Effect of smoke derivatives on in vitro pollen germination and pollen tube elongation of species from different plant families

Plant‐derived smoke stimulates seed germination in numerous plant species. Smoke also has a positive stimulatory effect on pollen germination and pollen tube growth. The range of plant families affected my smoke still needs to be established since the initial study was restricted to only three species from the Amaryllidaceae. The effects of smoke‐water (SW) and the smoke‐derived compounds, karrikinolide (KAR₁) and trimethylbutenolide (TMB) on pollen growth characteristics were evaluated in seven different plant families. Smoke‐water (1:1000 and 1:2000 v:v) combined with either Brewbaker and Kwack's (BWK) medium or sucrose and boric acid (SB) medium significantly improved pollen germination and pollen tube growth in Aloe maculata All., Kniphofia uvaria Oken, Lachenalia aloides (L.f.) Engl. var. aloides and Tulbaghia simmleri P. Beauv. Karrikinolide (10^?6 and 10^?7 m ) treatment significantly improved pollen tube growth in A. maculata, K. uvaria, L. aloides and Nematanthus crassifolius (Schott) Wiehle compared to the controls. BWK or SB medium containing TMB (10^?3 m ) produced significantly longer pollen tubes in A. maculata, K. uvaria and N. crassifolius. These results indicate that plant‐derived smoke and the smoke‐isolated compounds may stimulate pollen growth in a wide range of plant species.     

NATURAL HYBRIDIZATION BETWEEN PHLOX MACULATA AND PHLOX GLABERRIMA AND ITS EVOLUTIONARY SIGNIFICANCE

Levin, 1). A. (U. Illinois, Urbana.) Natural hybridization between Phlox maculata and Phlox glaberrima and its evolutionary significance. Amer. Jour. Bot. 50(7): 714–720. Illus. 1963.—Field and herbarium studies indicate that Phlox maculata ssp. pyramidalis is similar to P. glaberrima ssp. interior in a number of characteristics. A hybrid swarm involving P. maculata ssp. maculata and P. glaberrima ssp. interior was discovered which contained some plants that were almost identical to P. maculata ssp. pyramidalis. Crosses between P. maculata and P. glaberrima indicate that the 2 species cross readily. The chromosome complements of the 2 species are morphologically similar. These data suggest that P. maculata ssp. pyramidalis is a stabilized introgressant type.     

CHROMATOGRAPHIC EVIDENCE OF HYBRIDIZATION AND EVOLUTION IN PHLOX MACULATA

Representatives of P. maculata ssp. maculata and P. glaberrima ssp. interior and 36 putative hybrids were collected from a population in central Indiana. Chromatographic analysis revealed the presence of nine diagnostic components in P. maculata ssp. maculata and eight such components in P. glaberrima ssp. interior. Putative F₁ hybrids contained all or most of the parental marker components; markers of the non-recurrent parent were absent in the two classes of putative backcross progeny. The characters of P. maculata ssp. pyramidalis are a composite of those present in P. maculata ssp. maculata and P. glaberrima ssp. interior, and the former is virtually identical to certain hybrids from the population in question. The contention that P. maculata ssp. pyramidalis is a stabilized derivative of natural hybridization between these taxa is substantiated by the presence of all of the diagnostic constituents of the putative parents on its chromatograms. It is the author's opinion that the definitive data which chromatography affords will be invaluable in elucidating the complex pathways of evolution in Phlox.     

