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BACKGROUND The green mirid bug Apolygus lucorum is a dominant pest species on multiple crops over a wide area in northern China. However, the combined effect of photoperiod and temperature on diapause induction in this species across different latitudes is not clear. Thus, the combined effects of temperature (17-29 °C) and photoperiod (11:13 h to 15:9 h light/dark) on diapause induction for seven geographic populations, collected at latitudes between 30.47°N and 38.30°N, were investigated. RESULTS A model, I = (15 - p)/(30 - p - 1.923(t - 16)1/2 + 0.4499 t - 0.015 L - 19.5389) was established to predict diapause incidence (I) using photophase (p), temperature (t) and latitude (L). In most cases, the diapause incidence predicted by the model was within or close to the 95% confidence interval estimated from independently observed field data. CONCLUSION Diapause incidence in A. lucorum was influenced nonlinearly by temperature and photoperiod across different latitudes. The model established in this study is valid for predicting diapause incidence in this pest over a wide area in northern China, and thus can be incorporated into an areawide population dynamic model of this pest. © 2020 Society of Chemical Industry.

Barometric pressure is an important factor influencing several insect traits. Most studies have been conducted on the behavior of insects in relation to rapid and slight changes in pressure magnitudes or short-term pressure trends, but there is little information on the effect of long-term and large pressure variations on insect traits. Here, we assessed the effects of static low barometric pressure on the tethered flight, lifespan and reproductive performance of Mythimna separata (Walker), a long-distance migratory insect, using an apparatus simulating low barometric pressure at altitudes of 500 m above sea level. We found that both the flight distance and flight duration of M. separata moths were significantly longer under low barometric pressure conditions. Exposure to low barometric pressure conditions for 24 and 48 h significantly shortened the lifespan of female moths but had no influence on male moths. The ovaries of female moths developed earlier, and the preoviposition and oviposition periods were significantly shortened under low atmospheric pressure. Moreover, low atmospheric pressure reduced the respiration rate of female moths. However, there was an increase in the respiration rate of female moths after being returned to standard barometric pressure conditions. Our results show that the behavior and physiological traits of insects are affected by the low-pressure environment during migration. The low barometric pressure conditions at high altitudes is one of important factors accelerating reproductive behavior of M. separata after migration.

Background Ostrinia furnacalis (Guenee) is one of the most destructive pests of corn and is a major target of transgenic corn expressing Bt (Bacillus thuringiensis) toxins in the Huanghuaihai summer corn region of China. Prior to the widespread commercialization of transgenic Bt corn, it is necessary to estimate baseline susceptibility to Bt toxins and Bt toxin resistance allele frequencies in O. furnacalis. Results The median lethal concentration (LC50 ) values of the Bt toxins Cry1Ab, Cry1Ac and Cry1F for 15 different populations ranged from 0.887 to 1.617, 1.251 to 2.594 and 4.146 to 6.465 ng cm-2 , respectively. The LC99 values of 93, 45, and 197 ng cm-2 for Cry1Ab, Cry1Ac and Cry1F, respectively, killed > 99% of individuals of eight O. furnacalis populations collected in 2017 and were identified as diagnostic concentrations for monitoring susceptibility in O. furnacalis populations in this region. Using the F2 screening method with these diagnostic concentrations, the resistance allele frequencies related to Cry1Ab, Cry1Ac and Cry1F were found to be 0.002 (0.000283-0.006484), 0.001 (0.000030-0.004295) and 0.001 (0.000030-0.004295), respectively, in 2018. Conclusion Fifteen populations of O. furnacalis collected in the Huanghuaihai summer corn region of China were all susceptible to Cry1Ab, Cry1Ac and Cry1F toxins, and the susceptibility showed no significant variation among these O. furnacalis populations. The estimated resistance allele frequency to Cry1Ab, Cry1Ac and Cry1F was rare in this region. This provided essential knowledge for making the decision to commercialize Bt maize, and monitoring resistance development and evaluating resistance management strategies in the future in the Huanghuaihai summer corn region of China. © 2020 Society of Chemical Industry.

