Erratum: Floral Co 2 Reveals Flower Profitability to Moths

Global Change Biology, 2005

Moths can detect changes in environmental carbon dioxide (CO 2 ) with extremely high sensitivity, but the role of CO 2 in the biology of these and other insects is not well understood. Although CO 2 has been demonstrated to influence egg-laying (oviposition) behavior of the pyralid moth Cactoblastis cactorum and nectar foraging of the sphingid moth Manduca sexta, information about the generalized role of CO 2 in the behavioral biology of these species is lacking. Comparative data are necessary to properly assess how the behaviors of different species may be modified by steadily rising levels of greenhouse gases in the environment. Experiments carried out in Biosphere 2 addressed whether changes in ambient CO 2 levels play a role in the oviposition behaviors of M. sexta moths. In the first series of experiments, oviposition was measured inside a flight cage with different levels of nearly ambient or elevated CO 2 (400, 800 or 1200 ppm). For each concentration, hostplants used as oviposition sites were grown from seed at a CO 2 level that matched the environment inside the flight cage. Under homogenous levels of CO 2 , we observed no significant difference in oviposition behavior at the concentrations tested. In a second series of experiments, two groups of hostplants, each surrounded by a mini free-air CO 2 enrichment (FACE) ring, were assembled inside a flight cage. In this choice test, a dynamic plume of artificially high CO 2 was generated around one group of test plants, while ambient CO 2 was released around the second (control) group. After eggs were counted on both plant groups, M. sexta females showed a small preference for ovipositing on the control plants. Therefore, in contrast to C. cactorum females tested under similar dynamic flow conditions, M. sexta female oviposition was not strongly inhibited by elevated CO 2 . To investigate this phenomenon further, we used electrophysiological recording and found that the CO 2 receptor cells in M. sexta, unlike those in C. cactorum, are not readily affected by elevated levels of ambient CO 2 . These findings therefore suggest that elevated background levels of CO 2 affect the physiology of the CO 2 detection system of M. sexta to a lesser extent than that of C. cactorum, and this correlates well with the observed differences in oviposition behavior between the two species under elevated levels of environmental CO 2 . Hostplants of C. cactorum are crassulacean acid metabolism plants that generate nocturnal CO 2 sinks on the cladode surfaces, whereas, M. sexta hostplants are nocturnal sources of respiratory CO 2 . We hypothesize that the abrupt and continuing increase in global ambient CO 2 levels will differentially alter the behavior and physiology of moths that use CO 2 sinks and sources as sensory cues to find hostplants.

Psyche: A Journal of Entomology, 1981

Annals of Botany, 1999

Garden flowers can be valuable to wildlife if they produce nectar, pollen and\or seeds. To provide information needed by gardeners to select wildlife-friendly plants, we investigated nectar production and insect visits to Tropaeolum majus, Consolida sp., Antirrhinum majus, Violaiwittrockiana, Tagetes patula and Alcea rosea, in each case comparing a nearoriginal flower type with a cultivar that had spurless, doubled, peloric or enlarged flowers. All species showed high secretion rates and standing crops of nectar. In most cases the horticultural modifications affected the numbers or species composition of the assemblage of insect visitors, and they generally reduced the value of the floral reward to insects, often affecting accessibility. Effects on seed yield were not investigated directly here, but are likely to further reduce the wildlife value of modified variants.

Global Change Biology, 2003

The objective of this study was to determine how increasing atmospheric CO 2 change plant tissue quality in four native grassland grass species (Agrostis stolonifera, Anthoxanthum odoratum, Festuca rubra, Poa pratensis) which are all larval food-plants of Coenonympha pamphilus (Lepidoptera, Satyridae). We assessed the effect of these changes on the performance and larval food-plant preference of C. pamphilus in a greenhouse experiment. Furthermore, we tested the interactive effects of elevated CO 2 and soil nutritional availability in F. rubra and its effect an larval development of C. pamphilus. In general, elevated CO 2 decreased leaf water concentration, nitrogen concentration and specific leaf area (SLA), while leaf starch concentration was increased in all grass species. A species-specific reaction to elevated CO 2 was only found for foliar starch concentration. P. pratensis did not increase its starch concentration under elevated CO 2 conditions, whereas the other three species did. Fertilisation, investigated only for F. rubra, increased leaf nitrogen concentration and amplified the CO 2-induced decrease in leaf nitrogen. Development time of C. pamphilus was on the average prolonged by two days under elevated CO 2 and the prolongation differed from 0.7 to 5.3 days among foodplant species. Pupal fresh weight differed marginally between CO 2 treatments. Fertilisation of the larval food-plant F. rubra shortened development time by one day and significantly increased pupal and adult fresh weights. C. pamphilus larvae showed a clear food-plant preference among grass species at the age of 36 h or older. Additionally, a change of food-plant preference under elevated CO 2 was found. Larvae at ambient CO 2 preferred Agrostis stolonifera and F. rubra, while under elevated CO 2 Anthoxanthum odoratum and P. pratensis were preferred. The present study demonstrates that larval development of C. pamphilus is affected by food-plant species and CO 2 induced changes in foliar chemistry. Although we found some species-specific reactions to elevated CO 2 for foliar chemistry, no such CO 2 by species interaction was found for insect development. The change in food-plant preference of larvae under elevated CO 2 implies potential changes in selection pressure for grass species and might therefore affect evolutionary processes.

