Banker Plant Research Articles

Prospects for habitat management to suppress vegetable pests in Australia

AbstractHabitat management is an ecologically based approach to suppress pest densities, utilising properties of non‐crop vegetation to improve the impact of natural enemies or to directly affect pest behaviour. Research in this approach has escalated dramatically this century, extending to uptake in some crops, but adoption in Australia has been lower than overseas. Here, we address the need of the Australian vegetable sector to reduce reliance on insecticides by assessing the scope for habitat management in brassica (Brassicaceae), lettuce (Lactuca sativa) (Asteraceae), capsicum (Capsicum annuum) (Solanaceae), carrot (Daucus carota) (Apiaceae), French bean (Phaseolus vulgaris) (Fabaceae) and sweetcorn (Zea mays) (Poaceae) crops. Each crop is of major economic importance, and together, they represent contrasting botanical families and production systems that are associated with different arthropod complexes. We review studies of habitat management that are based on provision of shelter, nectar, alternative prey or pollen for natural enemies (top‐down effects) or changing pest behaviour (bottom‐up effects) through intercropping or trap crops. The likely utility of these approaches under Australian conditions is assessed, and recommendations are made to promote adoption and for adaptive research. Nectar‐ and pollen‐providing plants, such as alyssum (Lobularia maritima) (Brassicaceae), offer strong potential to promote natural enemies in multiple crops whilst trap crops, especially yellow rocket (Barbarea vulgaris) (Brassicaceae), have more targeted utility against diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae), the most serious pest of brassicas. Opportunities for intercrops and banker plant species are also identified. Our recommendations serve as a platform for researchers and for farmer‐led studies to help realise the full potential of habitat management approaches in Australian vegetable production systems.

The Host-Plant Origin Affects the Morphological Traits and the Reproductive Behavior of the Aphid Parasitoid Aphelinus mali

Diversifying agroecosystems through habitat management inside or outside production fields can provide alternative hosts and/or prey for natural enemies. In semi-natural habitats, parasitoids may find alternative host-plant complexes (HPC) that could allow their development when pest hosts are scarce in the field. However, morphological and physiological differences between alternative and targeted HPCs could affect the preference and fitness of the parasitoids, possibly altering their efficacy in regulating pests. In the present study, we examined two Aphelinus mali parasitoid populations developing on Eriosoma lanigerum from two host plants (Malus domestica-apple trees and Pyracantha coccinea). We hypothesized that A. mali from both HPCs will show different life history traits and behaviors because primary and alternative host-plants are known to induce variations in parasitoid biological performance. Our findings indicate that A. mali originating from E. lanigerum on P. coccinea parasitized more aphids and are smaller than those originating from E. lanigerum on apple. Furthermore, these parasitoids did not significantly vary their ability to attack and oviposit apple E. lanigerum, suggesting that P. coccinea could function as a suitable banker plant for A. mali. We discuss the potential use of P. coccinea in conservation biological control of E. lanigerum in apple orchards.

Diverse non-crop vegetation assemblages as banker plants for predatory mites in strawberry crop

Non-crop plant diversity plays a fundamental role in the conservation of predatory mite (PM) and can be proposed as a banker plant system (BPS). BPSs provide plants that host natural enemies in greenhouses or field crops and may improve the efficiency of biological control. The aim of this study was to investigate if a diverse plant composition could be a suitable BPS for PMs in strawberry crops. A plant inventory characterized 22 species of non-crop plants harboring PMs. The most abundant PMs, in decreasing order, were Neoseiulus californicus, Neoseiulus anonymus, Euseius citrifolius, and Euseius concordis. PMs were randomly distributed among plants. We also found specific associations of Phytoseiidae species and phytophagous or generalist mites on plants. Due to this, four species were deemed suitable as banker plants: Capsicum sp., Leonurus sibiricus, Solanum americanum, and Urochloa mutica. Moreover, these plants combined a high PMs density and a low occurrence or absence of pest-mites. This study suggests shifting the traditional view that BPSs are composed of a limited number of species to use plant assemblages. This contributes to both conservation and augmentative biological control.

The Fitness of Mass Rearing Food on the Establishment of Chrysopa pallens in a Banker Plant System under Fluctuating Temperature Conditions.

