Axyridis Adults Research Articles

Prey selection behaviour in the multicoloured Asian ladybird, Harmonia axyridis (Coleoptera: Coccinellidae)

The multicoloured Asian ladybird, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is a generalist predator of aphids and other soft-bodied insects. Its diet leads to negative impacts on non-target species, despite its beneficial effects offered as biocontrol agent. Herein, we evaluated prey preferences and predation success of H. axyridis adults and 4th instar larvae exposed to binary prey combinations of insects commonly found in Italian vineyards. These binary combinations included a classic prey, Aphis craccivora (Hemiptera: Aphididae) and an alternative prey, i.e., first instar larvae of the European grapevine moth Lobesia botrana (Lepidoptera: Tortricidae), second instar larvae of H. axyridis, to evaluate cannibalistic behaviour of H. axyridis, fourth instar larvae of the non-target ladybird Scymnus apetzi (Coleoptera: Coccinellidae), to evaluate intra-guild predation. Results showed that H. axyridis larvae and adults can act as potential predators of the moth pest L. botrana. They were also able to predate the non-target coccinellid species S. apetzi, thus adversely affecting aphidophagous guilds. Harmonia axyridis larvae did not significantly prefer to predate A. craccivora over the other tested preys. Harmonia axyridis adults did not show significant preferences on A. craccivora over S. apetzi larvae, whereas they prefer A. craccivora over L. botrana and H. axyridis larvae. As a general trend, the prey selection time was shorter in H. axyridis larvae, if compared to adults. Overall, our study adds basic knowledge to the prey location behaviour of H. axyridis larvae and adults, showing main differences in predation parameters of larvae and adults of this species evaluating selected binary combinations of potential preys.

Volatiles from aphid-infested plants attract adults of the multicolored Asian lady beetle Harmonia axyridis

Volatiles play important roles in the recruitment of arthropod natural enemies, and are widely used in foraging by the multicolored Asian lady beetle Harmonia axyridis Pallas (Coleoptera: Coccinellidae). In its native range in Asia and throughout its invaded range, H. axyridis preys upon multiple species of aphids in both natural and agricultural settings, yet little is known about the volatile cues it employs to locate prey items. In this study, we test the attractiveness of volatiles emanating from four different aphid × plant combinations to H. axyridis adults in a Y-tube olfactometer. More specifically, we exposed host plants from various plant families as such: Artemisia lavandulaefolia (Asteraceae) with Macrosiphoniella artemisiae; Gossypium hirsutum (Malvaceae) with Aphis gossypii; Triticum aestivum (Poaceae) with Sitobion avenae and Schizaphis graminum; and Vicia faba (Fabaceae) with Megoura viciae. Next, using coupled gas chromatography – electroantennogram detection (GC-EAD) and gas chromatography – mass spectrometry (GC-MS), we identified the volatile compounds from aphid × plant combinations that elicit electrophysiological activity in H. axyridis adults. Lastly, a total of five volatiles were assessed in open-field tests with barrel traps. In olfactometer assays, H. axyridis adults preferred aphid-infested plants over un-infested plants or aphids alone. In GC-EAD trials, seven electrophysiologically-active compounds were found; and in ensuing behavioral assays, ladybeetles preferred five kinds of volatiles (i.e., p-diethylbenzene, 3-ethylacetophenone, 1,2-diethylbenzene, α-pinene and butyl acrylate). In open-field tests, H. axyridis were significantly attracted to all five info-chemicals at a concentration 100 mg/ml. Our work not only sheds light upon H. axyridis chemical ecology, but equally provides important information that can facilitate the future development of integrated pest management (IPM) tactics for aphid control or volatile-based trapping and monitoring technologies for H. axyridis in its invaded range.

The effects of sugarcane aphid density in sorghum on predation by lady beetles and lacewings

