A mite parasitoid,Pyemotes zhonghuajia,negatively impacts the fitness traits and immune response of the fall armyworm,Spodoptera frugiperda

Parasitoids are key regulators in ecological communities and widely used as agents in biocontrol programmes.The fall armyworm,Spodoptera frugiperda,recently invaded multiple continents and caused substantial economic losses in agriculture.Pyemotes zhonghuajia,a newly identified mite parasitoid,has shown potential for controlling various agricultural insect pests.Therefore,this study tested the performance of P.zhonghuajia in parasitising S.frugiperda.We also investigated the sublethal effects of parasitism by P.zhonghuajia on host fitness traits,transgenerational impacts,and cellular and humoral immunity.Our result showed that the fifth-instar larvae of S.frugiperda parasitised by 40 P.zhonghuajia were all dead(i.e.,a lethal effect),while parasitism by 5 or 10 P.zhonghuajia was considered sublethal since many S.frugiperda survived to adulthood and produced offspring after mating.The sublethal influences from parasitism by P.zhonghuajia resulted in reduced pupal weight,adult emergence rate and fecundity,but increased developmental time and longevity.Parasitism at both lethal(40 mites)and sublethal(10 mites)levels impaired the cellular and humoral immunity of S.frugiperda.This study presents the first empirical evidence that mite parasitoids can negatively influence host immunity.Moreover,it provides insights into the biocontrol potential of mite parasitoids and their interactions with hosts.

Seasonal Dynamic of the Fall Armyworm, Spodoptera frugiperda (J.E Smith, 1797) (Lepidoptera: Noctuidae) on Maize Crop in the Sub-Sudanese Zone of Côte d’Ivoire

In Côte d’Ivoire, maize (Zea mays L) is the second most cultivated cereal after rice. Since the first report of Spodoptera frugiperda in Côte d’Ivoire, maize production in the northern regions has been affected resulting in maize production losses. This study aims to study the seasonal dynamic of Spodoptera frugiperda in maize fields in the sub-Sudanese zone, main zone of maize cultivation in Côte d’Ivoire. The study was done using pheromone trap lures. The results revealed a variation in the moth population at various growth stages during rainy and dry seasons. Notably, the highest numbers of moths were consistently trapped during the whorl stage with counts ranging from 131 ± 35.7 during the rainy season to 70.6 ± 15.01 in the dry season. The lowest numbers of moths were observed during pod maturation, with counts ranging from 30.3 ± 13.05 during the rainy season to 11.7 ± 3.05 in the dry season. Between the 7th and 21st days after sowing, the count of moths displayed a consistent upward trajectory, reaching 188 moths during the rainy season. The damages were particularly observed at whorl stage. The relationship between the numbers of moths and some climatic variables revealed a negative correlation between moths numbers and rainfall (r= −0.44) and relative humidity (r= −0.684). In contrast, there were positive relationships with temperature (r = 0.16), highlighting the significant impact of temperature changes on moth population dynamics. The research highlights the need for integrated pest management strategies that consider climatic factors and growth stages of maize to mitigate the impact of this insect pest on maize.

Accurate recognition of the reproductive development status and prediction of oviposition fecundity in Spodoptera frugiperda(Lepidoptera:Noctuidae)based on computer vision

Spodoptera frugiperda(Lepidoptera:Noctuidae)is an important migratory agricultural pest worldwide,which has invaded many countries in the Old World since 2016 and now poses a serious threat to world food security.The present monitoring and early warning strategies for the fall army worm(FAW)mainly focus on adult population density,but lack an information technology platform for precisely forecasting the reproductive dynamics of the adults.In this study,to identify the developmental status of the adults,we first utilized female ovarian images to extract and screen five features combined with the support vector machine(SVM)classifier and employed male testes images to obtain the testis circular features.Then,we established models for the relationship between oviposition dynamics and the developmental time of adult reproductive organs using laboratory tests.The results show that the accuracy of female ovary development stage determination reached 91%.The mean standard error(MSE)between the actual and predicted values of the ovarian developmental time was 0.2431,and the mean error rate between the actual and predicted values of the daily oviposition quantity was 12.38%.The error rate for the recognition of testis diameter was 3.25%,and the predicted and actual values of the testis developmental time in males had an MSE of 0.7734.A WeChat applet for identifying the reproductive developmental state and predicting reproduction of S.frugiperda was developed by integrating the above research results,and it is now available for use by anyone involved in plant protection.This study developed an automated method for accurately forecasting the reproductive dynamics of S.frugiperda populations,which can be helpful for the construction of a population monitoring and early warning system for use by both professional experts and local people at the county level.

