Neighbour specificity between Lolium perenne and Trifolium repens from a natural pasture

Summary Five genotypes of Trifolium repens and Lolium perenne were collected as neighbouring pairs along a fertility gradient in a natural pasture. After vegetative multiplication, the 25 possible combinations of Lolium genotype x Trifolium genotype were planted in the greenhouse in order to investigate competition between the genotypes. The comparison of the five combinations whose individual components had been neighbours with the combinations of genotypes that had not coexisted before disclosed no difference in total biomass production over 7 months. However, the yield of Trifolium increased when grown with the Lolium genotype which had been its natural neighbour, while the latter showed a decrease in yield. This neighbour specificity existed even when carryover effects from the sampling site had been eliminated (preconditioning period of 18 months) and when native Rhizobium strains were not present (inoculation with a non-native strain). The complex pattern of neighbour specificity with time indicated the importance of environmental conditions for its outcome. These results are a further confirmation of positive effects on the growth of Trifolium repens when grown together with its natural neighbour. They are discussed in the context of coexistence and coevolution     

Pollination in vitro: effects on the growth of pollen tubes,seed set and gametophytic self-incompatibility in Trifolium pratense L. and T. repens L.

Summary Growth of pollen tubes and seed set were compared after hand pollination in situ and in vitro in two self-incompatible species, Trifolium pratense and Trifolium repens. Adhesion of pollen grains to the stigma was greater in vitro for both species. After cross-pollination, in vitro culture gave a significant increase in the cumulative growth of pollen tubes in pistils of T. pratense compared to in situ conditions. After selfing in T. repens, pollen tube growth was significantly increased by in vitro culture of florets. Seed set after crossing in situ and in vitro was similar for both species. Seed set after selfing in vitro was not increased in T. pratense. Several genotypes of T. repens were classified as very good, good and poor selfers based on their capacity for seed set following selfing in situ. In vitro pollination increased self seed formation by 1.7-, 18.0- and 31.0-fold for each class, respectively. Ovules located nearest to the style were fertilized more often after selfing than after crossing.     

Increased NaCl-tolerance in wheat (Triticum aestivum L. andT. durum desf.) through in vitro selection

Summary Callus cultures were initiated from immature embryos of oneTriticum aestivum and threeT. durum cultivars. Growing morphogenic calli were exposed to different concentrations of NaCl (0, 0.3, 0.5, and 0.7%) added to the culture medium during two subsequent subcultures (4 wk each). The growth rate of the calli was determined by the relative fresh weight callus growth (RFWCG). The callus growth of all investigated genotypes was slightly changed in the presence of 0.3 and 0.5% NaCl, but strongly inhibited by 0.7% NaCl. Selected NaCl-tolerant clones were isolated and plants were regenerated on MS-based regeneration medium without NaCl. The regeneration capacity of the selected calli was highly reduced compared to the control. The highest number of regenerants was scored for cv. Gladiator (T. aestivum). All regenerated plants were morphologically normal and many developed to maturity and set seeds. Seedlings from the R₁ generation of selected and control plants were treated with 0.5% NaCl in vivo in liquid cultures for 6 wk. Salt tolerance of the progenies of selected plants appeared in all cultivars, but those derived from calli grown on medium with 0.7% NaCl showed the highest survival rate.T. aestivum showed higher tolerance to NaCl salinity thanT. durum.     

INTRA- AND INTERCLONAL COMPETITION IN THE CLEISTOGAMOUS GRASS AMPHIBROMUS SCABRIVALVIS

The relationship of differences in life history traits among genotypes to competitive ability is not well known for most clonal plants. It has been hypothesized that genetically identical clones will compete more intensively than genetically distinct clones. The perennial grass Amphibromus scabrivalvis, which produces basal corms and cleistogamous seeds enclosed by leaf sheaths, exhibits pronounced clonal growth via rhizome and ramet production. In a controlled greenhouse experiment, clones of four genotypes of this species were grown under three regimes: alone in the absence of competition, paired with a clone of the same genotype (intraclonal competition), and paired with a clone of a different genotype (interclonal competition). There were differences in some biomass measures and in ramet and corm production among the four genotypes grown in the absence of competition. All genotypes showed a significant reduction in total biomass under both intra- and interclonal conditions, indicating that competition had occurred. For three of four genotypes, biomass allocation to corm increased under competition, while allocation to cleistogamous seeds was constant or increased slightly. Although some genotypes in specific interclonal combinations were less affected by competition than in intraclonal combinations, there was no support for the contention that the effects of competition were more intense for genetically identical clones.     