Insect pest management is a very important aspect for plant protection in crops production. Remote sensing provides a large number of techniques that are beneficial in entomological research. Although entomological radars have been used for studying migrations of insects for many years, most of entomological radar studies have been vertically tracing high-altitude migration behaviour of insects. Light detection and ranging (lidar) is a counterpart to radar, now operating in the optical part of the electromagnetic spectrum, which has been recently applied for monitoring of insects at low altitude. Such techniques, in particular low-cost continuous-wave (CW) bi-static systems based on the Scheimpflug arrangement, have been rapidly developing during the last decade. As a result, optical methods present new and fascinating possibilities. Based on experience from a 2-week field campaign in rice paddy fields, we here present an overview of lidar remote sensing applied to the Chinese scene. The capability of a CW Scheimpflug lidar system in monitoring the insects was studied. We present results on insect abundance in relation to time of the day and weather conditions. We also identified insect species by analysing wing-beat frequencies and studied their attraction to ultraviolet (UV) lamp located close to the horizontal laser sampling path during night time. Results showed that the insect species were abundant, that insects detected by the lidar system were attracted to light and that light rain increased the insect activity. The lidar detection system had a high read-out frequency, enabling the estimation of insect wing-beat frequencies. (Less)

Genetically engineered crops with insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) have been planted in the world for two decades, aiming to control some major insect pests. While the Bt-crop strategy has been generally successful, a potential risk is the evolution of insect resistance to Bt crops. Modeling has been one of the main approaches to assessing the risk. To date, however, the importance of spatial heterogeneity in small-holder farm systems has not been adequately addressed. To address the question we developed and analyzed a spatially explicit model of insect population dynamics and genetics in which the proportion of Bt crops (PBt) is spatially heterogeneous (HD) or homogeneous (UD). We found that in both single- and two-locus models, the time it takes for insect to evolve regional resistance (TTR) varies among different HD patterns. The TTR could differ considerably between the case of HD and that of UD, depending on both spatial and non-spatial conditions. Under some conditions, regional evolution of resistance was much faster in the case of HD than in the case of UD. The difference between the two cases was caused by gene spread from hotspots of resistant alleles where the local PBt is much higher than average. Our results suggest that the spatial heterogeneity of PBt may significantly affect the speed of regional resistance and therefore is an important factor that should be taken into account for quantitative predictions as well as for design of resistance management strategies.

To escape or alleviate low temperatures in winter, insects have evolved many behavioral and physiological strategies. The rice pest insect, the purple stem borer, Sesamia inferens (Walker) is currently reported to be expanding their northern distributions and causing damage to summer maize in Xinxiang, China. However, their method of coping with the lower temperature in the new northern breeding area in winter is largely unknown. This paper investigates the overwinter site of S. inferens, and identifies the cold hardiness of larvae collected from a new breeding area in winter and explores a potential distribution based on low temperature threshold and on species distribution model, MaxEnt. The results show that the overwintering location of the S. inferens population is more likely to be underground with increasing latitude and,in the north, with the temperature decreasing, the larvae gradually moved down the corn stalk and drilled completely underground by February 18th. Those who were still above ground were all winterkilled. The cold hardiness test shows the species is a moderate freeze-tolerant one, and Supercooling Points (SCP), Freezing Points (FP) and mortality rate during the middle of winter (January, SCP: −7.653, FP: −6.596) were significantly lower than early winter (October) or late winter (March). Distribution in the new expansion area was predicted and the survival probability area was below N 35° for the Air Lower Lethal Temperature (ALLT50) and below N 40° for the Underground Lower Lethal Temperature (ULLT50), The suitable habitat areas for S. inferens with MaxEnt were also below N 40°. This study suggests the overwinter strategies have led to the colonization of up to a five degree more northerly overwintering latitude. This behavior of S. inferens could help maize producers to propose a control method to increase pest mortality by extracting the maize stubble after harvest.