Mutagenesis of odorant coreceptor Orco reveals the distinct role of olfaction between sexes in Spodoptera frugiperda

Odorant receptor(OR)is crucial for insects to detect and recognize external chemical cues closely related to their survival.The insect OR forms a heteromeric complex composed of a ligand-specific receptor and a ubiquitously odorant receptor coreceptor(Orco).This study used the CRISPR/Cas9 technique to knock out(KO)Orco and reveal its essential role in acting on OR-meditated olfactory behavior in a critical invasive agricultural pest,the fall armyworm(FAW),Spodoptera frugiperda.Electroantennogram(EAG)results suggested that the Orco mutants of both male and female moths severely reduced their electrophysiological responses to the eight tested plant volatiles and two sex pheromones.However,the Orco gene played distinct roles in mating behavior between sexes:the mating behavior was fully disrupted in mutated males but not in mutated females.The oviposition result indicated that the Orco KO females displayed reduced egg laying by 24.1%compared with the mated wild type(WT)females.Overall,these results strongly suggest that Orco is an excellent target for disrupting FAW’s normal behavior and provides a feasible pest control approach.

Inventory of Host Plants and Parasitoids of the Fall Armyworm (FAW), Spodoptera frugiperda (JE Smith), in the Southern Agricultural Zone of Niger

The fall armyworm, Spodoptera frugiperda (JE Smith), is a polyphagous pest reported in sub-Saharan Africa since 2016 and has expanded rapidly in almost Africa. In Niger, Spodoptera frugiperda (JE Smith) is considered like a major pest of maize, to which it causes significant damage, in a context where proven control methods against this moth remain almost non-existent. The objective of the present study was to determine the economic importance of FAW through the damage caused to the different host plants and to identify the parasitoids of this caterpillar. The study was conducted in the southern agricultural zone of Niger, specifically in the regions of Dosso, Maradi, Tahoua and Zinder. FAW eggs and caterpillars were collected from six villages in each region and then incubated and reared in the entomology laboratory of INRAN in Maradi. The rate of infestation of the different crops by FAW was determined as well as the observation of the beneficiaries. The results obtained indicate the presence of FAW on millet with an attack rate varying from 45.7% to 68%, sorghum with 47.2% to 62.25% and sesame with 9.7%. This work also revealed an oophagous parasitoid, Telenomus remus with 138 ± 23 and larval parasitoids, Cotesia sp with 16 ± 1 maximum number of individuals emerged from the collected material. Also, it was identified the parasitoid Cotesia icipe with a rate of parasitism from 4.6% to 5.75%;the Charops ater whose rate of parasitism varies from 4.5% and 12.25% but for Chelonus insularis with 17.25% and Tachnidae with 53%. These very interesting results will constitute a basis for the development of biological control and a component of an agroecological management strategy of caterpillar.

Occurrence Characteristics and Prevention and Control Measures of Spodoptera frugiperda in Maize

Based on practical work experience,this paper analyzed the occurrence characteristics and control measures of Spodoptera frugiperda in maize.The measures including forecasting and early warning,regional prevention and control,agricultural prevention and control,physical prevention and control,chemical prevention and control,and biological prevention and control can effectively control the damage of S.frugiperda and guarantee the safety of food production.The results will provide some reference for the prevention and control of S.frugiperda.