Sterol limitation in a pollen-fed omnivorous lady beetle (Coleoptera: Coccinellidae)

Nutritional constraints of non-prey foods for entomophagous arthropods are seldom investigated, yet are crucial to understanding their nutritional ecology and function within natural and managed environments. We investigated whether pollen from five maize hybrids was of variable quality for the lady beetle, Coleomegilla maculata, whether suitability of these pollens was related with their sterol profiles, and how augmenting sterols (β-sitosterol, cholesterol, or ergosterol) affected the fitness and performance of C. maculata. Preimaginal survival, development rates, the duration of the pre-oviposition period, post-mortem adult dry weight, adult hind tibial length, sex ratio, fecundity, cohort generation time (T_c), net replacement rate (R₀) and intrinsic rate of increase (r) were measured. Individual sterols in the pollens were quantified using GC-MS. Pollens were of variable suitability for C. maculata; the development rate was positively correlated with the amount of 24-methylene-cholesterol and r was positively correlated with episterol and 24-methylene-lophenol found in the pollens. Performance of C. maculata was entirely unaffected by augmenting pollen meals with sterols. This research shows that pollens clearly vary in their sterol contents intraspecifically, which affects their suitability for omnivores that rely on pollen. However, sterols appear to be only one of the limiting nutrients in pollens.     

Suitability of pollen sources for the development and reproduction of Coleomegilla maculata (Coleoptera: Coccinellidae) under simulated drought conditions

Laboratory experiments compared the nutritive value of various pollen sources for the development of Coleomegilla maculata DeGeer under conditions of continuous water availability and simulated drought. When water was continuously available, larval survival was not different from 100% on diets of frozen eggs of Ephestia kuehniella Zeller, corn pollen, sorghum pollen, or pulverized bee pollen, whereas survival of larvae was significantly reduced on the latter three diets in the simulated drought treatment. Pollen of cultivated sunflower, Helianthus annus L., proved fatal to both larvae and adults; its surface structure caused clumping and accumulation on the insect cuticle that led to death from exhaustion/desiccation in petri dishes. The Ephestia egg diet yielded shorter developmental times and heavier adult weights than any pollen diet in both treatments. The drought treatment increased developmental time on all diets with a significant treatment–diet interaction. Drought reduced the adult weight of females on the sorghum pollen diet, and that of both sexes on the bee pollen diet, again with a significant treatment–diet interaction. Initial water content was highest in corn pollen (36.8%), followed by Ephestia eggs (29.2%), sorghum pollen (25.3%), sunflower pollen (8.7%), and bee pollen (4.6%), but did not appear correlated with C. maculata larval survival on pollen sources under drought conditions. Reproductive adult females that received corn or sorghum pollen as a supplement to Ephestia eggs did not differ in fecundity or fertility from those fed only Ephestia eggs.     

Evaluation of dietary effects of transgenic corn pollen expressing Cry3Bb1 protein on a non-target ladybird beetle, Coleomegilla maculata

A transgenic corn event (MON 863) has been recently developed by Monsanto Company for control of corn rootworms, Diabrotica spp. (Coleoptera: Chrysomelidae). This transgenic corn event expresses the cry3Bb1 gene derived from Bacillus thuringiensis (Berliner), which encodes the insecticidal Cry3Bb1 protein for corn rootworm control. A continuous feeding study was conducted in the laboratory to evaluate the dietary effect of MON 863 pollen expressing the Cry3Bb1 protein on the survival, larval development, and reproductive capacity of the non-target species, Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae). First instar C. maculata (less than 24 h old) and newly emerging adults (less than 72 h old) were fed individually on a diet mixture containing 50% of MON 863 pollen, non-transgenic (control) corn pollen, bee pollen (a component of normal rearing diet), or potassium arsenate-treated control corn pollen. In the larval tests, 96.7%, 90.0%, and 93.3% of C. maculata larvae successfully pupated and then emerged as adults when fed on MON 863 pollen, non-transgenic corn pollen, and bee pollen (normal rearing) diets, respectively. Among the larvae completing their development, there were no significant differences in the developmental time to pupation and adult emergence among the transgenic corn pollen, non-transgenic corn pollen, and bee pollen diet treatments. All larvae fed on arsenate treated corn pollen diet died as larvae. For tests with adults, 83.3%, 80.0%, and 100% of adult C. maculata survived for the 30 days of the test period when reared on diets containing 50% of MON 863 pollen, non-transgenic corn pollen, and bee pollen respectively. While the adult survival rate on MON 863 pollen diet was significantly less than that on the bee pollen diet, there was no significant difference between the MON 863 and non-transgenic corn pollen treatments. During the period of adult testing, an average of 77, 80, and 89 eggs per female were laid by females fed on the MON 863 pollen, control corn pollen, and bee pollen, respectively; no significant differences were detected in the number of eggs laid among these treatments. These results demonstrate that when offered at 50% by weight of the dietary component, transgenic corn (MON 863) pollen expressing Cry3Bb1 protein had no measurable negative effect on the survival and development of C. maculata larvae to pupation and adulthood nor any adverse effect on adult survival and reproductive capacity. Relevance of these findings to ecological impacts of transgenic Bt crops on non-target beneficial insects is discussed.     

