Harmonia Axyridis Research Articles

The Molecular Properties and Roles of Pannier in Harmonia axyridis's Metamorphosis and Melanin Synthesis.

The GATA transcription factor Pannier is identified as the major regulatory gene in color pattern formation in the Asian multi-colored ladybird beetle (Harmonia axyridis). however, the mechanisms of Pannier in regulating melanin synthesis and development in H. axyridis remain elusive. In this study, we identified and characterized Pannier in H. axyridis (HaPnr) and showed it to have two alternative spliced variants named HaPnr-α and HaPnr-β. Analyses of developmental stage expression patterns revealed that HaPnr, HaPnr-α and HaPnr-β were constitutively expressed throughout all developmental stages. To examine the role of HaPnr in H. axyridis development, RNA interference was performed in late larvae (the fourth instar) and early pupae (the first day of pupa stage). The transcript levels of HaPnr were effectively suppressed after the injection of double-stranded RNA of HaPnr (dsHaPnr). The fourth instar larvae injected with dsHaPnr reduced the pupation rates to only 61.50%, compared with 88.5% in the dsGFP-injected group. The un-pupated larvae gradually died after 1 week, and visually unaffected pupae emerged into abnormal adults with malformed hind wings and melanin absent from the cuticle. These abnormal adults gradually died 10 days after eclosion. However, when early pupae were injected with dsHaPnr, the normal eclosion rate was achieved at 88.41% on day 6 after the injection. In addition, these successful eclosion adults also showed an absence of melanin in the cuticle, but they could mate normally and have normal fecundity as compared with the control. We further demonstrated that the suppression of HaPnr-α or HaPnr-β individually did not affect the pupation and eclosion process. The suppression of HaPnr-α expression resulted in elytra melanin decreasing in both the conspicua and the succinea subgroup in H. axyridis. Even though the suppression of HaPnr-β expression only affected the melanin synthesis in the succinea subgroup, it significantly prolonged the time taken for melanin synthesis to occur in the conspicua subgroup in H. axyridis. These results indicate that HaPnr plays an essential role in insect development, especially during their metamorphosis, and also support our hypothesis that HaPnr could regulate melanin synthesis in H. axyridis under the combined action with its two splicing variants, HaPnr-α and HaPnr-β.

Effects of long-term cold storage on maternal and progeny fitness of laboratory-reared Harmonia axyridis adults

Effects of long-term cold storage on maternal and progeny fitness of laboratory-reared Harmonia axyridis adults

Do Biotic and Abiotic Factors Influence the Prevalence of a Common Parasite of the Invasive Alien Ladybird Harmonia axyridis?

Hesperomyces virescens (Ascomycota, Laboulbeniales), a fungal ectoparasite, is thus far reported on Harmonia axyridis from five continents: North and South America, Europe, Africa, and Asia. While it is known that He. virescens can cause mortality of Ha. axyridis under laboratory conditions, the role of biotic and abiotic factors in influencing the distribution of He. virescens in the field is unknown. We collected and screened 3,568 adult Ha. axyridis from 23 locations in seven countries in Central Europe between October and November 2018 to test the effect of selected host characters and climate and landscape variables on the infection probability with He. virescens. Mean parasite prevalence of He. virescens on Ha. axyridis was 17.9%, ranging among samples from 0 to 46.4%. Host sex, climate, and landscape composition did not have any significant effect on the infection probability of He. virescens on Ha. axyridis. Two color forms, f. conspicua and f. spectabilis, had a significantly lower parasite prevalence compared to the common Ha. axyridis f. novemdecimsignata.