Simple SummaryThe predatory lacewing, Chrysopa pallens, a generalist predator in the field, plays an important role in sustainable, integrated pest management strategies by allowing a reduction in the use of chemical pesticides. However, the effect of mass rearing food, i.e., eggs of the rice moth Corcyra cephalonica, on the establishment of C. pallens in a banker plant system in the field is unknown. Based on the age-stage, two-sex life table, and predation rate data of C. pallens ever cultured on the C. cephalonica eggs or the aphid Megoura japonica preying on Aphis craccivora under fluctuating temperature conditions in a greenhouse, we found that C. pallens could complete their development fed on A. craccivora regardless of the food used during culture. This suggests that rice moth eggs could be provided for the mass rearing of predatory lacewings without affecting their population development and biological performance in practical applications compared with lacewings cultured on aphids. This information can serve as a basis for the application of a banker plant system with the mass reared C. pallens in the field.Banker plant systems can be used to sustain a reproducing population of biological control agents (BCAs) within a crop, thus providing long-term pest suppression. The founder population of natural enemies in banker plant systems is usually mass-reared on factitious hosts. Thus, a better understanding of the population fitness and pest control performance of mass-reared BCAs in the field is crucial when developing integrated pest management (IPM) strategies. In this study, we determined the fitness of the generalist predator, Chrysopa pallens (Hemiptera: Chrysopidae) ever cultured on different food sources (i.e., mass rearing food, Corcyra cephalonica eggs, and aphid food, Megoura japonica) preying on Aphis craccivora in a banker plant system in a greenhouse based on Chi’s age-stage, two-sex life table analysis method. The life tables and predation rate parameters of C. pallens were not significantly different between both treatments under fluctuating temperature conditions. Corcyra cephalonica eggs did not significantly weaken the performances of C. pallens in a Vicia faba–A. craccivora banker plant system compared to aphids. In conclusion, C. cephalonica eggs can be used for the mass production of C. pallens as the founder population in a banker plant system. Moreover, linking the life table data with the predation rate is an effective strategy for evaluating mass rearing programs in establishing banker plant systems.

Combining banker plants to achieve long-term pest control in multi-pest and multi-natural enemy cropping systems

Combining banker plants to achieve long-term pest control in multi-pest and multi-natural enemy cropping systems

Banker plants and landscape composition influence colonisation precocity of tomato greenhouses by mirid predators

Conservation biological control involves manipulation of the environment to enhance the effectiveness of natural enemies in controlling crop pests. In this study, we combined historical data, sticky trap sampling of tomato greenhouses and beat sampling of adjacent vegetation to identify which greenhouse characteristics, habitat management practices and landscape features favour an early colonisation of tomato greenhouses by the key mirid predator Macrolophus pygmaeus and its establishment in NE Spain. Results show that landscape composition and the use of Calendula officinalis banker plants inside the greenhouse are key factors. In general, greater amounts of herbaceous semi-natural cover at the landscape scale promoted M. pygmaeus colonisation, while the use of C. officinalis banker plants encouraged M. pygmaeus colonisation independently of the landscape context. We identified host plants adjacent to tomato greenhouses that sustain M. pygmaeus populations; however, they did not have a major effect on M. pygmaeus colonisation compared to larger landscape and banker plant effects. Early colonisation of greenhouses by this predator species also translated into lower accumulated incidence of pests at the end of the sampling period. This study demonstrates the importance of active habitat management practices in promoting the early arrival of M. pygmaeus in greenhouses with delayed spontaneous colonisation.

Establishment of a Faba Bean Banker Plant System with Predator Orius strigicollis for the Control of Thrips Dendrothrips minowai on Tea Plants under Laboratory Conditions

Simple SummaryThe banker plant system may provide an effective and economical method for long-term suppression of insect pests. We developed a non-crop banker plant system aiming to improve the control of stick tea thrips Dendrothrips minowai in tea plantations. In this system, we used the polyphagous predator Orius strigicollis (Poppius) as the biocontrol agent, the black bean aphid Aphis fabae (Scopoli) as an alternative food, and the faba bean Vicia faba L. as the banker plant to support the predator in controlling pest thrips. Laboratory tests revealed that the control efficacy of the banker plant system was higher than that of directly releasing O. strigicollis. These results indicate that this banker plant system may be used in the field to provide a more effective and economical way to control pest thrips in tea plantations compared with the direct release of O. strigicollis.The stick tea thrip Dendrothrips minowai (Priesner) (Thysanoptera: Thripidae) is a destructive pest in tea plantations in south and southwest China. To control this pest, a non-crop banker plant system was developed using a polyphagous predator Orius strigicollis (Poppius) (Heteroptera: Anthocoridae) with the black bean aphid Aphis fabae (Scopoli) (Hemiptera: Aphididae) as an alternative prey and the faba bean Vicia faba as the banker plant to support the predator in targeting the pest. The fitness of A. fabae on tea plants and faba bean was evaluated to determine its host specificity. Moreover, the control efficacy of the banker plant system on D. minowai on tea plants was tested in the laboratory and compared with that of direct release of O. strigicollis. The experiments showed that faba bean was an excellent non-crop host for A. fabae because, while the aphid population increased quickly on faba bean, it could only survive for up to 9 days on tea plants. Compared with direct release of O. strigicollis, lower densities of pest were observed when introducing the banker plant system. Our results indicate that this banker plant system has the potential to be implemented in the field to improve the control of the pest thrips.