Do virus‐resistant plants pose a threat to non‐target ecosystems? II. Risk assessment of an Australian pathosystem using multi‐scale field experiments

It has been widely argued that the acquisition of novel disease resistance genes by wild host populations following the release of novel pathogen‐resistant plants into agricultural systems could pose a significant threat to non‐target plant communities. However, predicting the magnitude of ecological release in wild plant populations following the removal of disease remains a major challenge. In this paper we report on the second phase of a tiered risk assessment designed to investigate the role of disease on host growth, survival, fecundity and fitness in a model pathosystem (the pasture species Trifolium repens infected with Clover yellow vein virus, ClYVV) and to assess the level of risk posed to at‐risk native plant communities in southeast Australia by newly developed genetically modified and conventionally bred virus‐resistant T. repens genotypes. Multi‐year field experiments conducted in woodland and grassland environments using host‐pathogen arrays derived from 14 ClYVV isolates and 21 T. repens genotypes indicate that viral infection reduces fecundity, growth and survival of wild T. repens plants but that the severity of these effects depends on host tolerance to infection, isolate aggressiveness and specific spatial and temporal environmental conditions. Demographic modelling showed that by reducing host survival and growth, ClYVV also limits the intrinsic population growth rate and niche size of wild T. repens populations. Given the significant fitness cost associated with viral infection we conclude that virus‐resistant T. repens genotypes may pose a threat to some high conservation‐value non‐target ecosystems in SE Australia. We also argue that long‐term, multi‐tiered experiments conducted in a range of controlled and non‐controlled environments are necessary to detect and accurately quantify risks associated with the release of disease‐resistant plants in general.     

Nodulation of Trifolium repens with modified Bradyrhizobium and the nodulation of Parasponia with Rhizobium leguminosarum biovar trifolii

Thirty one strains of Rhizobium leguminosarum biovar trifolii isolated from the North and South American continents, New Guinea, USSR, Turkey and Australia, nodulated P. andersonii ineffectively when grown in plant growth tubes and in Leonard jars. Nodules were slow to form, sometimes taking over 100 days. Reisolates of R. leguminosarum biovar trifolii from P. andersonii nodulated Trifolium repens and their identity was confirmed using serological techniques. Dual occupation of nodules by Rhizobium and Bradyrhizobium in P. andersonii is reported. The reduced effectiveness of the Bradyrhizobium symbiosis depended on the relative numbers of Rhizobium occupants in this dual system. R. leguminosarum biovar trifolii and Bradyrhizobium strains from Parasponia were able to co-exist in nodules on P. andersonii and maintain similar populations in the rhizosphere and on culture media. Bradyrhizobium strains, separated from R. leguminosarum biovar trifolii, were able to initiate and form nodule-like structures on T. repens. Bradyrhizobium bacteria were identified as the sole occupants of the cells of the nodule-like structures on Trifolium repens using an immunogold labelling technique applied to ultrathin sectins. The re-isolates of Bradyrhizobium obtained from these nodule-like structures on T. repens were able to effectively nodulate P. andersonii.     

Response of Solidago canadensis clones to competition

Summary Transplants of ten Solidago canadensis clones were grown under high and low competition in the field to determine whether clones differed in survival, growth, and reproduction under natural conditions. Transplants had higher probability of survival and flowering and were larger in all measures of size when competition was experimentally reduced. Clones differed in almost all these measures of success, but only when variance among transplants within clones was reduced by excluding transplants that experienced heavy herbivore damage. Differences among clones were more apparent under low competition than under high competition, despite higher coefficients of variation within clones under low competition. Adjusting transplant size for initial size (parent ramet rhizome mass) did not change these results, although clones did differ in parent rhizome mass. All of these results suggest that there is little potential for selection to discriminate among these clones. Despite the strong differences in transplant performance between the competition treatments and among clones, the clones did not differ in competitive ability-almost none of the clone x competition interactions were significant. In addition, the measures of success of each clone were usually positively correlated between the high and low competition treatments, suggesting there were no tradeoffs between performance under high and low competition for these clones.     

