Molecular Characterization and Expression Profiles of Cryptochrome Genes in a Long-Distance Migrant, Agrotis segetum (Lepidoptera: Noctuidae)

Knockout of cryptochrome 1 disturbs the locomotor circadian rhythm and development of Plutella xylostella

Cryptochrome 1 (CRY1) functions as a light-responsive photoreceptor, which is crucial for circadian rhythms. The identity and function of CRY1 in Plutella xylostella remain unknown. In this study, cry1 was cloned and identified in P. xylostella. Then, a cry1-knockout strain (Cry1-KO) of P. xylostella with a 2-bp deletion was established from the strain Geneva 88 (G88) using the CRISPR/Cas9 technology. No daily temporal oscillation of cry1 was observed in G88 and Cry1-KO, and cry1 mean daily transcription of Cry1-KO was lower than that of G88. Both G88 and Cry1-KO demonstrated rhythmic locomotion under the light/dark condition with Cry1-KO being more active than G88 in the daytime, whereas Cry1-KO completely lost rhythmicity under constant darkness. The developmental period of pre-adult of Cry1-KO was longer than that of G88; the lifespan of the Cry1-KO male adult was shorter than that of G88; the fecundity of Cry1-KO was lower than that of G88; and Cry1-KO showed lower intrinsic rate of increase (r), net reproduction rate (R₀ ), finite increase rate (λ), and longer mean generation time (T) than G88. Our results indicate that cry1 is involved in the regulation of locomotor circadian rhythm and development in P. xylostella, providing a potential target gene for controlling the pest and a basis for further investigation on circadian rhythms in lepidopterans.

Lethal and sublethal effects of chlorantraniliprole on the migratory moths Agrotis ipsilon and A. segetum: New perspectives for pest management strategies

BACKGROUND

Agrotis ipsilon and A. segetum are major migratory pests of many crops in China, and frequent regional outbreaks cause severe yield losses. Use of food attractants is one of the most promising control methods against adult lepidoptera, notably through the attract-and-kill strategy. Chlorantraniliprole's acute toxicity and sublethal effects on both moths were evaluated.

RESULTS

Chlorantraniliprole showed high activity against both adults of both species, with LC₂₀ and LC₅₀ values of 0.08 and 0.21 mg L^-1 (A. ipsilon), and 0.14 and 0.51 mg L^-1 (A. segetum). The fecundity, effective oviposition rate, and egg hatching rate of both species in dual-sex exposure treatments were all significantly reduced compared with the control, and the population growth coefficients in the LC₅₀ ♀ × LC₅₀ ♂ treatments were only 0.32% (A. ipsilon) and 3.35% (A. segetum) that of the control. Furthermore, the flight distance was significantly suppressed from 6.67 km (control) to 0.01 km (LC₅₀ ) for A. ipsilon, and from 7.39 km (control) to 0.78 km (LC₅₀ ) for A. segetum. The proportions of robust- and medium-flight individuals of A. ipsilon and A. segetum in exposure treatments were greatly reduced.

CONCLUSIONS

Low lethal concentration exposures to chlorantraniliprole can drastically reduce the reproduction and flight performance of A. ipsilon and A. segetum, while inhibiting the production of offspring, suggesting chlorantraniliprole would be an excellent compound for use in combination with food attractants. Chlorantraniliprole has good potential for management of the two long-range migratory pests tested using an attract-and-kill strategy. © 2022 Society of Chemical Industry.

The Circadian Clock in Lepidoptera

With approximately 160,000 identified species of butterflies and moths, Lepidoptera are among the most species-rich and diverse insect orders. Lepidopteran insects have fundamental ecosystem functions as pollinators and valuable food sources for countless animals. Furthermore, Lepidoptera have a significant impact on the economy and global food security because many species in their larval stage are harmful pests of staple food crops. Moreover, domesticated species such as the silkworm Bombyx mori produce silk and silk byproducts that are utilized by the luxury textile, biomedical, and cosmetics sectors. Several Lepidoptera have been fundamental as model organisms for basic biological research, from formal genetics to evolutionary studies. Regarding chronobiology, in the 1970s, Truman's seminal transplantation experiments on different lepidopteran species were the first to show that the circadian clock resides in the brain. With the implementation of molecular genetics, subsequent studies identified key differences in core components of the molecular circadian clock of Lepidoptera compared to the dipteran Drosophila melanogaster, the dominant insect species in chronobiological research. More recently, studies on the butterfly Danaus plexippus have been fundamental in characterizing the interplay between the circadian clock and navigation during the seasonal migration of this species. Moreover, the advent of Next Generation Omic technologies has resulted in the production of many publicly available datasets regarding circadian clocks in pest and beneficial Lepidoptera. This review presents an updated overview of the molecular and anatomical organization of the circadian clock in Lepidoptera. We report different behavioral circadian rhythms currently identified, focusing on the importance of the circadian clock in controlling developmental, mating and migration phenotypes. We then describe the ecological importance of circadian clocks detailing the complex interplay between the feeding behavior of these organisms and plants. Finally, we discuss how the characterization of these features could be useful in both pest control, and in optimizing rearing of beneficial Lepidoptera.

Rotating magnetic field delays human umbilical vein endothelial cell aging and prolongs the lifespan of Caenorhabditis elegans

The biological effects of magnetic fields are a research hotspot in the field of biomedical engineering. In this study, we further investigated the effects of a rotating magnetic field (RMF; 0.2 T, 4 Hz) on the growth of human umbilical vein endothelial cells (HUVECs) and Caenorhabditis elegans. The results showed that RMF exposure prolonged the lifespan of C. elegans and slowed the aging of HUVECs. RMF treatment of HUVECs showed that activation of adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) was associated with decreased mitochondrial membrane potential (MMP) due to increased intracellular Ca2+ concentrations induced by endoplasmic reticulum stress in anti-aging mechanisms. RMF also promoted the health status of C. elegans by improving activity, reducing age-related pigment accumulation, delaying Aβ-induced paralysis and increasing resistance to heat and oxidative stress. The prolonged lifespan of C. elegans was associated with decreased levels of daf-16 which related to the insulin/insulin-like growth factor signaling pathway (IIS) activity and reactive oxygen species (ROS), whereas the heat shock transcription factor-1 (hsf-1) pathway was not involved. Moreover, the level of autophagy was increased after RMF treatment. These findings expand our understanding of the potential mechanisms by which RMF treatment prolongs lifespan.

Up-regulation of cryptochrome 1 gene expression in cotton bollworm (Helicoverpa armigera) during migration over the Bohai Sea

Cryptochromes (CRYs) are flavoproteins and play a pivotal role in circadian clocks which mediate behavior of organisms such as feeding, mating and migrating navigation. Herein, we identified novel transcripts in Helicoverpa armigera of six isoforms of cry1 and seven isoforms of cry2 by Sanger sequencing. Phylogenetic analysis showed that the transcripts of cry1 and cry2 align closely with other insect crys, indicating within-species divergence of Hacry. A dn/ds analysis revealed that the encoding sequence of the cry1 was under purifying selection by a strong negative selection pressure whereas the cry2 was less constraint and showed a less strong purification selection than cry1. In general, Hacrys were more abundantly transcribed in wild migrating populations than that in laboratory maintained populations, and expression of the cry2 was lower than cry1 in all samples tested. Moreover, when compared with the migrating parental population, offspring reared in laboratory conditions showed a significant reduction on transcription of the cry1 but not cry2. These results strongly suggest that cry1 was more related to the migration behavior of H. armigera than cry2.