Chrysomelid Beetle Research Articles

The demise of enemy release associated with the invasion of specialist folivores on an invasive tree

There is a long history of humans either intentionally or accidentally moving plant species to areas outside of their native ranges. In novel environments, populations of many of these plant species exhibit explosive population growth and spread, in part due to the absence of coevolved enemies such as herbivorous insects. However, over time such enemies can ‘catch up' with their host and re‐establish host–herbivore relationships. Though this phenomenon has been documented in several systems, little evidence exists on how this re‐assembly of enemies results in increased levels of herbivory. In this study we focus on the case of black locust Robinia pseudoacacia, a sparsely populated tree species when growing on undisturbed sites in its limited native range in the eastern USA but a highly invasive species, especially in disturbed environments, in most temperate world regions. We recorded folivore damage on invasive populations in five continents, including both native and invaded portions of North America. Here, we investigated 1) how total foliage damage and damage caused by different groups of folivores differs among regions; 2) how seasonal development of folivore damage differs among regions; 3) how folivory varies with distance from the native range within North America; and 4) how the number of recorded specialist folivores correlates with the amount of folivory. We observed strong differences among regions in the amount and type of folivore damage, with the native range experiencing the highest damage, especially that caused by the native chrysomelid beetle Odontota dorsalis, which is limited to the native and invaded North American range of R. pseudoacacia. Among world regions, total folivory is negatively associated with the distance from the native range and positively associated with the number of established R. pseudoacacia specialist folivore species, supporting the hypothesis that global patterns of herbivore invasions are associated with diminished enemy release.

GREGARINA LUTESCENS N. SP. INFECTING THE HARLEQUIN LADYBIRD HARMONIA AXYRIDIS (COLEOPTERA: COCCINELLIDAE).

Gregarina lutescens n. sp. is described from the alimentary canal of the harlequin ladybird or multicolored Asian lady beetle, Harmonia axyridis (Coleoptera: Coccinellidae) collected from prairie fleabane, Erigeron strigosus, at Peru State College, Peru, Nemaha Co., Nebraska. Our specimens differ from all 11 known species of Gregarina infecting coccinellid beetles worldwide by differences in size and relative shape, color, and association structure. Gregarina lutescens n. sp. is smaller than 7 known species infecting coccinellid beetles but larger than the other 4 known species based on confidence interval exclusion of means. Our specimens are unique among known species of interest in their quince-yellow cytoplasm and precocious but ephemeral serial associations of up to 5 satellites. Nucleotide sequence (18S) phylogenetic analyses place the new species basal to a member of an internal clade of Gregarina that comprises gregarines parasitizing chrysomelid beetles. Phylogenetically, the analysis recovered 3 major lineages within the gregarines, representing the superfamilies Gregarinoidea, Stenophoroidea, and Stylocephaloidea and indicating the propensity of gregarines to track host lineages and environments through evolutionary time. These findings confirm the polyphyletic nature of Gregarina, which currently comprises over 300 described species, only a handful of which have documented genetic sequences suitable for phylogenetic analysis. Recollection, redescription, and molecular clarification of gregarine species infecting coccinellids would likely result in identification of a unique clade that would be an excellent system for studying the effect of intraguild host competition on parasite diversification and community structure. Ecologically, patterns of prevalence in this study indicate that G. lutescens reproduces primarily in larval hosts but depends on infections in adult beetles to overwinter, reflecting the differential vagility and frost tolerance of larval and adult host life cycle stages.

A new Chrysomelid-Pinaceae relationship: Calomicrus foveolatus (Coleoptera, Chrysomelidae) feeding on the Andalusian fir, Abies pinsapo (Pinaceae) in the Sierra de las Nieves National Park (Málaga, Spain)