Quantification of consumption of corn pollen by the predator Coleomegilla maculata (Coleoptera: Coccinellidae) during anthesis in an Illinois cornfield

Abstract 1 Coleomegilla maculata DeGeer feeds on corn pollen in the field, but the degree to which this predator relies on corn pollen as part of its diet is not well understood. We quantified the amount of pollen consumed by C. maculata second, third and fourth instars and adults in the field. 2 Laboratory experiments were conducted to determine the digestion rate and duration of different stadia or stages using temperature regimens that reflected field conditions during anthesis. Coleomegilla maculata larvae and adults were collected from the field and the amount of pollen in their digestive tracts was determined gravimetrically. The rate of digestion, duration of each life stage and the field observations were used to estimate the amount of pollen consumed by second, third and fourth instars and adults. 3 Our models estimate that larvae consume 0.66, 1.67 and 3.30 mg of pollen during the second, third and fourth stadia, respectively. Adults consumed an estimated 13.15 mg during anthesis. 4 The relevance of our results to ecological risk assessment of transgenic insecticidal corn and predator life history strategies is discussed. The results presented here are a first attempt to quantify pollen consumption by a predator, and future areas of research are suggested.     

Is Tetranychus urticae suitable prey for development and reproduction of nafve Coleomegilla maculata？

The lady beetle Coleomegilla maculata De Geer is an omnivorous predator that could help suppress aphid and spider mite populations on plants in greenhouses, plantscapes or interiorscapes. We are assessing the nutritional requirements and feeding behavior of C. maculata on target prey （spider mites） and factitious （unnatural） food. Our ultimate goal is to develop an efficacious diet to mass produce C. maculata. In this study, we tested the hypothesis that Tetranychus urticae Koch （two-spotted spider mite） is not suitable prey for development and reproduction of naive C. maculata （i.e., with no prior exposure to T. urticae）. Our objectives were to （i） provide baseline data on the effects of consuming T. urticae on C. maculata life history, （ii） to compare the effects of consuming all stages of T. urticae versus eggs ofMusca domestica L. （common housefly）, and （iii） to determine if the consumption of plant products was beneficial. We used C. maculata from a colony reared only on Ephestia kuehniella Zeller （Mediterranean flour moth） eggs. In experiments, C. maculata larvae were reared from the first instar to adult stage with prey/food in replicated arenas; adult females were paired with a single male with prey/food. The results showed that naive C. maculata readily attacked and consumed T. urticae. Nevertheless, T. urticae was less suitable than M. domestica eggs for C. maculata development and reproduction. Applying a synthetic pollen-Chlorella alga powder （SPCA） in arenas containing T. urticae appeared to boost C. maculata female development and reproduction.     