Çanakkale ili yumuşak ve sert çekirdekli meyve bahçelerindeki predatör coccinellidler (Coleoptera: Coccinellidae) ve afitlerin (Hemiptera: Aphididae) etkileşimleri

This study revealed the tritrophic interactions of predatory coccinellids-host aphids-host plants on pome and stone fruit trees and herbaceous plants in fruit orchards of Çanakkale Province, Turkey. Field sampling was done during the spring and summer seasons in 2020 and 2021. Twelve predatory species belonging to eight genera from the family Coccinellidae (Coleoptera) were found interacting with eleven host aphids from the family Aphididae (Hemiptera) on eight host plants. A total of 33 tritrophic interactions of predatory coccinellids-host aphids-host plants were revealed on the pome and stone fruit orchards in the Çanakkale Province. From the predators, Harmonia axyridis (Pallas) associated with seven aphids was the most common coccinellid, followed by Oenopia conglobata (L.) which was associated with six aphids. From the aphids, Brachycaudus helichrysi (Kaltenbach) was the most common species; it was associated with ten different predatory coccinellids. Also, from the host plants, the highest number of the interactions of predatory coccinellids-host aphids were revealed on Cydonia oblonga Mill. (Rosaceae) and Prunus domestica L. (Rosaceae) in the pome and stone fruit orchards of Çanakkale Province. As a result, it is considered that the tritrophic interactions of predatory coccinellids-host aphids-host plants should be better understood to increase the success of biological control of pest aphids on the fruit orchards.

Fungal ectoparasites increase winter mortality of ladybird hosts despite limited effects on their immune system.

Winter represents a challenging period for insects inhabiting temperate regions. A plethora of studies have investigated how environmental conditions such as temperature affect insect overwintering success. However, only a few studies have focused on biotic factors and the mechanisms affecting the overwintering performance of insects. Here, we investigated the effects of the parasitic fungus Hesperomyces virescens on the overwintering performance and immune system functioning of the invasive ladybird Harmonia axyridis. Winter survival was significantly lower for infected than for uninfected ladybirds. Body mass loss during overwintering tends to be higher for infected individuals compared to uninfected ones and for larger ladybirds. In addition, parasitic infection reduced post-winter longevity without food in male but not female ladybirds. Total haemocyte and protein concentration as well as antimicrobial activity against Escherichia coli significantly decreased during ladybird overwintering. However, haemolymph parameters were only poorly affected by Hesperomyces infection, with the exception of antimicrobial activity against E. coli that tended to be higher in infected ladybirds. Interestingly, none of the pre-winter haemolymph parameters were good predictors of ladybird winter survival. Overall, our results indicate that energy exhaustion unrelated to immune system challenge is the most probable explanation for increased overwintering mortality in infected ladybirds.

Relationship Between the Duration of Death-Feigning and Temperature in Black and Red Elytral Types of a Polymorphic Ladybug, Harmonia axyridis

Relationship Between the Duration of Death-Feigning and Temperature in Black and Red Elytral Types of a Polymorphic Ladybug, Harmonia axyridis

Understanding nutritive need in Harmonia axyridis larvae: Insights from nutritional geometry.

The multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), is an important natural enemy in agricultural ecosystems. In spite of being a carnivore consuming protein-rich preys, the lady beetles often consume carbohydrate-rich food like nectar or honeydew. However, most studies on nutrition regulation of carnivores mainly focus on protein and lipid, two major macronutrients in preys. In this study, nutrition regulation of protein and carbohydrate has been investigated in the 4th instar larvae of H. axyridis using Geometric Framework. We provided the insects two pairs of foods, one a protein-biased one and the second carbohydrate-biased, to determine the intake target. We then confined them to nutritionally imbalanced foods to examine how they regulated food intake to achieve maximal performance. The larvae performed well on the 2 foods that containing the closest P:C ratios to the intake target, but, surprisingly, the lipid content was much lower than that in the choice experiment. The lady beetles seemed to maintain the optimal lipid content by consuming carbohydrate-rich food. Moreover, consuming the carbohydrate-rich food was less metabolically expensive than the protein-rich food. Therefore, switching behavior between plant and animal foods actually reflects their nutritive needs. These findings extended our understanding of predator forage behavior and its influence on food web in ecosystems, and shed light on the role of agri-environment schemes in meeting the nutritional need of predators in field.