Aim of study: A defoliating insect, Calomicrus foveolatus, feeding on the Andalusian endemic fir Abies pinsapo (Pinaceae) is herein reported for the first time. Until now, this chrysomelid beetle was known to feed exclusively on Quercus spp. (Fagaceae). Area of study: The study was carried out in the forests of A. pinsapo, restricted to protected mountainous areas of western Málaga and eastern Cádiz in southern Spain. Material and methods: Since 2001 we carried out monitoring for potentially damaging insects at five sites of the pinsapo forests at least once a year. The monitoring visits were increased to 2-3 times a year at the sites that contained the phytophagous species. Main results: Calomicrus foveolatus was observed feeding on pinsapo needles in sites of Sierra de las Nieves National Park, in Málaga province. Besides, damaged pinsapos were also observed in Sierra de Grazalema Natural Park in Cádiz Province. Feeding activity consisted of partial and superficial damage from gnawing on the upper side of the needles; eventually producing death of the needles and finally death of the entire shoot. The recognition characteristics of the beetle and its injury on the needles and branches are described. Research highlights: It is described, for the first time, the attack of a phytophagous leaf beetle, C. foveolatus, to the endemic conifer A. pinsapo, in the National Park “Sierra de las Nieves” in the province of Málaga, Spain. Further monitoring of this beetle is necessary for the sustainable management of this protected fir endemic to the Baetic regions.

Biodiversity and Succession of Insects of Blackgram (Vigna mungo (L.) Hepper) During rabi in the Western Undulating Zone of Odisha

The field experiment was conducted to study about insect biodiversity and their succession in blackgram crop at the crop research farm, College of Agriculture, OUAT, Bhawanipatna during rabi 21. Twenty seven insects belong to seven orders and twenty two families were recorded during different growth stages of crop in an overlapping manner. Beside the insects twelve numbers of predators, three numbers of parasitoids and two pollinators were also noticed. The highest diversity index and evenness of insects were recorded at 42 SMW (0.902 and 1.000) followed by 50 SMW (0.833 and 0.710) respectively. The diversity of insects was almost uniform because of the evenness of the species. The insect order homoptera and the insect white fly came under superdominant class of dominance during all the growth stages of crop, whereas coleoptera and hemiptera were categorized under sub-dominant class at vegetative stage and flowering to podding stage of crop growth respectively. The insect orders hemiptera, coleoptera, diptera and hymenoptera and the insects i.e., galerucid beetle, jassid, stem fly, aphids and thrips came under recedent class of dominance. The relative abundance and dominant status of insect’s revealed that the maximum numbers of insects were belongs to orders homoptera (75.22%) followed by hemiptera (7.92%), coleoptera (6.30%), diptera (4.62%), hymenoptera (4.05%), orthoptera (0.89%), lepidoptera (0.86%) and odonata (0.09%).Chrysomelid beetles were noticed first during the early vegetative stage of crop followed by stem fly, white fly, leaf webber and semiloopers at the vegetative stage, tobacco caterpillar from late vegetative to pod filling stage, thrips in flowering stage, pod borers, pod bugs, aphids, pentatomid bugs and bihar hairy caterpillar from flowering to crop maturity stage and the pod fly and pod wasp from pod filling to pod maturity stage of the crop. Jassids, grasshoppers and predators like spiders, coccinellids beetles and parasitoids were appeared from mid vegetative stage and continued till fag end of the crop. The peak activities of insects were recorded from flowering to pod maturity stage of the crop.

Host-specificity of biocontrol agents in the field – The significance of sampling sympatric relatives of target weeds (Acacia holosericea versus A. auriculiformis)

Acacia auriculiformis is an invasive weed that causes significant environmental damage across Florida, USA. Previous native range surveys in Australia identified a number of herbivores that are commonly associated with this plant, including several species of leaf-tying moths (Macrobathra spp.) and a chrysomelid beetle (Calomela intemerata). These herbivores are considered strong candidates as biological control agents, but the range of host species they use has not been determined. We therefore conducted a transect survey of herbivorous insects on A. holosericea, a closely-related sympatric relative of A. auriculiformis. These species share areas of sympatry and the latter was sampled simultaneously (in sympatry and allopatry). DNA barcoding approach identified an array of herbivorous insects feeding on A. holosericea, but few were found on both the Acacia species sampled. A literature survey suggested this pattern of host specificity may be consistent across Australian acacias, to the extent that each Acacia species may largely host its own suite of herbivores. These results do not negate the need for host testing procedures in biological control, but they do increase our confidence substantially that several promising potential biological control agents of A. auriculiformis (Macrobathra moths and Calomela beetles) have a restricted host species range. Our study illustrates how exploring the herbivore diversity of plant species closely related to the target weed can provide crucial information for biological control researchers.

