Host specificity of Argopistes tsekooni (Coleoptera: Chrysomelidae), a potential biological control agent of Chinese privet

Chinese privet, Ligustrum sinense Lour., is a perennial semi-evergreen shrub that is a serious invasive weed in the United States. Classical biological control offers the best hope for controlling it in an economic, effective, and persistent way. Host specificity of one of the most promising biological control agents of Chinese privet, a flea beetle, Argopistes tsekooni Chen (Coleoptera: Chrysomelidae), was evaluated in China by using laboratory no-choice and choice tests on 13 species of Oleaceae and eight species in other families that have important economic value. In adult no-choice survival and oviposition tests, the flea beetle fed and survived for 30 d on Syringa oblata Lindl., Jasminum nudiflorum Lindl., and three species in the genus Ligustrum. Females also oviposited on these species, but only larvae from eggs laid on S. oblata and Ligustrum spp. developed successfully. In addition, the beetles did not feed or oviposit on the species of economic importance. In choice tests, adults preferred L. sinense for feeding and oviposition. These results show that A. tsekooni is relatively host specific and warrants further testing as a biocontrol agent of Chinese privet in the United States.     

Host-specificity and virus-vector potential ofAphis chloris [Hemiptera: Aphididae], a biological control agent for St John's wort in Australia

Under laboratory conditionsAphis chloris Koch has been demonstrated to be specific to plants belonging to the genusHypericum. It can effect severe damage to its principal host,H. perforatum L., and shows good potential for contributing to the control of this noxious weed. Other species ofHypericum are less favoured hosts ofA. chloris and would not be endangered by it. A. chloris shows a high level of host-discrimination and does not transmit persistent viruses between non-host plants. Whereas in the laboratory it is capable of transmitting non-persistent viruses, it would contribute only marginally to the risk of virus transfer posed by the Australian aphid fauna as a whole, and its release would not necessitate changes to existing control practices, where these are required to reduce plant virus transmission. As a consequence,A. chloris is considered safe for release againstH. perforatum in Australia.      

Galerucella birmanica (Coleoptera: Chrysomelidae), a promising potential biological control agent of water chestnut,Trapa natans

Water chestnut, Trapa natans, has become a major invasive plant in shallow water bodies in the northeastern United States. The failure of chemical and mechanical means to provide long-term and economically sustainable suppression of the species resulted in interest in the development of biological control. Field surveys in Asia and Europe identified a number of potential biological control agents in the native range of T. natans. The most promising species appeared to be the leaf beetle Galerucella birmanica, which is considered a pest of farmed T. natans in China. However, initial attempts to develop biological control faltered when field observations in China suggested that G. birmanica may not be host specific. Of particular concern was attack on water shield, Brasenia schreberi, a species native to China and North America. We conducted a number of laboratory and field investigations in China to assess preference and performance of G. birmanica on T. natans and B. schreberi. Initial no-choice experiments using 19 different plant species in 13 different families demonstrated that G. birmanica oviposited and was able to complete development only on Trapa spp. and B. schreberi. In larval no-choice tests G. birmanica was able to complete development on B. schreberi, however, larvae showed a 20% increase in mortality and longer development time compared to larvae developing on T. natans. In laboratory and field choice tests adults strongly preferred T. natans and in the field only occasionally laid eggs on B. schreberi. In addition, adults emerging from larvae reared on B. schreberi were less fit with reduced feeding and a declining oviposition rate. Their strong preference for T. natans was maintained in the field, even when T. natans was completely defoliated and adults were forced to migrate. We found only occasional “spill-over” of beetles onto B. schreberi and our data indicate that G. birmanica is a more promising biological control agent of T. natans than previously thought, although additional host specificity tests with many more North American plant species need to be completed.     

