Host range testing and life history of the defoliator Hymenomima nr. memor: an unsuitable biological control agent for Schinus terebinthifolia in the U.S.A.

Host range of larvae of Hymenomima nr. memor (Lepidoptera: Geometridae) was examined in quarantine to evaluate its suitability as a biological control of Brazilian peppertree, Schinus terebinthifolia. Brazilian peppertree, S. terebinthifolia is an environmental and agricultural weed from South America that had invaded many subtropical and tropical areas of the world including Florida and Hawaii, USA. Laboratory life history and quarantine host range studies of H. memor were conducted with no-choice feeding tests. These tests included eight species of the Anacardiaceae and one species of Sapindaceae. Larvae of H. memor had five to six instars with each head capsule width increasing by 1.68-X. Development time from neonate to adult was 46.7?±?2.2 days. In host range tests, neonates completed development to the adult stage on all non-target species, except Toxicodendron radicans. Moreover, developmental times were delayed and pupal weights were reduced for larvae fed Spondias purpurea leaves. Due to the broad host range exhibited by H. memor larvae, this species will not be considered as a biological control agent of S. terebinthifolia in the continental U.S.A.     

Effect of herbivory on growth and biomass allocation of Brazilian peppertree (Sapindales: Anacardiaceae) seedlings in the laboratory

Brazilian peppertree (Schinus terebinthifolius Raddi), native to South America, is invading many ecosystems in south and central Florida. The defoliating tortricid moth Episimus unguiculus Clarke was selected as a potential biocontrol agent of Brazilian peppertree in Florida. The objective of this study was to examine the effect of different levels of herbivore damage on growth and biomass allocation of Brazilian peppertree seedlings in the laboratory. Three treatments were established: (1) no herbivory (control), (2) low herbivory (~4 larvae/plant), and (3) high herbivory (~12 larvae/plant). High levels of herbivory significantly reduced the number of leaflets, plant height, foliar biomass, foliar relative growth rate (RGR) and shoot: root ratio of Brazilian peppertree seedlings. Moreover, plants were not able to recover from herbivory after 2 months. The performance of Brazilian peppertree subjected to low herbivory levels did not differ from the control plants (no herbivory). The potential effectiveness of the biocontrol agent E. unguiculus to suppress this noxious weed is examined.     

Host range tests reveal Paectes longiformis is not a suitable biological control agent for the invasive plant Schinus terebinthifolia

The most critical step during a weed biological control program is determination of a candidate agent’s host range. Despite rigorous protocols and extensive testing, there are still concerns over potential non-target effects following field releases. With the objective to improve risk assessment in biological control, no-choice and choice testing followed by a multiple generation study were conducted on the leaf-defoliator, Paectes longiformis Pogue (Lepidoptera: Euteliidae). This moth is being investigated as a biological control agent of Schinus terebinthifolia Raddi (Sapindales: Anacardiaceae), which is one of the worst invasive plant species in Florida, USA. Results from no-choice testing showed higher larval survival on S. terebinthifolia (48 %) and its close relative Schinus molle L. (47 %), whereas lower survival was obtained on six non-target species (<25 %). When given a choice, P. longiformis females preferred to lay eggs on the target weed, but oviposition also occurred on four non-target species. An improved performance on the native Rhus aromatica Aiton was found when insects were reared exclusively on this non-target species for one or two generations. Results from host range testing suggest that this moth is oligophagous, but has a preference for the target weed. Non-target effects found during multiple generation studies indicate that P. longiformis should not be considered as a biological control agent of S. terebinthifolia.     

Host range evaluation of the leaf-feeding beetle,Zygogramma bicolorata and the stem-boring weevil,Listronotus setosipennis demonstrates their suitability for biological control of the invasive weed,Parthenium hysterophorus in Ethiopia

