Noctuid moths as pollinators of Habenaria sagittifera (Orchidaceae): floral adaptations for the transfer of pollinaria on the thoraxes of moths.

Orchids attach their pollinaria (cohesive masses of pollen) to specific body parts of flower visitors, but usually not to the hairy and scaly body parts of flower-visiting moths, because hairs and scales are easily detached. We demonstrate that pollinaria of Habenaria sagittifera (Orchidaceae) are transferred among flowers on the hairy thoraxes of moths in Japan. Diurnal and nocturnal insects visited the orchid flowers. However, pollinaria were attached only to the hairy thoraxes of plusiine moths (Lepidoptera: Noctuidae). All pollinaria were directly attached to the ventral thorax surfaces at the bases of hairs. Orchid spur lengths matched plusiine proboscis lengths so that nectar-feeding moths contacted the viscidia (sticky pads of pollinaria) and stigma. Other flower visitors did not contact the viscidia or stigmas while feeding on nectar. Habenaria sagittifera appears to have a floral morphology that is adaptive for the transfer of pollinaria on the thoraxes of plusiine moths.

Characterizing the differential susceptibility and resistance to insecticides in populations of Chrysodeixis includens and Rachiplusia nu (Lepidoptera: Noctuidae) in Brazil.

BACKGROUND: Chrysodeixis includens (Walker) and Rachiplusia nu (Guenée) are major Plusiinae pests of soybean in the Southern Cone region of South America. In recent decades, C. includens was the main defoliator of soybean in Brazil, but from 2021 onwards, R. nu emerged as an important soybean pest in various regions of the country. Here, we characterize the differential susceptibility and resistance to insecticides in these Plusiinae pests from two soybean regions of Brazil. RESULTS: Except for spinetoram and chlorfenapyr (comparable lethality against both species) and a Bt-based biopesticide (more lethal for C. includens), the tested insecticides showed higher lethality against R. nu than against C. includens, but populations of the same species, even separated by long distances, presented similar resistance levels. For both species, the 90% lethal concentration (LC90) values of most insecticides were higher than the field-recommended dose. Nevertheless, the field-recommended doses of spinetoram, metaflumizone, emamectin benzoate, cyclaniliprole and chlorfenapyr showed comparable control efficacy against both species, whereas indoxacarb, chlorantraniliprole, flubendiamide, teflubenzuron and chlorfluazuron were more lethal for R. nu, and methoxyfenozide and the Bt-based insecticide were more lethal for C. includens. Thiodicarb, methomyl and lambda-cyhalothrin showed low lethality against both species. CONCLUSIONS: Large interspecific differences in the susceptibility to insecticides was found in major Plusiinae pests of soybean in Brazil. Furthermore, variations in susceptibility to insecticides occurred consistently among species and populations, regardless of the collection site and thus despite unequal temporal and spatial exposure to insecticides. These results demonstrate that accurate species identification is essential for effective control of Plusiinae in soybean. © 2024 Society of Chemical Industry.

Effects of temperature on the development of Rachiplusia nu (Lepidoptera: Noctuidae) and Chrysodeixis includens (Lepidoptera: Noctuidae) and implications on population growth in Brazil.

Temperature is an elementary component in mathematical models for predicting the biotic potential of insects. In this study, the objective was to evaluate the impact of different constant temperatures of 8, 10, 15, 20, 25, 30, and 32°C on the biological parameters, lower temperature thresholds (TT), and estimating the number of annual generations (NAG) of Rachiplusia nu and Chrysodeixis includens, both pests associated with the soybean crop in Brazil. There was no development of the immature stages of R. nu at 8°C, as was also found for C. includens at 8 and 10°C. However, at 10°C all stages of R. nu developed. In general, temperatures of 20 and 25°C were the most suitable for the development of R. nu and C. includens, providing egg to adult viability of over 60% and the highest total fecundities. However, the temperature of 32°C negatively affected the parameters of the fertility life table. Rachiplusia nu showed the lowest TT (eggs: 4.9°C; larvae: 10.8°C; pupa: 14.1°C; and egg to adult: 8.9°C) when compared with C. includens (eggs: 7.5°C; larvae: 15.3°C; pupa: 16.1°C; and egg to adult: 11.3°C). Based on TT values, the NAG varied from 3.9 in cold regions to 7.5 in warm regions. However, for C. includens, we can infer that the species can reach up to 8.8 generations in warm regions. The results of the present study are important for understanding the occurrence of R. nu and C. includens in field conditions and can help with the implications of management strategies.

Taxonomy and distribution of agriculturally important plusiinae (Lepidoptera: Noctuidae) from southern Punjab, Pakistan.