To escape or alleviate low temperatures in winter, insects have evolved many behavioral and physiological strategies. The purple stem borer, Sesamia inferens (Walker) is currently reported to be expanding their northern distributions and causing damage to summer maize in Xinxiang, China. However, their method of coping with the lower temperature in the new northern breeding area in winter is largely unknown. This paper investigates the overwinter site of S. inferens, and identifies the cold hardiness of larvae collected from a new breeding area in winter and explores a potential distribution based on low temperature threshold and on species distribution model MaxEnt. The results show that the overwintering location of the S. inferens population is more likely to be underground with increasing latitude and the population gradually moved down the corn stalk and drilled completely underground in later winter (February) in the north. The cold hardiness test shows the species is a moderate freeze-tolerant one, and Supercooling Points (SCP), Freezing Points (FP) and the incidence of mortality during the middle of winter (January, SCP: -7.653, FP: -6.596) were significantly lower than early winter (October) or late winter (March). Distribution in the new expansion area was predicted and the survival probability area was below N 35° for the Air Lower Lethal Temperature (ALLT50) and below N 40° for the Underground Lower Lethal Temperature (ULLT50). The suitable habitat areas for S. inferens with MaxEnt were also below N 40°. This study suggests the overwinter strategies of S. inferens have led to the colonization of up to a five degree more northerly overwintering latitude.

A joint Chinese-Swedish field campaign of Scheimpflug continuous-wave lidar monitoring of rice-field flying pest insects was pursued in very hot July weather conditions close to Guangzhou, China. The occurrence of insects, birds and bats with almost 200 hours of round-the-clock polarization-sensitive recordings was studied. Wing-beat frequency recordings and depolarization properties were used for target classification. Influence of weather conditions on the flying fauna was also investigated.

The black cutworm, Agrotis ipsilon (L.) (Hufnagel), is a worldwide pest infesting >30 crops. Previous studies on its migration in East Asia have been mostly carried out in the regions where it could safely overwinter; however, it's still unknown what pattern of seasonal migration this species exhibits across different climate zones (i.e., in north of East Asia). Our study determines combination of searchlight trapping and ovarian dissection on a small island in the center of the Bohai Strait during 2003–2014, providing direct evidence that A. ipsilon undertakes regular migration across the sea every year. The results of ovarian dissection indicated that the ovarian developmental level, the proportion of sexually mature females, mating rate, mating frequency, and sex ratio decreased from spring to autumn. Some degrees of ovarian development and relatively higher proportion of mated females suggest that A. ipsilon is not completely bound by “oogenesis-flight syndrome” and “autumn reproductive diapa...

Macdunnoughia crassisigna (Warren) is an important polyphagous pest of bean crops and cruciferous vegetables. Whether this species is a migrant, and if so, what pattern of seasonal migration it exhibits in northern China remains unknown. The combination of searchlight trapping, ovarian dissection, and carbon isotope analysis on a small island in the center of the Bohai Strait during 2003–2013, provided direct evidence that both male and female M. crassisigna moths migrate at least 40–60 km across the sea. There was considerable annually and monthly variation in the number of M. crassisigna caught in the searchlight trap, with the vast majority (80.40 ± 4.84 %) was trapped in the summer. The mean time from the earliest trapping within a year was 143 ± 10 days from 2003 to 2013, with the shortest time span of 54 days in 2003 and the longest of 173 days in 2012. Carbon isotope analysis showed that 5.82 ± 0.92 % to 17.88 ± 8.10 % of the tested M. crassisigna moths originated from C4 plants from May to September 2010–2013, which provides additional evidence that this species is a migrant because there are no C4 plants on this island. The vast majority of the trapped females were virgins (86.29 ± 1.97 % to 89.29 ± 1.67 %) with little or no ovarian development (level 1–2, 81.06 ± 4.98 % to 87.34 ± 2.76 %) from May to September 2009–2013, as suggests that the onset of migration this species exhibits is initiated mainly by sexually immature individuals, which is termed the ‘oogenesis-flight syndrome’. Given that large numbers of adult M. crassisigna were captured while flying up to 500 m above sea level at a site with no local populations, the findings indicate that M. crassisigna is a long-distance migrant, and the pattern of seasonal migration this species exhibits is a regular ecological behavior in northern China. Such results highlight a new route for developing sound forecasting systems of M. crassisigna.