Life history and host range of Alagoasa extrema (Coleoptera: Chrysomelidae: Alticinae), a potential biological control agent of Lantana spp. (Verbenaceae) in Australia

The life history and host range of the lantana beetle, Alagoasa extrema, a potential biocontrol agent for Lantana spp. were investigated in a quarantine unit at the Alan Fletcher Research Station, Brisbane, Australia. Adults feed on leaves and females lay batches of about 17 eggs on the soil surface around the stems of plants. The eggs take 16 days to hatch and newly emerged larvae move up the stem to feed on young leaves. Larvae feed for about 23 days and there are three instars. There is a prepupal non-feeding stage that lasts about 12 days and the pupal stage, which occurs in a cocoon in the soil, lasts 16 days. Teneral adults remain in the cocoon for 3 days to harden prior to emergence. Males live for about 151 days while females live for about 127 days. The pre-oviposition period is 19 days. In no-choice larval feeding trials, nine plant species, representing three families, supported development to adult. Three species, Aloysia triphylla, Citharexylum spinosum and Pandorea pandorana were able to support at least two successive generations. These results confirm those reported in South Africa and suggest that A. extrema is not sufficiently specific for release in Australia. Furthermore, it is not recommended for release in any other country which is considering biological control of lantana.     

Biology and host specificity of Ceutorhynchus scrobicollis (Curculionidae; Coleoptera), a root-crown mining weevil proposed as biological control agent against Alliaria petiolata in North America

Ceutorhynchus scrobicollis is a root-crown mining weevil proposed for release as biological control agent of Alliaria petiolata (Brassicaceae, Thlaspideae), a European biennial herb, currently invading temperate North America. Using a combination of laboratory, common garden and fieldwork we studied biology, ecology and host range of C. scrobicollis, a univoltine species that oviposits and develops in A. petiolata rosettes in fall and spring. Individual C. scrobicollis can be long-lived (>2 years) and females show a second oviposition period. Weevils did not attack any of 31 test plant species outside the Brassicaceae. Within the Brassicaceae, five species allowed complete larval development under no-choice conditions. In subsequent choice tests, three of these five species (Nasturtium officinale, Peltaria alliacea and Thlaspi arvense; which are of European origin) were attacked. North American Rorippa sinuata was the only native species to be attacked by C. scrobicollis and only under no-choice conditions. Results of subsequent impact experiments showed that C. scrobicollis attack changed plant architecture but had no effect on overall plant vigour and reproductive output of R. sinuata, suggesting lack of impact on demography or population dynamics. A petition for field release of C. scrobicollis in North America has been submitted.     

Trichilogaster sp. [Hymenoptera: Pteromalidae], a potential biocontrol agent for the weedAcacia pycnantha [Fabaceae]

The gall wasp,Trichilogaster sp., was imported from Australia to assess its potential as an agent for the control of the invasive shrub/treeAcacia pycnantha Benth. in South Africa. Host specificity tests indicate safety for release; of 19 tree/shrub species tested, including 16 species closely related toA. pycnantha, galls developed only onA. pycnantha. However, galling intensity remained consistently low on the host plant; only 21–29% of the branches exposed to the wasp were galled during 3 years of rearing. Neither the prolonged presence of males in test cages (someTrichilogaster species are thelytokous) nor the stage of maturity of reproductive buds exposed to oviposition affected the percentage of branches galled. It is not recommended thatTrichilogaster sp. be released before the possibility of insect-plant homeostasis or mis-matching of wasp and host plant populations/strains/subspecies is investigated, especially since galling intensities of 30% were ineffective in reducing seed production of a relatedTrichilogaster species/Acacia association.      

Gallerucida bifasciata (Coleoptera: Chrysomelidae), a potential biological control agent for Japanese knotweed (Fallopia japonica)

Host specificity of foreign natural enemies are becoming more and more critical in classical biological control programs, as concerns about potential risk from introduced biocontrol agents have been increasing recently. Understanding the insect's fundamental and ecological host ranges is the first step in determining the potential for introduction of an insect to control invasive plants. Japanese knotweed, Fallopia japonica (Houttuyn) Ronse Decraene (Polygonaceae) is an invasive weed in the United States and Europe. A leaf beetle, Gallerucida bifasciata (Coleoptera: Chrysomelidae) is an important natural enemy attacking this plant in Asia. However, its host range records were ambiguous. This study examined the beetle's host specificity through a set of choice and no-choice tests in the laboratory and field in its native China. Gallerucida bifasciata larvae were able to complete development on seven of 87 plant species in larval development tests, while adults fed and oviposited on 10 plants in no-choice tests. Multiple choice tests showed adults strongly preferred Fallopia japonica, Persicaria perfoliata (L.) H. Gross and Polygonum multiflorum Thunb over all other plants. Open field tests and field surveys further revealed that these three species were in its ecological host range. The results of this study suggest that G. bifasciata is a potential promising agent for control of Japanese knotweed in the United States and Europe, although additional host specificity tests and risk assessment should be completed.     

