Diversity of Flower Visiting Beetles at Higher Elevations on the Yulong Snow Mountain (Yunnan, China)

Background: Flowers are one of the important microhabitats promoting beetle diversity, but little is known about variation in the diversity of these insects at higher elevations. We do not know how divergent habitats influence the distribution of beetles among montane flora. Methods: We sampled beetles systematically in angiosperm flowers at 12 sites at two elevations (2700 m and 3200 m) and in two habitats (meadows and forests) for two consecutive years (2018 and 2019) on the Yulong Snow Mountain in Yunnan, southwestern China. Beetle diversity among sites were compared. Their interactions with flowers of identified plant species were analyzed using bipartite networks approach. Results: We collected 153 species of beetles from 90 plant species recording 3391 interactions. While plant species richness was lower at the higher, 3200 m elevation regardless of habitat type, beetle species richness was not significantly different among sites. Plant-beetle interaction networks were strongly modular and specialized. The structure of networks showed greater differences between elevations than between habitats. The turnover of networks was determined by species composition showing a weak influence by interaction rewiring. Conclusion: Our study showed a high diversity of beetles in flowers at higher elevations within this mountain complex. The role of beetles in plant–insect interactions within some sections of temperate, montane sites appear to be underestimated and warrant further study.

Cooperative herbivory between two important pests of rice

Normally, when different species of herbivorous arthropods feed on the same plant this leads to fitness-reducing competition. We found this to be different for two of Asia’s most destructive rice pests, the brown planthopper and the rice striped stem borer. Both insects directly and indirectly benefit from jointly attacking the same host plant. Double infestation improved host plant quality, particularly for the stemborer because the planthopper fully suppresses caterpillar-induced production of proteinase inhibitors. It also reduced the risk of egg parasitism, due to diminished parasitoid attraction. Females of both pests have adapted their oviposition behaviour accordingly. Their strong preference for plants infested by the other species even overrides their avoidance of plants already attacked by conspecifics. This cooperation between herbivores is telling of adaptations resulting from the evolution of plant-insect interactions, and points out mechanistic vulnerabilities that can be targeted to control these major pests.

Volatiles Emission by Crotalaria nitens after Insect Attack

Plants are known to increase the emission of volatile organic compounds upon the damage of phytophagous insects. However, very little is known about the composition and temporal dynamics of volatiles released by wild plants of the genus Crotalaria (Fabaceae) attacked with the specialist lepidopteran caterpillar Utetheisa ornatrix (Linnaeus) (Erebidae). In this work, the herbivore-induced plant volatiles (HIPV) emitted by Crotalaria nitens Kunth plants were isolated with solid phase micro-extraction and the conventional purge and trap technique, and their identification was carried out by GC/MS. The poly-dimethylsiloxane/divinylbenzene fiber showed higher affinity for the extraction of apolar compounds (e.g., trans-β-caryophyllene) compared to the Porapak™-Q adsorbent from the purge & trap method that extracted more polar compounds (e.g., trans-nerolidol and indole). The compounds emitted by C. nitens were mainly green leaf volatile substances, terpenoids, aromatics, and aldoximes (isobutyraldoxime and 2-methylbutyraldoxime), whose maximum emission was six hours after the attack. The attack by caterpillars significantly increased the volatile compounds emission in the C. nitens leaves compared to those subjected to mechanical damage. This result indicated that the U. ornatrix caterpillar is responsible for generating a specific response in C. nitens plants. It was demonstrated that HIPVs repelled conspecific moths from attacked plants and favored oviposition in those without damage. The results showed the importance of volatiles in plant–insect interactions, as well as the choice of appropriate extraction and analytical methods for their study.

Prey Capture in Anthocyanin-free Sarracenia leucophylla (Sarraceniaceae) Is Associated with Leaf Size, But Not Red Pigmentation

Anthocyanin pigmentation is a significant horticultural feature in plants and can be a crucial mediator of plant–insect interactions. In carnivorous plants, the modified leaves that capture prey can be visually striking and are traditionally considered prey attractants. Nevertheless, the question of whether bold color and venation patterns function as lures for insect prey remains ambiguous, and appears to vary across taxa. Furthermore, vegetative pigments can have alternate functions as protectants against thermal and oxidative damage. Our dual-year study compares the wild-type pitcher phenotype with a true-breeding anthocyanin-free mutant of the white-topped pitcher plant (Sarracenia leucophylla Raf.). We bred full-sibling crosses of S. leucophylla carrying either the wild-type anthocyanin gene or the anthocyanin-free variant. In both experimental years, growth points were established in outdoor plots and pitchers were allowed to capture prey before harvest at the end of each growing season. Dry weight of prey biomass was measured from pitchers of both pigment morphs, along with nectary counts, pitcher size, and internal temperature. The presence of anthocyanins in trapping leaves did not affect the biomass of insects captured. Nor did wild-type or anthocyanin-free pitcher morphs differ in size, temperature, or nectary counts. Instead, pitcher height, and, nominally, mouth diameter were better predictors of prey biomass. Despite striking visual differences in pitcher color, wild-type and anthocyanin-free plants did not catch significantly different quantities of prey. Our study provides empirical data that anthocyanin pigmentation in S. leucophylla does not affect the capture of prey biomass, and supports a growing body of literature showing that pigmentation traits serve in multiple contexts.

Host Plants Association with Longhorn Beetles of Food Value: Traditional Knowledge of the Guaraní as Cultural Identity Keepers

The study of plant-insect interactions and how cultural groups perceive and manage them constitutes one of the interests of ethnoentomology. This work describes the association between host plants and longhorn beetles (Order: Coleoptera; Family: Cerambycidae), an important food among the Guaraní peoples of the province of Misiones, Argentina. Different management methods of host tree species are analyzed in order to promote the rearing of larvae for edible use. We also discuss a story about the mythical origin of cerambicids relayed by the Ava Chiripa Guaraní community. We reflect on the importance of the local worldview in the maintenance of ancestral practices, such as the cultural tasks involved in slash-and-burn agriculture and the intimate knowledge of biological relationships between the cerambycids and their woody host plants.

Small-Scale Habitat Conditions Are More Important Than Site Context for Influencing Pollinator Visitation

The ability of insects to persist in urban greenspace depends on their ability to usefully interact with available plant resources. Greenspace design influences plant–insect interactions by: (1) limiting the plant-species pool available for interaction through plant choice, (2) limiting the insects that are available for interaction through site-occupancy dynamics, and (3) mediating insect preferences based on the context of particular plant–insect interactions through structural barriers, microclimatic changes or competition. We designed an experiment to measure the effect of greenspace design attributes on site occupancy and insect preferences while keeping plant availability constant. Using a set of five functionally distinct flowering plant species (“phytometres”), we used occupancy-detection modelling to test factors affecting probability of visitation for eight groups of pollinating insects (ants, beetles, butterflies, bumblebees, honeybees, small bees, and hoverflies amend other flies) across 102 urban squares in Munich, Germany. We found that the probability of detecting an interaction was low for most functional groups, and situational factors, such as weather or competition from co-occurring flowers, were the primary drivers of visitation. Increasing the proportion of unsealed surfaces and quantity or diversity of flowers on the site had a positive influence on the probability of interaction, and, to a lesser extent, on probability of occupancy. Landscape connectivity and site area were important for only a few groups. Together, our results suggest that small-scale habitat conditions are more important than site context for influencing pollinator visitation. Designers can encourage interaction through contiguous provision of floral resources and unsealed surfaces while limiting internal barriers.