Biocontrol of St John’s wort (Hypericum perforatum) provides huge ongoing benefits to New Zealand agriculture

ABSTRACT An ex-post economic evaluation of biocontrol of St John’s wort (SJW), Hypericum perforatum, in New Zealand (NZ), used ecological niche modelling, GIS-mapped land-use vulnerabilities and a logistic equation to predict that SJW could have infested 660,000 ha of low-value hill-country pasture. To calculate productivity losses, we assumed serious infestations of SJW caused 30% decreases in farm income per hectare. Investment in SJW biocontrol totalled NZ$0.28 million (2022 rates) associated with the 1943–1992 releases of the chrysomelid beetles, Chrysolina hyperici and C. quadrigemina, and the cecidomyiid gall midge, Zeuxodiplosis giardi. Biocontrol effectiveness increased linearly in our model from 1943 (when initial local defoliation occurred) to reach 99% control nationwide by 1993 (when SJW was no longer considered a significant agricultural weed). We estimate that SJW biocontrol in NZ provided a national benefit of NZ$15.5 million in 2022, with a historical benefit–cost ratio of 6254:1. Both figures remained large in sensitivity testing. Uncertainties remain concerning whether biocontrol caused all reductions in SJW, or whether SJW infestations were partially replaced by other weeds. Despite such caveats, benefits of SJW biocontrol to NZ appear huge and sustainable.

Report of Nonartha birmanicum (Jacoby) (Coleoptera, Chrysomelidae) on mango inflorescence

Nonartha birmanicum (Jacoby) from the tribe Aliticini, is reported on mango for the first time. The chrysomelid beetles were found in abundance; nearly around 60 to 90 numbers on a panicle in full bloom stage. The beetle population was spotted particularly during the month of November, on the panicles in full bloom. These are bluish-black minute beetles and were noticed feeding mainly on pollen.

Consequences of squash (Cucurbita argyrosperma) domestication for plant defence and herbivore interactions

Main conclusionCucurbita argyrosperma domestication affected plant defence by downregulating the cucurbitacin synthesis-associated genes. However, tissue-specific suppression of defences made the cultivars less attractive to co-evolved herbivores Diabrotica balteata and Acalymma spp.Plant domestication reduces the levels of defensive compounds, increasing susceptibility to insects. In squash, the reduction of cucurbitacins has independently occurred several times during domestication. The mechanisms underlying these changes and their consequences for insect herbivores remain unknown. We investigated how Cucurbita argyrosperma domestication has affected plant chemical defence and the interactions with two herbivores, the generalist Diabrotica balteata and the specialist Acalymma spp. Cucurbitacin levels and associated genes in roots and cotyledons in three wild and four domesticated varieties were analysed. Domesticated varieties contained virtually no cucurbitacins in roots and very low amounts in cotyledons. Contrastingly, cucurbitacin synthesis-associated genes were highly expressed in the roots of wild populations. Larvae of both insects strongly preferred to feed on the roots of wild squash, negatively affecting the generalist’s performance but not that of the specialist. Our findings illustrate that domestication results in tissue-specific suppression of chemical defence, making cultivars less attractive to co-evolved herbivores. In the case of squash, this may be driven by the unique role of cucurbitacins in stimulating feeding in chrysomelid beetles.

Life Histories and Host-Range Evaluation of Two Chrysomelid Beetles (Zygogramma spp.) Released against Tithonia rotundifolia in South Africa.

