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Voltinism and life‐history traits of the invasive fall armyworm (FAW) Spodoptera frugiperda were investigated under semi‐natural conditions for a period of 2 years. The FAW invaded the corn field in the suburbs of Nanchang (28°46′ N, 115°50′ E) in early summer and produced six complete generations. FAW had the characteristics of short developmental time, high survival rates and strong fecundity. The development time of female pupae was significantly faster than that of male pupae, resulting in the emergence of female pupae earlier than male pupae. Except for the sixth generation in 2021, there was no significant difference between female and male sex ratio, which was close to 1:1. FAW showed male‐bias sexual size dimorphism with male pupae being significantly larger than female pupae. Unlike pupal weight, in most generations, male adult weighed significantly less than females, because the weight loss of male pupae during metamorphosis was significantly greater than that of female pupae. The temporal variation of pupal weight did not conform to the temperature–size rule. Compared with 22.8°C, the 29.2°C high temperature not only significantly reduced the development time of larvae but also significantly increased pupal weight. The adult fecundity feeding on fresh corn leaves was higher than that feeding on live corn plants in most generations. In most generations, pupal weight was positively correlated with larval development time and adult weight was positively correlated with fecundity. In conclusion, climate differences between generations and years have significant effects on developmental time, body weight, sexual size dimorphism and fecundity of the FAW. These results add to the understanding of the evolution of life‐history traits in the FAW and may have important implications for predicting population dynamics of the FAW and optimising control strategies. [ABSTRACT FROM AUTHOR]

The fall armyworm (FAW) Spodoptera frugiperda (J. E. Smith; Lepidoptera; Noctuidae) has invaded Jiangxi Province, Southeast China for the past 3 years. Although the FAW displays a wide host range, its main host plants in Jiangxi Province are field corn. Understanding the population dynamics of the FAW on different host plants is critical for developing an appropriate control strategy. This study investigated the effects of food plants (corn, peanut, soybean and sugarcane) on life‐history traits of FAW and tested the leaf contents of the total flavonoids, reducing sugars, sucrose and C/N ratio of these host plants. We found that the FAW fed on corn leaves exhibited significantly shorter larval and pupal development times, larger body weight, higher growth rate, lower weight loss, smaller sexual size dimorphism, shorter preoviposition period and higher fecundity than those fed on peanut, soybean and sugarcane leaves. The FAW showed a protogyny phenomenon because the pupal development stage was significantly longer in males than females. Food plants changed the relationships between larval development time and pupal weight and between fecundity and longevity. The corn leaves showed significantly higher contents of reducing sugars and sucrose, lower content of the total flavonoids and a moderate C/N ratio compared with the other leaves, suggesting that the corn leaf tissues are more nutritious. Our results provide the most comprehensive information about the life‐history traits of this newly invasive pest. These findings may help us understand why the FAW mainly infests corn plants and may be critical for the development of strategies to predict infestation levels. [ABSTRACT FROM AUTHOR]

A southern population (S) from Xiushui County (29°1′N, 114°4′E) and a northern population (N) from Shenyang city (41°48′N, 123°23′E) of the cabbage beetle, Colaphellus bowringi vary greatly in their life-history traits, and may serve as an excellent model with which to study the inheritance of life-history traits. In the present study, we performed intraspecific hybridization using the two populations, comparing the key life-history traits (fecundity, development time, body weight, growth rate, and sexual size dimorphism (SDD)) between the two populations (S♀ × S♂ and N♀ × N♂) and their two hybrid populations (S♀ × N♂ and N♀ × S♂ populations) at 19, 22, 25, and 28°C. Our results showed that there were significant differences in life-history traits between the two parental populations, with the S population having a significantly higher fecundity, shorter larval development time, larger body weight, higher growth rate, and greater weight loss during metamorphosis than the N population at almost all temperatures. However, these life-history traits in the two hybrid populations were intermediate between those of their parents. The life-history traits in the S × N and N × S populations more closely resembled those of the maternal S population and N population, respectively, showing maternal effects. Weight loss for both sexes was highest in the S population, followed by the S × N, N × S, and N populations at all temperatures, suggesting that larger pupae lost more weight during metamorphosis. The changes in SSD with temperature were similar between the S and the S × N populations and between the N and the N × S populations, also suggesting a maternal effect. Overall, our results showed no drastic effect of hybridization on C. bowringi, being neither negative (hybrid inferiority) nor positive (heterosis). Rather, the phenotypes of hybrids were intermediate between the phenotypes of their parents. [ABSTRACT FROM AUTHOR]

In mid‐May, 2019, the fall armyworm (FAW) Spodoptera frugiperda invaded Jiangxi Province, China, and caused extensive damage to corn crops. However, little attention has been given to the life‐history traits of the FAW. In the present study, we systematically investigated the life‐history traits of the newly invasive FAW on corn leaves at 19, 22, 25, 28, and 31°C under a photoperiod of LD 15:9 hr. The FAW thrived on the corn leaves with short developmental periods, high survival rates of larvae and pupae, very high mating success rates, and high fecundity. The pupal developmental stage was significantly longer in males than females at all temperatures, thus resulting in a protogyny phenomenon. The pupal weight was heaviest after a relatively shorter larval development stage at a higher temperature (25°C); thus, the FAW did not follow the temperature–size rule. Females were smaller than males, indicating sexual size dimorphism. A small proportion of females delayed their pre‐oviposition period and began to lay eggs on the 7th to 9th day after adult emergence. There were positive relationships between pupal weight and larval developmental time and between adult weight and fecundity. There was a negative relationship between fecundity and longevity. These findings can help us to predict the population dynamics of the FAW on corn and to develop a suitable and practical management strategy. [ABSTRACT FROM AUTHOR]