PHYSIOLOGICAL EVIDENCE OF HYBRIDIZATION AND RETICULATE EVOLUTION IN PHLOX MACULATA

A comparative physiological analysis was conducted on a hybrid swarm involving P. maculata subsp. maculata and P. glaberrima subsp. interior. The population contained an array of segregates and introgressants. Hybrids displayed a high degree of heterogeneity in their physiological attributes, some characters being intermediate to, similar to, or transgressing those of the parental taxa. For example, both net photosynthetic rates and net photosynthetic/dark respiratory ratios were enhanced in the hybrids, and the level of enhancement was associated with the level of morphological intermediacy. Conversely, no enhancement was noted in either respiration rates or foliar fresh weight/ovendry weight ratios of the hybrids. Because of physiological imbalance, about one-third of the hybrids were eliminated early in their development. Representatives of P. maculata subsp. pyramidalis, a putative stabilized derivative of hybridization between the above two parental species, were intermediate in most physiological features and closely resembled some natural hybrids. The data verify that the physiological features of subspecies pyramidalis can be assembled through recombination of the P. maculata and P. glaberrima genomes.     

Influence of temperature on the in vitro pollen germination and pollen tube growth of various native Iranian almonds (Prunus L. spp.) species

Pollen germination and pollen tube growth was quantified among various native Iranian wild almonds (P. dulcis (Mill.) D. A. Webb, P. eleaegnifolia Mill., P. orientalis Mill., P. lycioides Spach, P. reuteri Bioss. et Bushe, P. arabica Olivier, P. glauca Browick and P. scoparia Spach in order to identify differences in the tolerance of pollen to temperature variations. Pollen germination and pollen tube growth were observed after incubation in darkness in a germination medium for 24?h at 10?C50°C at 5°C intervals. Maximum pollen germination of the wild almond species and specify that 60% was obtained for P. orientalis pollen and 98% for P. scoparia. Pollen tube length ranged from 860???m was obtained in P. lycioides and 1490???m in P. scoparia. A modified bilinear model best described the response to temperature of pollen germination and pollen tube length. Almond species variation was found for cardinal temperatures (T _min, T _opt and T _max) of pollen germination percentage and pollen tube growth. Mean cardinal temperatures averaged over eight almond species were 14.7, 24.2, and 43.7°C for maximum percentage pollen germination and 14.48, 25.3, and 44.4 °C for maximum pollen tube length. The principal component analysis (PCA) identified maximum percentage pollen germination and pollen tube length of the species, and T _max for the two processes as the most important pollen parameters in describing a species tolerance to high temperature. PCA also classified Prunus L. spp. into four groups according to the tolerance of pollen to temperature variations. The T _min and T _opt for pollen germination and tube growth, rate of pollen tube growth were less predictive in discriminating species for high temperature tolerance.     

An approach to the knowledge of pollen and allergen diversity through lipid transfer protein localisation in taxonomically distant pollen grains

The aim of the present study is to localise non‐specific lipid transfer proteins (nsLTPs), obtained from Rosaceae (Prunus persica (L.) Batsch) in pollen grains of taxonomically distant plants, such as Iridaceae (Aristea latifolia G.J. Lewis), Platanaceae (Platanus acerifolia (Aiton) Willd.) and Urticaceae (Parietaria judaica L.), in order to compare pollen and nsLTP diversity. A combination of transmission electron microscopy, immunocytochemical techniques, and rabbit specific antiserum against peach nsLTPs (Pru p 3) were used. Abundant labelling to Pru p 3‐like proteins was observed in the cytoplasm, walls and pollenkitt of A. latifolia pollen grains. The presence of nsLTPs associated with the pollenkitt proves that it takes part in the defence mechanism of pollen grains. The labelling was less intense in the cytoplasm and walls of P. acerifolia. Immuno‐stained gold particles were associated with the vacuoles, lipid inclusions, endoplasmic reticulum and Golgi complex. No significant labelling was found in the P. judaica pollen grains incubated with anti‐Pru p 3 polyclonal antibodies. These results indicate important variations in the nsLTPs of different pollen species. Consequently, no taxonomic relationship between pollen grains and nsLTPs could be established.     

