No-choice Tests Research Articles

Biology and host specificity of the stem-boring weevil Gasteroclisus tricostalis, a candidate agent for the biological control of fireweed (Senecio madagascariensis) in Australia

ABSTRACT Senecio madagascariensis Poiret (Asteraceae) is a target for biological control in Australia, due to substantial impacts on agriculture and native environments. Studies in the plant’s native range in South Africa prioritised the stem-boring weevil Gasteroclisus tricostalis (Thunberg) (Curculionidae) as a candidate agent. In this study, we assessed the biology and host specificity of G. tricostalis during laboratory trials conducted in both South Africa and Australia. No-choice trials in South Africa revealed that, despite oviposition on 15 non-target Senecio species (seven Australian and eight South African), there was significantly lower oviposition relative to S. madagascariensis, with no survival to pupation or adulthood on any non-target species. In contrast, no-choice tests in quarantine in Australia, recorded oviposition on 12 non-target Australian native Senecio species, with oviposition on two species not significantly different to that on S. madagascariensis. Furthermore in Australia, larvae developed to adulthood on five non-target species, in numbers that were not significantly different to S. madagascariensis. These discrepancies can mostly be explained by the lower phylogenetic distance from S. madagascariensis to the susceptible non-target species tested in Australia and, likely, optimal plant growth conditions in quarantine in two cases. Although no-choice tests are renowned for their conservative nature, preliminary paired-choice trials in both South Africa and Australia failed to demonstrate clear oviposition preferences for S. madagascariensis. These results suggest that, given the high diversity of the genus Senecio in Australia, the weevil is likely unsuitable for release and further trials were suspended.

Natural enemies of Lemna minuta in its native range and their potential as biological control agents for Europe

ABSTRACT Lemna minuta is native to North America but an invasive alien plant in Europe, where it poses significant threats to freshwater ecosystems. Explorations for biological control agents were conducted in two regions of the United States (Louisiana and California), revealing three candidate species. Subsequent laboratory investigations focused on the weevil Tanysphyrus lemnae and the fly Lemnaphila scotlandae as the most promising agents and confirmed that both the herbivorous insects attack L. minuta plants. To evaluate the host specificity of these two potential agents, insects were exposed to five species of duckweed commonly occurring in North America and Europe. Preliminary host-range testing indicated that T. lemnae develops on all evaluated duckweed species, including those from different genera (Lemna, Spirodela, Landoltia). Conversely, data revealed that feeding and development of the dipteran L. scotlandae are limited to species in the genus Lemna, but this includes L. minor, a native European species threatened in Europe due to the spread of L. minuta. No-choice and choice tests confirmed that neither larvae nor adults of L. scotlandae discriminate between the two Lemna species, except for pupation, which occurs more frequently in L. minor under choice conditions. We conclude that the broad host-range of T. lemnae and L. scotlandae render them unsuitable as biological control agents of L. minuta in Europe.

Susceptibility of Capsicum varieties to Thaumatotibia leucotreta (Lepidoptera: Tortricidae) infestation for production optimization.

Thaumatotibia leucotreta Meyrick (Lepidoptera: Tortricidae) is a major threat to the production and marketing of pepper (Capsicum spp.) in Ghana. To reduce the damage of the pest on pepper farming, it is important to find appropriate control methods, which may include the use of resistant host plants. This study investigated the relative susceptibility of 6 pepper varieties commonly cultivated in Ghana: Legon 18, Bird's eye, Scotch bonnet, Cayenne, KA2, and sweet pepper (Yolo wonder+ variety). Choice and no-choice ovipositional preference tests were conducted and the population growth rate of T. leucotreta was determined by establishing life table parameters including the net reproductive rates (R0), the mean generation time (G), intrinsic rate of natural increase (rm), the population doubling time (T), and the finite rate of increase (λ). In the no-choice test, females exhibited oviposition preference for sweet pepper (12.08 eggs/fruit), while Bird's eye was the least preferred (5.00 eggs/fruit). The same results were observed in the choice test. However, the population growth rate of T. leucotreta was highest on the Scotch bonnet and Cayenne, with rm of 0.124 and 0.127, respectively, while the Bird's eye and sweet pepper recorded the least rm of 0.116. Thus, the tested varieties had varying levels of susceptibility to T. leucotreta infestation. Bird's eye was the least susceptible variety, while Cayenne and Scotch bonnet were the most susceptible varieties. These findings could direct farmers on the choices of pepper varieties for cultivation and proffer potential opportunities to breed new varieties resistant to T. leucotreta infestation.