The sugarcane aphid, Melanaphis sacchari Zehntner (Hemiptera: Aphididae), is a new and devastating pest of sorghum (Sorghum bicolor (L.)) in the United States. Arthropod predators, especially lady beetles and green lacewings, are often abundant in sugarcane aphid-infested sorghum, but little is known about the effects of these predators on sugarcane aphid populations. We quantified the effect of two species of lady beetles (larvae and adults of Coccinella septempunctata L. and Harmonia axyridis Pallas) (Coleoptera: Coccinellidae) and green lacewings (larvae of Chrysoperla rufilabris Burmeister) (Neuroptera: Chrysopidae) on aphid colony growth across several aphid densities (20, 40, 80, 160). We found that all predator species and life stages significantly reduced the growth of sugarcane aphid populations at low to intermediate aphid densities (20, 40, and 80 aphids per colony). At the highest aphid density (160 aphids), however, H. axyridis larvae were much less effective than C. septempunctata larvae and adults and H. axyridis adults and lacewing larvae did not suppress sugarcane aphid colony growth. We incorporated these predator effects into a dynamic predator-prey model to predict the impact of predators on the short-term population dynamics of sugarcane aphids in sorghum (2–14 days) and the ability of these predators to suppress aphids below action thresholds (50–75 aphids per leaf). The model illustrated that all the predators we studied prevented aphid densities between 20 and 40 per leaf from reaching action thresholds. At initial densities of 80 aphids per colony, all predators were able to suppress aphids below threshold in two to four days. At the highest initial aphid density (160), however, H. axyridis larvae could not suppress aphids below the action threshold by four days and lacewing larvae never suppressed aphids below the threshold. Our results suggest that common predators in sorghum have the potential to suppress sugarcane aphid population growth and reduce the number of insecticide applications needed to control sugarcane aphids.

Sublethal and transgenerational effects of thiamethoxam applied to cotton seed on Chrysoperla externa and Harmonia axyridis.

Thiamethoxam, when applied as a seed treatment, can contaminate plant products, such as extrafloral nectar, and have non-target effects on beneficial arthropods. This study assessed the non-target effects of thiamethoxam applied to cotton seed on the life history parameters of the predators Chrysoperla externa (Neuroptera: Chrysopidae) and Harmonia axyridis (Coleoptera: Coccinellidae). Exposure of C. externa larvae to plants grown from thiamethoxam-treated seeds caused sublethal and transgenerational effects. Thiamethoxam treatment doubled the proportion of pharate adults and reduced egg fertility in C. externa F0 and F1 generations. In addition, the insecticide prolonged pupal developmental time in the C. externa F1 generation. Thiamethoxam treatment also had a transgenerational effect on exposed H. axyridis larvae, reducing pupal survival in the F1 generation. In the adult bioassay, thiamethoxam treatment reduced egg fertility of C. externa, prolonged the larval period, and reduced both fecundity and egg fertility of the F1 generation. Thiamethoxam also caused transgenerational effect on H. axyridis adults, reducing larval survival of the F1 generation. Thiamethoxam seed treatment was harmful for both predators, but C. externa was more affected by the insecticide than H. axyridis. © 2018 Society of Chemical Industry.

Extrafloral nectar of Hibiscus cannabinus promotes adult populations of Harmonia axyridis

ABSTRACTHigh numbers of Harmonia axyridis adults were observed even when aphid populations were low or absent in kenaf (Hibiscus cannabinus) fields. Compared to a control group given access to water alone or cotton aphids and water, longevity of H. axyridis adults provided with kenaf leaves containing extrafloral nectar significantly increased.

The status of Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) in Greece: A case of an exotic predator that failed to establish?

During 1994 -1999 several hundred thousands of Harmonia axyridis adults were released at various cultivations infested by aphids (citrus, vegetable and bean crops, maize, etc.) or in urban places on ornamental plants in central and southern Greece (mainly Attica and Peloponnessos region) as well as on several islands. During 1995-2007, samplings were conducted in some areas, in spring just before any new releases, in order to determine if H. axyridis overwintered in the field. In spring 1995 (the year that followed the first releases) as well in spring 1996-97 and 2000-07, no presence of H. axyridis was recorded in any of the orchards where the predator had been released. Only in spring 1998 and 1999 small colonies (<50 individuals) of overwintered H. axyridis adults were observed in Attica region. The above results indicate an inability of the H. axyridis released populations to establish in Greece, although in some areas this species became an important biocontrol agent during the season. In addition, some data collected regarding the composition of native coccinelid species pre- and post- release of H. axyridis could be an indication of no adverse effects imposed by H. axyridis on the native coccinellid fauna in Greece. Despite that, any re-initiation of releases of H. axyridis would not be wise because of its multiple negative effects observed in other countries of Europe and the USA. Contrary to this, the application of a survey and monitoring programme that will allow us to be prepared in case of a possible invasion of H. axyridis from northern Europe is suggested.