The invasive weed, parthenium (Parthenium hysterophorus L.) (Asteraceae: tribe Heliantheae), damages agriculture, adversely impacts biodiversity and is hazardous to human and animal health in Ethiopia. The host range of two natural enemies, a leaf-feeding beetle, Zygogramma bicolorata (Coleoptera: Chrysomelidae) and a stem-boring weevil, Listronotus setosipennis (Coleoptera: Curculionidae) was evaluated for biological control of the weed in Ethiopia. The specificity of Z. bicolorata and L. setosipennis was assessed against 29 and 31 non-target plant species, respectively. The host range of Z. bicolorata and L. setosipennis was first assessed using no-choice tests to examine their oviposition and feeding response on non-target plants. Although oviposition by Z. bicolorata occurred on six non-target species in four Asteraceae species in no-choice tests, it was significantly lower than on parthenium and no larvae developed. Zygogramma bicolorata nibbled the leaves of one of the five niger seed (Guizotia abyssinica L. – an oil seed crop closely related to parthenium) cultivars tested, but feeding and oviposition were significantly less than on parthenium. Furthermore, choice tests indicated that Z. bicolorata did not oviposit nor feed on G. abyssinica when parthenium was present. In no-choice tests, L. setosipennis did not oviposit on any of the non-target species assessed. Mean oviposition on parthenium was 39.0?±?3.4 eggs per plant whereas no eggs were laid on any of the 31 species tested. Based on these and other host range tests, permission was obtained to field release Z. bicolorata and L. setosipennis in Ethiopia.     

Supplementary host specificity testing of the sawfly <Emphasis Type="Italic">Heteroperryia hubrichi</Emphasis>, a candidate for classical biological control of Brazilian peppertree, <Emphasis Type="Italic">Schinus terebinthifolius</Emphasis>, in the USA

Supplementary host specificity tests were conducted with the defoliating sawfly Heteroperreyia hubrichi (Hymenoptera: Pergidae), a candidate for classical biological control of Brazilian peppertree, Schinus terebinthifolius (Sapindales: Anacardiaceae), in the United States. These tests were conducted as part of the environmental assessment required by the National Environmental Policy Act (NEPA). The suitability of the federally listed endangered native plant Rhus michauxii (Anacardiaceae) and the economically important Litchi chinensis (Sapindaceae) as potential host plants for H. hubrichi was evaluated in a series of no-choice larval development tests conducted in a Florida quarantine laboratory. Neonate larvae transferred to individual test plants failed to develop to the pupal stage on R. michauxii or L. sinensis, whereas Brazilian peppertree supported development of the sawfly to pupation. The results of the additional host specificity tests indicated these critical non-target plants are not at risk from attack by H. hubrichi if it were released in Florida, USA.     

Influence of host-plant quality on the performance of <Emphasis Type="Italic">Episimus unguiculus</Emphasis>, a candidate biological control agent of Brazilian peppertree in Florida

Brazilian peppertree, Schinus terebinthifolius Raddi (Sapindales: Anacardiaceae), introduced from South America, invades a variety of habitats in Florida (e.g. disturbed sites, coastal mangrove forests). The objective of this study was to evaluate the effect of host-plant quality on the performance of Episimus unguiculus Clarke (=E. utilis Zimmerman) (Lepidoptera: Tortricidae), a potential biocontrol agent of Brazilian peppertree. Experiments were conducted in the laboratory using Brazilian peppertrees exposed either to different salinity levels (0, 6, 12 parts per thousand), or to different nutrient levels (low, medium, high). Higher survival (55%) and faster development (32 day) to adulthood was observed on plants grown in fresh-water environments (0 ppt) compared to low (6 ppt) or high-salinity environments (12 ppt). In addition, higher survival (40%), faster development (34 day) and higher fertility (88% eggs hatched) occurred in high-nutrient treatments. Based on these results, field releases should be conducted in favorable habitats (e.g., low salinity, high fertility soils) to maximize the possibility of establishment and population growth of E. unguiculus in Florida. Handling Editor: John Scott.     

Galls induced by Calophya latiforceps (Hemiptera: Calophyidae) reduce leaf performance and growth of Brazilian peppertree

Schinus terebinthifolia Raddi (Anacardiaceae) (Brazilian peppertree) is one of the most serious terrestrial invasive plants in Florida. The leaf galling psyllid, Calophya latiforceps Burckhardt (Hemiptera: Calophyidae), was discovered feeding on the Brazilian peppertree in Bahia, Brazil, in 2010, and is being evaluated for release as a biological control agent. In order to understand how this candidate biological control agent affects the growth of S. terebinthifolia, we measured the effect of the psyllid on photosynthesis, leaf chlorophyll content and plant growth. Infested plants had lower photosynthesis compared to uninfested plants 30 and 45 days after gall initiation, and chlorophyll content was lower over a 70-d period. Plant height was reduced 31% and biomass 11% after three months of infestation. Results of these studies suggest that C. latiforceps will negatively affect the growth of the Brazilian peppertree if released in Florida.     

