Understanding predator–prey interactions is essential for successful pest management by using predators, especially for the suppression of novel invasive pest. The green lacewing Chrysopa formosa is a promising polyphagous predator that is widely used in the biocontrol of various pests in China, but information on the control efficiency of this predator against the seriously invasive pest Spodoptera frugiperda and native Spodoptera litura is limited. Here we evaluated the predation efficiency of C. formosa adults on eggs and first- to third-instar larvae of S. frugiperda and S. litura through functional response experiments and determined the consumption capacity and prey preference of this chrysopid. Adults of C. formosa had a high consumption of eggs and earlier instar larvae of both prey species, and displayed a type II functional response on all prey stages. Attack rates of the chrysopid on different prey stages were statistically similar, but the handling time increased notably as the prey developed. The highest predation efficiency and shortest-handling time were observed for C. formosa feeding on Spodoptera eggs, followed by the first-instar larvae. C. formosa exhibited a significant preference for S. litura over S. frugiperda in a two-prey system. In addition, we summarized the functional response and predation efficiency of several chrysopids against noctuid pests and made a comparison with the results obtained from C. formosa. These results indicate that C. formosa has potential as an agent for biological control of noctuid pests, particularly for the newly invasive pest S. frugiperda in China.

Spodoptera litura is an important pest that causes significant economic damage to numerous crops worldwide. Sex pheromones (SPs) mediate sexual communication in S. litura and show a characteristic degree of rhythmic activity, occurring mainly during the scotophase; however, the specific regulatory mechanisms remain unclear. Here, we employed a genome-wide analysis to identify eight candidate circadian clock genes in S. litura. Sequence characteristics and expression patterns were analyzed. Our results demonstrated that some circadian clock genes might regulate the biosynthesis and perception of SPs by regulating the rhythmic expression of SP biosynthesis-related genes and SP perception-related genes. Interestingly, all potential genes exhibited peak expression in the scotophase, consistent with the SP could mediate courtship and mating behavior in S. litura. Our findings are helpful in elucidating the molecular mechanism by which circadian clock genes regulate sexual communication in S. litura.

We associate the existence or non-existence of rotational invariant circles of an area-preserving twist map on the cylinder with a physically motivated quantity, the depinning force, which is a critical value in the depinning transition. Assume that $H:\mathbb{R}^{2}\mapsto \mathbb{R}$ is a $C^{2}$ generating function of an exact area-preserving twist map $\bar{\unicode[STIX]{x1D711}}$ and consider the tilted Frenkel–Kontorova (FK) model:

$$\begin{eqnarray}{\dot{x}}_{n}=-D_{1}H(x_{n},x_{n+1})-D_{2}H(x_{n-1},x_{n})+F,\quad n\in \mathbb{Z},\end{eqnarray}$$

$F\geq 0$

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Very high cycle bending fatigue behaviors of FV520B steel under fretting wear were studied by the ultrasonic fatigue technique. The specimen system for ultrasonic bending testing was designed and the stress distribution of fatigue specimen was obtained by finite element method. The microstructure of FV520B steel was characterized by means of optical microscope, transmission electron microscope, and energy-dispersive spectroscope. The P–S–N curve was drawn based on fatigue data. The micromorphology characteristics of fretting wear surface and fracture surface for fatigue specimen were observed. The results indicate that the microstructure of FV520B steel is mainly composed of lath martensite, ferrite, and precipitation particles, with some randomly distributed internal inclusions. The P–S–N curve shows that there exists no “conventional fatigue limit” and the fatigue life decreases continuously with the increase of applied stress Smax. Most of fatigue cracks are observed on fractography and initiate from the overlap region of fretting wear zone and stress concentration zone. The fracture failure for tested specimen is ascribed to fretting wear and bending vibration fatigue.

We associate the topological entropy of monotone recurrence relations with the Aubry–Mather theory. If there exists an interval $[{\it\rho}_{0},{\it\rho}_{1}]$ such that, for each ${\it\omega}\in ({\it\rho}_{0},{\it\rho}_{1})$, all Birkhoff minimizers with rotation number ${\it\omega}$ do not form a foliation, then the diffeomorphism on the high-dimensional cylinder defined via the monotone recurrence relation has positive topological entropy.

In order to obtain the dynamic variation rule of the sulfur content of liquid steel inthe LF refining process, a complete mathematical model including a desulfurization kineticmodel and temperature model in the deep desulfurization process is presented, based on thepractical production and reaction mechanism of ultra-low-sulfur steel in a LF. The resultsshow that the calculated values of the sulfur content in liquid steel using the model fitthe experimental values well, and the relative error is less than 8%. The effects ofrefining slag on the desulfurization process are analyzed in this paper, which shows thatslag basicity is most important at the early and middle stages of the process, while slagweight is most important at the middle and late stages. The effect of the above factors onthe final sulfur content of liquid steel is further analyzed quantitatively. The simulatedresults provide a theoretical basis to segment control the refining process in order toachieve the maximum effect, improving efficiency, saving energy and reducingconsumption.