Life cycle and host range of Phycita sp. rejected for biological control of prickly acacia in Australia

Prickly acacia (Vachellia nilotica subsp. indica), a native of the Indian subcontinent, is a serious weed of the grazing areas of northern Australia and is a target for classical biological control. Native range surveys in India identified a leaf webber, Phycita sp. (Lepidoptera: Pyralidae) as a prospective biological control agent for prickly acacia. In this study, we report the life cycle and host‐specificity test results Phycita sp. and highlight the contradictory results between the no‐choice tests in India and Australia and the field host range in India. In no‐choice tests in India and Australia, Phycita sp. completed development on two of 11 and 16 of 27 non‐target test plant species, respectively. Although Phycita sp. fed and completed development on two non‐target test plant species (Vachellia planifrons and V. leucophloea) in no‐choice tests in India, there was no evidence of the insect on the two non‐target test plant species in the field. Our contention is that oviposition behaviour could be the key mechanism in host selection of Phycita sp., resulting in its incidence only on prickly acacia in India. This is supported by paired oviposition choice tests involving three test plant species (Acacia baileyana, A. mearnsii and A. deanei) in quarantine in Australia, where eggs were laid only on prickly acacia. However, in paired oviposition choice trials, only few eggs were laid, making the results unreliable. Although oviposition choice tests suggest that prickly acacia is the most preferred and natural host, difficulties in conducting choice oviposition tests with fully grown trees under quarantine conditions in Australia and the logistic difficulties of conducting open‐field tests with fully grown native Australian plants in India have led to rejection of Phycita sp. as a potential biological control agent for prickly acacia in Australia.     

Life history of Anomalococcus indicus (Hemiptera: Lecanodiaspididae), a potential biological control agent for prickly acacia Vachellia nilotica ssp. indica in Australia

Babul scale Anomalococcus indicus Ramakrishna Ayyar, a major pest of Vachellia nilotica (L.f.) P.J.H. Hurter & Mabb. on the Indian subcontinent, has been identified as a potential biocontrol agent for prickly acacia V. nilotica subsp. indica (Benth.) Kyal. & Boatwr. in Australia and was imported from southern India for detailed assessment. The life history of A. indicus under controlled glasshouse conditions was determined as a part of this assessment. Consistent with other scale species, A. indicus has a distinct sexual dimorphism which becomes apparent during the second instar. Females have three instars, developing into sexually mature nymphs after 52 days. The generation time from egg to egg was 89 days. Females are ovoviviparous, ovipositing mature eggs into a cavity underneath their body. An average of 802 ± 114 offspring were produced per female. Reproductive output was closely associated with female size; larger females produced more than 1200 offspring. Crawlers emerged from beneath the female after an indeterminate period of inactivity. They have the only life stage at which A. indicus can disperse, though the majority settle close to their parent female forming aggregative distributions. In the absence of food, most crawlers died within three days. Males took 62 days to develop through five instars. Unlike females, males underwent complete metamorphosis. Adult males were small and winged, and lived for less than a day. Parthenogenesis was not observed in females excluded from males. The life history of A. indicus allows it to complement other biological control agents already established on prickly acacia in Australia.     

The introduction and release of Chiasmia inconspicua and C. assimilis (Lepidoptera: Geometridae) for the biological control of Acacia nilotica in Australia

Two geometrid moths Chiasmia inconspicua and Chiasmia assimilis, identified as potential biological control agents for prickly acacia Acacia nilotica subsp. indica, were collected in Kenya and imported into quarantine facilities in Australia where laboratory cultures were established. Aspects of the biologies of both insects were studied and CLIMEX® models indicating the climatically favourable areas of Australia were developed. Host range tests were conducted using an approved test list of 74 plant species and no-choice tests of neonate larvae placed on both cut foliage and potted plants. C. inconspicua developed through to adult on prickly acacia and, in small numbers, Acacia pulchella. C. assimilis developed through to adult on prickly acacia and also in very small numbers on A. pulchella, A. deanei, A. decurrens, and A. mearnsii. In all experiments, the response on prickly acacia could be clearly differentiated from the responses on the non-target species. Both insects were approved for release in Australia. Over a three-year period releases were made at multiple sites in north Queensland, almost all in inland areas. There was no evidence of either insect’s establishment and both colonies were terminated. A new colony of C. assimilis was subsequently established from insects collected in South Africa and releases of C. assimilis from this new colony were made into coastal and inland infestations of prickly acacia. Establishment was rapid at one coastal site and the insect quickly spread to other infestations. Establishment at one inland area was also confirmed in early 2006. The establishment in coastal areas supported a CLIMEX model that indicated that the climate of coastal areas was more suitable than inland areas.     