Simple SummaryTithonia rotundifolia (Mill.) S.F. Blake (Asteraceae) is among the three Tithonia species from Mexico that are invasive in many countries, including South Africa. To curb the invasiveness and negative impact of T. rotundifolia in South Africa, two chrysomelid beetles, Zygogramma signatipennis (Stål) and Zygogramma piceicollis (Stål), from Mexico were assessed to determine their suitability for release against this invader. Biological attributes such as a short pre-oviposition period, short egg incubation period, short lifecycle and long longevity suggest that the two beetle species could successfully establish in their introduced range. Feeding, oviposition and development of both beetle species were confined within the tribe Heliantheae, but showed a very strong preference for the invasive T. rotundifolia. The only non-target species that supported development to adulthood was the exotic weed Tithonia diversifolia (Hemsl.) A. Gray, itself a target for biocontrol. Although some sunflower (Helianthus annuus L.) cultivars were partially utilized during host-specificity tests, none supported complete development. Since their potential threats to H. annuus cultivars are minimal, both Zygogramma species were cleared for release in South Africa in 2014. Tithonia rotundifolia (Mill.) S.F. Blake (Asteraceae) is among the three Tithonia species from Mexico that are invasive in South Africa. To curb its invasiveness and negative impact in South Africa, two chrysomelid beetles, Zygogramma signatipennis (Stål) and Zygogramma piceicollis (Stål), from Mexico were investigated as candidate biological control agents. The life histories and host ranges of these beetles were studied under laboratory conditions to determine their suitability for release. The two beetle species displayed very similar life histories, including a short pre-oviposition period (13–14 days), incubation period (4–5 days) and lifecycle (40–45 days). The longevity of Z. signatipennis and Z. piceicollis was 113 and 125 days, while their fecundities were 1146 and 1133 eggs per female, respectively. Feeding, oviposition and development of both beetle species were confined within the tribe Heliantheae, but showed a very strong preference for the invasive T. rotundifolia. The only non-target species that supported development to adulthood was the exotic weed Tithonia diversifolia (Hemsl.) A. Gray, itself a target for biocontrol. Although some sunflower (Helianthus annuus L.) cultivars were partially utilized during host-specificity tests, none supported complete development, suggesting that both Zygogramma species are suitable for release in South Africa.

Core members and differential abundance of chrysomelid microbiota in the life stages of Podontiaaffinis (Galerucinae) and adult Silanafarinosa(Cassidinae, Coleoptera).

The chrysomelid beetlesPodontiaaffinis and Silanafarinosa are members of the subfamilies Galerucinae and Cassidinae, respectively. This study, based on 16S rRNA gene-targeted metagenomics sequencing, reports the core members and differential abundance of bacterial communities in the larvae and adult beetles of P.affinis and the adult S.farinosa. Cyanobacteria/Melainabacteria group was the predominant phylum in the larvae of P.affinis, while Proteobacteria was the predominant phylum in adult P.affinis and S.farinosa. The number of Order, Family, Genus and Species OTUs in the adult stage of P.affinis was higher than that in the larval stage. The bacterial species richness of adult P.affinis was significantly higher than that of adult S.farinosa. Betaproteobacteria was the predominant class in adult P.affinis, Cyanobacteria in the larvae of P.affinis and Gammaproteobacteria in S.farinosa. The larvae and adult beetles of P.affinis and adult S.farinosahad a low number of unique and shared bacterial OTUs (> 5% relative abundance). The differences in the microbiota indicate possible differences in nutrient assimilation, host taxonomy and other stochastic processes. These findings provide new information to our understanding of the bacteria associated with specialist phytophagous chrysomelid beetles and beetles in general.

Progress and Prospects for Biological Control of Cestrum Species (Solanaceae) in South Africa