Do virus‐resistant plants pose a threat to non‐target ecosystems? I. Evidence from an Australian pathosystem based on glasshouse challenge experiments

One key environmental risk associated with the release of novel disease‐resistant plants is the potential for non‐target host populations to acquire resistance genes and undergo enemy release, leading to damage to associated native plant populations in high conservation‐value ecosystems. Unfortunately, the dynamics of most natural pathosystems are poorly understood, and risk assessment of disease‐resistant plants remains a challenge. Here we describe the first stage of a multi‐tiered risk assessment strategy aimed at quantifying potential ecological release in a model pathosystem (the weedy pasture species Trifolium repens infected with Clover yellow vein virus; ClYVV) in order to assess the level of risk posed by genetically modified and conventionally bred disease‐resistant host genotypes to non‐target plant communities in south‐eastern Australia. Glasshouse inoculation and growth experiments using 14 ClYVV isolates and 20 wild T. repens lines collected from high conservation‐value montane grassland and woodland communities show that viral infection reduces the survival and growth of host plants by on average 10–50%. However, T. repens lines exhibited variable levels of resistance and tolerance to virus infection and ClYVV isolates differed in infectivity and aggressiveness, with grassland isolates having a greater pathogenic effect on associated host plants than woodland isolates. We conclude that ClYVV potentially plays an important role in limiting the size of T. repens populations in some at‐risk non‐target ecosystems and that second‐tier field experiments are required to adequately quantify the risk associated with the commercial release of V‐R T. repens genotypes in Australia.     

Leaf shape variation and herbivore consumption and performance: a case study with Ipomoea hederacea and three generalists

The effect of leaf shape variation on plant-herbivore interactions has primarily been studied from the perspective of host seeking behavior. Yet for leaf shape to affect plant-herbivore coevolution, there must be reciprocal effects of leaf shape variation on herbivore consumption and performance. We investigated whether alternative leaf morphs affected the performance of three generalist insect herbivores by taking advantage of a genetic polymorphism and developmental plasticity in leaf shape in the Ivyleaf morning glory, Ipomoea hederacea. Across four experiments, we found variable support for an effect of leaf shape genotype on insects. For cabbage loopers (Trichoplusia ni) and corn earworms (Helicoverpa zea) we found opposing, non-significant trends: T. ni gained more biomass on lobed genotypes, while H. zea gained more biomass on heart-shaped genotypes. For army beetworms (Spodoptera exigua), the effects of leaf shape genotype differed depending on the age of the plants and photoperiod of growing conditions. Caterpillars feeding on tissue from older plants (95 days) grown under long day photoperiods had significantly greater consumption, dry biomass, and digestive efficiency on lobed genotypes. In contrast, there were no significant differences between heart-shaped and lobed genotypes for caterpillars feeding on tissue from younger plants (50 days) grown under short day photoperiods. For plants grown under short days, we found that S. exigua consumed significantly less leaf area when feeding on mature leaves than juvenile leaves, regardless of leaf shape genotype. Taken together, our results suggest that the effects of leaf shape variation on insect performance are likely to vary between insect species, growth conditions of the plant, and the developmental stage and age of leaves sampled. Handling editor: May Berenbaum.     

Is the isotopically exchangeable phosphate of a loamy soil the plant-available P?

Carduus nutans L. is an invasive pasture/grassland species which may undergo rapid population growth through positive feedback. Plants ofC. nutans produce a vegetative rosette, and after several months produce stems containing flower-heads, during which time the rosette leaves die and decompose. We investigated the influence ofC. nutans on the nitrogen-fixation ability ofTrifolium repens L. in three experiments. The first experiment was set up in a mixture design, and demonstrated that seedlings ofT. repens were more susceptible to competition with otherT. repens seedlings than toC. nutans seedlings. Nodule numbers and acetylene reduction per unit root, and acetylene reduction per unit nodules were adversely affected by increasingT. repens, but notC. nutans densities. The second experiment was of an additive design, with separate partitions to isolate above-ground and below-ground interference. FloweringC. nutans plants strongly inhibitedT. repens root growth, nodulation and acetylene reduction, but usually only when shoot interference was permitted. This appears to be due to decomposition of rosette leaves, which was maximal at this stage. The third experiment involved monitoring effects of taggedC. nutans individuals againstT. repens in the field. This experiment showed that acetylene reduction was severely influenced by floweringC. nutans (when rosette leaves were decomposing), even when only mild reduction ofT. repens growth was observed, and these effects persisted for some months after theC. nutans plants had died. The results of these experiments in combination suggest that decomposing rosette leaves have a strong potential to inhibitT. repens nitrogen fixation. It appears that allelopathy is involved, since alternative explanations (e.g. root competition byC. nutans; effects ofC. nutans on soil moisture, microbial nutrient immobilisation and light availability; facilitation of herbivores byC. nutans) can be effectively discounted. Although invasive species are often assumed to be associated with soil nitrogen build-up, we believe that some invasive species such asC. nutans have the potential to induce long-term decline of soil nitrogen input.     