Survey and prioritisation of potential biological control agents for prickly acacia (Acacia nilotica subsp. indica) in southern India

Prickly acacia, Acacia nilotica subsp. indica (Benth.) Brenan (Mimosaceae), a multi-purpose tree native to the Indian subcontinent, is a weed of national significance, widespread throughout the grazing areas of western Queensland and has the potential to spread throughout northern Australia. Biological control of prickly acacia has been in progress since the early 1980s, but with limited success to date. Based on genetic and climate matching studies, native surveys for potential biological control agents were conducted in 64 sites in Tamil Nadu state and eight sites in Karnataka state from November 2008 to December 2011. Surveys yielded 33 species of phytophagous insects (16 species of leaf-feeders, eight species of stem feeders, four species with leaf-feeding adults and root-feeding larvae, two stem-borers and bark-feeders and three flower-feeders) and two rust fungi. The number of species recorded at survey sites increased with the number of times the sites were surveyed. Using a scoring system based on field host range, geographic range, seasonal incidence and damage levels, we prioritised a scale insect (Anomalococcus indicus Ramakrishna Ayyar), two leaf-webbing caterpillars (Phycita sp. A and Phycita sp. B), a leaf weevil (Dereodus denticollis Boheman), a leaf beetle (Pachnephorus sp.), a gall-inducing rust (Ravenelia acacia-arabica Mundk. & Thirumalachari) and a leaf rust (Ravenelia evansii Syd. & P.) for detailed host specificity tests. The two rusts were sent to CABI-UK for preliminary host-specificity testing. Three insects (A. indicus, D. denticollis and Phycita sp. A) were imported into a quarantine facility in Brisbane, Australia where host-specificity tests are in progress.     

Implications of the changing phylogenetic relationships of Acacia s.l. on the biological control of Vachellia nilotica ssp. indica in Australia

Plant relationships have implications for many fields including weed biological control. The use of DNA sequencing and new tree building algorithms since the late 1980s and early 1990s have revolutionised plant classification and has resulted in many changes to previously accepted taxonomic relationships. It is critical that biological control researchers stay abreast of changes to plant phylogenies. One of the largest plant genera, Acacia, has undergone great change over the past 20 years and these changes have ramifications for weed biological control projects in a number of countries. Vachellia nilotica (prickly acacia) is a major weed in Australia, originating from the Indian subcontinent and Asia, and it has been a target for biological control since 1980. Once a member of Acacia, a large (>1,000 spp.) and iconic group in Australia, prickly acacia is now part of the genus Vachellia. Current knowledge suggests that Vachellia is more closely related to mimosoid genera than it is to Acacia s.s. There has also been a recent reclassification of legume subfamilies with subfamily Mimosoideae now part of subfamily Caesalpinioideae, and four new subfamilies. In this paper we review the changes that have occurred to this group since the prickly acacia biological control project began and discuss the implications for the project. A new host test list for quarantine testing is proposed. Developed following the modernisation of the centrifugal‐phylogenetic method, it is shorter than past lists, containing 46 species, although still lengthy because of the expectations of regulatory bodies, which are slower to accept advances in scientific knowledge. The list includes five Vachellia species, six “Mimoseae” species and 26 Acacia species. The number species from legume subfamilies other than the new Caesalpinioideae is greatly reduced.     

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.     

Isolation and characterization of microsatellite loci from Acacia nilotica ssp. indica (Mimosaceae)

Five microsatellite loci are presented for prickly acacia, Acacia nilotica ssp. indica (Benth.) Brenan, an introduced weed of national significance in Australia. These microsatellite loci were obtained through the construction of an enriched library and their use will enable us to determine the genetic origin and extent of genetic diversity of this weed in Australia.     