Cestrum (Solanaceae) species have become invasive in conservation and agricultural areas in South Africa, resulting in the initiation of a biological control (biocontrol) programme against these species in 2007. Of the four Cestrum species recorded in South Africa, Cestrum laevigatum Schltdl. and C. parqui L'Herit., which are both commonly referred to as inkberries, have become invasive while C. aurantiacum Lindl. and C. elegans (Brongn.) Schltdl. are still isolated at a few sites in the country. The biocontrol programme against Cestrum species (commonly called cestrum) was initially focussed on pathogens associated with these plants. Although the fungus Uromyces cestri Bertero ex Mont. (Pucciniales: Pucciniaceae) was found to be a promising agent for cestrum, the pathogen project was shelved due to lack of capacity. Field surveys conducted in Argentina from 2012 to 2020 revealed a total of eight phytophagous insects that could be candidate agents. Among these is a leaf-feeding flea beetle Epitrix sp. (Coleoptera: Chrysomelidae) that has been tested for host specificity. Out of 47 plant species tested to date, Epitrix sp. has only fed and developed on three Cestrum species, suggesting that it is suitable for release against cestrum in South Africa. Permission to release Epitrix sp. will be sought once it has been identified to the species level or it has been described as a new species. Two chrysomelid beetle species, a root-feeding flea beetle (Diphaulaca sp.) and an unidentified leaf-feeding flea beetle, were also collected on C. parqui, but attempts to rear the former were unsuccessful. Three other leaf-miners collected from C. parqui include: Acrocercops leucographa Clark (Lepidoptera: Gracillariidae), an unidentified moth (Lepidoptera: Argyresthiidae) and Liriomyza sp. nr. schlingerii (Diptera: Agromyzidae). A glass-winged butterfly (Lepidoptera: Nymphalidae) was the only herbivore that may be of biocontrol value on C. laevigatum. Whilst it is essential to extend the surveys to other regions of the native range, it is also important to prioritize the most promising potential biocontrol agents for further testing in South Africa. Given the suite of potential biocontrol agents in the native range, there are good prospects for the biocontrol of cestrum species in South Africa.

New discovery of rare insect damage in the Pliocene of India reinforces the biogeographic history of Eurasian ecosystems

Plant–insect interactions in the fossil record are, as yet, sparsely known and understudied. Here, we document evidence of a new type of insect skeletonization on Abroma augustum (L.) L. f. (Malvaceae) leaf remains from the latest Neogene (Pliocene) sediments of Chotanagpur plateau, Jharkhand, eastern India. This unique skeletonization feeding trace attributable to herbivorous insects occurs all over the surfaces of our recovered Pliocene leaf remains. In the skeletonized area, the interveinal tissues are completely removed leaving behind only the tough leaf veins. This type of insect feeding behaviour is documented for the first time on Indian Cenozoic leaf remains. Based on published data, as well as our survey of modern forests adjacent to the fossil locality, we suggest that probable damage inducers of this skeletonization on Abroma Jacq. fossil leaves might be Chrysomelid (Coleopteran) beetles. This finding also reveals that specific insect feeding damage, such as the one presented here, can reveal similarity of environments despite the difference of plant species observed. Such results strengthen the importance of using plant–insect interactions on leaves as a complementary proxy to others revealing paleoenvironmental conditions.

Impact of sublethal doses of Piper guineense (Schum and Thonn) on the biological parameters of Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) reared on different cowpea varieties

• The response of C . maculatus to P . guineense was influenced by the variety of the stock culture. • Fecundity, hatchability, and survival differed among the exposed varietal populations. • Oviposition and hatchability index of C. maculatus postively correlated with the cowpea varieties. • Varietal difference, and not just exposure to sublethal doses of P. guineense , explained observed response. • Thus, white cowpea seeds predisposed C. maculatus to sublethal effects of P. guineense than colored seeds. Cowpea varieties show a wide range of characteristics in their composition that can determine Callosobruchus maculatus (Fabricius) response and survival. Consequently, this work investigated the influence of sublethal doses of Piper guineense on C. maculatus raised on four cowpea varieties: ART-98–12, Niger White, Oloyin, and Ife Brown. Our results demonstrated that C. maculatus from different varieties, despite being reared under the same conditions, responded differently to sublethal doses of P. guineense . Cowpea beetles from ART-98–12 were the most susceptible while those reared on Ife Brown were the least susceptible. Across varieties, survival and reproductive parameters of C. maculatus differed. Furthermore, the ranking for the percentage reduction in the number of eggs laid by C. maculatus was ART-98–12 > Niger White > Oloyin > Ife Brown. According to the log-rank statistic test, the difference observed in C. maculatus ’ survival can be explained by variety (log-rank statistic: χ2 [df = 3, N = 16] = 15, p = 0.004). Conversely, the survivability of the chrysomelid beetles reared on Niger white was significantly lower (p = 0.012) compared to the other varieties. This study highlights the role of cowpea variety in dictating the efficacy of a given botanical against C. maculatus .