Variation in growth and ion accumulation between two selected populations of Trifolium repens L. differing in salt tolerance

Two divergent populations of T. repens cv. Haifa developed from two generations of recurrent selection for shoot chloride concentration, were grown in the greenhouse at 0 and 40 mol m^–3 NaCl. Over two harvest cycles at 40 mol m^–3 NaCl, the population selected for a low concentration of chloride in the shoot maintained a significantly lower chloride and sodium concentration compared with those plants selected for a high shoot chloride concentration. The distribution of chloride in the shoots was further examined in a subsample of plants from both populations. In all plants, concentrations of chloride were lower in the expanding and fully expanded leaves than in the older leaf tissue or petioles.While there were no significant differences in the photosynthetic rates between lines, shoot yields and relative leaf expansion rates were higher in the low chloride population. Plant death was greater in plants selected for high shoot chloride. These results suggest that selections based on measurements of low shoot chloride concentrations may be successful in developing a cultivar of T. repens with improved salt tolerance.     

In vitro micropropagation of Primula scotica: a rare Scottish plant

A simple micropropagation method is reported for Primula scotica, a rare plant, endemic to the North of Scotland. The technique involves the clonal proliferation of seed-derived plantlets on either hormone free tissue culture medium or on medium containing benzyl amino purine and indole acetic acid. Average multiplication rates of 4–6 were obtained for plants grown on plant growth regulator supplemented medium. The micropropagation method was applied to four different clones of P. scotica and clonal differences were observed in relation to media type. Some plants from certain clones did display hyperhydricity, however, this was circumvented by using frequent sub-culturing intervals and transferring the plants to hormone-free medium. Plantlets rooted on both media types and displayed normal, true-to-type rosette morphology. The cultures did not callus and development proceeded via shoot and root production only. The in vitro-grown plants could be transferred to ex vitro conditions and a range of growth substrates were assessed for their efficacy in supporting ex vitro growth, with a view to developing longer-term strategies for the transfer and reintroduction of micropropagated P. scotica plants into natural habitats. The simple method described in this paper may offer the potential of being applied to other endangered Primula spp.     

Within-population variation in localized and integrated responses of Trifolium repens to biotically patchy environments

Summary Genets of Trifolium repens (white clover) were collected from three patches of old permanent pasture dominated by Agrostis capillaris, Holcus lanatus or Lolium perenne. Plants derived from the genets were grown with plants of one grass species present on one side of each T. repens, and a different grass species on the other side, in all combinations of two of the three grasses. Different modules (a node with its associated internode, leaf, and axillary bud) on the same clover plant responded independently to the microenvironment provided by their own neighbouring grasses. In contrast, all apical meristems on the plant reacted similarly, showing a unified response and integrating the effects of the different microenvironments experienced by the whole clover plant. This is consistent with what is known both physiologically about the nutrition of meristems and modules, and ecologically about the exploratory growth habit of the species. Averaged over all associated grasses, there was no significant variation in the final dry weight of the different clover genets but these differed in their growth habit response to different grasses. In response to Agrostis as a neighbour, each meristem of T. repens rapidly produced many small modules. New modules were produced more slowly and were larger when Holcus or Lolium was the neighbour. The same pattern of differences occurred among clovers sampled from different backgrounds. Either genetic differences paralleled plastic responses, or plastic changes in phenotype that developed in response to different neighbours in the field persisted in the greenhouse. Plants taken from backgrounds of different grass species showed different responses to growing with those grass species. The differences were manifest primarily in a positive leading diagonal effect of Holcus or not-Holcus. They were the result primarily of differences in the dry weight per module and the probability of development of the axillary bud into a branch. This confirms earlier results, and implicates the central importance of branching as a means of local response to the microenvironment.     