Entomologia Experimentalis et Applicata, 1999

Many insects have coevolved with certain angiosperm taxa to act as pollinators. However, the nectar and pollen from such flowers is also widely fed upon by other insects, including entomophagous species. Conservation biological control seeks to maximise the impact of these natural enemies on crop pests by enhancing availability of nectar and pollen-rich plants in agroecosystems. A risk with this approach is that pests may also benefit from the food resource. We show that the flowers of some plants (viz., buckwheat, Fagopyron esculentum Moench and dill, Anethum graveolens L.), and the extrafloral nectaries of faba bean (Vicia faba L.) benefit both Copidosoma koehleri Blanchard (Hymenoptera: Encyrtidae) and its host, the potato pest, Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae). In contrast, phacelia (Phacelia tanacetifolia Benth) and nasturtium (Tropaeoleum majus L.) benefited only the parasitoid. When adult moths of P. operculella were caged with flowers of phacelia or nasturtium, longevity of males and females, egg laying life, fecundity, average oviposition rate, and number of eggs in ovaries at death were no greater than in the control treatment with access to shoots without flowers plus water. All the foregoing measures were increased compared to the control when the moths were allowed access to dill, buckwheat or faba bean extrafloral nectaries. Such 'selectivity' has the potential to make the use of floral resources in conservation biological control more strategic. We present morphometric and observational evidence to illustrate how such mechanisms may operate.

Journal of Chemical Ecology, 2009

In the Silene latifolia-Hadena bicruris nursery pollination system, the Hadena moth is both pollinator and seed predator of its host plant. Floral scent, which differs among S. latifolia individuals and populations, is important for adult Hadena to locate its host. However, the success of moth larvae is strongly reduced if hosts are infected by the anther smut fungus Microbotryum violaceum, a pathogen that is transmitted by flower visitors. There were no qualitative differences between the scent of flowers from healthy and diseased plants. In addition, electroantennographic measurements showed that Hadena responded to the same subset of 19 compounds in samples collected from healthy and diseased plants. However, there were significant quantitative differences in scent profiles. Flowers from diseased plants emitted both a lower absolute amount of floral scent and had a different scent pattern, mainly due to their lower absolute amount of lilac aldehyde, whereas their amount of (E)-β-ocimene was similar to that in healthy flowers. Dual choice behavioral wind tunnel tests using differently scented flowers confirmed that moths respond to both qualitative and quantitative aspects of floral scent, suggesting that they could use differences in floral scent between healthy and infected plants to discriminate against diseased plants. Population mean fruit predation rates significantly increased with population mean levels of the emission rates of lilac aldehyde per flower, indicating that selection on floral scent compounds may not only be driven by effects on pollinator attraction but also by effects on fruit predation. However, variation in mean emission rates of scent compounds per flower generally could not explain the higher fruit predation in populations originating from the introduced North American range compared to populations native to Europe.

2008

Rising atmospheric CO2 is regarded as the main driver of global warming (Crowley, 2000). While temperature changes directly affect plants and animals (Root et al., 2003; Parmesan, 2006), the effects of CO2 on herbivores are mediated through changes in nutrient quality. Elevated concentrations of atmospheric CO2 are likely to increase photosynthetic activity and thus provide more C-based compounds which may alter plant chemical profiles and plant–herbivore–natural enemy interactions. There are several scenarios how insects will react when confronted with a different food quality. A nutrient poor diet, induced by nitrogen dilution, may result in compensatory feeding with either no adverse effects on insect performance or with negative effects on insect growth due to low digestibility of plant structural compounds (e.g. lignin) or toxic effects of secondary metabolites (e.g. tannins). Here we present data from on-tree feeding trials with larvae of the generalist herbivore Lymantria dis...