Host specificity ofDisonycha argentinensis [Col.: Chrysomelidae], an agent for the biological control ofalternanthera philoxeroides (Alligator weed) in Australia

The biology and host specificity of a South American flea beetle,Disonycha argentinensis Jacoby was investigated in quarantine facilities in Australia. Damage from feeding by larvae and adults ofD. argentinensis onAlternanthera philoxeroides (Mart.) Griseb (alligator weed) indicated that it might be a useful biological control agent for the plant when growing in terrestrial situations. Complete development of the immature stages took place only onAlternanthera philoxeroides. Adults produced a few feeding scars onBeta vulgaris L. (beetroot) andAmaranthus spinosus L. (spiny amaranth) but failed to oviposit. Host specificity studies indicated that establishment of this beetle in Australia would be without significant risk to nontarget plant species.D. argentinensis was first released in Australia in 1980.     

Host-specificity of a root borer,Bembecia chrysidiformis [Lep.: Sesiidae], a potential control agent forRumex spp. [Polygonaceae] in Australia

Bembecia chrysidiformis (Esper) [Lep.: Sesiidae] was examined for its natural history and specificity toRumex spp. (Polygonaceae) which are weeds in Australia. Adults of this southern European insect appear in late spring to summer. Eggs are laid on the dried, seed bearing stems of perennialRumex plants. The larvae tunnel inside the root during summer through to the next spring. In nature, the larvae are round inRumex species of the subgeneraRumex andAcetosa. In host-specificity tests with 1st instar larvae, the roots of a number of genera within thePolygonaceae were attacked. Larvae died on a range of plants from other families except inPersea americana Miller(Lauraceae), Helianthemum nummularium (L.) Miller (Cistaceae) andQuercus ilex L. (Fagaceae) where larvae fed on the stems. The insect was judged safe for release in Australia by assessing aspects of its biology, its known host plants, and the lack of reported attack on other plants.      

Life cycle and abundance oflongitarsus jacobaeae [Col.: Chrysomelidae], biocontrol agent ofSenecio jacobaea

The life cycle and abundance of the tansy ragwort flea beetle,Longitarsus jacobaeae (Waterhouse), were investigated in a dune area in the Netherlands. The beetle overwinters in the egg stage, which is parasitised by a Mymarid wasp. No larvae were found until spring. Three larval instars can be separated by head capsule size and coloration. Initial larval numbers are high (up to 214 larvae per plant), but drop to very low levels by late spring. Adults appear during June or July, the numbers are high until October, the adults can be found until the end of December. This life cycle differs remarkably from those described for the species in Switzerland, Italy and Britain. Possible causes for these differences are discussed, as well as implications for the use ofLongitarsus in biological control.      

Host specificity ofAceria (Eriophyes) malherbe, [Acari: Eriophyidae], a biological control agent for the weed,Convolvulus arvensis [Convolvulaceae]

The host specificity of the gall mite,Aceria (Eriophyes) malherbe (Nalepa), from Greece was studied under quarantine conditions at Albany, California USA. Of the species, ecotypes, or strains tested, onlyConvolvulus andCalystegia spp. supported gall formation and mite reproduction. Although 2 of the native, North AmericanCalystegia species that served as laboratory hosts are threatened or endangered species,A. malherbe is considered safe for release in the USA as a biological control agent of the weed,Convolvulus arvensis (L.).      

The biology and host specificity of the stem-boring weevilListronotus setosipennis [Col.: Curculionidae] A potential biocontrol agent forParthenium hysterophorus [Asteraceae]

The stem-boring weevilListronotus setosipennis (Hustache) is widespread and damaging to its hostParthenium hysterophorus L. in northern Argentina and southern Brazil. In detailed host-testing it was shown to have a restricted host-range and, despite some feeding and development on sunflower in tests, to be a safe biological control agent againstP. hysterophorus. Field releases in Queensland, Australia took place from 1982 to 1986 and the weevil has established over several thousand hectares at numerous sites. Spread is however slow and the effect on the plant still negligible.      