Computer-aided identification of allergenic species of Urticaceae pollen

Plant species of the family Urticaceae have periods of extensive and overlapping flowering. Two genera Urtica (U. urens L., U. membranacea Poir. in Lam) and Parietaria (P. judaica L.) are abundant throughout the Iberian Peninsula. Both have substantial allergenic potential, but patient sensitivity is specific to each genus. As a result, interest from the medical profession in the identification of the pollen from these genera has arisen. It would be useful to be able to estimate the relative percentages of pollen of these genera in the air, which would allow clinicians to recommend the appropriate safety measures to patients. Unfortunately, palynologists are unable to distinguish between the species of genera (Parietaria and Urtica). Additionally, traditional methods of pollen counting are laborious and therefore not optimal for routine on-line analysis. Recent biometrical analysis enables us to discriminate between pollen species of the genera Parietaria and Urtica, but they fail to solve the problem of genera identification. Alternative methods for counting and distinguishing genera of Urticaceae have long been awaited by medical experts among others. In this paper we present a computational system to discriminate between genera by using image analysis. It is based on the definition and computation of digital shape measures on pollen images taken by an optical microscope. The system correctly classifies more than 86% of all experiments done. A set of shape parameters are tested and the subset with the highest discrimination power includes: area (A), diameter (DM), mean distance to centroide (D_mean) and roundness (R) of the pollen grain.     

Seasonally different modes of seed dispersal in the prostrate annual, <Emphasis Type="Italic">Chamaesyce maculata</Emphasis> (L.) Small (Euphorbiaceae), with multiple overlapping generations

The modes of seed dispersal in the prostrate annual, Chamaesyce maculata, with multiple overlapping generations were investigated. We found that C. maculata has two modes of seed dispersal; autochory in the summer and myrmecochory in the autumn. Seasonally different modes of seed dispersal have not been known in other plant species. The large proportion of seeds produced in the summer was positioned further than the expanse of the parent plants by automatic mechanical seed dispersal. Therefore, autochory would be effective for avoiding competition between parent and offspring plants. No autochory occurred in the seeds produced in the autumn. The seeds of C. maculata without an elaiosome were dispersed by seed-collecting ants in the autumn. Although 18 ant species in total visited the plants of C. maculata at the 50 sites investigated, only two ant species, Tetramorium tsushimae and Pheidole noda frequently carried the seeds of C. maculata. The low frequency of seeds carried out of the nest by P. noda suggests that the workers of P. noda carry the seeds as food into their nest. So, P. noda might be a less effective seed disperser for C. maculata, corresponding to the effectiveness of seed dispersal by harvester ants. However, T. tsushimae ants frequently carried the seeds into and out of their nest, suggesting that T. tsushimae do not regard the seeds of C. maculata as a food resource. Thus, T. tsushimae may be an effective seed disperser for C. maculata.     

Pollen competition among Populus deltoides Marsh., P. nigra L. and P. maximowiczii Henry in fertilizing P. deltoides ovules and siring its seed crop

Summary Interspecific pollen competition among Populus deltoides, P. nigra and P. maximowiczii in fertilizing P. deltoides ovules was studied by using a pollen mixture technique, allozymes and leaf morphology. The frequencies of F₁ seedlings of different paternities in pollen-mix crosses showed highly significant (P<0.01) departures from the 11 ratio expected if pollen selection was random. P. deltoides pollen was the most competitive. The mean percentages of F₁ seedlings of P. deltoides paternity in crosses with pollen mixes P. deltodes + P. nigra, P. deltoides + P. maximowiczii, and P. deltoides + P. nigra + P. maximowiczii were 95.0, 92.5, and 84.8, respectively. P. maximowiczii pollen was more competitive than P. nigra pollen, which was at a selective disadvantage. An average of 83.6% of F₁ progenies of the eight crosses with P. nigra + P. maximowiczii pollen showed P. maximowiczii paternity. Also, in four crosses with P. deltoides + P. nigra + P. maximowiczii pollen, the relative proportion of P. deltoides × P. maximowiczii seedlings (13.4%) was higher than that of P. deltoides × P. nigra seedlings (1.8%). Pollen proportions in the pollen mixes and pollen size did not significantly affect the competitive ability of the pollen. The relative pollen competitive ability indicated reproductive affinities among the species.     