Preliminary Study of Predation Effectiveness of the Assassin Bug Rhynocoris rapax Stal (Heteroptra: Reduviidae) on Fall Armyworm Spodoptera frugiperda Smith (Lepidoptera: Noctuidae), a Major Pest of Maize Crops

Maize is a staple food in many sub-Saharan African countries, grown on large surfaces and with high production. However, maize’s cultivation is often confronted with attacks by the fall armyworm, which considerably reduces production. Thus, the use of biological agents in the control of the fall armyworm would contribute effectively to the sustainability of agriculture. It is in this context that this study, conducted at the La Mé station of the National Centre for Agronomy Research, aims to test the effectiveness of Rhynocoris rapax, a powerful predator of various insect families, on the fall armyworm Spodoptera frugiperda, for biological control of this maize pest in Côte d’Ivoire. Therefore, 3 batches of 1 adult individuals of Rhynocoris rapax were captured in trial plots set up at the La Mé station. These individuals were then put in contact with 3 batches of 5, 20 and 40 larvae of the pest in rearing boxes at an average temperature of 26.4°C and an average relative humidity of 60%, in order to evaluate the efficiency of the predation. The results showed that Rhynocoris rapax kills more larvae when these are in large numbers. The mortality of the high number of larvae was observed during the first three days, probably due to the voracity and aggressiveness of Rhynocoris rapax that period. So R. rapax is a potential predator of fall armyworm and should be protected.

Perception and Management Strategies of the Fall Armyworm, Spodoptera frugiperda J.E. Smith (1797) (Lepidoptera: Noctuidae) on Maize, Millet and Sorghum by Farmers in Western Burkina Faso

Since it was first detected in Africa in early 2016, the fall armyworm (FAW), Spodoptera frugiperda Smith (Lepidoptera: Noctuidae), has spread to over 50 African countries, including Burkina Faso. This insect pest attacks important cereals, such as maize, millet and sorghum, which are the staple food in Burkina Faso. Since the invasion of the FAW in Africa, data on farmers’ knowledge and their perceptions of this insect’s pest are scarce and fragmented in Burkina Faso. Although this issue has been already addressed in some African countries, farmers’ perceptions of this invasive insect pest may differ from one country to another. This reality justifies our study, the main objective of which is to assess the perception and level of knowledge of farmers on this new invasive insect pest and the consequences of its damage to cereal production in western Burkina Faso. To do this, a stratified survey was conducted among 355 farmers in two important agricultural regions of Burkina Faso, namely the Hauts-Bassins and the Cascades. At the end of these surveys, it was found that the age of the people surveyed varied from 18 to 80 years. People between the ages of 41 and 50 and 31 and 40 were the most numerous, with 31.27% and 30.14% of the target population, respectively. In addition, the majority of the farmers were male, 94.08% of them being men and 5.92% being women. More than half (50.42%) of this population was non-literate. Almost all of the farmers surveyed (97.46%) said they had heard of S. frugiperda and 80.85% of them said they could identify the insect pest. The date of appearance of the FAW was variously perceived by the farmers of the study area. According to these cereals growers, the years 2016, 2017, 2018, and 2019 were to be remembered in terms of the insect pest’s appearance. While for sorghum and millet the change in yields from 2010 to 2019 seemed slight, it was quite remarkable for maize according to the farmers. The average maize yield in 2016 and 2017 was 1.95 and 1.83 t/ha, respectively. These values will increase slightly in 2018 and 2019 with 2.08 and 2.39 t/ha, respectively. In the field, several management methods were used by the farmers to control the insect pest’s attacks. These include chemical, cultural, and physical control. Insecticide spray frequencies ranged from 1 to 4 and even more depending on the duration of the maize cycle.