The status and distribution of Pennington’s Protea butterfly Capys penningtoni (Lepidoptera: Lycaenidae: Theclinae)

The Red List status of Pennington’s protea butterfly Capys penningtoni has deteriorated from Vulnerable to Critically Endangered since 2009. This species is endemic to part of the midlands and Drakensberg foothills of the province of KwaZulu-Natal, South Africa. Capys penningtoni is restricted to protea savanna where its hostplant, Protea caffra, occurs. A research programme was started when the Red List status of the species was Vulnerable, with the aims of preventing the extinction of C. penningtoni and improving its conservation status. An initial requirement was to more accurately determine the distribution and conservation status of C. penningtoni. A further requirement was to ascertain what might be the main threats facing the species in the wild. Surveillance of the species at some sites was carried out to try and ascertain whether the conservation status of the species was deteriorating further. Our knowledge of the distribution range of the species has improved with the identification of seven previously unknown sites where the species was present. A distribution model was developed for the species that predicted that C. penningtoni could be more widely distributed in the central midlands and Drakensberg foothills of KwaZulu-Natal. The model did not predict the occurrence of the species at three of the newly discovered sites. Further ground-truthing of the model is required. Surveillance results suggest that C. penningtoni may have become locally extinct or less abundant at sites where it was previously recorded, indicating that its conservation status has deteriorated. The main threats to C. penningtoni appears to be the presence of the alien invasive Harlequin ladybird beetle Harmonia axyridis and the inappropriate fire regimes and burning practices in the protea savanna habitat of the species.

Binding Affinity Characterization of Four Antennae-Enriched Odorant-Binding Proteins From Harmonia axyridis (Coleoptera: Coccinellidae).

Harmonia axyridis is an important natural enemy that consumes many agricultural and forestry pests. It relies on a sensitive olfactory system to find prey and mates. Odorant-binding proteins (OBPs) as the first-step of recognizing volatiles, transport odors through sensillum lymph to odorant receptors (ORs). However, little is known about the molecular mechanisms of H. axyridis olfaction. In this study, four H. axyridis antenna specific OBP genes, HaxyOBP3, 5, 12, and 15, were bacterially expressed and the binding features of the four recombinant proteins to 40 substances were investigated using fluorescence competitive binding assays. Three-dimensional structure modeling and molecular docking analysis predicted the binding sites between HaxyOBPs and candidate volatiles. Developmental expression analyses showed that the four HaxyOBP genes displayed a variety of expression patterns at different development stages. The expression levels of HaxyOBP3 and HaxyOBP15 were higher in the adult stage than in the other developmental stages, and HaxyOBP15 was significantly transcriptionally enriched in adult stage. Ligand-binding analysis demonstrated that HaxyOBP3 and HaxyOBP12 only combined with two compounds, β-ionone and p-anisaldehyde. HaxyOBP5 protein displayed binding affinities with methyl salicylate, β-ionone, and p-anisaldehyde (Ki = 18.15, 11.71, and 13.45 μM). HaxyOBP15 protein had a broad binding profile with (E)-β-farnesene, β-ionone, α-ionone, geranyl acetate, nonyl aldehyde, dihydro-β-ionone, and linalyl acetate (Ki = 4.33–31.01 μM), and hydrophobic interactions played a key role in the binding of HaxyOBP15 to these substances according to molecular docking. Taken together, HaxyOBP15 exhibited a broader ligand-binding spectrum and a higher expression in adult stage than HaxyOBP3, 5, and 12, indicating HaxyOBP15 may play a greater role in binding volatiles than other three HaxyOBPs. The results will increase our understanding of the molecular mechanism of H. axyridis olfaction and may also result in new management strategies (attractants/repellents) that increase the biological control efficacy of H. axyridis.

Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae) in the Cities of Moscow and Yalta: Its Competition with Native Species of Coccinellids and the Influence of Parasitoids on Its Number

Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae) in the Cities of Moscow and Yalta: Its Competition with Native Species of Coccinellids and the Influence of Parasitoids on Its Number

Consumption patterns of the multicolored Asian ladybird Harmonia axyridis on the broad bean aphid Aphis craccivora

• Consumption patterns of ladybirds is meaningful for biological control programs. • Ladybird females were superior predator of aphids base on functional response. • Fourth-instar ladybird larvae suffered from greater intraspecific competition. • Adults and 4th-instar larvae of ladybirds are more effective in controlling aphids. • Intraspecific competition should be considered during field releases of ladybirds. The multicolored Asian ladybird Harmonia axyridis Pallas is often used as a biological control agent against Aphis craccivora Koch, a key pest aphid of broad bean. Understanding consumption characteristics of biological control agents is critical for developing effective biological control programs. Here, under laboratory conditions we studied consumption patterns of H. axyridis on A. craccivora including functional response and intraspecific competition. All larvae (1st-, 2nd-, 3rd-, 4th-instar) and adults (male and female) of H. axyridis exhibited a Type II functional response to A. craccivora . We found H. axyridis females were superior to individuals of other developmental stages, based on three key parameters in functional response model, i.e. attack rate ( a = 90.0%), handling time ( T h = 2.7 min), and consumption threshold ( N max = 526.7 individuals). Results from our analysis of intraspecific competition showed that when attacking A. craccivora , 4th-instar larvae of H. axyridis suffered from the greatest intraspecific competition (coefficient of mutual interference, m = 0.48). Our results show that 4th-instar larvae and adults of H. axyridis are most effective in controlling A. craccivora , and proper density of H. axyridis released will reduce intraspecific competition. This analysis reveals both prey-predator and predator-predator interactions, and highlights the value of biological control in reducing pesticide use and protecting ecological environments.

Provision of small sterile eggs is a circumstance-dependent maternal investment in sibling cannibalism in the ladybird beetle Harmonia axyridis (Coleoptera: Coccinellidae)

Many aphidophagous ladybird beetles lay clusters of eggs and sibling cannibalism occurs at hatching. Larvae that hatch early tend to cannibalize undeveloped eggs and those that hatch late. The cannibalized eggs, especially those that are sterile, represent a maternal investment in the cannibal and are regarded as "trophic" eggs, which increase their chances of surviving. The characteristics of cannibalized eggs, however, are poorly studied. In this study, I determined the sizes of eggs that developing and undeveloped eggs within egg clusters of Harmonia axyridis (Coleoptera: Coccinellidae). Developing eggs were significantly larger (on average 3.45% larger) than the undeveloped sterile ones, which were mainly small. Furthermore, the hatchability of eggs was also significantly associated with their size, inclusive of the maternal effects. These results indicate that the production of relatively small sterile eggs functions as circumstance-dependent maternal investment in improving the survival of the first instar larvae to hatch in each egg cluster.

Contribution to the lady beetle fauna of the Yucatan Peninsula and integrative taxonomy for species delimitation

Lady beetles (Coleoptera: Coccinellidae) are among the most familiar insects; many species are of economic importance, but their diversity in the tropics is poorly known. We aimed to contribute to the knowledge of the lady beetle fauna of the Yucatan Peninsula, particularly for Quintana Roo state. We used an integrative approach for species identification, comparing classical morphological identifications and quick automated methods for species delimitation using DNA barcode sequences. Through a literature review and a survey of lady beetles in gardens in Quintana Roo, we further provide an updated list of the species found on the Yucatan Peninsula. Out of the 40 species delimited in our study, 34 are new reports for the peninsula, and 36 are new for Quintana Roo state. Overall, 62 species of lady beetles are now recorded for the entire region, including three exotics: the invasive Harmonia axyridis, Chilocorus nigrita, and Delphastus catalinae. Our study also contributed to public reference libraries with 110 barcode sequences for the tropics belonging to 34 delineated species. We showed that cytochrome oxidase 1 (COI) sequences can be useful for lady beetle species delimitation and that the Automatic Barcode Gap Discovery algorithm (ABGD) was the best method, complementing the number of initially delineated morphospecies. The Barcode Index Number (BIN) approach overestimated seven putative species due to the splitting of conspecifics, while the ABGD method suggested two additional MOTUs at a prior intraspecific distance of 0.059. Combined molecular and morphological data in our study revealed one additional putative species of Diomus, initially considered a tentative colour variation. Our study exemplifies how molecular methods paired with classical taxonomy can efficiently assist in delineating species when descriptions and identification keys are unavailable and highlights the possible great richness of coccinellid species awaiting exploration and description on the Yucatan Peninsula.