Eriocereophaga humeridens [Col.: Curculionidae], a potential agent for the biological control ofEriocereus martinii [Cactaceae] in Australia

The weevilEriocereophaga humeridens O'Brien attacks the cactusEriocereus adscendens (Gurke) in N.E. Brazil. Laboratory tests and field observations demonstrate that it will also acceptEriocereus martinii Lab. as host, and does not damage plants except in the sub-familyCereanae of theCactaceae. Young plants and regrowth are preferentially attacked and larval feeding inE. martinii results in the death of attacked stems.E. humeridens was approved for liberation in Queensland, Australia in February 1976, for the control ofEriocereus spp., and field releases were made in 1976.

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Résumé Le coléoptèreEriocereophaga humeridens O'Brien attaque le cactusEriocereus adscendens (Gurke) qui est indigène du Nord-Est du Brésil. Il a été établi par des essais en laboratoire ainsi que par des observations en champ d'expérimentation, qu'E. humeridens peut également vivre surEriocereus martinii Lab., et qu'il n'est nuisible que pour les plantes de la sous-familleCereanae desCactaceae. Il attaque de préférence les jeunes pousses et les rejetons; et ses larves tuent en les mangeant les tiges d'E. martinii qui sont atteintes. En février 1976, afin de limiter les espèces d'Eriocereus, l'approbation fut donnée de lacherE. humeridens en Queensland, Australie, ce qu'on a fait sur les lieux au cours de la même année.

     

Host specificity and biology of the weevilNeohydronomus affinis [Coleoptera: Curculionidae] a biological control agent ofPistia stratiotes

Waterlettuce,Pistia stratiotes L., has been successfully controlled in Australia with the weevil,Neohydronomus affinis Hustache. In this study, the weevil was tested in quarantine against 34 plant species in 27 families. In non-replicated no-choice tests, it fed and oviposited on 3 species of duckweeds [(Lemna minor L.,Spirodela punctata (Meyer) Thomps.,S. polyrhiza (L.) Schleid.], frogbit [(Limnobium spongia (Bosc.) Steud.], mosquitofern (Azolla caroliniana Willd) and waterfern (Salvinia mimima Baker). Feeding also occurred on golden club (Orontium aquaticum L.) and one egg was laid on the terrestrial panda plant (Kalanchoe tomentosa Baker). Plants oviposited and fed upon were retested in choice tests. The weevils then fed and oviposited exclusively on waterlettuce. Various aspects of weevil biology, including larval feeding and mining, plant response to weevil attack, and adult behavior are discussed. Florida Agric. Expt. J. series No 8580.     

Life history and host range of Sauris nr. purpurotincta,an unsuitable biological control agent for Chinese tallowtree

Foreign surveys in China discovered a defoliating insect species feeding on the leaves of Chinese tallowtree (Triadica sebifera), an invasive weed of the southeastern U.S.A. The life history of this species, Sauris nr. purpurotincta (Lepidoptera: Geometridae), was examined and larval no-choice and adult multiple-choice host range tests were conducted in quarantine to evaluate their suitability for biological control of Chinese tallowtree. The results indicated that the larvae have five instars and require approximately 22 days to complete development to the adult stage. Host range tests indicated that the larvae could not feed and complete development on most species tested. However, 40% of the larvae survived when fed leaves of Hippomane mancinella, a state-listed endangered species in Florida, and all larvae survived when fed Morella cerifera, a common native species of the southeastern U.S.A. Multiple-choice oviposition tests indicated eggs were laid on leaves of both a south Florida native plant Gymnanthes lucida and Chinese tallowtree. Considering this broad host range, this species will not be considered further for biological control of Chinese tallowtree in the U.S.A.     