Host specificity of Puccinia spegazzinii (Pucciniales: pucciniaceae), a biological control agent for Mikania micrantha (Asteraceae) in Australia

The biology and host specificity of the rust fungus Puccinia spegazzinii, a biological control agent for Mikania micrantha, was studied in a quarantine laboratory in Brisbane, Australia. Nineteen plant species, all from the family Asteraceae were inoculated during host specificity trials. Spore formation occurred only on M. micrantha and no other plant was infected. The first signs of infection (white spots on leaves, petioles and stems) occurred 7 days after exposure to inoculum, becoming yellow by day 11. Mature pustules containing teliospores had developed by 20 days. Results obtained here support testing in other countries showing that P. spegazzinii is host specific to M. micrantha and no that other plant in Australia would be at risk if it were to be released in the environment. Recommendations on assessing pathogens to improve trials were proposed. Counting infected plants, plant parts and pustules formed can demonstrate that all test plants would have been adequately exposed to inoculum and thus increase the confidence in host specificity of pathogens in weed biological control.     

A systematic approach to biological control agent exploration and prioritisation for prickly acacia (Acacia nilotica ssp. indica)

Abstract  Agent selection for prickly acacia has been largely dictated by logistics and host specificity. Given that detailed ecological information is available on this species in Australia, we propose that it is possible to select agents based on agent efficacy and desired impact on prickly acacia demography. We propose to use the 'plant genotype' and 'climatic' similarities as filters to identify areas for future agent exploration; and plant response to herbivory and field host range as 'predictive' filters for agent prioritisation. Adopting such a systematic method that incorporates knowledge from plant population ecology and plant–herbivore interactions makes agent selection decisions explicit and allow more rigorous evaluations of agent performance and better understanding of success and failure of agents in weed biological control.     

The tortoise beetle Physonota maculiventris (Chrysomelidae: Cassidinae) is suitable for release against the weedy Mexican sunflower Tithonia diversifolia (Asteraceae) in South Africa

The biology and host range of the defoliating beetle Physonota maculiventris Boheman (Chrysomelidae: Cassidinae) were studied in quarantine to determine its suitability for release as a biological control agent against Mexican sunflower, Tithonia diversifolia (Hemsl.) A. Gray (Asteraceae), in South Africa. Females laid 5.25?±?0.25 (mean?±?SE) egg batches during their lifetimes, with each batch consisting of approximately 33 eggs. Larvae were highly gregarious as early instars and both larvae and adults fed voraciously, often defoliating the plants completely. The life cycle of the beetle was completed in 67.5?±?7.5 days under quarantine conditions. Among the 58 test plant species subjected to no-choice tests, P. maculiventris developed successfully on T. diversifolia and some sunflower (Helianthus annuus L.) cultivars. However, only minor damage was recorded on non-target species, notably the exotic weed Xanthium strumarium L. and some H. annuus cultivars. Also, survival to adulthood was considerably lower on sunflower cultivars than on the target weed during these tests. During choice tests, P. maculiventris oviposited and developed successfully on T. diversifolia only, with only minor feeding damage on some H. annuus cultivars, suggesting that the beetle’s field host range will be confined to the target weed. Risk analysis also showed that P. maculiventris presents an extremely low risk to non-target plant species (e.g. within the tribe Heliantheae and other close relatives). The study concluded that P. maculiventris is safe for release in South Africa and an application for its release is being considered by the relevant South African regulatory authorities.     

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.     