Population dynamics of Frankliniella occidentalis Pergrande and its predator Orius similis Zheng on common crops and surrounding plants

• Plants surrounding Capsicum annuum fields can provide habitat for predator Orius similis . • Hypericum beanii and Trifolium repens are the important sources of Frankliniella occidentalis on C. annuum . • Zea mays is the potential banker plant of O. similis in C. annuum planting. Frankliniella occidentalis Pergrande is important invasive pests in China, causing damage to agricultural production, and Orius similis Zheng is the dominant predator species of F. occidentalis . A two-year survey was conducted to determine the population density of F. occidentalis and O. similis , on chili ( Capsicum annuum L.) and maize ( Zea mays L.) crops and surrounding weed species, which included white clover ( Trifolium repens L.), St. John's wort ( Hypericum beanii N. Robson), alfalfa ( Medicago sativa L.) and beggarticks ( Bidens pilosa L.) in Kunming, southern China. The activity of F. occidentalis on these 6 host plant species was determined using the quartile method. F. occidentalis mainly damaged plants during their flowering stage. The main activity period of F. occidentalis occurred earlier on H. beanii and T. repens than on C. annuum . The peak activity of F. occidentali s occurred in the middle of May (on T. repens ). During the whole activity period, the highest thrips densities were recorded on H. beanii among all of the sampled host plant species, followed by C. annuum . The lowest density was recorded on B. pilosa . Dynamics of immature F. occidentali s were more irregular than that of adults. The highest density of O. similis was recorded on Z. mays . It was 2.27–26.43-fold (2017) and 2.01–19.09-fold (2018) higher than that on other host plant species. This study showed that F. occidentali s could migrate between C. annuum and surrounding weeds. The weeds were the main source of thrips on C. annuum . The results indicated that Z. mays can be planted around C. annuum fields as a potential banker plant, to attract O. similis to control F. occidentalis on C. annuum , T. repens and B. pilosa . The flowering period of plants and surrounding plant species has a great effect to the population activities of F. occidentalis and predator O. similis on crops.

Augmenting Nesidiocoris tenuis (Nesidiocoris) with a Factitious Diet of Artemia Cysts to Control Bemisia tabaci (Gennadius) on Tomato Plants under Greenhouse Conditions.

Simple SummaryNesidiocoris tenuis (Hemiptera: Miridae) is an important biocontrol agent of several key arthropod pests, such as greenhouse and tobacco whiteflies, the South American tomato pinworm, thrips, plant mites, and other pests in the greenhouse. However, optimizing N. tenuis utilization in the greenhouse to control greenhouse pests such as whiteflies still needs further studies, especially in Japan. Here, we showed that factitious supplementary dietary in the form of Artemia cysts enhanced with high fructose corn syrup and honey, and delivered using a hemp rope could promote N. tenuis proliferation and spread among tomato plants. Nesidiocoris tenuis spread among tomato plants therefore, can maintain whitefly (Bemisia tabaci) eggs and nymph numbers at minimum in the greenhouse conditions.Natural predators such as Nesidiocoris tenuis are known for their role in managing greenhouse pests. However, techniques in maximizing the biological control potential of N. tenuis under field conditions are still lacking. We evaluated under greenhouse conditions the prospects of Artemia cysts enhanced with high fructose corn syrup and honey, and delivered using hemp strings (hemp rope) as supplementary factitious dietary in augmenting the proliferation and spread of N. tenuis on tomato plants. Results showed that N. tenuis supplemented with hemp rope could establish, proliferate and disperse among tomato plants compared to the N. tenuis supplemented with banker plants. Even though N. tenuis proliferated exponentially on banker plants, their movement and relocation to tomato plants, as expected, were only congested on tomato plants near the banker plants. However, as the survey continued, they relocated to the rest of the tomato plants. Furthermore, the number of Bemisia tabaci eggs and nymphs, a serious greenhouse pest of tomato, was observed to be significantly reduced in hemp rope greenhouse compared to banker plants and the negative control (no pest control system) greenhouses. This study, therefore, establishes foundational data on the usage of Artemia cysts enhanced with isomerized sugar (high fructose corn syrup) and honey under greenhouse conditions as factitious supplementary dietary in supporting N. tenuis establishment and spread, traits that are essential towards development of whitefly Integrated Pest Management (IPM) system. enhanced with isomerized sugar (high fructose corn syrup) and honey.