3D-printed insect models offer a feasible method for mating studies of chrysomelid beetles

A variety of models have been used in mating bioassays of insects to assess the contribution of chemical and visual signals to mate location and mate selection. Although the use of such ‘dummies’ has had varying degrees of success, some insect species refuse to accept simplistic models. In the present study, we developed a 3D-printed model to explore whether more realistic models will be more successful than simplistic models in mating assays of difficult to manipulate species such as the flea beetle Altica fragariae. We ran five experiments to test (1) whether males could discriminate between males and females solely based on differences in cuticular hydrocarbons (CHCs), (2) whether males use shape or (3) color to choose mates, and (4) whether males can discriminate between 3D-printed models and freshly killed beetles either with or (5) without legs and antennae. The results of these experiments confirmed that male A. fragariae preferred models coated with CHCs of females over that of male CHCs, providing strong support for the role of CHCs in mate choice in Altica. We also showed that males use both shape and color in mate selection, and that males are capable of discriminating between the models and real beetle specimens. Together, the results indicate that 3D-printed models can provide a feasible and cost-effective method for mating studies of insects.

Impact of summer temperatures on Agasicles hygrophila, a key biocontrol agent of the invasive weed Alternanthera philoxeroides in Hunan province, China

Agasicles hygrophila , a leaf-feeding Chrysomelid beetle, was introduced into China in 1986 as a biological control for Alternanthera philoxeroides (alligatorweed), a noxious perennial invasive weed. However, Hunan’s Ag. hygrophila populations decrease suddenly during summers (at high temperatures), leading to the inefficient control of alligatorweed. To investigate this phenomenon, herein, the effects of four different temperatures (26, 30, 36, or 39°C) on the reproductive capacity and egg-hatch, pupation, eclosion, and adult survival rates of Ag. hygrophila were explored. The effects of four different durations of each temperature treatment (4, 8, 12, or 16 days) were investigated. All the studied parameters were significantly affected following each of the four temperature and time treatments. At 30°C, the egg-hatch, pupation, and eclosion rates were considerably lower than those in the control group at 26°C. However, there were no significant differences in the number of eggs laid and the adult survival rates. Heat-shock at 36°C and 39°C led to significant decreases in the number of eggs laid, and the egg-hatch, pupation, eclosion, and adult survival rates compared to those at 26°C. Furthermore, high temperature had the greatest effect on Ag. hygrophila pupae, and the eclosion rate was close to zero; this may have caused the sharp decrease in the Ag. hygrophila population. The results will help better understanding the impact of biological control on Al. philoxeroides during summer temperatures and will also support optimization of biocontrol strategies, notably for the release of biocontrol agents across different geographical regions with different climates.

Cuticular hydrocarbons C14-C36 are potential contact pheromonal elements modulating some behaviors in Zygogramma bicolorata (Coleoptera: Chrysomelidae)

Chrysomelid beetle, Zygogramma bicolorata (Pallister, 1953) (Coleoptera: Chrysomelidae), is an important biocontrol agent for the weed Parthenium hysterophorus. The insect spends its whole life on the same plant, which acts as an essential site for feeding, mating and oviposition. These insects were studied for repeated mating, either to same or different mates, and the results indicated both polyandrous and polygamous mating with same-pair mating preferences. Apart from this, a preliminary bioassay was performed individually for both the sexes to detect the presence of contact pheromones. These chemicals, ranging from C14 to C36 and often known as cuticular hydrocarbons (straight and branched), were further identified by reading their mass spectra. Although the hydrocarbon profiles of males and females resembled each other qualitatively, the compounds showed a significant difference with respect to their relative proportions. The antennal response to some of the corresponding synthetic straight chain alkanes (Pentacosane, Hexatriacontane, Docosane, Tetracosane, Heneicosane, Hexacosane, Octadecane, Eicosane and Tetratriacontane) were also tested using electroantennography (EAG) at four different concentrations (0.1%, 0.01%, 0.001% and 0.0001%). The mean EAG response obtained was observed to be sex dependent for all compounds tested. The antennae of female responded strongly to these compounds with Tetratriacontane eliciting the highest response of – 0.684 mV at the concentration 0.01%. The difference in the responses may be attributed to the differences in the release rates of these compounds and the sensitivity of antennal responses between the sexes.