Comparison of two populations of Pseudophilothrips ichini (Thysanoptera: Phlaeothripidae) as candidates for biological control of the invasive weed Schinus terebinthifolia (Sapindales: Anacardiaceae)

Brazilian peppertree, Schinus terebinthifolia Raddi (Sapindales: Anacardiaceae) (hereafter Schinus), is one of the worst invasive species in Florida and Hawaii. The thrips Pseudophilothrips ichini Hood (Thysanoptera: Phlaeothripidae) is being considered as a potential biological control agent of Schinus. Two populations of this thrips were collected in the weed's native range; one from central-east Brazil (Ouro Preto thrips) and a second from north-east Brazil (Salvador thrips). Temperature requirements, adult fecundity and impact on different plant haplotypes by P. ichini were examined in the laboratory. Complete development of thrips from both populations occurred at temperatures ranging from 20 to 30°C. Two approaches were used to model the predicted distributions of the thrips populations in the USA: the physiological model (NAPPFAST) based on cold tolerance and the ecological niche model based on climatic variables (MaxEnt). The physiological model predicted that both populations of P. ichini may establish in similar areas of the USA, overlapping with the distribution of Schinus. However, the niche model predicted that only the Ouro Preto thrips could establish in the USA. The difference in model predictions suggests an apparent preadaptation of the Salvador thrips to lower temperatures than those experienced at the locations they were collected in Brazil. The Ouro Preto thrips had similar fecundity on two Florida Schinus haplotypes, whereas lower fecundity on haplotype A was found for the Salvador thrips. Based on these results, the Ouro Preto population may be better adapted to the climatic conditions and plant haplotypes found in Florida. Moreover, greenhouse studies indicated that Schinus growth was greatly reduced by thrips feeding, which may result in lower weed reproduction and densities in the field.     

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.     

Risk to non-target plants from Charidotis auroguttata (Chrysomelidae: Coleoptera), a potential biocontrol agent for cat’s claw creeper Macfadyena unguis-cati (Bignoniaceae) in Australia

The potential of the leaf beetle Charidotis auroguttata as a biocontrol agent for cat’s claw creeper Macfadyena unguis-cati (Bignoniaceae), an environmental weed in Australia, and risk to non-target plants was evaluated under quarantine conditions. In no-choice tests, C. auroguttata adults and larvae fed on many plant species across different families, but egg to adult development occurred only on the target weed. However, when neonate larvae from the target weed were transferred onto Myoporum boninense australe (Myoporaceae), a non-target native plant, 11.7% completed development, as compared to 95% of larvae that completed development on the target weed. Larval development on this non-target species also took twice as long as on the target weed. No larvae completed development on other test plants. In choice tests, leaf area consumption by adults and larvae was significantly more on the target weed than on other plants, and oviposition occurred only on the target weed. In the no-choice demography trials, adults laid eggs from the second week after emergence on the target weed, with an average of 0.286 eggs/female/day, resulting in an 18-fold increase in the adult population over 16 weeks. On My. boninense australe adult survival remained high, but oviposition commenced only from the 10th week after emergence with an average of 0.023 eggs/female/day, and none of the eggs developed into adults. In the choice demography trials, oviposition on the target weed was evident from the fourth week onwards, while on the non-target plant oviposition commenced only from the 14th week. Only 10% of total adults and 11.3% of total eggs were found on the non-target plant, and none of these eggs developed into adults. Although the biocontrol agent can ‘spill-over’ from the target weed to the non-target native plant and cause adult feeding damage, the non-target plant could not sustain a viable insect population on its own. This agent was not approved for field release in Australia due to perceived risk to non-target species.     