Tracking the movement of Nesidiocoris tenuis among banker plants and crops in a tomato greenhouse by DNA markers of host plants

The zoophytophagous predator, Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae), is an important biological control agent. To maintain this insect, several non-crop host plants are used as banker plants in greenhouse crop systems. To optimize the efficiency of the predator-banker plant interaction, it is necessary to investigate how individual predators move between banker plants and crops. However, the movement is difficult to quantify under field conditions. Therefore, we investigated the movement of N. tenuis between tomato plants (Solanum lycopersicum L., Solanales: Solanaceae) and three banker plants (Cleome hassleriana Chod., Brassicales: Cleomaceae; Sesamum indicum L., Lamiales: Pedaliaceae; and Verbena × hybrida Voss, Lamiales: Verbenaceae) in a greenhouse by conducting PCR using plant-species-specific primers. Laboratory analysis results showed that our molecular method could detect N. tenuis activity within a relatively short time (≤ 24 h). In addition, N. tenuis predation on a pest species was unlikely to result in false detection of plant DNA in the pest (suggesting that N. tenuis had been on the plants). Multiple plant species were detected in adult insects collected from the greenhouse plants, indicating that N. tenuis frequently moved across the mentioned plant species. The movement patterns of N. tenuis between plant species varied substantially based on the plant species from which they were collected, which suggested each of the plant species had different functions for N. tenuis. Our findings revealed that planting multiple host plants would stabilize the N. tenuis population in biological control programs.

Evaluation of Eleven Plant Species as Potential Banker Plants to Support Predatory Orius sauteri in Tea Plant Systems.

Simple SummaryThe tea plant is an economically significant beverage crop globally, especially in China. However, tea green leafhoppers and thrips are key pests in Asian tea production systems, causing serious damage to its yield and quality. With growing concerns about pesticide residues on tea and their adverse effects on natural enemies of tea pests, biological pest control is gaining more importance in tea plantations. Orius sauteri is a polyphagous predator used as a biological control agent. Here, we reported 11 plants as banker plants to support the predatory Orius sauteri in tea plant systems. Among them, white clover, red bean, mung bean, peanut, soybean, kidney bean, bush vetch, smooth vetch, and common vetch were found suitable; red bean performed relatively better than the others. Tea green leafhoppers and thrips are key pests in tea plantations and have widely invaded those of Asian origin. Pesticides are currently a favorable control method but not desirable for frequent use on tea plants. To meet Integrated Pest Management (IPM) demand, biological control with a natural enemy is viewed as the most promising way. Orius sauteri are slated to be a natural enemy to tea pests. However, more knowledge of rearing O. sauteri and selecting banker plant systems is strongly needed. The reproductive biology evaluation of the egg oviposition and population life parameters of O. sauteri under laboratory conditions were examined, and the supporting ability of 11 plant species—motherwort, white clover, red bean, mung bean, peanut, soybean, kidney bean, herba violae, bush vetch, smooth vetch, and common vetch—in a greenhouse was assessed. Most of the selected plants, except for herba violae, performed relatively well with high oviposition quantity and survival. The mean fecundity per female on red bean and motherwort was 148.75 eggs and 148.25 eggs, respectively, and 90.20 eggs for tea plants (the smallest); there also were significant differences. In an experiment to determine the life parameters of O. sauteri, all the tested plants, except herba violae, were found to be able to complete the growth and development of the life cycle; there also were significant differences. The intrinsic rate of increase of motherwort and red bean was 1.18 and 1.17, respectively, and higher compared to that of the other plants, including tea plants (1.13). This result of the O. sauteri population development index was also confirmed in a greenhouse with the number of motherwort and red beans being as high as 113.33 and 112.67. Since motherwort was found to be susceptible to aphids and powdery mildew in each trial, it cannot be used for intercropping in tea gardens. Among the 11 plants, red bean was found to be the most suitable to support O. sauteri in tea plantations.

