synthetic polyploid, C1-P-1, C1-P-31, C1-P-20, and C1-P-36 were least preferred for oviposition by whitefly, falling under the resistant category and exhibiting an antixenosis mechanism of resistance. Various biophysical and biochemical parameters were estimated for each treatment and correlated with both settling and oviposition preference. Among biophysical parameters, trichome density, leaf area, and vascular bundle length showed significantly positive correlations, whereas leaf lamina thickness was negatively correlated with settling behavior and ovipositional preference. Sugars were predominantly higher in whitefly susceptible lines, whereas phenols, tannins, and proteins were comparatively higher in resistant genotypes. Among biochemical parameters, total soluble sugars and reducing sugars registered a positive  association, while total soluble proteins, crude proteins, total phenols, and total tannins showed negative correlations with whitefly settling and ovipositional preference. It may thus be concluded that the antixenosis mechanism of resistance is operating in cotton lines and that biophysical and biochemical parameters play a predominant role in imparting resistance against B. tabaci. These identified resistant cotton introgression lines can be used to obtain whitefly-resistant cultivars.

Pod borer, Helicoverpa armigera Hubner is a major insect pest inflicting significant losses in pigeonpea, Cajanus cajan (L.). Lack of viable pod borer resistant source in the primary gene pool of pigeonpea has led to initiation of pre-breeding programmes with wild Cajanus species. The present study was conducted with 38 promising introgressed lines (ILs) derived from Cajanus scarabaeoides (L.) Thouars into agronomic background of ‘early 3’ and ‘UPAS120’. The ILs were screened for pod borer resistance under natural field infestation during kharif 2019–2021 along with the reference genotypes. The pod fly, Melanagromyza obtusa Malloch (14.39–29.11%) and pod borer (1.78–2.52%) has recorded highest mean percent pod damage. The 2 IL’s, WDBCE 6-3-4-6 and WDBCE 6-3-4-7 were found to be pod borer resistant based on PRSR score (4, 4 and 3) and the same has been confirmed in detached pod, no-choice assay. The lower infestation was correlated to the higher phenol content (14.21 and 11.52) and lower total soluble sugar (TSS) (29.96 and 27.34) in the resistant genotypes. Further, PCA-biplot analysis on seven morphometric traits revealed that 4 morphological traits (pod wall thickness, pedicel length, seed thickness, and seed length) and 2 floral characters viz., ‘purple’ colored flowers with ‘sparse’ streak pattern were strongly associated with WDBCE 6-3-4-6 and WDBCE 6-3-4-7. The identified 2 genotypes hold immense potential as pod borer resistance donor in further breeding program or it may be released as varieties after confirming the yield stability in the multilocation trials.

Understanding how resource quality influences the life-history traits of organisms has been a pivotal question in ecological and evolutionary studies, especially for insects, which usually present short generation times and are easily reared in the laboratory. Using the study system composed by the host plant Leucaena leucocephala and the seed-feeding beetle Acanthoscelides macrophthalmus, we investigated which of the following seed traits, biomass (i.e., seed size), water content, C/N ratio, hardness, and phenolic contents, influenced the body size and the sexual size dimorphism (SSD) of this beetle. The effect of seed quality was investigated over two generations, excluding larval competition. We also evaluated female fecundity over one generation. For both generations, we found that female body size was not affected by any of the seed traits investigated. However, for the males of the F₁ generation, the pronotum width was positively related to seed biomass and inversely related to the C/N ratio, and the elytron width and length were both positively related to biomass and hardness, whereas in the F₂ generation the three morphological traits were all positively related to hardness and inversely related to water content. We also found that the number of eggs laid decreased linearly with hardness. The SSD was significant only for the F₁ generation according to changes in seed biomass and hardness. In summary, we found that biomass and hardness were the most important traits that affected body size variation and SSD when larval competition was absent, even though this effect was observed only for the males.

Syrphids play diverse roles in agroecosystems, acting as pollinators and biological control agents. Despite their importance, syrphids and their trophic interactions have been rarely studied in horticultural systems in Argentina. In this work we examined syrphid communities, spatiotemporal distribution of its species and trophic interactions among syrphids–aphids–horticultural crops and syrphids–floral resources in wild plants along field margins. Thirteen horticultural fields near the City of Córdoba were sampled during the 2015–2016, 2018–2019, and 2019–2020 spring and summer seasons. Six syrphid species were collected in crops, three of them were associated with four aphid species on several cultivated plants. Eleven syrphid species were found in field margins that visited 12 flowering wild plants, with Asteraceae being the most visited family. Allograpta exotica (Wiedemann) was the most abundant and frequent species, dominating spatiotemporal distributions and interactions in crops and field margins. It became evident that the abundance of syrphid reared from polyphagous aphids in a given host crop was not proportional to its frequency of occurrence in the field. Understanding syrphid interactions with key resources (aphids and flowers) is crucial for developing pest management strategies that are compatible and sustainable with the environment.