Invasion of the gall mite Aceria genistae (Acari: Eriophyidae), a natural enemy of the invasive weed Cytisus scoparius,into California,U.S.A. and predictions for climate suitability in other regions using ecological niche modelling

Scotch broom (Cytisus scoparius (L.) Link) is a European shrub that has naturalised in several countries worldwide and is recognised as an invasive weed in much of western North America. The mite Aceria genistae (Nalepa) is a coevolved, gall-inducing herbivore associated with Scotch broom in its native range and has been intentionally introduced as a classical weed biological control agent of C. scoparius in Australia and New Zealand. An adventive, never intentionally introduced, population of A. genistae was discovered in Washington and Oregon, U.S.A. in 2005. Surveys for A. genistae in California resulted in the discovery of the gall mite in 11 counties, with a widely scattered distribution. Molecular and morphological assessments confirm the mites collected from galls in California are A. genistae. Whether natural or anthropogenic, the estimated rate of long range dispersal for A. genistae from Washington or Oregon to California ranges from 39 to 62?km/yr. Niche model predictions indicate that A. genistae will continue to expand its distribution throughout much of the Scotch broom-invaded lands of California but areas supporting the weed in the Eastern U.S.A. appear less suitable. Modelling evidence also indicates that portions of Chile and Argentina are suitable for colonisation by A. genistae, also suggesting that expansion of the mite is possible in areas of Tasmania, southeastern Australia, and New Zealand where the mite was released. The environmental safety of A. genistae in relation to non-target plants and the influence of herbivory on Scotch broom fitness are discussed.     

Initial screening of the stem-boring weevil Osphilia tenuipes, a candidate agent for the biological control of Bryophyllum delagoense in Australia

A stem-boring weevil, Osphilia tenuipes (Fairmaire) (Coleoptera: Curculionidae), from Madagascar, was screened in South Africa to determine its potential as a biological control agent for Bryophyllumdelagoense (Ecklon & Zeyher) Schinz(Crassulaceae) in Australia. Favourableattributes of the weevil include ease ofculturing, multiple generations per year, andhigh levels of damage inflicted on B. delagoense under laboratory conditions. Despite indications that O. tenuipes hasa narrow field host range, no-choice andmultiple-choice trials in quarantine revealedthat it could oviposit and develop to adulthoodon seven non-target species in the familyCrassulaceae, without an obvious loss offitness on four of those species. Despitethese results, O. tenuipes is consideredto have potential for release against B. delagoense in Australia because the continenthas very few native Crassulaceae which couldpotentially serve as alternative hosts in thefield.     

Prospects for the classical biological control of Calotropis procera (Apocynaceae) using coevolved insects

Calotropis procera (Apocynaceae), a native of tropical Africa, the Middle East and the Indian subcontinent, is a serious environmental and rangeland weed of Australia and Brazil. It is also a weed in Hawaii in the USA, the Caribbean Islands, the Seychelles, Mexico, Thailand, Vietnam and many Pacific Islands. In the native range C. procera has many natural enemies, thus classical biological control could be the most cost-effective option for its long-term management. Based on field surveys in India and a literature search, some 65 species of insects and 5 species of mites have been documented on C. procera and another congeneric-invador C. gigantea in the native range. All the leaf-feeding and stem-boring agents recorded on Calotropis spp. have wide host range. Three pre-dispersal seed predators, the Aak weevil Paramecops farinosus, the Aak fruit fly Dacus persicus in the Indian subcontinent and the Sodom apple fruit fly Dacus longistylus in the Middle East, have been identified as prospective biological control agents based on their field host range. In Australia and Brazil, where C. procera has the potential to spread across vast areas, pre-dispersal seed predators would help to limit the spread of the weed. While the fruits of C. procera vary in size and shape across its range, those from India are similar to the ones in Australia and Brazil. Hence, seed-feeding insects from India are more likely to be suitable due to adaptation to fruit size and morphology. Future survey efforts for potential biological control agents should focus on North Africa.     

Biology and host range of Heterapoderopsis bicallosicollis: a potential biological control agent for Chinese tallow Triadica sebifera

Chinese tallow, Triadica sebifera, is an invasive weed that infests natural and agricultural areas of the south-eastern USA. A candidate insect for biological control of Chinese tallow has been studied under quarantine conditions. The biology and host range of a primitive leaf-feeding beetle, Heterapoderopsis bicallosicollis, were examined between July 2008 and February 2010. H. bicallosicollis adults fed on 16 of 29 non-target species and survived >10 days on all 29 species, more than the number of days that adults survived when deprived of food. Additionally, adult feeding, oviposition and partial larval development occurred on a Florida endangered species, Heterosavia bahamensis. These data indicated that H. bicallosicollis adult feeding and oviposition may not be limited to the target weed and included several valued North American natives. Therefore, as its release could pose unacceptable risks, testing of this species was discontinued and the quarantine colony destroyed.     