Biological control of the foxglove aphid using a banker plant with Eupeodes americanus (Diptera: Syrphidae) in experimental and commercial greenhouses

The foxglove aphid, Aulacorthum solani (Kaltenbach) (Hemiptera: Aphididae), has become a significant pest in horticulture as it can build high populations from 10 to 18 °C, when no commercially available biocontrol agent is efficient. The American hoverfly, Eupeodes americanus (Wiedemann) (Diptera: Syrphidae), has demonstrated good active flight, oviposition, and larval voracity at low temperature. In the present study, the efficiency of a banker plant system using the American hoverfly was evaluated in a cage experiment (enclosed space) and commercial greenhouses (open environment) at production temperatures (heating temperature was 18 °C). The results demonstrate that banker plants with the American hoverfly provided an adequate control of foxglove aphid populations in both environments. In a cage experiment, the predator used the banker plant for nutritional resources and successfully developed and reproduced on them. Green pepper plants infested by foxglove aphids and exposed to hoverflies show a significantly lower abundance of aphids by the end of the trial, compared to the control cages. In commercial greenhouses (real situation), adult hoverflies were able to mate, locate infested plants, and oviposit. Subsequently their offspring provided an efficient control of aphid populations after 6 weeks. This study demonstrates the high potential of a banker plant using hoverflies in greenhouse environments. It also demonstrates the importance of studying new potential biocontrol agents.

Augmentative biological control in greenhouses in Japan

Abstract In Japan, augmentative biological control is mainly implemented in greenhouses using arthropod natural enemies. Two imported natural enemy species, Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) against spider mites and Encarsia formosa Gahan (Hymenoptera: Aphelinidae) against the greenhouse whitefly, Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae), were first commercialised in greenhouses in 1995, followed by the commercialisation of other exotic species. Exotic arthropod natural enemies are used to control both exotic and indigenous pests in greenhouses. Currently, the most popular exotic natural enemy species are predatory mites such as P. persimilis and Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae). Recently, there has been a shift from using exotic to using indigenous natural enemies in greenhouses. Currently, the importation of generalist predators for augmentative biological control is very difficult in Japan. Several collaborative studies have been conducted in Japan to develop biological control using indigenous natural enemies. These studies developed innovative technologies, such as new banker plant systems based on combinations of two natural enemies or flightless Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae). Indigenous natural enemies have been commercialised following the registration of Orius strigicollis (Poppius) (Hemiptera: Anthocoridae). Biological control can be achieved using an indigenous strain of Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) with a banker plant system, on which the bug can reproduce without alternative prey. Research and development of biological control using indigenous natural enemies should be continued in Japan.

Effect of three oviposition feeding substrates on biology and life table parameters of Orius laevigatus

The western flower thrips (WFT), Frankliniella occidentalis (Pergande), is one of the most important thysanopteran pests belonging to the family Thripidae. This species is a cosmopolitan and serious insect pest of greenhouse and field crops worldwide. Orius laevigatus (Fiber) (Heteroptera: Anthocoridae) is an important zoophytophagous insect that attacks a wide variety of insect pests and is commercially available as a biological control agent of F. occidentalis. However, the biological control success by this predator strongly depends on the morphological characteristics and nutritional quality of the host plant. In the present study, the suitability of green bean, marigold, and strawberry as banker plants for O. laevigatus were evaluated in the laboratory condition (25 ± 1 °C, a relative humidity of 70 ± 5% with a 16-h day). The shortest and longest developmental time of whole nymphal periods of O. laevigatus was on the green bean (10.6 days) and marigold (13.2 days) plants, respectively. The highest fecundity of O. lavigatus was on the green bean (113.0 eggs) and the lowest on the marigold (38.4 eggs). The highest net reproductive rate (R0: 47.3 female/female), intrinsic rate of increase (rm: 0.10 female/female/day), finite rate of increase (λ: 1.16 female/female/day), and generation time (T: 24.1 days) were obtained on the green bean. Based on our results, the green bean can be a good candidate as a banker plant for O. laevigatus in integrated pest management programs.

