Physiological and behavioral basis of diamondback moth Plutella xylostella migration and its association with heat stress.

BACKGROUND: Migration is a strategy that shifts insects to more favorable habitats in response to deteriorating local environmental conditions. The ecological factors that govern insect migration are poorly understood for many species. Plutella xylostella causes great losses in Brassica vegetable and oilseed crops, and undergoes mass migration. However, the physiological and behavioral basis for distinguishing migratory individuals and the factors driving its migration remain unclear. RESULTS: Daily light trap catches conducted from April to July in a field population of P. xylostella in central China revealed a sharp decline in abundance from late-May. Analysis of ovarian development levels showed that the proportion of sexually immature females gradually increased, while the mating rate decreased, indicating that generations occurring in May mainly resulted from local breeding and that emigration began in late-May. Physiological and behavioral analyses revealed that emigrant populations had a higher take-off proportion, stronger flight capacity and greater energy reserves of triglyceride compared to residents. Furthermore, a gradual increase in temperature from 24 °C to >30 °C during larval development resulted in a significant delay in oogenesis and increased take-off propensity of adults compared with the control treatment reared at a constant temperature of 24 °C. CONCLUSION: Our results provide the physiological and behavioral factors that underpin mass migration in P. xylostella, and demonstrate that exposure to increased temperature increases their migration propensity at the cost of reproductive output. This study sheds light on understanding the factors that influence population dynamics, migratory propensity and reproductive tradeoffs in migratory insects. © 2023 Society of Chemical Industry.

Monitoring the Resistance of the Beet Armyworm (Lepidoptera: Noctuidae) to Four Insecticides in Southern China from 2014 to 2018.

The beet armyworm Spodoptera exigua (Hübner) is a serious polyphagous pest that infests vegetable crops worldwide and has rapidly developed resistance due to its long-term exposure to insecticides. The current resistance statuses to four insecticides exhibited by three field populations of beet armyworms collected in southern China from 2014 to 2018 were investigated. Monitoring data from five consecutive years demonstrated that all three tested S. exigua populations developed extremely high resistance to chlorantraniliprole in 2018 (220.58- to 2,597.39-fold). Two populations (Baiyun and Fengxian) developed low to moderate resistance to spinosad, whereas the Huangpi population remained susceptible (except in 2014, with RR of 6.11-fold). The RR of the Fengxian and Baiyun populations to indoxacarb steadily increased over the years, whereas that of the Huangpi population increased relatively slowly. The Baiyun and Fengxian populations developed moderate to high resistance to indoxacarb and methoxyfenozide, whereas the Huangpi population exhibited susceptibility to low resistance (1.06- to 6.45-fold) to indoxacarb and susceptibility to moderate resistance (1.53- to 14.22-fold) to methoxyfenozide. These results suggest that chlorantraniliprole should not be employed to control this pest in southern China. Reduced use of indoxacarb and methoxyfenozide or the use of alternating insecticides with low levels of resistance is recommended. Spinosad remains an effective insecticide for the management of S. exigua. To avoid the rapid development of insecticide resistance, rotations of insecticides with low levels of resistance and different modes of action based on the resistance patterns of S. exigua should be performed in southern China.

Sublethal Effects of Thiamethoxam on the Demographic Parameters of Myzus persicae (Hemiptera: Aphididae).

The green peach aphid, Myzus persicae Sulzer (Hemiptera: Aphididae), is an important sap-sucking pest of many crops, including Chinese cabbage, Brassinca oleracea L. The neonicotinoid insecticide thiamethoxam has been used as an effective insecticide to control M. persicae in cabbage fields. In this study, we assessed the effects of sublethal concentrations of thiamethoxam on demographic parameters of M. persicae. In leaf-dip bioassays, thiamethoxam showed a relatively high toxicity against M. persicae with an LC50 of 6.80 mg liter-1. The duration of the preadult stage was not significantly affected in the sublethal bioassay. Additionally, the longevity and adult preoviposition period were not significantly affected by sublethal thiamethoxam. However, sublethal thiamethoxam significantly increased fecundity (LC10) and prolonged the total preoviposition period (LC40). Consequently, the finite rate of increase (λ) and the intrinsic rate of increase (rm) of aphids exposed to the LC40 were significantly lower than those of control aphids, whereas the net reproductive rate (R0) was higher, and the generation time (T) and the population doubling time (DT) were longer in the treated group. Based on these results, hormesis was induced by sublethal thiamethoxam in M. persicae, with the population growth of M. persicae negatively affected at higher sublethal concentrations of thiamethoxam. Therefore, our study indicated that the possible effects of thiamethoxam on aphids require further study to develop optimized integrated pest management strategies.