Habitat Preferences of the Invasive Harlequin LadybeetleHarmonia axyridis(Coleoptera: Coccinellidae) in the Western Cape Province, South Africa

The invasive and predatory harlequin lady beetle, Harmonia axyridis, has been introduced as a biological control agent to many agricultural areas worldwide and has now spread from agricultural to natural habitats where it threatens native arthropod biodiversity. The aim of this study was to determine how H. axyridis uses the local landscape during different times of the year in the Western Cape Province, South Africa. We also determined its association to native arthropod diversity. Harmonia axyridis adults and larvae, as well as arthropod herbivores, predators and other ladybeetles were sampled every second month for a year with a vacuum sampler in vineyards, natural habitats, edges between natural habitats and vineyards, and urban areas. Highest adult and larval H. axyridis abundance occurred in urban areas during all sampling periods, with a peak in May and July (winter). Vineyards and natural vegetation had very low abundances of H. axyridis. Harmonia axyridis had some, but limited effect on the local arthropod community abundance. There was also a negative relationship between H. axyridis and the overall arthropod community as well as a positive relationship between H. axyridis abundance and that of other ladybeetles. Harmonia axyridis appeared to influence the assemblage composition of other ladybeetles and herbivores. Overall, the native arthropod assemblage responded primarily to season and habitat and secondary to the presence of H. axyridis. Harmonia axyridis has a strong association with the urban environment, seemingly in association with the exotic aphid Tuberculatus annulatus that feeds on cultivated oak trees. Outside of the urban area, H. axyridis numbers were very low and its ecological impacts may be negligible.

Modification of Flight and Locomotion Performances, Respiratory Metabolism, and Transcriptome Expression in the Lady Beetle Harmonia axyridis through Sublethal Pesticide Exposure.

Biological control is usually used in combination with chemical control for practical agricultural applications. Thus, the influence of insecticides on the natural predators used for biological control should be investigated for integrated pest management. The ladybird Harmonia axyridis is an effective predator on aphids and coccids. Beta-cypermethrin is a broad-spectrum insecticide used worldwide for controlling insect pests. H. axyridis is becoming increasingly threatened by this insecticide. Here, we investigated the effect of a sublethal dose of beta-cypermethrin on flight, locomotion, respiration, and detoxification system of H. axyridis. After exposure to beta-cypermethrin, succinic female adults flew more times, longer distances, and during longer time periods. Exposure to a sublethal dose of beta-cypermethrin also promoted an increase in walking rate, walking distance, walking duration, and also an increase in respiratory quotient and respiratory rate. To investigate the effects of beta-cypermethrin on H. axyridis detoxification system, we analyzed the transcriptome of H. axyridis adults, focusing on genes related to detoxification systems. De novo assembly generated 65,509 unigenes with a mean length of 799 bp. From these genes, 26,020 unigenes (40.91% of all unigenes) exhibited clear homology to known genes in the NCBI non-redundant database. In addition, 10,402 unigenes were annotated in the Cluster of Orthologous Groups database, 12,088 unigenes were assigned to the Gene Ontology database and 12,269 unigenes were in the Kyoto Encyclopedia of Genes and Genome (KEGG) database. Exposure to beta-cypermethrin had significant effects on the transcriptome profile of H. axyridis adult. Based on uniquely mapped reads, 3,296 unigenes were differentially expressed, 868 unigenes were up-regulated and 2,248 unigenes were down-regulated. We identified differentially-expressed unigenes related to general detoxification systems in H. axyridis. This assembled, annotated transcriptome provides a valuable genomic resource for further understanding the molecular basis of detoxification mechanisms in H. axyridis.

The contribution of a beneficial insectary plant Scaevola aemula to survival and long-term establishment of flightless Harmonia axyridis in greenhouses

The fairy fan flower, Scaevola aemula R. Br., is a primary candidate insectary plant for maintaining populations of generalist predators. We conducted release experiments in greenhouses of cultivated eggplants to evaluate the effects of intercropping S. aemula on the establishment of flightless Harmonia axyridis Pallas. Compared with a monoculture of eggplant, all release experiments showed that flightless H. axyridis remained in greater numbers in plots with S. aemula planted alongside eggplant. In the release experiment of flightless H. axyridis larvae, the incidence of aphids in the plot with transplanted S. aemula was suppressed compared with that in the release plot without transplanted S. aemula. In a laboratory experiment, the longevity of flightless H. axyridis adults on blossom stems of S. aemula was greater than when open flowers and buds were removed, suggesting that the insects fed on floral resources such as the pollen of S. aemula. Our findings showed that the floral resources of S. aemula can enhance aphid suppression by improving the establishment of flightless H. axyridis.