Estimating population characteristics of two saproxylic beetles: a mark-recapture approach

Using a mark-release-recapture technique we describe adult sex ratios, recapture rates and other sample characteristics of two saproxylic species: the nationally threatened longhorn beetle Leptura (Rutpela) maculata (Coleoptera: Cerambycidae) and the common L. quadrifasciata in southeastern Finland over two summers. Over 350 individuals of L. maculata and 150 individuals of L. quadrifasciata were captured on floral resource or in flight, and marked each summer. For L. maculata, the sex ratio was male-biased (2:1), whereas for L. quadrifasciata the bias was less clear. For both species, the male-bias may reflect behavioral differences between sexes, rather than true population differences. The proportion of recaptured individuals was low and varied between 7 and 33% depending on the species and year, which allowed us to estimate population parameters only for L. maculata in 2006. A model which assumed constant survival, but time-dependent catchability and entrance probability from a larger superpopulation, fit the data best. The precision of the total population size estimates were reasonable for all the models tested (coefficient of variation = 7–14%). Based on the estimated local adult population size (mean ± 95% confidence interval = 865 ± 131), and the current distribution area of L. maculata, we infer that the species is not in immediate risk of extinction in Finland. Our analysis shows that mark-recapture technique can provide precise estimates of adult population size of saproxylic beetles which have different adult and larval habitats, and thus be useful in assessing extinction risk and monitoring population trends.     

The effect of soil pH on the ability of ectomycorrhizal fungi to increase the growth of Eucalyptus globulus Labill.

We examined the effect of two levels of soil pH (5 and 6) on the ability (effectiveness) of ectomycorrhizal fungi to increase the growth of Eucalyptus globulus Labill. at a deficient supply of P. Plants were inoculated with one of six fungal isolates [Laccaria laccata (Scop. ex Fr.) Berk. and Br. (isolates A and B), Pisolithus tinctorius (Pers.) Coker and Couch (isolates A and B), Descolea maculata Bough. and Mal. and Setchelliogaster sp. nov.] and were grown in a P-deficient sand, in pots, in a temperature-controlled glasshouse. Seedlings were harvested 89 days after planting and were assessed for dry matter production, tissue P concentrations, ectomycorrhizal colonization of roots and hyphal development in soil.Uninoculated plants had less than 5% of their fine root length colonized by ectomycorrhizal fungi. In contrast, inoculated plants had 30% or greater of their fine root length ectomycorrhizal. Inoculation increased the uptake of P and growth of plants for all isolates and at both levels of soil pH, although growth responses to inoculation were greater at pH 6, particularly for the two L. laccata isolates. Isolates which colonized roots most extensively increased plant growth to the greatest extent. D. maculata was the most effective fungal isolate at pH 5, and both D. maculata and L. laccata A were most effective at pH 6. The effects of soil pH on plant growth were also related to some extent to the effects of soil pH on colonized root length. Growth responses to inoculation were related less well to hyphal development in soil. The L. laccata isolates formed more hyphae in soil (on a per pot, per m of fine root, and per m of colonized fine root basis) than other fungal isolates, but were not always more effective in increasing plant grown.     