Galerucella (Neogalerucella) anserina Ødegaard amp; Hanssen, sp. nov., a new speciesof Chrysomelidae (Coleoptera, Chrysomelidae, Galerucinae) from Norway.

A new chrysomelid beetle, Galerucella anserina Ødegaard Hanssen, sp. nov., belonging to the Galerucella tenella-group (subgenus Neogalerucella) is described, illustrated and distinguished from similar species within the genus. The type specimens were collected in coastal wetlands in southeastern Norway. The species is associated with Potentilla anserina L. (Rosaceae), and lives sympatrically with the closely related G. tenella (L.).

Assessing plant-to-plant communication and induced resistance in sagebrush using the sagebrush specialist Trirhabda pilosa

Plants respond to damage by herbivores or to reliable cues of damage by changing in ways that provide greater resistance and increase their fitness. Sagebrush has been a model system for understanding induced resistance, although resistance in this system is commonly assessed by quantifying damage at the end of the season; this measure is slow and lacks accuracy and interpretability because so many other factors also affect levels of damage. Herbivore choice offers a potentially rapid and accurate alternative assay of induced resistance. Here we evaluate whether feeding behavior of a specialized Chrysomelid beetle, Trirhabda pilosa, could be used to assay induced changes in plant quality. Beetle larvae were offered the choice between two leaves in Petri dish arenas. We found that beetles avoided leaves that were naturally damaged by herbivores, experimentally clipped with scissors, and exposed to the volatiles from naturally or experimentally damaged neighboring leaves compared to control leaves. Experiments varied the source of the damage, the duration of the feeding test, and how damage was measured, still, beetles consistently preferred uninduced controls by a 2:1 ratio over leaves exposed to cues of damage. These results suggest that behavioral assays using T. pilosa larvae can be used to rapidly evaluate induced resistance in this system. More generally, movement and feeding behaviors of herbivores are an important and underappreciated component of induced plant responses.

How to better predict long-term benefits and risks in weed biocontrol: an evolutionary perspective.

Classical biological control (also called importation biological control) of weeds has a remarkable track record for efficiency and safety, but further improvement is still needed, particularly to account for potential evolutionary changes after release. Here, we discuss the increasing yet limited evidence of post-introduction evolution and describe approaches to predict evolutionary change. Recent advances include using experimental evolution studies over several generations that combine -omics tools with behavioral bioassays. This novel approach in weed biocontrol is well suited to explore the potential for rapid evolutionary change in real-time and thus can be used to estimate more accurately potential benefits and risks of agents before their importation. We outline this approach with a chrysomelid beetle used to control invasive common ragweed.

Plastid-expressed Bacillus thuringiensis (Bt) cry3Bb confers high mortality to a leaf eating beetle in poplar.

The Bacillus thuringiensis (Bt) cry3Bb gene was successfully introduced into poplar plastid genome, leading to transplastomic poplar with high mortality to Plagiodera versicolora. Poplar (Populus L.) is one of the main resource of woody industry, but being damaged by insect pests. The feasibility and efficiency of plastid transformation technology for controlling two lepidopteran caterpillars have been demonstrated previously. Here, we introduced B. thuringiensis (Bt) cry3Bb into poplar plastid genome by biolistic bombardment for controlling P. versicolora, a widely distributed forest pest. Chimeric cry3Bb gene is controlled by the tobacco plastid rRNA operon promoter combined with the 5'UTR from gene10 of bacteriophage T7 (NtPrrn:T7g10) and the 3'UTR from the E. coli ribosomal RNA operon rrnB (TrrnB). The integration of transgene and homoplasmy of transplastomic poplar plants was confirmed by Southern blot analysis. Northern blot analysis indicated that cry3Bb was transcribed to both read through and shorter length transcripts in plastid. The transplastomic poplar expressing Cry3Bb insecticidal protein showed the highest accumulation level in young leaves, which reach up to 16.8μg/g fresh weight, and comparatively low levels in mature and old leaves. Feeding the young leaves from Bt-Cry3Bb plastid lines to P. versicolora caused 100% mortality in the first-instar larvae after only 1day, in the second-instar larvae after 2days, and in the third-instar larvae for 3days. Thus, we report a successful extension of plastid engineering poplar against the chrysomelid beetle.