Effective monitoring of flying insects is of major societal importance in view of the role of insects as indispensable pollinators, destructive disease vectors and economically devastating agricultural pests. The present paper reports on monitoring of flying agricultural pests using a continuous-wave lidar system in a rice-field location in Southern China. Using a Scheimpflug arrangement, range resolution over several 100 m long observational paths was achieved. The system operates with two perpendicularly polarized near-infrared lasers, which are activated intermittently, and back-scattered radiation from insects was recorded by a linear array detector placed after a linear polarizer. Our polarization sensitive system was used to monitor the flying insect diurnal activity and also the influence of changes in weather conditions, e.g., the occurrence of rain. Activity strongly peaked at dusk and rose again, although to a lower extent, just before dawn. At the onset of rainfall, a strong increase in insect counts occurred which was interpreted as the rain-induced bringing down of high-altitude migrant insects.

The beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae), is a serious polyphagous insect pest worldwide. This species is known as a long-distance migrant, and previous studies on its migration have been mostly carried out in regions where it can overwinter. However, what pattern of seasonal migration this species exhibits in regions where it cannot overwinter (i.e., the 'summer breeding region') remains unknown. Here, we present data from 14-years of monitoring on a small remote island located in the center of the Bohai Strait, in northern China, by means of searchlight trapping and ovarian dissection. We found that the population size of this overseas migration varied significantly among years, with very large migrations in 2005, 2007, 2009, and 2014 that resulted in annual total catches of more than ten thousand individuals. In addition, nightly catches exhibited a significant inter-month variability, with the vast majority of S. exigua moths being trapped in August and September, (81.1 ± 3.6%), making S. exigua one of the most frequently encountered species in that period. The mean time from the earliest trap capture to the latest capture within a given year was 113 ± 22 d (range 57 d [2003] to 138 d [2008]). The sex ratio (females: males) was significantly less than 1:1 in each month, but the proportion of females showed an upward trend from June to October. The majority of trapped females in summer were mated (94.4 ± 10.7% in June, 80.0 ± 6.4% in July) and sexually mature (88.9 ± 11.1% in June, 61.8 ± 12.3% in July), suggesting the onset of mating and/or sexual maturation does not terminate the migration behavior in this species. These findings provide a good starting point for study of the trans-regional migration of S. exigua across different climate zones.

Ctenoplusia agnata (Staudinger) (Lepidoptera: Noctuidae) is an important polyphagous pest in East Asia. Previous studies showed that C. agnata moths possesses the potential to undertake long-distance migration; however, knowledge of whether or not the migration of C. agnata moths is a regular ecological behavior and what the pattern of seasonal migrations is in case of regular migration is currently lacking. In the current study, systemic monitoring of population dynamics of C. agnata was conducted by a searchlight trap on an island in the center of Bohai gulf in northern China, during 2003–2013. Our results provided strong evidence for the hypothesis that C. agnata is one of the pest species undertaking regular high altitude long-distance migration and we have depicted the seasonal migration pattern over the Bohai Sea. The first capture of C. agnata generally appeared in late April and early May, then the daily number of catches increased to high levels in late July and formed two waves of migration through August and early September, and finally, the moths disappeared in late October. The mean time from the earliest trapping to the latest trapping within a year was 141.0 ± 3.0 days. The index of ovarian development of female C. agnata showed seasonal variability and suggested that its migratory flight may be independent of the degree of ovarian development and mating status. In addition, strong migration events took place in 2003, 2004, 2008, and 2010 (annual sum of catches >10,000). The research result from this work is helpful for understanding the occurrence regularity of C. agnata and developing an integrated pest management strategy.

With widespread planting of Bt cotton and an associated reduction in the use of broad-spectrum insecticides, the mirid bugs Apolygus lucorum (Meyer-Dur) and Adelphocoris suturalis Jakovlev (Hemiptera: Miridae) become major pests of cotton in northern China in recent years. Both species overwinter as diapausing eggs that may enhance ability to survive the cold winter. The effects of photoperiod and temperature on diapause induction in A. lucorum and A. suturalis were investigated under laboratory conditions. Egg diapause was induced primarily by short photoperiod. Temperatures ranging between 17 and 26°C had little effect on diapause induction for both species. The impact of photoperiod (x) on diapause incidence (y) was described with modified Michaelis—Menten models y = 1.1(14 - x)/(14.82 - x) for A. lucorum and y = 1.07(14 - x)/(14.79 - x) for A. suturalis. The critical photoperiod for diapause induction in the first instars of parental A. lucorum and A. suturalis calculated from the models abov...