Risk assessment of the laboratory host range and a molecular characterisation determining the field host range of Lixus aemulus, for the biological control of Chromolaena odorata in South Africa

Chromolaena odorata (Asteraceae: Eupatorieae) is a sprawling shrub native to the Americas, and a destructive invader of much of the humid tropics and subtropics of the Old World. Opportunistic native-range exploration in 1995 identified a stem-boring weevil, Lixus aemulus, as a promising biological control candidate agent. Host-specificity testing was conducted on L. aemulus in South Africa using laboratory no-choice and paired-choice tests. Three invasive alien plants closely related to C. odorata may be utilized by L. aemulus but no indigenous, ornamental or crop species in South Africa was or is expected to be attacked by the weevil. A native-range field survey was conducted in Brazil to determine the exact identity of the host plant L. aemulus had been collected in 1995, and to identify additional host-plant species. Genetic assessments of the Lixus sp.(p.). adults collected on the three host plants (C. odorata, Chromolaena laevigata and Heterocondylus vitalbae) reveal these individuals are L. aemulus and the weevil can be classed as an oligophage in its native range. Over 5,500 adults were released in South Africa, but overall establishment has been poor. The most likely explanation appears to be a climate mismatch between the region of South Africa invaded by C. odorata and the collection locality in Rio Branco, Acre state, Brazil. Additionally, because the full extent of the native range of L. aemulus is unknown, it is uncertain whether individuals can be sourced from an area whose climate resembles that of South Africa. Furthermore, despite being oligophagous, L. aemulus may perform sub-optimally on the southern African C. odorata biotype.

Volatolomics to Decrypt the Monophagous Nature of a Rice Pest, Scirpophaga Incertulas (Walker).

Scirpophaga incertulas Walker (Lepidoptera: Crambidae, yellow stem borer, YSB) is a monophagous insect pest that causes significant yield loss in rice (Oryza staiva L.). Semiochemical based pest management is being sought as an alternate to chemical pesticides to reduce pesticide footprints. We hypothesized differential release of volatiles from host rice and two companion non-host weeds, Echinochloa colona and Echinochloa crus-galli could be responsible for oviposition and biology of YSB and these chemicals could be used for YSB management. Number of eggs laid, and number of larvae hatched were significantly higher in rice plant as compared to weeds. YSB could only form dead hearts in rice plants. YSB significantly preferred host-plant volatiles compared to the non-host plants both in choice and no-choice tests in an Y-tube olfactometer. 2-Hexenal, hexanal, 2,4-hexadienal, benzaldehyde, nonanal, methyl salicylate and decanal were found in the leaf volatolomes of both the host and non-host plants in HS-SPME-GC-MS (Headspace-Solid phase micro extraction-Gas chromatography-Mass spectrometer). Pentene-3-one, 2-pentyl furan, 2,4-heptadienal, 2-octenal, 2-octenol and menthol were present only in the non-host plants. Fourteen rice unique compounds were also detected. The built-in PCA (Principal Component Analysis) and PLS-DA (Partial least squares-discriminant analysis) analysis in the MS-DIAL tool showed that the volatiles emitted from TN1 formed a cluster distinct from Echinochloa spp. and 2-octenal was identified as a unique compound. Olfactometer bioassays using synthetic compounds showed that rice unique compounds, like xylene, hexanal served as attractants whereas non-host unique compounds, like 2-pentylfuran, 2-octenal acted as repellent. The results indicate that the rice unique compounds xylene, hexanal along with other volatile compounds could be responsible for higher preference of YSB towards rice plants. Similarly, the non-host unique compounds 2-pentylfuran, 2-octenal could possibly be responsible for lower preference and defence against YSB. These compounds could be utilised for devising traps for YSB monitoring and management.