Double Infections of the Invasive Ladybird Harmonia axyridis

The dramatic spread of invasive alien species over the past century is considered to be an important threat to ecosystems worldwide. The harlequin ladybird,Harmonia axyridis, from eastern Asia, is considered to be one of the most invasive species. Originally introduced across the world as a biological control agent against crop pests owing to its voracious appetite and hardiness, those same qualities have madeH. axyridisan invader that is difficult to eradicate.Harmonia axyridishas proven resilient against a variety of pathogens that have negative effects on other coccinellids. However, little research has examined the effects of simultaneous infections of multiple natural enemies onH. axyridis. Here we present the available information on such double infections onH. axyridis, and discuss further research directions in this area.

Zelus renardii Roaming in Southern Italy.

Simple SummaryThe leafhopper assassin bug Zelus renardii (Hemiptera: Reduviidae) first entered Europe in 2012 and has since acclimatised. Z. renardii is now a common insect predator in agroecosystems and urban and peri-urban areas. We performed a metadata analysis of 165 years of Z. renardii literature. Moreover, we provide laboratory tests of Z. renardii predation. The latter indicates Z. renardii interplay with relevant insect targets, such as Philaenus spumarius, Neophilaenus campestris, Bactrocera oleae, Kermes vermilio, Nidularia pulvinata, Harmonia axyridis, Apis mellifera, Aleurocanthus spiniferus, Aleurothrixus floccosus, Macrohomotoma gladiata, Drosophila suzukii, Drosophila melanogaster, Megaselia scalaris, Pseudococcidae, Miridae, and Issidae. Furthermore, predation on Aphrophoridae and other olive pests brands Z. renardii as a good mass-rearing candidate for inundative biocontrol programs of Xylella fastidiosa pauca ST53 infections and could also reduce damage caused by other olive pests. Overall, this reduviid is harmless to humans and beneficial insects.This study collects data from the literature and updates our Zelus renardii Kolenati, 1856 (Leafhopper Assassin Bug, LAB) prey knowledge. The literature consists of ca. 170 entries encompassing the years 1856 to 2021. This reduviid originated in the Nearctic region, but has entered and acclimatised in many Mediterranean countries. Our quantitative predation experiments—in the laboratory on caged plants plus field or environmental observations—confirm that LAB prefers a selected array of prey. Laboratory predation tests on living targets (Hemiptera, Coleoptera, Diptera, and Hymenoptera) agree with the literature. Zelus renardii prefers comparatively large, highly mobile, and readily available prey. LAB preferences on available hemipterans targets suggest that Zelus renardii is a good inundative biocontrol agent for Xylella fastidiosa pauca ST53 infections. LAB also prey on other important olive pests, such as Bactrocera oleae. Therefore, Zelus renardii is a major integrated pest management (IPM) component to limit Xylella fastidiosa pandemics and other pest invasions.

Dietary Effects on Biological Parameters and Gut Microbiota of Harmonia axyridis.