草地贪夜蛾(Spodoptera frugiperda)与东方粘虫(Mythimna separata)种间竞争的室内模拟研究

研究草地贪夜蛾(Spodoptera frugiperda)和东方粘虫(Mythimna separata)在室内以不同的初始种群密度(50头草地贪夜蛾初孵幼虫+50头东方粘虫初孵幼虫;25头草地贪夜蛾初孵幼虫+50头东方粘虫初孵幼虫;10头草地贪夜蛾初孵幼虫+50头东方粘虫初孵幼虫)取食相同寄主时二者的种群竞争行为并分析原因。结果表明,在以小麦苗为寄主的条件下,当初始种群为50头草地贪夜蛾+50头东方粘虫时,混合后13 d,东方粘虫存活率为0,而草地贪夜蛾的存活率为51.0%;随着初始混合种群中草地贪夜蛾比例的下降,混合后13 d,各处理中东方粘虫的存活率逐渐增加,2种昆虫种群达到共存。在以玉米苗为寄主的条件下,当初始种群为50头草地贪夜蛾+50头东方粘虫时,混合后10 d,东方粘虫存活率即为0,而草地贪夜蛾的存活率为81.0%;随着初始混合种群中草地贪夜蛾比例的下降,混合后13 d,各处理中东方粘虫均不能完成幼虫历期,2种昆虫种群不能达共存。草地贪夜蛾和东方粘虫在相同生态位的种群竞争中,草地贪夜蛾具有明显的优势;无论寄主为小麦还是玉米,东方粘虫在与草地贪夜蛾的混合种群中每日存活率通常低于草地贪夜蛾及单独饲养的东方粘虫种群,甚至不能完成幼虫发育,造成东方粘虫种群可能被草地贪夜蛾取代。

Case study on the first immigration of fall armyworm,Spodoptera frugiperda invading into China

The fall armyworm(FAW),Spodoptera frugiperda is one of the most damaging crop pests,and it has become major threat to the food security of many countries.In order to monitor possible invasion of this pest into China,a searchlight trap was established in March 2018 in western Yunnan Province,China,where it has served as the"first station"for many pests that have migrated from Myanmar to China.A number of suspected FAW moths were captured and identified by DNA sequencing.The results showed that the FAW moth was first captured on December 11 and formed its first immigration peak in mid-December 2018.DNA detection revealed that the early invading FAW population was the"corn-strain".The field survey indicated that the pest mainly colonized corn in Pu’er,Dehong and Baoshan areas.Migration trajectory simulation implied that the moths might have mainly come from the eastern area in the mid-latitude region of Myanmar(20-25°N,94-100°E).This case study confirmed the first immigration of FAW into China,and will be helpful for guiding monitoring and management work to control this pest.

Spread of invasive migratory pest Spodoptera frugiperda and management practices throughout China

The fall armyworm(FAW),Spodoptera frugiperda(J.E.Smith)(Lepidoptera:Noctuidae),a notorious migratory pest native to tropical and subtropical America,invaded China in December 2018,then spread through 26 provinces(autonomous regions,municipalities)in 2019 and 27 in 2020,damaging 1.125 and 1.278 million hectares of crops,respectively.Maize was the most severely affected crop,although wheat and other plants were also ruined.Considering the biological characteristics,incidence regularity and migration patterns of the FAW populations,Chinese government implemented a regional control strategy and divided the areas infested with FAW into the annual breeding grounds in Southwest and South China,the transitional migration area in Jiangnan and Jianghuai and the key preventive area in the Huang-Huai-Hai region and North China.The National Agro-Tech Extension and Service Center constructed"the National Information Platform for the Prevention and Control of the Fall Armyworm"at the county level,which would entail people reporting and mapping the spread of fall armyworm.According to forecasting information,millions of extension workers and small-scale growers in entire country were rallied by local governments to fight the pest through comprehensive control tactics including chemical,physical,biological and ecological measures.Thanks to the joint prevention and control,the final loss of crops infested was controlled within 5%of the total in 2019 and 2020.This review also gives a discussion on existing problems and future management scenarios.