Resistência de poáceas forrageiras ao Blissus pulchellus Montandon (Hemiptera: Blissidae)

ABSTRACT Chinch bugs [Blissus pulchellus Montandon (Hemiptera: Blissidae)] suck the phloem from susceptible forage grasses, injecting toxins that destroy plant vessels and compromise the flow of water and nutrients, leading to plant death. Thus, the aim of this study was to assess eight forage grasses for antixenosis resistance to B. pulchellus and compare the anatomical characteristics of leaf sheath tissue from resistant and susceptible species/cultivars. Experiments were conducted in a laboratory and greenhouse, using choice and no-choice tests with the following forage grasses: Urochloa ruziziensis, U. humidicola, U. brizantha ‘Piatã’, U. brizantha ‘Paiaguás’, U. brizantha ‘Marandu’, Panicum maximum ‘Mombaça’, P. maximum ‘Zuri’, and Andropogon gayanus. The oviposition results demonstrated that in the choice test there was a change in the stink bug’s behavior in relation to grasses four hours after infestation, with U. humidicola, P. maximum ‘Mombaça’ and ‘Zuri’, U. brizantha ‘Marandu’ and A. gayanus, proving to be less attractive to insects. It is concluded that U. humidicola, P. maximum ‘Mombaça’ and ‘Zuri’, U. brizantha ‘Marandu’, and A. gayanus are less attractive to B. pulchellus. A. gayanus and P. maximum ‘Mombaça’ and ‘Zuri’ showed non-preference resistance (antixenosis) to oviposition by B. pulchellus. The resistance of U. humidicola, P. maximum ‘Zuri’, and A. gayanus to B. pulchellus may be associated with greater compaction and lignification of the parenchyma and sclerenchyma cells of leaf sheaths.

Life cycle, host specificity and potential impact of a gall-inducing thrips Acaciothrips ebneri, a biological control agent for prickly acacia (Vachellia nilotica subsp. indica) in Australia

Prickly acacia (Vachellia nilotica subsp. indica (Benth.) Kyal. & Boatwr.; Fabales: Fabaceae) is a Weed of National Significance and a target for biological control in Australia. Currently there are no effective biological control agents for the weed in Australia. Based on genetic and climate matching, a gall thrips (Acaciothrips ebneri Karny; Thysanoptera: Phlaeothripidae) inducing rosette galls resulting in shoot tip dieback, was identified as a prospective biological control agent from Ethiopia. No-choice host-specificity tests were conducted on 59 test plant species in a high security quarantine in Brisbane, Australia. Acaciothrips ebneri is host-specific, inducing galls and reproducing only on prickly acacia. Acaciothrips ebneri, as predicted by the CLIMEX model, is suited to hot and arid western Queensland where major prickly acacia infestations occur. The Australian Government approved A. ebneri for field release in October 2022. This is the first time a true gall-inducing thrips has ever been approved as a weed biological control agent. Field releases commenced in January 2023 and are in progress. There are early signs of field establishment resulting in shoot tip die back in the field, and field release and monitoring will continue.

Unveiling the potency of ready-to-use brodifacoum blocks in lesser bandicoot rats: exploring toxicity, blood clotting factors, and organ histology.

The present study unveiled the effectiveness of ready-to-use brodifacoum blocks (0.005%) against the prevalent field rat species in southeast Asia, Bandicota bengalensis. Brodifacoum, a more potent second-generation anticoagulant, offers a solution for managing rodents resistant to other anticoagulants of its class. Male and female bandicoot rats caught wild were exposed to brodifacoum for 1, 2, and 3days in both the no-choice and bi-choice tests. The observations included mortality rates, impact on body weight, food consumption, blood clotting factors, organ weights, and histological changes. Results indicated 100% mortality within 2-3days in the no-choice tests, and 50.00%-83.33% mortality in the bi-choice tests within 5 to 8days. The median lethal feeding periods were determined to be 2.10 and 2.33days for male and female rats, respectively. Toxicity symptoms included bleeding from the nose, gums, and feet. While no significant effects were observed on body weight or organ weights, food consumption decreased notably in no-choice tests. Additionally, significant increases in prothrombin time and activated partial thromboplastin time were noted 24h post-treatment in the no-choice tests, with post-treatment international normalized ratios of 9.45-14.20 and 1.52-3.03 in the no-choice and the bi-choice tests, respectively. Histological analysis revealed mild to severe necrotic changes in the liver and kidneys after brodifacoum treatment. Overall, this study underscores the potential of ready-to-use brodifacoum blocks as an effective tool for rodent population control, offering a viable alternative to other second-generation anticoagulant rodenticides.