Multiple processes influence species interactions and may shape the structure of ecological networks. Although evolutionary processes may influence interactions via shared inherited traits, their importance in comparison to contemporary ecological processes remains underappreciated. Here, we investigated how the evolutionary isolation of hawkmoths and plants is associated with interaction frequencies and the emergence of modularity in a mutualistic interaction network from Pampa grasslands. Further, we evaluated the importance of these effects in relation to morphological matching, phenological overlap, and relative abundances. We found that higher interaction frequencies occur for hawkmoths with intermediate evolutionary isolation and for plants with low evolutionary isolation, besides increasing with morphological matching and phenological overlap of partners. It suggests that intermediately isolated hawkmoths could achieve a balance between generalization and specialization, increasing interaction frequencies, and that flowers of closely related plant species are visited more frequently, presumably due to shared pollinator-attracting traits. Modules composition indicates that interactions inside modules are at least in part influenced by hawkmoth phylogeny, especially on the genera level. Also, hawkmoths’ ecological traits differ between modules, but this difference is given by interaction frequencies and not by hawkmoths’ composition itself. Our study illustrates how evolutionary history contributes to shaping plant–hawkmoth interaction frequencies through ecological traits and beyond them and that the emergence of modules may be linked to additional processes related to community assembly.

Ants protect plants from herbivores in exchange for extrafloral nectar, but they can also disrupt pollination by visiting flowers and deterring pollinators, thereby reducing plant fitness. The Distraction Hypothesis suggests that extrafloral nectaries (EFNs) attract ants away from flowers to mitigate pollination disruption. In the present study, we tested this hypothesis by conducting an ant exclusion experiment in Ferocactus recurvus to evaluate the impact of ants on plant fecundity (seed production). Ant presence in flowers was associated with reduced seed production and overall plant fecundity, as flowers visited by ants produced fewer seeds and were smaller in size compared to ant-excluded flowers. According to the hypothesis, an increased number of EFNs was associated with a lower likelihood of ants visiting the flowers. Ferocactus recurvus plants produces EFNs with high-sucrose nectar for plant defense and to reduce conflicts between ants and pollinators. Plant width was positively correlated with the number of EFNs and flowers, and there was an optimal number of EFNs that attracted a higher number of ants, thereby keeping them away from flowers. Overall, our findings highlight the complex and dynamic nature of interactions between plants, ants, and pollinators, and the potential trade-offs that exist between ant protection and pollinator attraction. Our findings suggest that while ants can protect plants, their presence can also negatively impact plant reproduction, and EFNs play a key role in managing this balance by reducing conflicts between ants and pollinators.

Maize faces significant threats from fall armyworm, Spodoptera frugiperda (JE Smith), which impacts yield and quality, especially in tropical and subtropical regions. The development of resistant maize hybrids requires an understanding of how plant traits influence pest biology. To address this need, the present study deciphered variation in phenological traits and photosynthetic pigment levels in maize lines and their effect on the biological attributes of S. frugiperda. The study revealed significant differences among the test maize lines for phenological traits, constitutive and insect-induced photosynthetic pigments, and biological attributes of S. frugiperda. The A-lines AI 196, DMS 4B, DDM 2309-O and AI 544, and R-lines AI 125, AI 1100, AI 541, PML 105, PDM 4061, and CML 442 were found with greater anthocyanin pigmentation, moderate leaf glossiness, and moderate number of leaf trichomes as compared to other test maize lines. The larval preference and leaf damage by S. frugiperda was significantly lower in A-lines AI 546, AI 544, and PDIM 639, and R-lines AI 125, AI 542, AI 155, AI 1100, and CML 442. Further, the S. frugiperda developmental durations and life span were longer, while larval survival, adult emergence and fecundity lower on the A-lines CML 565, AI 544, AI 196, and PDIM 639, and R-lines AI 125, AI 155, AI 1100, AI 542, and CML 442 in comparison to other test lines, except in a few cases. The female pupal weight was also recorded as predictor of S. frugiperda fecundity. Thus, the aforementioned maize parental lines were found to possess significant resistance attributes in terms of phenological traits and photosynthetic pigments and could be utilized in maize breeding program.