Identification of Development-Related Genes in the Ovaries of Adult Harmonia axyridis (Pallas) Lady Beetles Using a Time- Series Analysis by RNA-seq.

Adults of the lady beetle species Harmonia axyridis (Pallas) are bred artificially en masse for classic biological control, which requires egg-laying by the H. axyridis ovary. Development-related genes may impact the growth of the H. axyridis adult ovary but have not been reported. Here, we used integrative time-series RNA-seq analysis of the ovary in H. axyridis adults to detect development-related genes. A total of 28,558 unigenes were functionally annotated using seven types of databases to obtain an annotated unigene database for ovaries in H. axyridis adults. We also analysed differentially expressed genes (DEGs) between samples. Based on a combination of the results of this bioinformatics analysis with literature reports and gene expression level changes in four different stages, we focused on the development of oocyte reproductive stem cell and yolk formation process and identified 26 genes with high similarity to development-related genes. 20 DEGs were randomly chosen for quantitative real-time PCR (qRT-PCR) to validate the accuracy of the RNA-seq results. This study establishes a robust pipeline for the discovery of key genes using high-throughput sequencing and the identification of a class of development-related genes for characterization.

Predation by generalist arthropod predators on Apolygus lucorum (Hemiptera: Miridae): molecular gut-content analysis and field-cage assessment.

The mirid bug Apolygus lucorum (Meyer-Dür) is a principal pest of cotton that also causes great damage to many other crops in China. A study was conducted to assess the mortality of A. lucorum from generalist arthropod predators using both molecular methods and a field-cage trial. The species-specific primer pair for the detection of A. lucorum tissues in predators was designed according to the sequences of the cytochrome oxidase subunit I (COI) gene. A total of 2096 generalist predators that consisted of ladybeetles, lacewings and spiders were collected, and A. lucorum remains were detected using the designed primers. Only 1.6% of these predators contained A. lucorum DNA, with the highest positive proportion (6.1%) for Harmonia axyridis larvae. In the field-cage experiment, the daily predation rates of second-instar A. lucorum nymphs by H. axyridis adults and larvae were 4.7 and 5.2% respectively. The overall low positive proportion of generalist predators with A. lucorum DNA detected using the molecular method, combined with the low predation rate in the field-cage experiment, indicated that the primary generalist predators likely had a limited role in the suppression of A. lucorum in the field. © 2016 Society of Chemical Industry.

Sequestration and Transfer of Cry Entomotoxin to the Eggs of a Predaceous Ladybird Beetle.

In the past 10 years, sequestration of Cry toxins and transfer to offspring has been indicated in three insect species in laboratory studies. This work directly demonstrates the sequestration and intergenerational transfer of Cry1F by the parents of the aphidophagous coccinellid predator, Harmonia axyridis, to its offspring. Recently emerged adults (10 individual couples/cage/treatment) were exposed during 20 days to aphids (100 Myzus persicae each day) that fed on a holidic diet containing 20 μg/mL Cry1F (and a control-group). Egg batches and neonate larvae were monitored daily, and counted and weighed for immunodetection of Cry1F by ELISA. At the end of the bioassay, the parents were weighed and analyzed by ELISA. Cry1F was detected in the offspring, both eggs and neonate larvae, of exposed H. axyridis adults. On average the neonate larvae had 60% of the Cry1F concentration of the eggs from the same egg batch. The Cry1F concentration in the adults was positively correlated with the concentration in their eggs. These three results provided independent evidence of transfer to offspring. No detrimental effects of Cry1F were observed on the age of first reproduction, total number of eggs laid per female, age-specific fecundity, egg development time, hatching rate, or fertility rate. The occurrence and generality of intergenerational transfer of Cry toxins should be investigated in the field to determine its potential ecological implications.

Wind Turbines as Overwintering Sites Attractive to an Invasive Lady Beetle,Harmonia axyridisPallas (Coleoptera: Coccinellidae)

One of the most invasive species of insects in Europe is the Asian lady beetle, Harmonia axyridis (Pallas, 1773). This species is often observed in anthropogenic areas, especially during autumn and winter when the adults enter buildings and start the overwintering process in large aggregations. On wind farms in intensively used farmland in Poland, H. axyridis uses wind turbines as overwintering sites. We hypothesize that H. axyridis adults are attracted to wind turbines for heat and protection from the wind. We examined H. axyridis aggregations on 33 wind turbines and surrounding areas and measured temperatures on different parts of the turbines. Turbines had a higher temperature than the surrounding areas. The lady beetles mostly occupied the northwestern side of the turbines, which is the side protected from wind. A possible explanation for the beetle’s preference for turbines as overwintering sites is the lack of other anthropogenic structures available for overwintering in a homogenous farmland.