斑蝥素诱导草地贪夜蛾(Spodoptera frugiperda)卵巢细胞系Sf9凋亡的临界条件

为进一步利用昆虫细胞研究斑蝥素对鳞翅目昆虫的毒杀机理,采用细胞形态学观察法和DNA凝胶电泳法研究斑蝥素诱导草地贪夜蛾(Spodoptera frugiperda)卵巢细胞系Sf9细胞凋亡的临界条件。结果表明:供试细胞凋亡率与斑蝥素处理剂量、时间呈现密切相关性;在较低剂量处理下,可观察到细胞凋亡。当斑蝥素质量浓度达到6.25μg/mL,处理细胞3 h或3.125μg/mL处理细胞12 h时,斑蝥素处理Sf9导致细胞出现明显畸形、形成凋亡小体等凋亡症状。DNA Ladder条件要求严格,在冰浴条件下,当斑蝥素处理质量浓度达到6.25μg/mL处理细胞24 h时,或者12.5μg/mL处理细胞12 h时,可观察到明显的DNA梯度条带。

Insecticide resistance monitoring for the invasive populations of fall armyworm,Spodoptera frugiperda in China

Fall armyworm has invaded China and colonized its populations in tropical and sub-tropical regions of South China since December 2018.Chemical spray has been widely used to control the pest,which shall lead to resistance evolution.In this research,we collected five populations of the pest from Yunnan,Hainan,Tibet,and Fujian of China,and tested their susceptibilities to pyrethroid,organophosphorus,oxadiazine,diamide,antibiotics and other types of insecticides(14 insecticides totally)in the laboratory.Based on the susceptible baseline published from the previous studies,the resistance ratio was 615-1068-fold to chlorpyrifos,60-388-fold to spinosad,26-317-fold to lambda-cyhalothrin,13-29-fold to malathion,9-33-fold to fenvalerate,8-20-fold to deltamethrin,3-8-fold to emamectin benzoate and 1-2-fold to chlorantraniliprole,respectively.The median lethal concentration(LC_(50))of other six insecticides without the susceptible baselines was 148.27-220.96μgmL^(-1) for beta-cypermethrin,87.03-128.43μgmL^(-1) for chlorfenapyr,16.35-99.67μgmL^(-1) for indoxacarb,10.55-51.01μgmL^(-1) for phoxim,7.08-8.78μgmL^(-1) for M-EBI(the mixed insecticide of emamectin benzoate and indoxcarb)and 1.49-4.64μg mL^(-1) for cyantraniliprole.This study can be helpful for chemical control as well as for resistance monitoring and management of the pest in China.

Analysis of phototactic responses in Spodoptera frugiperda using Helicoverpa armigera as control

Light traps are widely utilized to monitor and manage insect pest populations.In late 2018,the fall armyworm(FAW),Spodoptera frugiperda,invaded China through Yunnan Province representing a huge threat to grain production.To estimate the efficiency of light traps on FAW moths,we first identified the opsin genes from FAW by using the transcriptome.Phylogenetic analysis indicated that the four opsins of FAW were clustered with those of other Noctuidae species.The expressed levels of opsins in S.frugiperda were lower than in Helicoverpa armigera,suggesting a different phototactic response between the two species.Then,we determined the phototactic behavior of FAW using H.armigera as a control,which is widely monitored and managed using light traps in China.Our results indicated that the two moths species showed significantly different phototactic behavior and both female and male FAW displayed faster flight-to-light speed than H.armigera.This may be due to a faster flight capacity in FAW compared to H.armigera.However,the capture rate of both female and male of S.frugiperda was significantly lower than that of H.armigera,which was consistent with the expression levels of opsins.These results support the positive phototaxis of S.frugiperda moths and suggest light traps could be used for monitoring and managing the pests,but with a lower efficiency than H.armigera.