COMPARATIVE RESISTANCE OF SELECTED WHEAT VARIETIES TO TROGODERMA GRANARIUM EVERTS

Triticum aestivum is the most important cultivated crop in Indian farming. Compared with other grains, it is relatively safer from insect pests during standing crop, but in storage state, it is heavily damaged due to various stored grain pests. Trogoderma granarium Everts (Khapra beetle) is the most severe critical pest. The relative resistance of 17 genotypes of wheat grains was evaluated through no-choice progeny tests under the uniform state of temperature, relative humidity, and wheat grain moisture. Investigation resulted in the identification of resistance to T. granarium, including the most resistant strains identified were D.B.W. 17, P.B.W. 502, P.B.W. 343, P.B.W. 373, W.H. 542, D.B.W. 303, W.H. 533, P.B.W.226, and U.P. 2382 with infestation ranging between 8.0 and 12.33 beetles/20 grains. These lines could be utilized in further breeding programs.. KEYWORDS :Genotypes, Plant breeding, Resistance, Trogoderma granarium, Wheat

The feeding and foraging behaviour of three ladybird beetles on Phenacoccus solenopsis (Hem.: Pseudococcidae) at different temperatures

ABSTRACT Ladybird beetles Scymnus nubilus Mulsant, Scymnus interruptus (Goeze), and Hippodamia convergens Guérin-Méneville are key contributors to biological control of some pests including Phenacoccus solenopsis Tinsley. This study explores their feeding preferences, functional response, and interference in controlled laboratory conditions. Feeding experiments, including both no-choice and free-choice tests, were conducted at temperatures ranging from 15 to 35°C fed on different developmental stages of P. solenopsis. The study analyzed the functional response with Holling's disc equation and assessed mutual interference among predators using the Hassell and Varley model. In the no-choice feeding tests, H. convergens adults exhibited the highest consumption at 26°C, with values of 46.0 1st instar nymphs, 40.9 2nd instar nymphs, and 34.9 adult females of P. solenopsis, followed by S. interruptus. Free-choice feeding tests also showed a preference for 26°C, with H. convergens consistently consuming the most prey at all stages, followed by S. interruptus. Functional response analysis revealed a type II functional response for three predators. Hippodamia convergens exhibited a significantly higher attack rate (1.0250 h−1) and a shorter handling time (0.0449 h) compared to the other species. Interference among predators was observed, with a progressive decline in prey consumption as predator density increased. Mutual interference constants (m) were calculated as 1.70, 1.74, and 1.77 for S. nubilus, S. interruptus, and H. convergens, respectively. As predator densities increased, searching efficiency declined. This suggest that H. convergens and S. interruptus adults at 26°C with a prey density of 40 can effectively contribute to sustainable P. solenopsis management.

Does intraspecific variation in Trissolcus japonicus affect its response to non-target hosts?

Host specificity is a key criterion for the implementation of any biological control program. In parasitoid wasps, host specificity is mediated by their response to chemical cues directly and indirectly associated with their hosts during foraging. Although intraspecific variation in foraging behaviour is documented, it is rarely integrated into risk assessment studies of potential biological control agents, as is the case for Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae), an Asian egg parasitoid and biological control agent of the invasive Halyomorpha halys (Stål) (Hemiptera: Pentatomidae). In the present study, we compared the behavioural response of T. japonicus females of an adventive line present in Switzerland and an Asian line (Beijing USDA), recently mass released in Italy, to cues of its target host H. halys and non-target host Pentatoma rufipes (L.) (Hemiptera: Pentatomidae). We observed minimal differences in host acceptance, exploitation and suitability in no-choice tests. In contrast, the behavioural response to host contact kairomones left on leaf substrates significantly differed between the two lines. While both lines preferred chemical footprints of H. halys in comparison to P. rufipes, females of the Beijing USDA line responded more strongly to host kairomones. The observed intraspecific variation in behavioural traits highlights the relevance of considering genetically distinct parasitoid lines and their host foraging behaviour in biological risk assessment studies. However, the implications of intraspecific variation in parasitoid foraging behaviour for biological control of a pest and non-target effects in the field remain challenging to predict.