The plant bug Apolygus lucorum (Meyer-Dur) is a major pest on Bt cotton and multiple crops in northern China. A modified NI artificial diet called T7 was developed to rear this pest for 10 successive generations both individually and in groups. This T7 diet was similar in components and preparation process to the NI diet used for Lygus hesperus in North America, but was comprised of more whole chicken eggs, soybean lecithin, and Vanderzant vitamin mixture, and less brewer's yeast, wheat germ, lima bean meal, soy flour, and sugars than NI diet. While being reared individually on T7 diet, A. lucorum nymphs had a developmental duration of ≈12 d and survival rate of ≈80%, which was not significantly different from that on green beans. While being reared in groups, nymphal survival rate was above 81% (indeed above 90% for the first four generations), the weight of adults was heavier than on green beans and the average fecundity had a logistic increase through generations. The replacement rate of A. lu...

Transgenic Bt (Bacillus thuringiensis) cotton has been effectively used to control the cotton bollworm, Helicoverpa armigera (Hubner) in China. However, in recent years, following the wide commercialization of Bt cotton in northern China there have been frequent outbreaks of the non-target pest Apolygus lucorum (Meyer-Dur). To clarify how transgenic cotton contributes to these outbreaks, a four-year field investigation of population dynamics and laboratory life table studies were carried out from 2007 to 2010 to evaluate the impact of two transgenic cotton cultivars (SGK321 expressing Cry1Ac + CpTI and GK12 expressing Cry1Ac) and their corresponding parental non-transgenic lines (Shiyuan321 and Simian3) on A. lucorum. There were no significant differences in the population densities of A. lucorum found in Bt cotton and non-Bt cotton plots, whether one compared those that had received insecticide treatments or those that had not. However, population densities of A. lucorum were significantly lower in pesticide treated plots than in controls. Furthermore, there were no significant differences in the net reproductive rates, generation times or intrinsic rates of increase of A. lucorum when reared on either Bt or non-Bt cotton cultivars. These results suggest that Bt cotton has no direct positive or negative effects on the biology of A. lucorum, so the most logical explanation for the observed outbreaks is the decrease in pesticide applications following the commercial release of Bt cotton.

Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) is a key insect pest of cotton in the Henan cotton growing region of China. In this region, cotton is grown on small acreages in rich agricultural landscapes, contrary to cropping systems in the United States or Australia. Under such cropping regimes, naturally occurring refuges (with non-Bt plants) may be sufficient to prevent H. armigera resistance development to Bt toxins. In order to gain a timely understanding of the evolution of resistance of H. armigera to Bt toxin after continuous cultivation of Bt cotton for c. 10 years, we assessed the frequency of alleles conferring resistance to Cry1Ac toxin in field populations of H. armigera sampled from Xinxiang County in Henan province during 2007–2009. Screening F 1 and F 2 generations from isofemale lines, derived from female moths trapped in the field, were used with a discriminating dose of Cry1Ac diet to estimate the frequency of resistance alleles. Totals of 625, 516 and 488 isofemale lines were screened for the F 1 generation in 2007, 2008 and 2009, respectively. Resistance gene frequency in Xinxiang fluctuated between 0.0000 and 0.0005, and it did not increase significantly from 2007 to 2009. Based on the relative average development rates (RADR) of H. armigera larvae in F 1 tests, no substantial increase in Cry1Ac tolerance was found in the Xinxiang region over the 3-yr period.

The cotton bollworm Helicoverpa armigera (Lepidoptera: Noctuidae) is one of the most serious crop pests in northern China, calling for accurate prediction of pest outbreaks and strategies for pest control. A computer model is developed to simulate the population dynamics of H. armigera over a wide area in northern China. The area considered covers 12 provinces where serious outbreaks of H. armigera have been observed. In this model, pest development is driven by local ambient temperature, and adults migrate long distances between regions and select preferred hosts for oviposition within a region. Six types of host including cotton, wheat, corn, peanut, soybean and a single category composed of all other minor hosts are considered in this model. Survival rates of eggs and larvae are based on life-table data, and simulated as a function of host type, host phenology and temperature. The incidence of diapause depends on temperature and photoperiod experienced during the larval stage. Survival rate of non-diapause pupae is a nonlinear function of rainfall, and overwinter survival rate is a nonlinear function of temperature. Insecticide is applied when population density exceeds the economic threshold on a host crop within a region. Comparisons of model output with light-trap data indicate that our model reflects the pest population dynamics over a wide area, and could potentially be used for testing novel pest control strategies in northern China.