Biology,invasion and management of the agricultural invader:Fall armyworm,Spodoptera frugiperda(Lepidoptera:Noctuidae)

The fall armyworm(FAW),Spodoptera frugiperda(J.E.Smith),is native to the Americas.It has rapidly invaded 47 African countries and 18 Asian countries since the first detection of invasion into Nigeria and Ghana in 2016.It is regarded as a super pest based on its host range(at least 353 host plants),its inherent ability to survive in a wide range of habitats,its strong migration ability,high fecundity,rapid development of resistance to insecticides/viruses and its gluttonous characteristics.The inherently superior biological characteristics of FAW contribute to its invasiveness.Integrated pest management(IPM)of FAW has relied on multiple applications of monitoring and scouting,agricultural control,chemical pesticides,viral insecticides,sex attractants,bio-control agents(parasitoids,predators and entomopathogens)and botanicals.Knowledge gaps remain to be filled to:(1)understand the invasive mechanisms of S.frugiperda;(2)understand how to prevent its further spread and(3)provide better management strategies.This review summarizes the biological characters of FAW,their association with its invasiveness and IPM strategies,which may provide further insights for future management.

Genome editing of the SfABCC2 gene confers resistance to Cry1F toxin from Bacillus thuringiensis in Spodoptera frugiperda

ATP-binding cassette transporter C2(ABCC2)is known to be a receptor for Bacillus thuringiensis(Bt)toxins in several lepidopteran insects.Mutations in the ABCC2 gene have been genetically linked to field-evolved resistance to the Cry1 F toxin from Bt in Spodoptera frugiperda.Here we generated a SfABCC2 knockout strain of S.frugiperda using the CRISPR/Cas9 system to provide further functional evidence of the role of this gene in susceptibility and resistance to Cry1 F.Results from bioassays showed that the SfABCC2 knockout S.frugiperda strain displayed 118-fold resistance to Cry1 F compared with the parental DH19 strain,but no resistance to Vip3 A toxin from Bt.These results provide the first reverse genetic evidence for SfABCC2 as a functional receptor for Cry1 F.

Migration of invasive Spodoptera frugiperda(Lepidoptera:Noctuidae)across the Bohai Sea in northern China

The fall armyworm(FAW),Spodoptera frugiperda(J.E.Smith),is an important agricultural pest with a strong migratory ability.While the species is native to the Americas,it has recently invaded China,ravaging crops in many provinces(autonomous regions,municipalities).Its long-distance migration,which is critical to understand for pest management programs,has been well studied in its native region.In other regions however,the moth’s migration patterns have not yet been characterized.Here,the migratory behavior of FAW populations in China was studied on an isolated island located in the center of the Bohai Strait from spring to autumn 2019,the year in which FAW first reached this region,by using searchlight trapping,stable carbon isotopes and trajectory simulation.The main results were summarized as follows:(i)The number of FAW moths caught by searchlight trapping provided direct evidence that the species migrated across the Bohai Sea.(ii)Species identification was confirmed by both morphology and molecular methods,and only the"corn-strain"that preferentially infests maize and sorghum was found in the collections.(iii)Stable carbon isotope measurements showed that up to 95.07%of captured moths displayed the C4 isotope signature,thus providing additional evidence that this species is a migrant as there are no major C4 plants at the trapping site.(iv)Backward trajectory analysis indicated that the pest now threatens to expand its range into the agriculturally important region of Northeast China,and thus authorities in this region should be vigilant to the threat posed by this species.Together,these findings add to our knowledge concerning the occurrence of FAW in northern China,and will help us to develop sustainable and effective monitoring,forecasting,and pest management strategies.