Refining Gastrophysa atrocyanea (Coleoptera: Chrysomelidae) identification using UV marking in whole-plant assessment

The host plant quality is crucial for assessing the environmental safety of weed biological control agents, as they rely on the phenotypic characteristics of test plants in host specificity tests and for mass-rearing before field release. In this study, we explored the feasibility of using potted plants by applying ultraviolet (UV) fluorescent pigment to the elytra of the leaf beetle Gastrophysa atrocyanea. They were released separately on Rumex acetosa as the target weed and Buxus sinica var. insularis as a non-target plant in insect cages. UV marking reduced detection time by 2.7 times and increased the detection rates of female leaf beetles on the target weed compared to visible light, resulting in only 7.41% missing leaf beetles. Similarly, UV application reduced detection time by 2.3 times on the non-target plant, with no missing leaf beetles. Further, marking different sexes with UV pigments facilitated identification 4.8 times faster than visual light. The UV mark and recapture method exhibits promising potential in whole-plant testing, simplifying the identification of a potential biological control agent, G. atrocyanea, in insect cages under no-choice tests. Thus, UV marking enables the possibility of mass-rearing weed biological control agents and monitors the foraging behavior of phytophagous insects cost-effectively and non-disruptively in laboratory settings.

A strategy to improve rodent control while reducing rodenticide release into the environment

In addition to having a negative impact on the health of people and domestic animals, rodents often cause enormous damage to the environment by disrupting natural biodiversity. The negative impacts of rodents in urban and rural areas have required intensive use of rodentcides in spite of the proven risk of secondary poisoning of non-target predators and scavengers. Continuous and intensive use of rodenticides has led to environmental pollution through their retention in the environment. Commensal rodents are predominantly managed with anticoagulant rodenticides, which are very persistent in the environment and move up the food chain and accumulate in the bodies of predators and scavengers. Generally, the use of anticoagulant rodenticides continues, and there is a need to take appropriate measures to reduce their harmful impact. The efficacy of second generation anticoagulants (bromadiolone, difenacoum and brodifacoum), combined either mutually or with chlorophacinone at reduced doses (0.001 % and 0.0008 %), in controlling brown rats (Rattus norvegicus) was tested in a four-day no-choice feeding test. Combinations of second generation anticoagulants were more effective than the combination of chlorophacinone and second generation anticoagulants. The results indicate that combinations of different anticoagulants at multifold lower doses than the standard may provide a successful tool for brown rat control and a more environment-friendly method of rodent control and protection of non-target animals.

Gastropod grazing on fresh and senescent leaves of non-native invasive plants Reynoutria japonica and Impatiensglandulifera

In invaded regions, the introduced non-native plants Reynoutria japonica and Impatiens glandulifera show little grazing damage, most likely due to the absence of specialized herbivores and the deterrent effect of secondary metabolites on generalist herbivores. The low degree of grazing damage has been explained by the non-mutually exclusive enemy-release and novel weapon hypotheses. We tested assumptions of these hypotheses by conducting a series of preference tests in which leaf samples from R. japonica, I. glandulifera, and the native Urtica dioica were offered to five species of generalist gastropods (the native Arianta arbustorum, Cepaea nemoralis and Fruticicola fruticum, and the non-native invasive Hygromia cinctella and Arion vulgaris). In addition, we determined the C/N-ratio and total phenolic compounds (as a surrogate of secondary metabolites) of the plant species. In the choice experiment with fresh leaf samples, all snail species showed a preference for U. dioica, with the exception of the non-native invasive slug A. vulgaris, which ate leaf tissue from I. gladulifera almost as much as from U. dioica. The snails’ preference of U. dioica was even more pronounced when the fresh weight of leaf material eaten was considered. No-choice tests with either fresh or dead R. japonica leaves showed that most individuals of all species ate small amounts of fresh leaves, but less of dead leaves. In contrast, no-choice tests with either fresh or senescent I. glandulifera leaf tissue showed that individuals of all five gastropod species consumed larger amounts of senescent leaves than fresh leaves, probably because secondary compounds have been broken down or leached or the leaf texture has changed. The low susceptibility of these non-native invasive plants to the gastropods can most likely be explained by a combination of chemical and physical plant characteristics.