Predicting the host range of Nystalea ebalea: Secondary plant chemistry and host selection by a surrogate biological control agent of Schinus terebinthifolia

The safety of weed biological control depends upon the selection and utilization of the target weed by the agent while causing minimal harm to non-target species. Selection of weed species by biological control agents is determined by the presence of behavioral cues, generally host secondary plant compounds that elicit oviposition and feeding responses. Non-target species that possess the same behavioral cues as found in the target weed may be at risk of damage by classical biological control agents. Here we conducted host range tests and examined secondary plant compounds of several test plant species. We studied the specialist herbivore Nystalea ebalea (Lepidoptera: Notodontidae) a Neotropical species, present in Florida as a surrogate biological control agent of the weed, Brazilian peppertree Schinus terebinthifolia, invasive in Florida and Hawaii. We found that the larvae had the greatest survival when fed the target weed, the Neotropical species Spondias purpurea, the Florida native species Rhus copallinum, and the ornamental Pistacia chinensis. Reduced survival and general larval performance were found on the native species Metopium toxiferum and Toxicodendron radicans. Both the volatiles and the allergen urushiols were chemically characterized for all species but urushiol diversity and concentration best predicted host range of this herbivore species. These results provide insight into host selection and utilization by one oligophagous Schinus herbivore. Other potential biological control agents may also be sensitive to plants that contain urushiols and if so, they may pose minimal risk to these native species.     

Assessing the risk of Eccritotarsus eichhorniae to pickerelweed,Pontederia cordata in North America

The mirid Eccritotarsus eichhorniae is a newly described species with potential as a biological control agent for water hyacinth, Eichhornia crassipes, in North America. A series of quarantine-based studies quantified E. eichhorniae usage of Pontederia cordata with no-choice, adult choice, nymph choice, multi-generation, and impact tests. Although greater numbers of E. eichhorniae adults developed on E. crassipes in two separate no-choice trials, some E. eichhorniae were able to complete development on P. cordata in both trials. Adults showed a clear oviposition preference for E. crassipes and F₁ progeny reduced the mean relative growth rate of E. crassipes but not P. cordata. Naïve nymphs were more likely to leave P. cordata for E. crassipes but not all nymphs left P. cordata when given a choice. Both multi-generation trials showed a rapid increase in the density of adults and nymphs on E. crassipes over four to five generations while population densities on P. cordata did not change, indicating that this insect can maintain populations on this plant. The modest damage inflicted by a sibling species on E. crassipes, coupled with the ability of E. eichhorniae to persist on P. cordata, may pose an interpretation challenge to U.S. regulatory agencies concerned with non-target impacts by biological control agents. Another option for the continuing efforts to increase the biological control of E. crassipes is to prioritise the evaluation of other potential agents like Taosa longula Remes Lenicov (Homoptera: Dictopharidae) or Thrypticus truncatus Bickel and Hernández (Diptera: Dolichopodidae) over E. eichhorniae.     

Host specificity assessment and potential impact of Megamelus scutellaris (Hemiptera: Delphacidae) on waterhyacinth Eichhornia crassipes (Pontederiales: Pontederiaceae)

The delphacid Megamelus scutellaris Berg was evaluated for host specificity and potential impact as part of a biological control program targeting Eichhornia. crassipes. Survival and development of adults and nymphs were used as metrics with no-choice, two-choice, nymph transfer, and sustainability tests conducted under quarantine conditions. A total of 69 plant species were tested including 12 from the Pontederiaceae (including E. crassipes). Additionally, 27 native and 5 exotic associated wetland species and 11 economic species were tested. Megamelus scutellaris exhibited a high level of oviposition and developmental fidelity to E. crassipes by failing to sustain populations on any non-target test plant past the F₁ generation. Nymph transfer tests which simulated potential spill-over events found that survival was virtually non-existent on associated wetland plants, regardless of taxonomic relatedness, including on Pontederia cordata, an important and widespread native species. Eichhornia crassipes plants exposed to two consecutive generations of feeding produced 66.9% less biomass and 73.4% fewer leaves than those in the controls. We conclude that Megamelus scutellaris is safe to release on E. crassipes in the United States.     

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.     

Pre-release evaluation of absolute spillover impact risk of Physonota maculiventris (Chrysomelidae: Cassidinae) on non-target plant species Helianthus annuus (Asteraceae) and Zea mays (Poaceae) in South Africa