Fitness of fall armyworm,Spodoptera frugiperda to three solanaceous vegetables

The fall armyworm(FAW),Spodoptera frugiperda Smith(Lepidoptera:Noctuidae)is an important agricultural pest that invaded China in the middle of December 2018.As a polyphagous pest,FAW is identified as a serious threat to agricultural production and food security in China.Pepper(Capsicum annuum L.),tomato(Solanum lycopersicum Mill.)and eggplant(Solanum melongena L.)are three of dominant solanaceous vegetables of this country.To our knowledge,the effects of these plants on the performances of FAW have not been well studied.In this study we assessed the fitness of this pest to these three plants.Results showed that FAW can complete its life cycle when fed with tomato and pepper,but not on eggplant.The population parameters of FAW fed with maize(Zea mays L.)and the three solanaceous vegetables were compared using the age-stage,two-sex life table method.Developmental duration was significantly different in the larval stage,but not in the pupae stage.FAW fed with pepper had the longest pre-adult period(41.73 d)and the lightest pupal weight(0.1134 g);the survival rate was lower than FAW fed with tomato.Significant differences were observed in the mean fecundity of female,with the highest(943.95 eggs)laid by FAW fed with tomato.FAW had the shortest mean generation time(T),the highest intrinsic rate of increase(r)and finite rate of increase(λ)on maize,and the highest net reproductive rate(R_(0))on tomato.Overall,FAW fitness on the three solanaceous vegetables was:tomato>pepper>eggplant.This study provides the foundation for further assessment of FAW risk to solanaceous vegetables and for establishing corresponding control strategies in China.

Cold hardiness of the invasive fall armyworm,Spodoptera frugiperda in China

Fall armyworm,Spodoptera frugiperda(J.E.Smith,1797),a crop pest native to tropical and subtropical regions of America,has invaded and spread into most regions in China,posing a severe threat to China’s agriculture.The cold hardiness directly determines its geographic distribution through adapting to winter temperatures of different regions.Here,we measured supercooling points and lethal time(LT)at low temperatures of S.frugiperda.The supercooling points for developmental stages in increasing order were:adults(-15.05℃)<pupae(-13.25℃)<prepupae(-10.50℃)<larvae(-9.03℃).Among eggs and 1st to 4th in star larvae,the 99%lethal time(LT_(99))was the highest for 4th in star larvae,with 99%of larvae dying after 18.59 d at 2℃,58.72 d at 7℃,and 66.28 d at 13℃.LT_(99) was the lowest for eggs with LTgg of 5.33 d at 2℃,9.28 d at 7℃,and 12.97 d at 13℃.This study provides mn understanding of overwintering regions of S.frugiperda in China which will be helpful for population forecasting and management.

Two-way predation between immature stages of the hoverfly Eupeodes corollae and the invasive fall armyworm(Spodoptera frugiperda J.E.Smith)

Since its 2018 invasion of eastern Asia,the fall armyworm Spodoptera frugiperda(Lepidoptera:Noctuidae)has become a key pest in local maize production.Though pesticides have been widely used to mitigate the initial S.frugiperda attack,biological control is receiving ample attention as a desirable,environmentally-sound alternative to chemical control.Hoverflies(Diptera:Syrphidae)are abundant natural enemies in Chinese maize fields and have been observed to consume S.frugiperda larvae.In this study,we use laboratory assays to study the two-way interaction between immature stages of S.frugiperda and the endemic syrphid Eupeodes corollae.To mimic natural conditions,assays were performed in the presence of fresh maize leaves.Those 2 nd or 3 rd instar larvae of E.corollae preyed on 1 st and 2 nd instar S.frugiperda larvae with a Holling type III response,consuming a respective theoretical maximum of 43.48 and 83.33 larvae over a 24-h period.Conversely,once S.frugiperda larvae reached 3 rd instar,they exhibited aggressive behavior and equally preyed on syrphid larvae with a Holling type III response.Those 5 th and 6 th instar larvae of S.frugiperda consumed a respective 16.39-19.23,6.02-19.61 and 6.76-8.26 of 1 st,2 nd and 3 rd instar E.corollae larvae per day.Though our results await field-level validation,S.frugiperda agonistic(i.e.,defensive)and consumptive behavior towards resident natural enemies such as E.corollae possibly degrades biotic resistance and raises its invasion potential.Our findings shine new light on the interaction between lepidopteran herbivores and their natural enemies,and can help advance the development of conservation biological control and other integrated pest management(IPM)strategies against S.frugiperda in China and abroad.