Trichopria anastrephae: A Promising Neotropical-Native Parasitoid for Drosophila suzukii Control

Trichopria anastrephae: A Promising Neotropical-Native Parasitoid for Drosophila suzukii Control

Predator-Prey Interaction Between Xylocoris sordidus (Hemiptera: Anthocoridae) and Enneothrips enigmaticus (Thysanoptera: Thripidae).

The peanut thrips, Enneothrips enigmaticus (Thysanoptera: Thrypidae), is an important pest of the peanut (Arachis hypogaea) in South America. Due to concerns about the environment and human health induced by the extensive use of pesticides in the management control of pests, environmentally and friendlier tactics must be targeted. Thus, this study investigates, for the first time, the behavior of Xylocoris sordidus (Hemiptera: Anthocoridae) as a biological control agent for E. enigmaticus. The methodology included no-choice tests to assess whether the predation rate varies according to the developmental stage of the prey, as well as the predator's developmental stage with the highest predation capacity. Additionally, an analysis of the functional response of adult and 5th instar nymphs of X. sordidus exposed to different densities of E. enigmaticus nymphs (1, 2, 4, 8, 16, and 32) was conducted. The results confirm the predation of peanut thrips by X. sordidus, with a higher predation rate in the nymphal stages of the prey. There was no difference in predation capacity between predator nymphs and adults, and exhibiting a type II functional response. Therefore, the potential of X. sordidus as a biological control agent for E. enigmaticus is confirmed, showing the importance of adopting measures to preserve this predator in peanut crops.

Comportamento de oviposição e consumo foliar de Chrysodeixis includens (Lepidoptera: Noctuidae) em genótipos de soja

ABSTRACT: The use of plant resistance acts by intervening in the herbivore-host relationship, through morphological, physical or chemical factors of the plant. This study evaluated the oviposition and foliar consumption of Chrysodeixis includens (Walker [1858]) in soybean genotypes, in free- and no-choice tests, correlating them with the factors, density and size of trichomes. The experiments were carried out in laboratory (25 ± 2 °C; RH= 70 ± 10%; photoperiod 14h) using five cultivars (BRS 391, BRS 6203 RR, BMX Valente RR, Tec Irga 6070 RR, BMX Icone Ipro) and two isolines (PELBR 10-6000 and PELBR 10-6049). The trichomes reported were filiform tectors and claviform multicellular glandular. The density of glandular trichomes, in stages V2 and V5, was higher on BRS 6203 RR and BRS 391, respectively. The higher density of glandular trichomes was observed in V5 and a higher density of tector trichomes in V2. The lowest densities and the smallest sizes of trichomes in V2 and V5 stages was observed on PELBR 10-6049. The size of tector trichomes and the number of eggs did not differ among the cultivars. Foliar consumption was lower for on BMX Icone Ipro and Tec Irga 6070 RR. Trichome density influences the consumption and oviposition behavior of C. includens.

Additional host range testing of Eucryptorrhynchus brandti (Coleoptera: Curculionidae) for the biological control of tree-of-heaven, Ailanthus altissima (Simaroubaceae) in the U.S.A.