Banker plants promote functional biodiversity and decrease populations of the cabbage whitefly Aleyrodes proletella

AbstractIn this study, potential banker plant systems against the cabbage whitefly Aleyrodes proletella Linnaeus (Hemiptera: Aleyrodidae) were developed under controlled conditions. The two most promising banker plant systems, that is, the parasitoid Encarsia tricolor Förster (Hymenoptera: Aphelinidae) either with Aleyrodes lonicerae Walker on European columbine (columbine system) or with Trialeurodes vaporariorum Westwood (Hemiptera: Aleyrodidae) on Hokkaido squash (pumpkin system), were further evaluated in the field. Although the pumpkin system produced three times more parasitoids than the columbine system, both banker plants led to an 1.5‐fold increase in A. proletella parasitism rates. However, only the pumpkin system increased the abundance of syrphid larvae on cabbage by 61.5% and reduced A. proletella populations on average by 4.4%–25.8% depending on the respective assessment date. In conclusion, the pumpkin system revealed to be a promising (supplementary) control measure against A. proletella. Options for further improvement and standardization of the pumpkin system as well as a potential implementation in cabbage production are discussed.

Suitability of Ornamental Pepper Cultivars as Banker Plants for the Establishment of Predatory Mite Amblyseius swirskii in Controlled Production

A banker plant system is a rearing and release method for biological control agents, and in recent years has gained serious attention among plant propagators for its use in regulating common greenhouse and nursery pests. In the current study, the suitability of four ornamental pepper (Capsicum annuum L.; Solanales: Solanaceae) banker plant candidates, Black Pearl (BP), Explosive Ember (EE), Masquerade (MA), Red Missile (RM), and a commercial pepper cultivar, Blitz (BL), were evaluated with three main objectives: (1) to assess host preference of three major arthropod pests of agricultural importance, Bemisia tabaci Gennadius, Polyphagotarsonemus latus Banks, and Frankliniella occidentalis Pergande among selected pepper cultivars; (2) to determine the susceptibility of plant cultivars to three different pests; and (3) to assess the effect of tuft domatia on the abundance of the predatory mite Amblyseius swirskii Athias–Henriot. In choice and no-choice assays, BL and BP were highly susceptible to P. latus with a moderately high damage rating index of >3.5/5; B. tabaci and F. occidentalis were abundant on BL and EE. A positive correlation was observed between the number of tuft domatia and the A. swirskii count. Although all ornamental pepper cultivars exhibited varying degrees of susceptibility to different arthropod pests, if used strategically, cultivars MA and RM can be used to develop a banker plant system and help reduce multiple pests in greenhouses or interiorscapes.

The effect of banker plants and pre-plant release on the establishment and pest control of Macrolophus pygmaeus in tomato greenhouses

Biological pest control in greenhouses generally depends on the release of natural enemies. Macrolophus pygmaeus (Hemiptera: Miridae) is one of the most used predators in European vegetable crops. However, its long establishment time is considered as one of the main drawbacks in regard to pest control. Pre-plant release in nurseries and the use of banker plants are strategies frequently used to enhance the response of predatory mirids. The aim of this work was to determine how the length of the pre-plant release period in banker plants (PRP) and banker plant species influenced the establishment and population dynamics of M. pygmaeus and its pest control in tomato crops. Two PRPs (24 h and 30 days) and two banker plants (tomato, Solanum lycopersicum—Solanaceae, and Ballota hirsuta—Lamiaceae) were assayed in a complete factorial design with three replicates, in individual greenhouses. The proportion of individuals established, founder population, abundance and population growth rate of M. pygmaeus were significantly higher for the long than for the short PRP. For the long PRP, the founder population and abundance of M. pygmaeus in greenhouses were higher when B. hirsuta, rather than tomato, was used as banker plant. Lower incidences of Bemisia tabaci (Hemiptera: Aleyrodidae) and Tuta absoluta (Lepidoptera: Gelechiidae) were registered in greenhouses with the long PRP, while the effect of the banker plant was not significant. The higher proportions of individuals established and higher population growth rates of M. pygmaeus in the greenhouses with the largest founder populations suggest the implication of Allee effects.