Collateral Damage Cotton crops that have been bioengineered to express the insecticidal toxin derived from Bacillus thuringiensis (Bt) carry their own insect control, particularly against the cotton bollworm, and are less dependent on externally applied pesticides. Lu et al. (p. 1151 , published online 13 April) now show that reduction in general pesticide use in cotton-growing regions of northern China has shifted the balance of regional pest populations. Bt-expressing cotton now serves as a source of herbivorous insects of the Miridae family, rather than the sink that nonengineered cotton was when less specific pesticides were used. Because these insects will eat a variety of plants, they are emerging as a threat to other crops, including grape, apple, peach, and pear.

Adelphocoris suturalis is one of the most serious pest insects of Bt cotton in China, however its molecular genetics, biochemistry and physiology are poorly understood. We used high throughput sequencing platform to perform de novo transcriptome assembly and gene expression analyses across different developmental stages (eggs, 2nd and 5th instar nymphs, female and male adults). We obtained 20 GB of clean data and revealed 88,614 unigenes, including 23,830 clusters and 64,784 singletons. These unigene sequences were annotated and classified by Gene Ontology, Clusters of Orthologous Groups and Kyoto Encyclopedia of Genes and Genomes databases. A large number of differentially expressed genes were discovered through pairwise comparisons between these developmental stages. Gene expression profiles were dramatically different between life stage transitions, with some of these most differentially expressed genes being associated with sex difference, metabolism and development. Quantitative real-time PCR results confirm deep-sequencing findings based on relative expression levels of nine randomly selected genes. Furthermore, over 791,390 single nucleotide polymorphisms and 2,682 potential simple sequence repeats were identified. Our study provided comprehensive transcriptional gene expression information for A. suturalis that will form the basis to better understanding of development pathways, hormone biosynthesis, sex differences and wing formation in mirid bugs.

Bt cotton has been widely planted in the Yellow River valley of China since 1998. Anci County in Hebei Province and Xiajin County in Shandong Province are two areas where almost 100% of the cotton grown produces Cry1A(c) toxin. These areas were therefore selected for analysis of the frequency of genes coding for resistance to Cry1A(c) in field populations of the bollworm, Helicoverpa armigera Hubner (Lepidoptera: Noctuidae). In 2002, adult females were collected using light traps. Females were caged individually and were allowed to lay eggs. At hatch, 25 ‐35 larvae from each female were screened for growth rate on normal artificial diet, and on diet containing 1.0 µg of Cry1A(c) toxin per ml of diet. This growth rate bioassay was designed to detect non-recessive resistance genes in heterozygous genotypes and to detect recessive resistance genes only when present in a homozygous resistant genotype. The bioassay detected one resistant individual out of 234 screened in Anci and one resistant individual out of 420 in Xiajin. These results suggest that a conservative estimate of the resistance gene frequency is 0.00107 in the Anci population, and 0.00059 in the Xiajin population. Our results indicate that minor resistance genes or less dominant genes for resistance may occur at higher frequencies, especially in the Xiajin population.

International audience; Transgenic Bacillus thuringiensis (Bt) crops play an increasing role in pest control, and resistance management is a major issue in large-scale cultivation of Bt crops. The fitness cost of resistance in targeted pests is considered to be one of the main factors delaying resistance when using the refuge strategy. By comparing 10 resistant Helicoverpa armigera (Hubner) strains, showing various resistance levels to Bt toxin (Cry1Ac), to a susceptible strain, we showed an increasing fitness cost corresponding with increasing levels of resistance. The relationship between overall fitness cost C and the resistance ratio R-r could be described by C = 24.47/(1 + exp([1.57 - Log(10)R(r)]/0.2)). This model predicted that the maximum overall fitness cost would be similar to 24% (+/- 5.22) in the strains with the highest resistance level. The overall fitness cost was closely linked to egg hatching rate, fecundity, emergence rate, larval survival rate, and developmental duration of adults. Among fitness components measured, fecundity was the most sensitive trait linked to the resistance selection. To integrate the results into simulation models would be valuable in evaluating how variation in fitness cost may influence the development of resistance in pest populations, thus helping to develop enhanced refuge strategies.