Biology and host specificity ofWeiseana barkeri (Col.: Chrysomelidae): A biological control agent forAcacia nilotica (mimosaceae)

The leaf-feeding beetleWeiseana barkeri Jacoby feeds onAcacia nilotica (L.) Willdenow ex Delile in Kenya. Host specificity tests show it is host specific toA. nilotica and approval has been given for its field release in northwest Queensland. A novel rearing and host specificity-testing technique is reported whereA. nilotica foliage stimulates oviposition into strips of corrugated cardboard.     

Larval parasitoids of Lilioceris lilii (Coleoptera:Chrysomelidae) in Sweden and potential for biological control

A survey of the parasitoid complex of lily leaf beetle (Lilioceris lilii) was conducted in Sweden from 2006 to 2007. Total parasitism varied between 21 and 57%. The most abundant parasitoids were the ichneumonids Lemophagus errabundus and L. pulcher and the eulophid Tetrastichus setifer. The potential for biological control is discussed.     

Life history and host range of Oxydia vesulia transpeneus,an unsuitable biological control agent of Brazilian peppertree

The suitability of Oxydia vesulia transpeneus (Cramer) (Lepidoptera: Geometridae) was assessed as a potential biological control agent of the invasive weed Brazilian Peppertree Schinus terebinthifolia Raddi. Larvae were collected in Brazil feeding on the plant in its native range and colonised in quarantine where life history and host range studies were conducted (27?±?2°C; 50RH). Development time from neonate to adults when fed Brazilian peppertree leaves was 48.0 (±2.2) days for females and 51.0 (±1.3) days for males. Larvae generally required five (occasionally six) instars to reach the adult stage. Females had greater pupal weights 1004.1 (±45.9) mg compared with males 668.5 (±19.7) mg. Larvae were tested on seven non-target plant species from Florida natives, ornamentals, to economic species. Larvae completed development on all but one of these valued plant species. These results suggest that the host range of O. vesulia is not sufficiently specific for release as a biological control against Brazilian peppertree in the USA.     

Biology and host specificity of Aulacobaris fallax (Coleoptera: Curculionidae), a potential biological control agent for dyer’s woad,Isatis tinctoria (Brassicaceae) in North America

Dyer’s woad, Isatis tinctoria, a plant of Eurasian origin is a problematic weed in western North America against which a classical biological weed control programme was initiated in 2004. Three European insect species were selected as candidate agents to control this invasive species, including the root‐mining weevil Aulacobaris fallax. To determine its suitability as an agent, the biology and host specificity of A. fallax were studied in outdoor plots and in the field between 2004 and 2006 in its native European range. Aulacobaris fallax is a univoltine species that lays its eggs from March to August into leaf stalks and roots of dyer’s woad. Larvae mine and pupate in the roots and adults emerge from August to October. Up to 62% of the dyer’s woad plants at the field sites investigated were attacked by this weevil. In no‐choice host‐specificity tests, A. fallax attacked 16 out of 39 species and varieties within the Family Brassicaceae. Twelve of these are native to North America. In subsequent multiple‐choice tests, seven species, all native to North America, suffered a similar level of attack as dyer’s woad, while none of the European species were attacked. Our results demonstrate the importance of including test plant species that have not co‐evolved with the respective candidate agent. In sum, we conclude that the risk of non‐target effects is too high for A. fallax to be considered as a biological control agent for dyer’s woad in the United States.     

A contribution to the biology ofBangasternus fausti [Col.: Curculionidae], a potential biological control agent of diffuse knapweed,Centaurea diffusa,and its effect on the host plant

The biology of the weevilBangasternus fausti (Reitter), the larvae of which live in the flowerheads ofCentaurea diffusa (De Lamarck) and some relatedCentaurea spp., was studied in the field and in the laboratory in northern Greece and in the laboratory in Rome, Italy. The species is univoltine and overwinters as adults. Under laboratory conditions adults lived up to 90 days and up to 359 eggs were deposited by a single female (n=18). The maximum number of eggs laid by a female per day was 12 and the maximum number of days a female laid eggs was 73. Generally, there is only one larva per seedhead. One-hundred percent seed destruction was recorded in 18.7% of 502 field collected seedheads, each with oneB. fausti egg. The average mortality of the species, from egg to adult, was 94.4% in the field during 1988 (n=200) and 95.8% during 1987 (n=502).