The multicolored Asian lady beetle (Harmonia axyridis, H. axyridis, Coleoptera, and Coccinellidae) is an effective biocontrol agent against agricultural pests. Previous studies have suggested that amount, type, and the quality of food can directly affect the biological aspects of H. axyridis. In this study, we investigated the influence of the food sources (Acyrthosiphon pisum Harris, Diaphorina citri Kuwayama, and artificial diets) on the gut microbiota diversity and the biology, reproductive variables, and population growth indicators of H. axyridis. Three kinds of diets were considered in this study: (1) HY: the adult of A. pisum Harris (HY group); (2) HM: the adult of D. citri Kuwayama (HM group); (3) HR: artificial diets prepared by blending a portion of fresh homogenized pork liver (15 g), honey (3 g), distilled water (35 ml) (HR group). We found that gut microbiota composition and diversity and the biological parameters differed when H. axyridis was fed with different diets. The abundance of Enterobacteriaceae was the highest in the HM group, followed by HY group, and was the lowest in the HR group. The abundance of Staphylococcaceae was highest in the HR group. Among the gut fungi, Davidiellaceae and Wallemiaceae were the highest and lowest in the HY group; Incertae_sedis were the major gut fungi in the HR group. Meanwhile, the changes of biological parameters may be correlated with the changes of Streptococcaceae abundance, Micrococcaceae abundance, Staphylococcaceae abundance, and Enterobacteriaceae abundance in responds to diet changes. To sum up, these data suggest that different diets can influence the changes in adult H. axyridis gut microbiota, consequently affecting the biological parameters.

Biotoxicity Evaluation of a Cationic Star Polymer on a Predatory Ladybird and Cooperative Pest Control by Polymer-Delivered Pesticides and Ladybird.

Although employing nanocarriers for gene/drug delivery shows great potential in agricultural fields, the biotoxicity of nanocarriers is a major concern for large-scale applications. Herein, we synthesized a cationic star polymer (SPc) as a pesticide nanocarrier/adjuvant to evaluate its safety against a widely used predatory ladybird (Harmonia axyridis). The application of SPc at extremely high concentrations nearly did not influence the hatching of ladybird eggs but it led to the death of ladybird larvae at lethal concentration 50 (LC50) values of 43.96 and 19.85 mg/mL through the soaking and feeding methods, respectively. The oral feeding of SPc downregulated many membrane protein genes and lysosome genes significantly, and the cell membrane and nucleus in gut tissues were remarkably damaged by SPc application, revealing that the lethal mechanism might be SPc-mediated membrane damage. Furthermore, the oral feeding of SPc increased the relative abundance of Serratia bacteria in ladybird guts to result in bacterial infection. Coapplication of ladybird and SPc-loaded thiamethoxam/matrine achieved desired control efficacies of more than 80% against green peach aphids, revealing that the coapplication could overcome the slow-acting property of ladybirds. To our knowledge, this is the first attempt to investigate the polymer-mediated lethal mechanism toward natural enemies and explore the possibility of coapplying SPc-loaded pesticides and natural enemies for pest management.

Effect of High Temperature and Natural Enemies on the Interspecies Competition Between Two Wheat Aphid Species, Rhopalosiphum padi and Sitobion miscanthi.

Interspecies competition affects the distribution, quantity, and community structure of insects, especially among closely-related (congeners) species. Some ecological factors differentially affect the fitness of co-existing species, thus conferring an advantage on one competitor, and then the structure of communities. The present work evaluated the effects of high temperature and natural enemies on the interspecific competition between the grain aphid Sitobion miscanthi (Takahashi) (Aphididae: Hemiptera) and bird cherry-oat aphid Rhopalosiphum padi (L.) (Hemiptera: Aphididae), two key pests of wheat in China. Results showed that the population growth of R. padi was faster at 30°C, and the intrinsic rate of natural increase (rm) value was 5 times that of S. miscanthi, indicating that R. padi was more high-temperature resistant and has advantages in interspecific competition at high temperature. Moreover, compared to S. miscanthi, the population of R. padi was less affected by their predator, larvae of the multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), and aphid parasitoids, Aphidius avenae (Haliday) or Aphidius gifuensis (Ashmead) (Hymenoptera: Aphidiidae), which made them gain an advantage in the interspecific competition. Our results enrich the knowledge of phytophagous insect interspecific completion and implicate the ecological mechanism of R. padi may become the dominant species in wheat fields in China.