Journal of Plant Protection and Pathology, 2019

The reaction of the insect predators, Eupeodes corollae Fabr (Diptera, Syrphidae), Coccinella undecimpunctata L. and Hippodamia tredecimpunctata L. (Coleoptera, Coccinellidae) and Chrysoperla carnea (Steph.) (Neuroptera, Chrysopidae) was compared in response to odor and color of five flowers (Marigold, Calendula officinalis; Chamomile, Matricaria chamomilla; Fennel, Foeniculum vulgare Miller; Caraway, Carum carvi L and Marguerite, Chysanthemum coronarium L.) under laboratory conditions. The experimental tube indicated that the tested predators exhibited different degrees of attractiveness in response to flower colors and nectars of the tested plants. The nectar plant species of Chamomile and Fennel were significantly more attracted to E. corollae and Ch. carnea as compared to other tested species. C. undecimpunctata and H. tredecimpunctata exhibited the highest attractiveness to Marigold and Chamomile nectars. All predators exhibited the lowest preferability toward Marguerite and Caraway nectars. Preferability experiments illustrated that all tested predators exhibited the highest preferability to yellow flower colors (Fennel, Marigold and Chamomile) followed by white colors (Caraway). The present study evaluates the role of C. officinalis; M. chamomilla; and Chy. Coronarium flowers as supplemental food on the longevity and foraging behavior of the coccinellid predators, C. undecimpunctata and H. tredecimpunctata adult females. Flowers increased survival and searching rate in C. undecimpunctata and H. tredecimpunctata in comparison with prey diet-only treatments. This suggests that the availability of flowers of Marigold and Chamomile as supplemental foods (pollen and nectar) in the field can serve to improve efficacy of coccinellid predators under conditions of prey limitation.

2009

Background and Aims While pollinators may in general select for large, morphologically uniform floral phenotypes, drought stress has been proposed as a destabilizing force that may favour small flowers and/or promote floral variation within species. † Methods The general validity of this concept was checked by surveying a taxonomically diverse array of 38 insect-pollinated Mediterranean species. The interplay between fresh biomass investment, linear size and percentage corolla allocation was studied. Allometric relationships between traits were investigated by reduced majoraxis regression, and qualitative correlates of floral variation explored using general linear-model MANOVA. † Key Results Across species, flowers were perfectly isometrical with regard to corolla allocation (i.e. larger flowers were just scaled-up versions of smaller ones and vice versa). In contrast, linear size and biomass varied allometrically (i.e. there were shape variations, in addition to variations in size). Most floral variables correlated positively and significantly across species, except corolla allocation, which was largely determined by family membership and floral symmetry. On average, species with bilateral flowers allocated more to the corolla than those with radial flowers. Plant life-form was immaterial to all of the studied traits. Flower linear size variation was in general low among conspecifics (coefficients of variation around 10 %), whereas biomass was in general less uniform (e.g. 200-400 mg in Cistus salvifolius). Significant among-population differences were detected for all major quantitative floral traits. † Conclusions Flower miniaturization can allow an improved use of reproductive resources under prevailingly stressful conditions. The hypothesis that flower size reflects a compromise between pollinator attraction, water requirements and allometric constraints among floral parts is discussed.

Biological Control - BIOL CONTROL, 2011

Resources for natural enemies are often lacking in agricultural fields. The provisioning of floral resources in crop fields can ameliorate this problem by providing nectar and pollen to natural enemies. To select an appropriate floral resource, plants must be screened for their flowering times and attractiveness to natural enemies and pests. We tested the attractiveness of nine species of annual flowering plants to hoverflies, which are important predators of aphids in California lettuce fields. We also sampled arthropods in the foliage of tested plants, to assess the abundances of other natural enemy and pest species that were present. Tested plants included three commonly-used insectary plants and six flowering plant species that showed potential as either harvestable herbs or cut flowers. Harvestable insectary plants may provide additional economic incentive for growers to set aside land for floral resources. The commonly-used insectary plant sweet alyssum consistently attracted the most hoverflies and the least bees, while potentially harvestable plants attracted few hoverflies. Competition with bees may have reduced hoverfly visits to several of the tested plant species. Sweet alyssum also stayed in bloom the longest, and contained the highest numbers of predatory hemipterans. Results suggest that plants should be screened for their attractiveness to not only the target biological control agent, but also to other potential competitors for floral resources. While this initial study focused on a limited selection of harvestable annual plants, a wide variety of other marketable plant species, particularly perennials, remain to be tested for their attractiveness to hoverflies or other beneficial arthropods.