Taxonomic identification and classifications of insect pest genera Chrysodeixis and Ctenoplusia of the subfamily Plusiinae is very compulsory due to their phytophagous nature and potential to damage the cash as well as cereal crops. Taxonomy plays a key role in proper not only in identification and classification of the pest but also in designing a successful managing strategy. In current study, specimens of Chrysodeixis and Ctenoplusia genera were collected from different geographical areas of south Punjab, Pakistan and their diagnostic features were examined following taxanomic keys. The data of temperature, relative humidity and rainfall were also recorded during the study period. Genitalia was extracted by dissecting of the abdomen and inspected under Stereo microscope. The results revealed two new species, Chryodeixis maxus and Ctenoplusia oleraceaus, from south Punjab region in addition to previously reported species: Chrysodeixis furihatai. Suitable management of the voracious insect pest at appropriate time may help in sustaining the agriculture in Pakistan.

DNA barcoding and Taxonomic account on some selected species of subfamily Plusiinae (Lepidoptera: Noctuidae) from India.

This study represents a detailed taxonomic account of 31 species of Plusiinae (Lepidoptera: Noctuidae) from India. The survey and collection of 39 localities from different regions of India between 2015 and 2018. The tribe Argyrogrammatini Eichlin Cunningham, 1978 with Ctenoplusia Dufey, 1970 was the most species rich genera with seven species, followed by Thysanoplusia Ichinose, 1973 and Chrysodeixis Hubner, 1821 with four and three species respectively. Among 31 species, 15 species are commonly found in Himalayan regions and while other species were distributed from subtropical to tropical region. Five species, T. orichalcea (Fabricius, 1775), Chrysodeixis eriosoma (Doubleday, 1843), C. acuta (Walker, 1858), C. chalcites (Esper, 1789), Trichoplusia ni (Hubner, 1803) are widespread throughout India and reported as serious crop pests. Present study also revealed range expansion of four species viz., Dactyloplusia impulsa (Walker, 1865), Ctenoplusia mutans (Walker, 1865), Ctenoplusia tarassota (Hampson, 1913) and Zonoplusia ochreata (Walker, 1865). Systematic accounts of all 31 species are discussed here with adult images, species diagnostic characters, collection localities, detailed distributions and reported larval host plants. In addition to morphological studies, for the first time, a preliminary barcode library for 25 species of Indian Plusiinae with average intra-specific distance (%), maximum intra-specific distance (%) and distance to nearest neighbor (%) for individual species is provided. Among 25 species, four species barcode data (Ctenoplusia mutans, C. kosemponesis, Plusiopalpa adrasta, Sclerogenia jessica) are novel to world and 18 species barcode sequences were novel to India.

The complete genome of Rachiplusia nu nucleopolyhedrovirus (RanuNPV) and the identification of a baculoviral CPD-photolyase homolog.

We described a novel baculovirus isolated from the polyphagous insect pest Rachiplusia nu. The virus presented pyramidal-shaped occlusion bodies (OBs) with singly-embed nucleocapsids and a dose mortality response of 6.9 × 103 OBs/ml to third-instar larvae of R. nu. The virus genome is 128,587 bp long with a G + C content of 37.9% and 134 predicted ORFs. The virus is an alphabaculovirus closely related to Trichoplusia ni single nucleopolyhedrovirus, Chrysodeixis chalcites nucleopolyhedrovirus, and Chrysodeixis includens single nucleopolyhedrovirus and may constitute a new species. Surprisingly, we found co-evolution among the related viruses and their hosts at species level. Besides, auxiliary genes with homologs in other baculoviruses were found, e.g. a CPD-photolyase. The gene seemed to be result of a single event of horizontal transfer from lepidopterans to alphabaculovirus, followed by a transference from alpha to betabaculovirus. The predicted protein appears to be an active enzyme that ensures likely DNA protection from sunlight.

Taxonomy and geographical distribution of Panchrysia Hübner, [1821] of China, with description of a new species (Lepidoptera, Noctuidae, Plusiinae).

Panchrysia can be readily recognized by the brilliant silvery markings diffused on forewings except Panchrysia marmorea (Ronkay, 1986) and Panchrysia deaurata (Esper), which are characterized by the lack of silvery marking. As currently, this genus is consisted of six species, all of species have been recorded from Eurasian geographic distribution (Ronkay et al., 2008). In China, P. marmorea, Panchrysia tibetensis Chou & Lu, 1982, Panchrysia dives (Eversmann, 1844) and Panchrysia ornate (Bremer, 1864) have been recorded (Chou & Lu, 1978, 1979, 1982; Ronkay, 1986; Han et al., 2005; Ronkay et al., 2008). In this article, four species of Panchrysia are reviewed and a new species Panchrysia longcanggouensis sp. nov. is described herein. Their distribution patterns indicate that Panchrysia has a rather wide range from South-West China through the central China to North-East China, and absent in southeastern and northwestern China. A key to species of the genus in China is provided. Adults and genitalia are illustrated. Also a briefly outline the distribution of the component species is given.