The plant bug Apolygus lucorum (Meyer-Dür) is a major pest on Bt cotton and multiple crops in northern China. A modified NI artificial diet called T7 was developed to rear this pest for 10 successive generations both individually and in groups. This T7 diet was similar in components and preparation process to the NI diet used for Lygus hesperus in North America, but was comprised of more whole chicken eggs, soybean lecithin, and Vanderzant vitamin mixture, and less brewer's yeast, wheat germ, lima bean meal, soy flour, and sugars than NI diet. While being reared individually on T7 diet, A. lucorum nymphs had a developmental duration of approximately 12 d and survival rate of approximately 80%, which was not significantly different from that on green beans. While being reared in groups, nymphal survival rate was above 81% (indeed above 90% for the first four generations), the weight of adults was heavier than on green beans and the average fecundity had a logistic increase through generations. The replacement rate of A. lucorum populations was expected to be approximately 29 times per generation while being reared at a density of 100 nymphs per box (20 x 12 x 7 cm). This is the first successful artificial diet reported for rearing A. lucorum and is superior to green beans. The diet offers an economic means for producing natural enemies for biological control of this pest on Bt cotton. The possibility of further improvement of the present artificial diet is also discussed.

With widespread planting of Bt cotton and an associated reduction in the use of broad-spectrum insecticides, the mirid bugs Apolygus lucorum (Meyer-Dür) and Adelphocoris suturalis Jakovlev (Hemiptera: Miridae) become major pests of cotton in northern China in recent years. Both species overwinter as diapausing eggs that may enhance ability to survive the cold winter. The effects of photoperiod and temperature on diapause induction in A. lucorum and A. suturalis were investigated under laboratory conditions. Egg diapause was induced primarily by short photoperiod. Temperatures ranging between 17 and 26°C had little effect on diapause induction for both species. The impact of photoperiod (x) on diapause incidence (y) was described with modified Michaelis-Menten models y = 1.1(14 - x)/(14.82 - x) for A. lucorum and y = 1.07(14 - x)/(14.79 - x) for A. suturalis. The critical photoperiod for diapause induction in the first instars of parental A. lucorum and A. suturalis calculated from the models above was almost identical, at 13.3 h (13 h, 18 min) in a 24-h cycle. The parental nymphal stage was sensitive to short photoperiod for diapause induction in both species, with the first-instar nymphs the most sensitive. The sensitivity to short photoperiod decreased gradually as the A. suturalis nymphs developed, whereas the sensitivity dropped sharply at the second instar of A. lucorum. The adults of both species exhibited little sensitivity to photoperiod for diapause induction.

The green mirid bug Apolygus lucorum is a regional pest of multiple crops in northern China, and the survival and development of diapausing eggs during winter plays an important role in the population dynamics of this species. The effect of water on the survival and development of A. lucorum eggs was investigated using laboratory-induced diapause. Diapausing eggs were exposed to various humidity regimes under three conditions: (1) termination of diapause with exposure to warm long-day (WLD) conditions (i.e., 26 ± 1°C and 75 ± 5% relative humidity (RH) under a photoperiod of 16 hours light and 8 hours dark), (2) termination of diapause by chilling at 4°C, or (3) during the post-diapause stage, i.e., from transfer to WLD conditions after chilling, until the hatching of nymphs. The results indicate that water availability is crucial for the post-diapause resumption of development of A. lucorum. However, exposure to excessive moisture was detrimental, as indicated by a decrease in diapause termination rate and a prolonged pre-hatching period of diapausing eggs, compared to limited moisture conditions. This implies that both too dry and too humid environmental conditions would suppress survival and postpone hatching of overwintered A. lucorum eggs, and might explain why this pest has not caused severe damage in either southern or western China where the respective climates are very humid or dry.

Fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a target species of transgenic corn (Zea mays L.) that expresses single and pyramided Bacillus thuringiensis (Bt) toxin. In 2014, S. frugiperda were collected from a light trap in North Carolina, and a total of 212 F1/F2 isofemale lines of S. frugiperda were screened for resistance to Bt and non-Bt corn. All of the 212 isolines were susceptible to corn tissue expressing Cry1A.105 + Cry2Ab, Cry1F + Cry1A.105 + Cry2Ab, and Cry1F + Cry1Ab + Vip3Aa20. Growth rate bioassays were performed to isolate non-recessive Bt resistance alleles. Seven individuals out of the 212 isofemale lines carried major non-recessive alleles conferring resistance to Cry1F. A pooled colony was created from the seven individuals. This colony was 151.21 times more resistant to Cry1F than a known-susceptible population and was also resistant to Cry1A.105, but was not resistant to Cry2Ab and Vip3Aa20. The results demonstrate that field populations of S. frugiperda collected from North Carolina are generally susceptible to Cry1F, but that some individuals carry resistant alleles. The data generated in this study can be used as baseline data for resistance monitoring.

Helicoverpa armigera Hübner (Lepidoptera: Noctuidae) is a key insect pest of cotton in Xinjiang cotton-planting region of northwest China. In this region, cotton is grown on average ≈ 1.65 million ha (1.53 ≈ 1.80 million ha) annually in largely monoculture agricultural landscapes, similarly to cropping systems in the United States or Australia. Under such cropping regimes, naturally occurring refuges (with non-Bt crops) may be insufficient to prevent H. armigera resistance development to Bt toxins. Therefore, we assessed frequency of alleles conferring resistance to Cry1Ac toxin of F(1) and F(2) offspring of H. armigera isofemale lines from two distinct localities in the region during 2005-2009. More specifically, a total of 224 isofemale lines was collected from Korla County (≈ 70% Bt cotton adoption) and 402 lines from Shache County (≈ 5% Bt cotton planting). Subsequent offspring was screened on Cry1Ac artificial diet. From 2005 to 2009, resistance gene frequency in Korla fluctuated between 0.0000 and 0.0040, while being 0.0000-0.0008 in individuals collected from Shache, and there were no significant increases in both counties from 2005 to 2009. Relative average development rates (RADRs) of larvae in F(1) tests showed significant increases from Korla, but not in Shache. RADR of F(1) larvae is significantly correlated with RADR of F(2) offspring, indicating genetic variation in response to toxin in field H. armigera population. Although the occurrence of Cry1Ac resistance alleles was low in Xinjiang cotton-planting region of China, particular attention should be given to H. armigera resistance development in Korla County.

The seasonal migration of the Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) over the Bohai Sea was observed with a searchlight trap and an entomological radar located on a small island in the center of the sea, and through a network of light-traps around the Bohai region. The H. armigera moths were observed to migrate over the sea at least as early as May and light trapping through a network suggested migration might start as early as April, as soon as the moths had emerged from overwintering pupae. H. armigera moths migrated toward the north in southerly winds during spring and summer, and returned south on nights with northerly winds, or at altitudes where the wind was northerly, during fall. The passage of a weather front (cold or warm) or trough at approximately 1700 hours provokes migration of H. armigera over the sea. The H. armigera generally flew at altitudes of below 1,500 m above sea level (asl) with layer concentrations at 200-500 m asl, where the wind direction, wind speed, and temperature were optimum. During fall migration, H. armigera tended to orient toward the southwest and was able to compensate for the wind drift by turning clockwise when the downwind direction was225 degrees but counterclockwise when it was225 degrees. The displacement speed measured with the radar was 24-41 km/h, the duration of flight was 8-11 h and the maximum migration rate was 1,894 moths per km per h.

Transgenic cotton that has been engineered to produce insecticidal toxins from Bacillus thuringiensis (Bt) and so to resist the pest cotton bollworm ( Helicoverpa armigera ) has been widely planted in Asia. Analysis of the population dynamics of H. armigera from 1992 to 2007 in China indicated that a marked decrease in regional outbreaks of this pest in multiple crops was associated with the planting of Bt cotton. The study area included six provinces in northern China with an annual total of 3 million hectares of cotton and 22 million hectares of other crops (corn, peanuts, soybeans, and vegetables) grown by more than 10 million resource-poor farmers. Our data suggest that Bt cotton not only controls H. armigera on transgenic cotton designed to resist this pest but also may reduce its presence on other host crops and may decrease the need for insecticide sprays in general.