Temperature is considered one of the most important mediators of phenotypic plasticity in ectotherms. Here, we investigated life history traits of the cabbage beetle, Colaphellus bowringi Baly (Coleoptera: Chrysomelidae), at a wide range of temperatures (16, 19, 22, 24, 26 and 28°C). The larval and pupal times were significantly decreased with increasing rearing temperature and growth rate was positively correlated with temperature. However, the relationship between body size and rearing temperature in C. bowringi did not follow the temperature-size rule; both males and females reached the highest body weight at 19°C. Females were significantly larger than males at all temperatures. Male pupae lost significantly more weight at metamorphosis compared to females. However, diapausing males gained significantly higher weight after feeding compared to diapausing females at higher temperatures of 22, 24, 26 and 28°C. Body weight tended to decrease with increasing rearing temperature, whereas sexual size dimorphism (SSD) tended to increase with increasing rearing temperature; thus, Rensch's rule is upheld. The degree to which SSD changed with temperature varied with different development stages. SSD was lowest in pupae, highest in newly emerged adults and intermediate in diapausing adults. [ABSTRACT FROM AUTHOR]

Temperature is a key environmental factor for ectotherms and affects a large number of life history traits. In the present study, development time from hatching to pupation and adult eclosion, pupal and adult weights of the rice stem borer, Chilo suppressalis were examined at 22, 25, 28 and 31 °C under L18:D 6. Larval and pupal times were significantly decreased with increasing rearing temperature and growth rate was positively correlated with temperature. Larval and pupal developmental times were not significantly different between females and males. The relationship between body weight and rearing temperature in C. suppressalis did not follow the temperature–size rule (TSR), both males and females gained the highest body weight at 31 °C. Females were significantly larger than males at all temperatures, showing a female biased sex size dimorphism (SSD). Contrary to Rensch's rule, SSD and body weight in C. suppressalis tended to increase with rising temperature. Male pupae lost significantly more weight at metamorphosis compared to females. We discuss the adaptive significance of the reverse-TSR in the moth's life history. [ABSTRACT FROM AUTHOR]

Life-history traits from four geographical populations (tropical Ledong population [ LD], subtropical Guangzhou [ GZ] and Yongxiu populations, and temperate Langfang population [ LF]) of the Asian corn borer, Ostrinia furnacalis were investigated at a wide range of temperatures (20-32°C). The larval and pupal times were significantly decreased with increasing rearing temperature, and growth rate was positively correlated with temperature. The relationship between body weight and rearing temperature in O. furnacalis did not follow the temperature-size rule ( TSR); all populations exhibited the highest pupal and adult weights at high temperatures or intermediate temperatures. However, development time, growth rate, and body weight did not show a constant latitudinal gradient. Across all populations at each temperature, female were significantly bigger than males, showing a female-biased sexual size dimorphism ( SSD). Contrary to Rensch's rule, the SSD tended to increase with rising temperature. The subtropical GZ population exhibited the largest degree of dimorphism while the temperate LF exhibited the smallest. Male pupae lose significantly more weight at metamorphosis compared to females. The proportionate weight losses of different populations were significantly different. Adult longevity was significantly decreased with increasing temperature. Between sexes, all populations exhibit a rather female-biased adult longevity. Finally, we discuss the adaptive significance of higher temperature-inducing high body weight in the moth's life history and why the moth exhibits the reverse TSR. [ABSTRACT FROM AUTHOR]

Temperature is a key environmental factor in ectotherms and influences many life history traits. In the present study, the nymphal development time, sex ratio and wing dimorphism of the small brown planthopper Laodelphax striatellus were examined under the conditions of constant temperatures, naturally varying temperatures (or different generations), and different temperatures combined with different photoperiod. The results showed that from 18 to 28 °C, the developmental time of nymphs was gradually shortened with the increase of temperature, whereas the high temperatures of 30 and 32 °C in the third to fifth instar nymphal stages and high summer temperature of 28.8 and 29.7 °C significantly delayed developmental time and resulted in higher mortality of nymphs. In all treatments, the developmental time was longer in females than males. The nymphs took significantly longer time to develop in the short daylength of 12 h than in longer daylengths of 13, 14, 15 and 16. Differences in developmental time were also found between wing morph, with long-winged individuals being significantly longer than the short-winged individuals at lower temperatures and significantly shorter than the short-winged individuals at higher temperatures. In all treatments, the sex ratio was stable, approaching 1:1, without being affected by temperature, generations and photoperiod. Photoperiod and temperature had significantly influence on the wing dimorphism. Long daylength combined with different temperatures resulted in significantly higher proportions of long-winged morph, whereas the low temperatures combined with the short daylengths in autumn and winter resulted in significantly high proportion of short-winged morph. This study broadens our understanding of the life-history traits of this planthopper and provides basic data for analyzing the effects of climate change on the planthopper reproduction. • Life-history traits of L. striatellus were tested at different rearing conditions. • Temperature, photoperiod, sexes, and wing morph affected nymphal development time. • High temperatures delayed nymphal time and resulted in high mortality. • Sex ratio was not affected by temperature, photoperiod and season. • Wing dimorphism ratio was affected by temperature and photoperiod. [ABSTRACT FROM AUTHOR]