Estimation of movement from insectary plants to crop plants in Orius bugs (Heteroptera: Anthocoridae) by molecular gut content analysis

The introduction of insectary and banker plants is widely used in agroecosystems to improve the survival and reproduction of natural enemies of pest arthropods. Natural enemies that are attracted to and/or maintained on insectary plants need to move from the insectary plants to crop plants to suppress pest populations effectively. In many cases, however, direct evidence supporting the migration of natural enemies is lacking. To investigate the movement of Orius bugs (Hemiptera: Anthocoridae), which are efficient zoophytophagous predators used in biological control, we performed gut content analyses based on DNA markers. Specific PCR primers were designed to detect the DNA of the insectary plant, Scaevola aemula. We also carried out gut content analyses using prey insect DNA markers to estimate Orius bugs’ predation spectrum. DNA of the insectary plant was detected in the abdomen of Orius bugs collected on eggplant leaves, suggesting that Orius bugs had consumed food resources from the insectary plants and relocated to the crop plants. DNA of three prey insect species—two thrips species, Thrips palmi and Frankliniella intonsa, and cotton aphid, Aphis gossypii—was detected in Orius bugs in the eggplant field, indicating that Orius bugs preyed on them.

Effects of Plants and Supplemental Prey on Establishment of Dicyphus hesperus (Hemiptera: Miridae)

Dicyphus hesperus Knight (Hemiptera: Miridae) is an omnivorous natural enemy used to control insect pests in greenhouse structures. The establishment and population development of predators in a banker plant system must be understood prior to their deployment in a pest management program. Banker plants are non-crop plants that are infested with a supplemental food source, which provides a suitable environment for predators to establish their population. The objective of this research was to investigate the effect of mullein (Verbascum thapsus L.; Scrophulariaceae) as banker plants and Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs as supplemental food on the development of D. hesperus in a tomato greenhouse production system. The nymphal development duration did not differ between mullein (22.5 d) and tomato (24.5 d) with E. kuehniella eggs but was significantly longer on mullein (25.8 d) without E. kuehniella eggs, whereas nymphs did not complete their life cycle on tomato without E. kuehniella eggs. Adult longevity and percentage survival to adulthood was 30.4 d and 91.9% on mullein with E. kuehniella eggs, and 26.9 d and 87.5% on tomato with E. kuehniella eggs, but were much reduced on mullein without E. kuehniella eggs (22.44 d and 75%). The population growth of the predator varied in response to host plant and presence of supplemental food source. In greenhouse experiments, the population of D. hesperus showed a greater increase on tomato provided with E. kuehniella eggs as a supplement food source than on mullein with supplemental food. We conclude that there was no benefit in our experiments to using mullein as a banker plant rather than using the commercial crop, tomato, supplemented with E. kuehniella eggs.

Host-range study about four aphid parasitoid species among 16 aphid species for constructing banker–plant systems

To provide fundamental information for the biological control of aphids in vegetable greenhouses, we compared the host ranges of four aphid parasitoid species, Aphidius colemani Viereck, Aphidius gifuensis Ashmead, Diaeretiella rapae (M’Intosh), and Ephedrus nacheri Quilis (Hymenoptera: Braconidae: Aphidiinae). The acceptability as host of 11 vegetable-pest aphids, Acyrthosiphon pisum (Harris), Aphis craccivora Koch, Aphis gossypii Glover, Aulacorthum solani (Kaltenbach), Brevicoryne brassicae (Linnaeus), Chaetosiphon fragaefolii (Cockerell), Lipaphis erysimi (Kaltenbach), Macrosiphoniella sanborni (Gillette), Macrosiphum euphorbiae (Thomas), Myzus persicae (Sulzer), and Uroleucon formosanum (Takahashi), in addition to five aphid species, Melanaphis sacchari (Zehntner), Rhopalosiphum maidis (Fitch), Rhopalosiphum padi (Linnaeus), Schizaphis graminum (Rondani), and Sitobion akebiae (Shinji) (Hemiptera: Aphididae) that serve as alternative hosts in banker–plant systems for the four aphid parasitoid species, were investigated. A newly emerged pair of parasitoid adults were provided to 100 aphids of each species on caged host plants in a 25 °C chamber for 24 h. The numbers of mummified aphids and emerged adults were counted in 10 trials for each aphid species. Aphidius colemani, A. gifuensis, D. rapae and E. nacheri parasitized four, two, three, and eight pest species, respectively, and four, three, three, and five alternative host species, respectively. Ephedrus nacheri had the broadest host range among the four species, and all the four species parasitized M. persicae, R. maidis, and S. graminum. This information will be useful for selecting candidate of biological control agents for aphids and for constructing banker–plant systems.