The tortoise beetle, Physonota maculiventris (Coleoptera: Chrysomelidae), a candidate biological control agent of Tithonia diversifolia (Hemsl.) A. Gray (Asteraceae) was screened for spillover risks on non-target plant species in South Africa. Studies were conducted to measure the absolute feeding damage and reproductive performance of P. maculiventris on non-target plant species, Helianthus annuus L. (Asteraceae) and Zea mays L. (Poaceae). The influence of spillover on generational build-up performance on the non-target plant species was also investigated. Adult female beetles were switched from T. diversifolia at 14 (actively feeding colony) or 24 (gravid colony) days to the non-target species. Likewise, as a backup or control, female beetles were exposed to H. annuus in a no-choice situation and switched to T. diversifolia and Z. mays. Feeding damage, adult longevity and egg production of P. maculiventris were significantly lower on H. annuus, compared to those metrics on T. diversifolia. Gravid P. maculiventris adults switched from T. diversifolia on the 14th day after emergence laid a few egg batches on the leaf surfaces of Z. mays, but no signs of feeding were observed. Furthermore, the population of P. maculiventris significantly increased by 11.7 fold (26.8–312.5 adults) between the first (F1) and second (F2) generations on T. diversifolia, while on the non-target, H. annuus, it decreased from 6.3 to zero (0). The study concludes that P. maculiventris will sustain its populations entirely on the target, T. diversifolia population stands associated with or without H. annuus and Z. mays cultivations at different scales in South Africa.     

Examining olfactory and visual cues governing host-specificity of a weed biological control candidate species to refine pre-release risk assessment

In weed biological control programs, pre-release host-specificity testing relies traditionally on no-choice and choice feeding, oviposition, and development tests. Rarely have they included detailed examination of behavioral responses to olfactory and visual cues of biological control candidates, although a better understanding of the mechanisms underlying host recognition may explain potential discrepancies between choice and no-choice tests, and/or between tests conducted in the lab versus field conditions. We investigated how the seed-feeding weevil, Mogulones borraginis, distinguishes its host plant, Cynoglossum officinale, from three native confamilial non-target species in North America. In behavioral bioassays, M. borraginis responded to olfactory and visual cues individually and, to an even greater extent, to both plant cue modalities when offered simultaneously. In tests with the combined cues, M. borraginis was attracted to C. officinale but responded with indifference or was repelled by non-target plants. In electrophysiological experiments, we identified that M. borraginis responded to ten volatile compounds and four wavelengths of lights from inflorescences of C. officinale. We propose that studies of responses to multimodal plant cues can advance our understanding of how biocontrol candidate species discriminate among host plants and closely related non-target species, thereby increasing the accuracy of environmental safety assessments pre-release.     

Host-range and cold temperature tolerance of Floracarus perrepae Knihinicki & Boczek (Acari: Eriophyidae), a potential biological-control agent of Lygodium microphyllum (Pteridophyta: Lygodiaceae)

Abstract The leaf galling eriophyid mite Floracarus perrepae is a widespread and damaging herbivore of Old World climbing fern, Lygodium microphyllum , across its native range in tropical and subtropical Asia and Australia; and was therefore selected as a candidate biological-control agent for the invasive fern in Florida, USA. The host testing of F. perrepae focused on Lygodium species from North America and the Neotropics, along with threatened or endangered ferns from Florida. Sporeling ferns were used for the initial no-choice screening and F. perrepae showed normal development on the Florida genotype of L. microphyllum with 33.0 ± 4.6 mites per marginal leaf roll gall, modest development on the North American native Lygodium palmatum with 29.0 ± 9.3 mites per roll, and minor development on six other fern species (4.0–0.3). Leaf rolls were induced only on Lygodium species and full rolls were common only on L. microphyllum . These same six non-target plant species were tested again as more mature plants in both no-choice and choice tests and F. perrepae developed only on L. microphyllum . Lethal minimum temperature and cold stress tests were also conducted on F. perrepae . These tests revealed that it would not likely establish north of USDA hardiness zone 8a (−9.5 to −12.2°C), which means it would not overlap with L. palmatum from temperate North America. Our studies conclude that F. perrepae is specific to L. microphyllum , poses little or no risk to native or cultivated ferns in North and South America, and therefore should be considered for release in Florida.     

