Visiting Plants of Mamestra brassicae (Lepidoptera: Noctuidae) Inferred From Identification of Adhering Pollen Grains

Virus-host coevolutionary analyses of an Alphabaculovirus with a wide host range

Baculoviruses are highly host specific, and their host range is usually restricted to a single or a few closely related insect species, except for few virus species, e.g. Alphabaculovirus aucalifonicae and Alphabaculovirus mabrassicae. In this study, two new alphabaculovirus isolates were isolated from the larvae of Mamestra brassicae and Mythimna separata, which were named as Mamestra brassicae multiple nucleopolyhedrovirus isolate QD (MbMNPV-QD) and Mythimna separata multiple nucleopolyhedrovirus isolate Hb (MyseMNPV-Hb), respectively. The Kimura two-parameter values based on the concatenated 38 core genes of baculovirus revealed that MbMNPV (isolates QD/CHb1/K1/CTa), MyseMNPV-Hb, Helicoverpa armigera multiple nucleopolyhedrovirus (HearMNPV) and Mamestra configurata nucleopolyhedrovirus B (MacoNPV-B) were different isolates of a same virus species. A phylogenetic tree of baculoviruses and nudiviruses constructed from their 20 homologous gene sequences, and that of their isolated hosts constructed from 13 protein-coding genes of the insect mitochondrial genomes, were used to analyse the coevolution of baculoviruses with their isolated hosts. The results showed that M. brassicae was the most likely ancestral host of these virus isolates, included MbMNPV isolates, MyseMNPV-Hb, HearMNPV, and MacoNPV-B. Therefore, we concluded that these virus isolates belong to the existing virus species - Alphabaculovirus mabrassicae with M. brassicae as their ancestral host.

Pollen Molecular Identification from a Long-Distance Migratory Insect, Spodoptera exigua, as Evidenced for Its Regional Pollination in Eastern Asia

Understanding plant-insect interactions requires the uncovering of the host plant use of insect herbivores, but such information is scarce for most taxa, including nocturnal moth species, despite their vital role as herbivores and pollinators. In this study, we determined the plant species visited by an important moth species, Spodoptera exigua, by analyzing attached pollen on migratory individuals in Northeast China. Pollen grains were dislodged from 2334 S. exigua long-distance migrants captured between 2019 and 2021 on a small island in the center of the Bohai Strait, which serves as a seasonal migration pathway for this pest species, and 16.1% of the tested moths exhibited pollen contamination, primarily on the proboscis. Subsequently, 33 taxa from at least 23 plant families and 29 genera were identified using a combination of DNA barcoding and pollen morphology, primarily from the Angiosperm, Dicotyledoneae. Moreover, the sex, inter-annual, and seasonal differences in pollen adherence ratio and pollen taxa were revealed. Notably, compared to previously reported pollen types found on several other nocturnal moths, we found that almost all of the above 33 pollen taxa can be found in multiple nocturnal moth species, providing another important example of conspecific attraction. Additionally, we also discussed the indicative significance of the pollen present on the bodies of migratory individuals for determining their migratory route. Overall, by delineating the adult feeding and pollination behavior of S. exigua, we advanced our understanding of the interactions of the moths with their host plants, and its migration pattern, as well as facilitated the design of (area-wide) management strategies to preserve and optimize ecosystem services that they provide.

Windborne migration amplifies insect-mediated pollination services

Worldwide, hoverflies (Syrphidae: Diptera) provide crucial ecosystem services such as pollination and biological pest control. Although many hoverfly species exhibit migratory behavior, the spatiotemporal facets of these movement dynamics, and their ecosystem services implications are poorly understood. In this study, we use long-term (16-year) trapping records, trajectory analysis, and intrinsic (i.e., isotope, genetic, pollen) markers to describe migration patterns of the hoverfly Episyrphus balteatus in northern China. Our work reveals how E. balteatus migrate northward during spring–summer and exhibits return (long-range) migration during autumn. The extensive genetic mixing and high genetic diversity of E. balteatus populations underscore its adaptive capacity to environmental disturbances, for example, climate change. Pollen markers and molecular gut analysis further illuminate how E. balteatus visits min. 1012 flowering plant species (39 orders) over space and time. By thus delineating E. balteatus transregional movements and pollination networks, we advance our understanding of its migration ecology and facilitate the design of targeted strategies to conserve and enhance its ecosystem services.