Invasive alien species under attack: natural enemies of Harmonia axyridis in the Netherlands

The aphid predator Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is an invasive alien species in Europe and North America with negative effects on non-target species (including a decline of native ladybird populations), as well as fruit production, and human health. It is, therefore, important to find out which natural enemies could be used to reduce their numbers. Knowledge of H. axyridis’ natural enemies is summarised and data collected from the Netherlands over the past ten years are presented. Beetles were sampled from winter aggregations and from spring through to autumn with illuminated screens at night. Natural enemies were not found in samples of H. axyridis from 2003–2007. From 2008 onward H. axyridis adults were infested by: Hesperomyces virescens Thaxt. fungi (summer and winter), Parasitylenchus bifurcatus Poinar and Steenberg nematodes (winter), Coccipolipus hippodamiae (McDaniel and Morrill) mites (winter), and Dinocampus coccinellae (Schrank) parasitoids (summer and winter). Our results indicate that these natural enemies are starting to use H. axyridis as a host, but are as yet not sufficiently abundant to control the population.

Trehalase in Harmonia axyridis (Coleoptera: Coccinellidae): effects on beetle locomotory activity and the correlation with trehalose metabolism under starvation conditions

Trehalose is important in the energy metabolism of insects and protects them from extreme environmental conditions. To study the synthesis and degradation of trehalose, which is hydrolyzed to glucose by trehalase, two soluble trehalase cDNAs of the beetle Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) (HaTreh1-1 and HaTreh1-2) were cloned. The HaTreh mRNA expression levels were higher during the larval than adult stages. The locomotory behavior of the beetle and its mRNA expression of HaTreh1-1 and HaTreh1-2 under starvation were then investigated. Sprint speed and maximum moving distance were increased, and the pause frequency decreased in H. axyridis adults starved for 8 h compared with control (0 h) adults. In contrast, the mRNA expression of both HaTrehs increased quickly in adults starved from 8 to 18 h, with HaTreh1-1 in particular being expressed 289-fold in adults starved for 18 h versus control. These results show that stored food reserves can provide energy to sustain vital activities for 8 h in H. axyridis adults. However, the beetles require trehalose and other energy sources to provide energy to find food and for vital activities when starved for more than 8 h.

The potential of different fruit species as food for Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae)

Harmonia axyridis was detected for the first time in Brazil in 2002. Since then, it has been recorded from the South to the Midwest of the country. Until now, almost all the registered cases were associated with the presence of aphids, its preferred source of food. Due to the occurrence of this species in areas of fruit growing in the South and Southeast of Brazil, the aim of this study was to analyze the preference and use of three different cultivars of fruit. The tests were set at 25ºC ± 1ºC, RH 70% ± 10%, and in a photophase of 12 h and with apples (Gala and Fuji), grapes (Niágara and Rubi), and pears (Williams and Asian). In the undamaged fruit experiment, the insects did not cause any noticeable damage. In the damaged and undamaged fruit experiment, a higher and statistically significant percentage of H. axyridis adults were found in the three damaged fruits. In the different cultivar experiment the Niágara grape, the Gala apple, and the Williams pear were significantly preferred by H. axyridis adults. These results may help in the management of this insect, preventing damage, which have been observed in other places where H. axyridis was introduced.

Harmonia axyridis (Coleoptera: Coccinellidae) Exhibits No Preference between Bt and Non-Bt Maize Fed Spodoptera frugiperda (Lepidoptera: Noctuidae)