Host specificity testing and examination for plant pathogens reveals that the gall‐inducing psyllid Calophya latiforceps is safe to release for biological control of Brazilian peppertree

Brazilian peppertree, Schinus terebinthifolia Raddi (Anacardiaceae), is one of the worst upland exotic weeds in Florida, USA. Foreign exploration for natural enemies led to the discovery of a pit‐galling psyllid, Calophya latiforceps Burckhardt (Hemiptera: Calophyidae), in the state of Bahia, Brazil, in 2010. Crawlers of C. latiforceps stimulate the formation of galls on the leaves of S. terebinthifolia resulting in leaf discoloration and in some cases leaf abscission. To determine whether C. latiforceps is a safe candidate for biological control of S. terebinthifolia, host specificity and the presence of selected plant pathogens were examined. Adult oviposition, gall formation, and adult survival of C. latiforceps were examined on 89 plant species under no‐choice and choice conditions. We found that C. latiforceps laid eggs on plants in seven families; however, crawlers stimulated gall formation and completed development to adult only on S. terebinthifolia. All crawlers on non‐target plants died, likely due to starvation caused either by the absence of a feeding stimulus or by a hypersensitive plant response. Under no‐choice conditions, 10% of adults lived for 19 days on the target weed, but adult survival was reduced to <3 days on non‐target plants. Choice testing revealed that females preferred to oviposit on S. terebinthifolia compared to non‐target plants. Molecular methods and indicator host inoculations did not detect the presence of ‘Candidatus Liberibacter solanacearum’, ‘Ca. L. asiaticus’, ‘Ca. L. americanus’, ‘Ca. L. africanus’, or plant viruses in adult C. latiforceps. We conclude that releasing C. latiforceps in the USA will have extremely low risk to non‐target plants, and provides another tool for the management of S. terebinthifolia.     

Evaluation of Cyphocleonus trisulcatus (Coleoptera: Curculionidae) as a potential biological control agent for Leucanthemum vulgare in North America

Leucanthemum vulgare, a perennial forb native to Eurasia, has become invasive in several other parts of the world. Since there is a lack of methods suitable for sustainable management of this plant across invaded landscapes, a biological control project has been initiated in North America and Australia. We evaluated the potential of the root-feeding weevil Cyphocleonus trisulcatus as a biological control agent for L. vulgare in North America by investigating its impact on L. vulgare and studying its larval host range under no-choice, multiple-choice cage and open-field conditions. Our impact experiment revealed that larval feeding by C. trisulcatus can severely damage and even kill plants. No-choice tests conducted with 41 non-target species showed that C. trisulcatus can develop on five closely related species. In a multiple-choice cage test established with three of these species, the medicinal plant Matricaria chamomilla and the native North American M. occidentalis were also attacked, but to a lower degree than L. vulgare. An open-field test conducted with four varieties of the ornamental Shasta daisy (Leucanthemum × superbum and L. × maximum) revealed similar attack on Shasta daisy as on L. vulgare. Due to the popularity of Shasta daisies, we suggest that C. trisulcatus, despite its potential to suppress L. vulgare populations, is not a suitable biological control agent for North America. However, C. trisulcatus may still be a potential biological control agent for L. vulgare in regions where Shasta daisy is less popular, such as Australia. Further host-range tests with species native to Australia as well as with additional species important for the horticultural industry in Australia are currently under way.     

Synergistic effect of insect herbivory and plant parasitism on the performance of the invasive tree Schinus terebinthifolius

Schinus terebinthifolius Raddi (Anacardiaceae) is an introduced tree from South America that has invaded many ecosystems throughout central and south Florida, USA. Exploratory surveys in the plant's native range identified several potential biocontrol agents, including the leaflet rolling moth, Episimus unguiculus Clarke (Lepidoptera: Tortricidae). The larval stages of E. unguiculus tie together the plant leaflets while feeding and can completely defoliate small plants. The native love vine, Cassytha filiformis L. (Lauraceae), has been found parasitizing S. terebinthifolius in Florida. Natural processes such as plant parasitism may be one of the components of an integrated approach for S. terebinthifolius management in Florida. Thus, the objective of this study was to evaluate the combined effects of insect herbivory and plant parasitism on the performance of S. terebinthifolius . A factorial design experiment was conducted in the greenhouse to determine the effect of C. filiformis parasitism and E. unguiculus feeding damage on the growth and biomass of S. terebinthifolius . Results showed that plant parameters, including leaflet biomass, growth rate, and flower production, were negatively affected by plant parasitism and insect herbivory. Moreover, the decrease in S. terebinthifolius performance was greater when these two factors were combined, indicative of a synergistic relationship. In addition, the combined effect of C. filiformis and E. unguiculus suppressed plant performance for at least 2 months after the moths were removed. Therefore, increased control of S. terebinthifolius stands may be achieved in those areas where C. filiformis is present in Florida (e.g., pinelands, hammock forests) if the biocontrol agent E. unguiculus is approved for release.