ABSTRACT Ailanthus altissima, native to China, is a highly invasive plant in North America, Europe, and other continents. This species displaces native plants by forming dense clonal thickets. Ailanthus altissima is shade intolerant, quickly invades fields, rights-of-way, urban areas, and areas in forests disturbed by logging, fire, or pests. This species is also a primary host of the economically damaging spotted lanternfly, Lycorma delicatula, recently introduced into the U.S. Eucryptorrhynchus brandti is native to China and has been identified as a potential biological control agent of A. altissima. Oviposition studies conducted on 11 non-target plant species demonstrated that E. brandti oviposited only on the U.S. native Leitneria floridana. All non- Leitneria species had adult feeding of less than 2% compared to A. altissima, with no oviposition or larval development. Longevity of E. brandti in no-choice tests with L. floridana and L. pilosa subsp. ozarkana, was shorter and the weevils consumed less foliage compared to A. altissima. Seventeen percent of the L. floridana trees tested had larval feeding and 18 E. brandti adults emerged from 10 replicates. No L. floridana trees with larval feeding died. All the A. altissima trees with larval development died. Eucryptorrhynchus brandti is projected to be an effective agent against A. altissima and pose no significant risk to native North American plant species, with potential to be an additional management tool for the spotted lanternfly.

Effects of different Ficus feeding experiences on host preference of Perina nuda larvae (Lepidoptera: Lymantriidae).

Perina nuda (Lepidoptera: Lymantriidae) is a serious pest of banyan trees (Ficus spp.), which is distributed in South China, but little is known about the host preference on the different banyan tree species. To address this gap, we conducted experiments to investigate larval feeding preferences, assessing the impact of feeding experience in both choice and no-choice conditions. Fifth and sixth instars were exposed to 4 banyan species, and food intake, feeding area, and relative ingestion index were measured. Our findings reveal that Ficus concinna was the preferred host of fifth instars in choice tests, while sixth instars exhibited a preference for this host in no-choice tests. In contrast, fifth instars did not display a significant preference for any of the 4 species in no-choice tests. However, sixth instars fed on F. microcarpa, F. altissima, and F. concinna continued to exhibit a preference for the original host. These observations indicate that larval feeding preference changes with instar, and feeding experience contributes to a preference for the original host. Consequently, the feeding preference of P. nuda larvae is influenced by multiple factors, including instar and previous feeding experience. These findings enhance our understanding of P. nuda's ecological interactions and its potential impact on various banyan tree species.

Host range, biology, and climate suitability of Callopistria exotica, a potential biological control agent of Old World climbing fern (Lygodium microphyllum) in the USA

Old World climbing fern, Lygodium microphyllum (Cav.) R. Br., is one of the worst environmental weeds of southern and central Florida. The weed climbs over other plants, forming thick mats that block sunlight to native shrubs and trees. In the introduced range, Old World climbing fern invades much of the southern peninsula of Florida where cost-effective, sustainable control methods are needed. A potential biological control agent, the defoliating moth Callopistria exotica Guenee, was collected in Hong Kong and examined in quarantine to determine if it was safe for release. Climate modeling analysis was also performed to predict the potential climate suitability of C. exotica in the invaded range. A series of no-choice tests was conducted on 68 plant species from 45 genera, 33 plant families, and 18 orders. The results indicated that C. exotica is highly specific to the target weed, L. microphyllum and a congener that is also an exotic invasive, L. japonicum. The results indicated that the neonates fed and matured to the adult stage on the target weed L. microphyllum (0.71 ± 0.02 proportion survived) and on another invasive fern, L. japonicum (0.84 ± 0.04 proportion survived). No C. exotica neonates survived when fed the non-target species L. oligostachyum. A low proportion survived to the adult stage when fed the non-targets L. palmatum (0.07 ± 0.03), L. venustum (0.01 ± 0.01), and L. volubile (0.07 ± 0.03). Additionally, the few larvae that survived to the adult stage when fed L. palmatum and L. volubile had longer development times (130–150 % longer) and lower pupal weights (70–90 % lower) than those fed the target weed. All neonates perished within 3 days when fed the remaining 62 species evaluated in these no-choice tests. Climate modeling indicated that the suitability of North American climates for the establishment of C. exotica are very high in south Florida but are very unsuitable north of the L. microphyllum invaded range. These results indicated that this potential biological control agent is highly specific to L. microphyllum and L. japonicum and will have no, or very low survival on other non-target species. The release of C. exotica is expected to assist in the effort to manage the invasive weed Old World climbing fern.