In vitro fertilization and seed development inTrifolium

Summary Pistils ofTrifolium repens L. andT. ambiguum Bieb. were cultured on an agar-based modified Murashige-Skoog medium. Pistils with and without accessory floral parts were removed from flowers of selected clones ofT. repens, hand-pollinated under aseptic conditions, and planted on the medium. Pistils cultured without accessory floral parts showed no evidence of fertilization after 2 weeks. However, 52% of thoseT. repens pistils cultured with calyx lobes and pedicels contained ovules with maturing embryos 12 days after in vitro cross-pollination. Pistils fromT. ambiguum intraspecific cross-pollinations could not be cultured successfully under the same conditions; however, addition of various combinations of auxin, cytokinin, and gibberellic acid enhanced embryo growth. Fertilization and partial embryo development occurred in interspecific crosses betweenT. ambiguum andT. repens orT. hybridum only whenT. ambiguum was used as the pistillate parent. These results indicate that embryological development under in vitro conditions closely parallels in situ development although growth regulator requirements may vary among species. This work is Technical Contribution 1785 from the South Carolina Agricultural Experiment Station and was supported by SCAES-USDA Cooperative State Research Agreement No. 616-15-65.     

Host selectivity and the mediation of competition by the root hemiparasite Rhinanthus minor

Summary Rhinanthus minor (Yellow-rattle) was grown in replacement series mixtures with Lolium perenne and Trifolium repens. The hemiparasitic interaction resulted in Relative Yield Totals (the sum of the yields in mixture relative to those in monoculture) considerably above 2. The hemiparasite caused a greater decrease in the yield of the legume and also performed better on the legume, indicating that T. repens was a better host for R. minor than L. perenne under the experimental conditions. When L. perenne and T. repens were grown in binary mixture with or without R. minor the hemiparasite affected considerably the competitive relationship between the two species by selectively parasitizing the legume. The effect of R. minor on competition between the two species was, however, dependent upon the nutrient status of the soil: the higher the level of soil nitrogen the fewer haustorial connections were made with T. repens and the less was the depression in its yield. In another series of experiments in which Festuca rubra, Holcus lanatus and L. perenne were grown in various binary mixtures with or without R. minor it was also shown that the yield of a preferred host was depressed to the advantage of a non-preferred host. It is suggested that the mediation of competition by the hemiparasite provides a mechanism by which it might affect the structure and diversity of plant communities.     

Root exudation and Fe uptake and transport in wheat genotypes differing in tolerance to Zn deficiency

Tolerance to Zn deficiency in wheat germplasm may be inversely related to uptake and transport of Fe to shoots. The present study examined eight bread (Triticum aestivum) and two durum (T. turgidum L. conv. durum) wheat genotypes for their capacity to take up and transport Fe when grown under either Fe or Zn deficiency. Bread wheat genotypes Aroona, Excalibur and Stilleto showed tolerance to Zn and Fe deficiency, while durum wheat genotypes are clearly less tolerant to either deficiency. Roots of bread wheats tolerant to Zn deficiency exuded more phytosiderophores than sensitive bread and durum genotypes. Greater amounts of phytosideophores were exuded by roots grown under Fe than Zn deficiency. A relatively poor relationship existed between phytosiderophore exudation or the Fe uptake rate and relative shoot growth under Fe deficiency. At advanced stages of Zn deficiency, genotypes tolerant to Zn deficiency (Aroona and Stilleto) had a greater rate of Fe uptake than other genotypes. Zinc deficiency depressed the rate of Fe transport to shoots in all genotypes in early stages, while advanced Zn deficiency had the opposite effect. Compared with Zn-sufficient plants, 17-day-old Zn-deficient plants of genotypes tolerant to Zn deficiency had a lower rate of Fe transport to shoots, while genotypes sensitive to Zn deficiency (Durati, Yallaroi) had the Fe transport rate increased by Zn deficiency. A proportion of total amount of Fe taken up that was transported to shoots increased with duration of either Fe or Zn deficiency. It is concluded that greater tolerance to Zn deficiency among wheat genotypes is associated with the increased exudation of phytosiderophores, an increased Fe uptake rate and decreased transport of Fe to shoots. This revised version was published online in June 2006 with corrections to the Cover Date.     