A recent shift in managing insect resistance to genetically engineered (GE) maize consists of mixing non-GE seed with GE seed known as “refuge in a bag”, which increases the likelihood of predators encountering both prey fed Bt and prey fed non-Bt maize. We therefore conducted laboratory choice-test feeding studies to determine if a predator, Harmonia axyridis, shows any preference between prey fed Bt and non-Bt maize leaves. The prey species was Spodoptera frugiperda, which were fed Bt maize (MON-810), expressing the single Cry1Ab protein, or non-Bt maize. The predators were third instar larvae and female adults of H. axyridis. Individual predators were offered Bt and non-Bt fed prey larvae that had fed for 24, 48 or 72 h. Ten and 15 larvae of each prey type were offered to third instar and adult predators, respectively. Observations of arenas were conducted at 1, 2, 3, 6, 15 and 24 h after the start of the experiment to determine the number and type of prey eaten by each individual predator. Prey larvae that fed on non-Bt leaves were significantly larger than larvae fed Bt leaves. Both predator stages had eaten nearly all the prey by the end of the experiment. However, in all combinations of predator stage and prey age, the number of each prey type consumed did not differ significantly. ELISA measurements confirmed the presence of Cry1Ab in leaf tissue (23–33 µg/g dry weight) and S. frugiperda (2.1–2.2 µg/g), while mean concentrations in H. axyridis were very low (0.01–0.2 µg/g). These results confirm the predatory status of H. axyridis on S. frugiperda and that both H. axyridis adults and larvae show no preference between prey types. The lack of preference between Bt-fed and non-Bt-fed prey should act in favor of insect resistance management strategies using mixtures of GE and non-GE maize seed.

Immune Response of Harmonia axyridis (Coleoptera: Coccinellidae) Supports the Enemy Release Hypothesis in North America

Abstract The multicolored Asian lady beetle, Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae), is an invasive species in North America that has a low susceptibility to indigenous natural enemies. We investigated the role of the immune system of H. axyridis in its resistance to North American population of the hymenopteran parasitoid Dinocampus coccinellae Schrank. An ultrastructural study of adult H. axyridis hemocytes under electron and light microscopy identified five different cellular types: plasmatocytes, granular hemocytes I, granular hemocytes II, oenocytoids, and spherule cells. Only granular hemocytes II and plasmatocytes are involved in the nodulation of bacteria and encapsulation of parasitoid eggs. Injection of Sephadex beads in H. axyridis adults induces an innate immune response and results in complete encapsulation of ≈28% of the beads after 24 h and 81% after 5 d. When H. axyridis was parasitized by D. coccinellae, we observed a decrease in the encapsulation response, and this pattern was inversely related to the number of parasitoid eggs in the H. axyridis hemolymph. The injection of polydnaviruses by D. coccinellae females and the multiple target hypotheses could both explain the encapsulation rate decreasing with increasing parasitoid egg load. Our results suggest that the immune system of H. axyridis could favor its escape from internal developing natural enemies indigenous to North America.

Control of Aphis gossypii and Myzus persicae (Hemiptera: Aphididae) by a flightless strain of Harmonia axyridis (Coleoptera: Coccinellidae) on green pepper plants in open fields

AbstractThe cotton aphid Aphis gossypii Glover and the green peach aphid Myzus persicae (Sulzer) are economically important pests with a worldwide distribution. We evaluated the efficacy of releasing a flightless adult strain of the multicolored Asian lady beetle Harmonia axyridis (Pallas) as a control measure against these aphids on green pepper plants in open fields. Flightless H. axyridis adults were observed on the green pepper plants in the releasing plots throughout the experimental period and were found to be effective biocontrol agents, markedly decreasing the numbers of aphids. These results suggest that adults of this flightless strain of H. axyridis are effective in controlling aphids on green pepper plants in open fields.

Visual and olfactory preference of Harmonia axyridis (Coleoptera: Coccinellidae) adults to various companion plants

Natural enemies can be attracted to companion plants that can provide them with suitable habitat including food and shelter. This study was conducted to determine if the multicolored Asian lady beetle, Harmonia axyridis Pallas (Coleoptera: Coccinellidae), could be attracted to olfactory and visual cues of various companion plant species. Ten potential plants that can attract and provide H. axyridis with alternate food sources (i.e. nectar and pollen) were selected for olfactory preference tests. These plants included dill ( Anethum graveolens), yarrow ( Achillea spp.), butterfly weed ( Asclepias tuberosa), dandelion ( Taraxacum officinale), bugleweed ( Ajuga reptans), marigold ( Tagetes tenuifolia), tansy ( Tanacetum vulgare), goldenrod ( Solidago spp.), morning glory ( Ipomoea spp.), and sunflower ( Helianthus annuus). Visual preference tests were conducted with six different colors: white, yellow, blue, red, green, and orange. The result of the olfactory preference test showed that H. axyridis adults significantly preferred sunflower and dill among the ten potential companion plants tested in this study. In a visual preference test, H. axyridis significantly preferred yellow to any other colors. The result of this study suggested that odor and color of some companion plants (olfactory and visual cues) could assist in the use of biological control by attracting H. axyridis adults to the cropping area.