Western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), is an important global pest of vegetables and ornamental crops that has strong host adaptability. Glutathione S-transferases (GSTs) detoxify and metabolise toxic plant allelochemicals during insect adaptation to host plant defence responses. However, how genes of different GST subfamilies affect adaptation of F. occidentalis after a host shift remains unclear. In this study, thrips were shifted from kidney bean pods to broad bean plants and kidney bean plants. Expression levels of the GST genes were determined in the second instar larvae and adult females of F₁, F₂, and F₃ generations. Four GST genes were cloned and identified, namely FoGSTd1, FoGSTs1, FoGSTt1, and FoGSTe1 belonging to the delta, sigma, theta, and epsilon subfamilies, respectively. Expression profiles of these four genes differed at each developmental stage of F. occidentalis, and the degree of FoGSTs1 expression change after the transfer to the kidney bean plants or broad bean plants were the strongest. When F. occidentalis adult females transferred to kidney bean plants or broad bean plants were fed with anti-FoGSTs1 double-stranded RNA (dsRNA), FoGSTs1 expression was significantly downregulated, and GST enzyme activity was significantly inhibited. Further, RNA interference-mediated knockdown of FoGSTs1 significantly decreased the survival rate of F. occidentalis female adults on kidney bean plants and broad bean plants. These results indicate that FoGSTs1 plays an important role in affecting the adaptation of F. occidentalis after host shift.

Climate change is a threat to agriculture and humankind. Sustainable cropping systems can enhance the resistance of crops against extreme weather events. The effects of drought stress on flower traits of insect-pollinated crops grown in sole stands and intercrops have rarely been studied, though. In this field study, we investigated how drought stress alters plant and flower traits of faba beans and the resulting pollinator behavior in faba bean sole crops and in faba bean–wheat intercrops. Plant height was reduced by drought stress and in intercrops (vs. sole crops). The number of open flowers per plant was unaffected by drought stress but reduced in intercrops. Drought stress increased the nectar sugar concentration but did not alter nectar volume and pollen production. Faba beans grown in intercrops produced higher nectar, sugar, and pollen grain amounts compared to sole crops. Drought stress effects on plant and flower traits were not affected by intercropping. Drought stress reduced the plant and flower visitation frequency by bumblebees. Although intercropping plots were visited less frequently, the individual flowers were visited more frequently than flowers in sole crops. The bumblebees’ nectar robbing activity increased with plant height and flower sugar amount. Our study shows that drought stress reduces crop plant growth and reduces pollinator visitation to crop flowers. Faba bean flowers in intercrops seem to be more attractive to bumblebees than flowers in sole crops, potentially enhancing pollination. The potential of intercropping should further be investigated in terms of mitigating detrimental effects of climate change on crop plants.

The predatory ring-legged earwig, Euborellia annulipes (Lucas, 1847) (Dermaptera: Anisolabididae), exhibits omnivorous feeding habits, enabling it to incorporate non-prey items into its diet. This behavior is thought to offer additional needed benefits from the occasional consumption of plant material. This study examined the hypothesis that herbivory of E. annulipes on various species of cultivated Brassica has a positive effect on its biological traits and is influenced by the availability of essential food sources. The provisioned plant material (pieces of leaf) consisted of the following Brassica species: pak choi cabbage, Portuguese cabbage, cabbage, and radish did not improve the biological performance of the earwig when compared to a diet without plant material. Nevertheless, 66.0% of the second instar nymphs developed successfully when fed only pak choi cabbage, and 43.3% did so when fed solely on Portuguese cabbage. Herbivory by E. annulipes on brassicas occurred in the presence and absence of a diet, although it was significantly more pronounced when no other food sources were available. Among the four Brassica species studied, pak choi cabbage exhibited the highest feeding frequency and consumption rate. Additionally, pak choi cabbage grown under controlled conditions and exposed to routine releases of earwigs showed no reduction in productivity. These findings indicate that E. annulipes can consume brassica leaves, demonstrating species-specific variations in this consumption. However, conditions of food scarcity lead to increased consumption of plant material, while repeated releases of earwigs do not affect the growth and yield of pak choi cabbage plants.