Members only: induced systemic resistance to herbivory in a clonal plant network

The stoloniferous herb Trifolium repens was used to study the expression of induced systemic resistance (ISR) to the generalist caterpillar Spodoptera exigua in interconnected ramets of clonal fragments. The ISR was assessed as caterpillar preference in dual choice tests between control and systemically induced plants. The ISR was detected in young ramets, after inducing older sibling ramets on the same stolon by a controlled herbivore attack. However, older ramets did not receive a defense induction signal from younger ramets unless the predominant phloem flow was reversed by means of basal shading. This provides evidence for the notion that in T. repens the clone-internal expression of ISR is coupled to phloem transport and follows source–sink gradients. The inducibility of the genotypes was not linked to their constitutive ability to produce cyanide, implying the absence of a trade-off between these two defense traits. To our knowledge, this is the first study that explores ISR to herbivory in the context of physiological integration in potentially extensive clonal plant networks.     

The effect of canopy filtered light on the growth of white clover Trifolium repens

Summary Plants of white clover (Trifolium repens) were grown under canopies of clover leaves floating on shallow glass tanks of water and their growth was compared with that of plants under canopies of black polythene leaves. The experimental design allowed the growth of the clover plants in canopy filtered light to be compared with that in unfiltered light at different intensities of Photosynthetically Active Radiation (P.A.R.). The effect of canopy filtered light was to exaggerate the effects of reduced P.A.R. especially in promoting petiole extension and inhibiting stolon branching. Two clones of white clover differed in their responses to P.A.R. and to light quality and there were significant interactions between the effects of the intensity of P.A.R. and type of shade. It is argued that it may be important for both ecologists and plant breeders to recognise the role of radiation quality in regulating the dynamics of pasture.     

Plant regeneration from the protoplasts of Solanum tuberosum, S. nigrum and S. bulbocastanum

The mesophyll protoplasts were isolated from the Solanum tuberosum (S. tbr) clones of different ploidy level (4x Bzura cv., 2x H-8105, and 2x ZEL-1136) as well as from the wild species: S. bulbocastanum (S. blb, 2x) and two accessions of S. nigrum (S. ngr, 6x). Additionally, the protoplasts were isolated from the cell suspensions of Bzura cv. and H-8105 clone. The conditions of protoplast isolation as well as the media for their culturing and regeneration, were selected and optimized for the studied genotypes. For mesophyll protoplasts, the shooting calli were produced by all the cultured protoclones except that of S. bulbocastanum. The shoots excised from the protoplast-derived calli developed into whole plants in all the studied potato clones but only in one accession of S. nigrum, i.e. S. ngr var. gigantea. As for suspension-cell-derived protoplasts, only H-8105 clone produced the regenerative type of calli, though normal shoots could not be obtained. The regenerative capacity of the protoplasts isolated from leaves and cell suspensions is compared and discussed. We regret to report the death of M. Sc. Maria Borkowska after the completion of this work.     

Variable correspondence of female host preference and larval performance in a phytophagous ladybird beetle Epilachna pustulosa (Coleoptera: Coccinellidae)

Genetic and environmental factors causing intraspecific variation of the thistle Cirsium kamtschaticum Ledeb. as a host plant of the phytophagous ladybird Epilachna pustulosa Kôno were investigated through simple food-choice tests and rearing of larvae. Two thistle clones (T1U₁ and T4H₂) were used, originally growing approximately 12 km apart. A previous study showed that adult female ladybirds preferred T1U₁ to T4H₂, and that larval performance was better on T1U₁, when leaves from the clones in situ were examined. The two clones retained their characteristics with respect to beetle preference after transplantation into a common garden. However, the difference between T1U₁ and T4H₂ with respect to larval performance was reduced after the transplantation. When leaves from shoots of T1U₁ exposed to different sunlight intensities were offered, adult female ladybirds did not show obvious preferences. Larval eclosion rates increased significantly with the increase in leaf sunlight intensity exposure. These results suggest strongly that both genetic and environmental factors are involved in interclonal variation of thistle quality in beetle preference and/or performance. It is suggested that the quality of thistle leaves for larval performance is largely affected by environmental factors, while leaf quality for beetle preference may be determined strictly by genetic factors. Under certain conditions, E. pustulosa females may behave maladaptively, preferring plants not appropriate for larval growth, or not choosing plants appropriate for the larval growth.