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.     

Prioritising potential guilds of specialist herbivores as biological control agents for prickly acacia through simulated herbivory

Understanding plant response to herbivory facilitates the prioritisation of guilds of specialist herbivores as biological control agents based on their potential impacts. Prickly acacia ( Acacia nilotica ssp. indica ) is a weed of national significance in Australia and is a target for biological control. Information on the susceptibility of prickly acacia to herbivory is limited, and there is no information available on the plant organ (i.e. leaf, shoot and root in isolation or in combination) most susceptible to herbivory. We evaluated the ability of prickly acacia seedlings, to respond to different types of simulated herbivory (defoliation, shoot damage, root damage and combinations), at varying frequencies (no herbivory, single, two and three events of herbivory) to identify the type and frequency of herbivory that will be required to reduce the growth and vigour. Defoliation and shoot damage, individually, had a significant negative impact on prickly acacia seedlings. For the defoliation to be effective, more than two defoliation events were required, whereas a single bout of shoot damage was enough to cause a significant reduction in plant vigour. A combination of defoliation + shoot damage had the greatest negative impact. The study highlights the need to prioritise specialist leaf and shoot herbivores as potential biological control agents for prickly acacia.     

Complete development on Elodea canadensis (Hydrocharitaceae) eliminates Hydrellia egeriae (Diptera,Ephydridae) as a candidate biological control agent of Egeria densa (Hydrocharitaceae) in the U.S.A.

The leaf-mining fly Hydrellia egeriae Rodrigues-Junior (Diptera: Ephydridae) was evaluated under quarantine conditions as a candidate biological control agent of the invasive aquatic weed Egeria densa Planchon (Hydrocharitaceae) in California, U.S.A. The objective of this study was to test the fly’s feeding preference for E. densa as compared to the North American native Elodea canadensis Michaux (Hydrocharitaceae), an important benchmark species. No choice testing revealed that H. egeriae can complete development on E. canadensis and choice testing indicated the fly presents little oviposition discrimination between E. densa and E. canadensis. It is concluded that the host range of H. egeriae is too broad for use as a biological control agent of E. densa in the U.S.A.     

Host range and risk assessment of Zygogramma bicolorata,a defoliating agent released in South Africa for the biological control of Parthenium hysterophorus

Parthenium hysterophorus (parthenium) is a weed of international importance and is spreading rapidly in sub-Saharan Africa. Consequently, it has been targeted for biocontrol in South Africa since 2003. Based on precedents elsewhere in the world, the defoliating beetle Zygogramma bicolorata was prioritised as a candidate agent. Although no-choice tests, involving some 48 test plant species, indicated a significant preference for parthenium, significantly reduced feeding and oviposition was recorded on some species. Multiple-choice tests resolved many of these non-target results; however, Helianthus annuus (sunflower) was still selected for oviposition and feeding. Of the 12 sunflower cultivars tested, four were selected for oviposition, while two were selected for oviposition and feeding. These six cultivars were then subjected to larval development trials, together with three native and two weed species (in the Asteraceae). These trials showed high levels of complete development on parthenium, significantly reduced development on sunflower cultivars, and partial development on only one of the weed species. Finally, a risk assessment was conducted on the six sunflower cultivars to quantify Z. bicolorata feeding and reproductive performance. Feeding risk calculations revealed these cultivars to have an extremely low risk (<0.2%) of supporting Z. bicolorata feeding and development. Similarly, reproductive risk calculations showed a very low risk (<0.16%) of supporting viable Z. bicolorata populations. These data are supported by findings from both the native (Mexico) and introduced ranges (Australia, India) of Z. bicolorata, where it has never been recorded as a pest of sunflower. These considerations were accepted by the regulatory authorities and in August 2013, Z. bicolorata became the second insect agent to be released in South Africa for the biocontrol of parthenium.     

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.