MOLECULAR CHARACTERIZATION OF AUTOPHAGY-RELATED GENE 5 FROM Spodoptera exigua AND EXPRESSION ANALYSIS UNDER VARIOUS STRESS CONDITIONS.

Autophagy is not only involved in development, but also has been proved to attend immune response against invading pathogens. Autophagy protein 5 (ATG5) is an important autophagic protein, which plays a crucial role in autophagosome elongation. Although ATG5 has been well studied in mammal, yeast, and Drosophila, little is known about ATG5 in lepidopteran insects. We cloned putative SeAtg5 gene from Spodoptera exigua larvae by the rapid amplification of cDNA ends method, and its characteristics and the influences of multiple exogenous factors on its expression levels were then investigated. The results showed that the putative S. exigua SeATG5 protein is highly homologous to other insect ATG5 proteins, which has a conserved Pfm domain and multiple phosphorylation sites. Next, fluorescence microscope observation showed that mCherry-SeATG5 was distributed in both nucleus and cytoplasm of Spodoptera litura Sl-HP cells and partially co-localized with BmATG6-GFP, but it almost has no significant co-localization with GFP-HaATG8. Then, the Western blot analysis demonstrated that GFP-SeATG5 conjugated with ATG12. Moreover, real-time PCR revealed that its expression levels significantly increased at the initiation of pupation and the stage of adult. In addition, the expression levels of SeAtg5 can be enhanced by the starvation, UV radiation, and infection of baculovirus and bacterium. However, the expression levels of SeAtg5 decreased at 24 h post treatments in all these treatments except in starvation. These results suggested that SeATG5 might be involved in response of S. exigua under various stress conditions.

Facile and efficient fabrication of photoresponsive microgels via thiol-Michael addition.

A photoresponsive microgel is designed by the combination of a noncovalent assembly strategy with a covalent cross-linking method. End-functionalized poly(ethylene glycol) with azobenzene [(PEG-(Azo)(2))] was mixed with acrylate-modified ß-CD (ß-CD-MAA) to form photoresponsive inclusion complex through host-guest interaction. The above photoresponsive complex was cross-linked by thiol-functionalized PEG (PEG-dithiol) via Michael addition click reaction. The photoreversibility of resulted microgel was studied by TEM, UV-Vis spectroscopy, and (1)H NMR measurements. The characterization results indicated that the reversible size changes of the microgel could be achieved by alternative UV-Vis irradiations with good repeatability.

[The effect of prostatectomy on nocturia in patients with benign prostatic hyperplasia].

OBJECTIVE: To explore the effect of prostatectomy on nocturia in patients with benign prostatic hyperplasia (BPH). METHODS: The data of patients who had received prostatectomy for BPH between June 2006 and December 2007 were collected. Nocturia severity was assessed preoperatively and 3 to 6 months after prostatectomy by the number of nocturia events, the time from falling sleep to the first awakening to void (hours of undisturbed sleep, HUS), the score of the nocturia quality of life (N-QOL) questionnaire, the International Prostatic Symptom Score (IPSS) and the quality of life (QOL) score. RESULTS: One hundred and twenty five cases were included. Of them, 73 patients finished the follow-up completely. There were 62 patients whose number of nocturia events before the operation was equal or more than 2. The data from these 62 patients were analyzed. Of them, 56 patients underwent transurethral resection of prostate, the remaining 11 patients suprapubic prostatectomy. Significant improvement (P < 0.01) was noted in all the following parameters after treatment: the number of nocturia events decreased from 4.2 ± 2.4 to 2.2 ± 1.0, HUS increased from (1.8 ± 0.7) h to (3.0 ± 1.4) h, N-QOL score raised from 30 ± 10 to 40 ± 7, IPSS decreased from 23 ± 5 to 8 ± 5, and QOL score fell down from 4.4 ± 0.7 to 1.5 ± 1.0. CONCLUSION: The prostatectomy can markedly improve the symptoms of nocturia, sleep and life quality in the BPH patients who accompanied with nocturia.