The Rare Five-Spot Ladybird Coccinella quinquepunctata (Coleoptera: Coccinellidae) Surviving in an Unstable Habitat

Coccinella quinquepunctata (the five-spot ladybird), was considered extinct in the UK until 1987. Since this time the species is abundant, however, only in very specific habitat in Wales and Scotland. As a result, it is classified as (RDB3) Rare, mainly as a result of its preferred habitat; exposed riverine sediment. This habitat is in a constant state of alteration by natural and anthropogenic means with the quality of the habitat being degraded to the point that specialised invertebrate species, such as C. quinquepunctata, are at risk. In recent years, the rapid spread of the invasive alien Harmonia axyridis (harlequin ladybird) has been linked to a decline in native coccinellid numbers. There is concern that the narrow habitat requirements of C. quinquepunctata, together with the continuing spread of H. axyridis, will result in a decline in the abundance of C. quinquepunctata. Two habitat types (exposed riverine sediment and grassland adjacent to the ERS) along 12 Welsh rivers were surveyed for C. quinquepunctata, H. axyridis, and other coccinellids. When an individual coccinellid was recorded, so too was its elevation from the substrate. Plant species that C. quinquepunctata were observed on and vegetation density on the shingle were assessed in broad categories. Of all recorded coccinellids, 76% were C. quinquepunctata while 7% were H. axyridis. A third of the sites had no records of H. axyridis, while C. quinquepunctata was recorded at all sites. A significantly greater number of C. quinquepunctata were observed within 0.5 m of the exposed riverine sediment rather than higher up on the vegetation. Presence of the invasive plant Himalayan balsam (Impatiens glandulifera) may have a negative effect on C. quinquepunctata, as it directly affects the vegetation growth on expose riverine sediment. These findings indicate that intraguild predation is unlikely to occur given the low abundance of H. axyridis in C. quinquepunctata habitat. However, the unstable nature of exposed riverine sediment, and a combination of threats from invasive alien species indicates that this species is still at risk of sudden decline and requires further monitoring and conservation efforts.

Molecular Identification and Functional Characterization of Methoprene-Tolerant (Met) and Krüppel-Homolog 1 (Kr-h1) in Harmonia axyridis (Coleoptera: Coccinellidae).

Juvenile hormone (JH) plays a key role in regulating insect reproductive processes. Methoprene-tolerant (Met), as a putative JH receptor, transduces JH signals by activating the transcription factor krüppel homolog 1 (Kr-h1). To understand the effects of Met and Kr-h1 genes on female reproduction of natural enemy insects, the Met and Kr-h1 were identified and analyzed from Harmonia axyridis Pallas (HmMet and HmKr-h1). The HmMet protein belonged to the bHLH-PAS family with bHLH domain, PAS domains, and PAC domain. HmMet mRNA was detected in all developmental stages, and the highest expression was found in the ovaries of female adults. The HmKr-h1 protein had eight C2H2-type zinc finger domains. HmKr-h1 mRNA was highly expressed from day 7 to day 9 of female adults. The tissue expression showed that HmKr-h1 was highly expressed in its wing, leg, and fat body. Knockdown of HmMet and HmKr-h1 substantially reduced the transcription of HmVg1 and HmVg2, inhibited yolk protein deposition, and reduced fecundity using RNA interference. In addition, the preoviposition period was significantly prolonged after dsMet-injection, but there was no significant difference after dsKr-h1-silencing. However, the effect on hatchability results was the opposite. Therefore, we infer that both HmMet and HmKr-h1 are involved in female reproduction of H. axyridis, and their specific functions are different in certain physiological processes. In several continents, H. axyridis are not only beneficial insects, but also invasive pests. This report will provide basis for applying or controlling the H. axyridis.