Taxonomic implications of pollen exine morphology in infrageneric classification of Scutellaria (Lamiaceae)

Scutellaria L. in Lamiaceae subfamily Scutellarioideae is a subcosmopolitan genus with about 360 species. According to the latest subgeneric classification, two subgenera are recognized: S. subgen. Scutellaria and S. subgen. Apeltanthus. We studied pollen grains from 29 species of Scutellaria belonging to both subgenera and from both the Old and the New World to evaluate their taxonomic importance for the infrageneric classification of the genus. Pollen grains were acetolysed and studied by scanning electron microscope (SEM) and light microscope (LM). All examined pollen grains are isopolar, tricolpate, suboblate, oblate spheroidal, prolate spheroidal to subprolate. The exine is mainly bireticulate perforate, but with variations in lumina shape and size as well as perforation size and uniformity. Based on the exine sculpturing, two subtypes are recognized within the bireticulate pollen type. In subtype I the primary reticulum of the exine consists of angular muri; the lumen has an irregular polygonal shape and the perforations of the secondary reticulum are more or less uniform and of the same size. This pollen subtype was observed in species of subgenus Scutellaria, sectt. Scutellaria p.p., Anaspis, Perilomia and Salazaria. In subtype II the primary reticulum of the exine consists of a more or less curved murus; the lumen is rounded or obtusely angular and the secondary reticulum consists of one or more large central perforations surrounded by some smaller ones. This pollen subtype was observed in species of subgenus Scutellaria sectt. Scutellaria p.p., Salviifoliae and in all members of subgenus Apeltanthus. The results of this study reveal that the exine ornamentation is a diagnostic character useful for the infrageneric classification of Scutellaria.     

Potential of the predatory mite Amblydromalus zannoui to control pest mites on Jatropha curcas

Amblydromalus zannoui Sourassou, Sarmento and Moraes is a phytoseiid mite of the limonicus group described from central Brazil from leaves of physic nut, Jatropha curcas L. (Malpighiales: Euphorbiaceae), a plant potentially useful as a source of biofuel. This plant is often attacked by the mites Polyphagotarsonemus latus (Banks) (Prostigmata: Tarsonemidae) and Tetranychus bastosi Tuttle, Baker and Sales (Prostigmata: Tetranychidae). The objectives of this work were to evaluate the predation rate of A. zannoui on those phytophagous mites, to assess its life cycle on these prey and on pollen of Ricinus communis L. (Euphorbiaceae), and to determine its attraction to physic nut leaves infested by P. latus or T. bastosi. Amblydromalus zannoui attacked more nymphs and adults than eggs of P. latus, and more eggs and larvae than adults of T. bastosi. The life table parameters suggest that A. zannoui performs better on P. latus (r_m: 0.20, R_o: 18.77; λ: 1.23) and pollen (r_m: 0.18, R_o: 23.32, λ: 1.18). The predator seems to be attracted to plants with P. latus, but attraction was not clear cut for plants with T. bastosi. The results suggested that A. zannoui is a potential control agent to be used against P. latus on physic nut plants, and that R. communis pollen can be used as supplementary food to maintain the predator population in the absence of prey.

     

Learning affects prey selection in larvae of a generalist coccinellid predator

Under natural conditions, generalist predatory insects have to cope with a variety of potential prey species that are not all equally suitable. Under these circumstances, learning may be adaptive if it allows adjustment to variations in resource quality and availability. Under laboratory conditions, we examined the learning ability and memory in the prey selection process of larvae of the predatory coccinellid Coleomegilla maculata ssp. lengi Timberlake (Coleoptera: Coccinellidae). Using choice tests, we studied prey rejection behaviour of C. maculata fourth instars towards prey of different quality and we also tested the influence of hunger and prior experience with other food types on the prey rejection behaviour of coccinellid larvae. Coleomegilla maculata larvae gradually changed their behaviour and rejected low‐quality hosts more frequently, whereas high‐quality hosts were nearly always accepted. After 48 h, the learned behaviour appeared to be partially forgotten. Hunger and experience with other food types prior to the test had little effect on the gradual change of behaviour but the quality of the food ingested influenced the initial level of prey rejection. Our results demonstrate that (1) C. maculata larvae can adjust their prey selection behaviour with experience to reject progressively less suitable prey, and (2) previous experience with other prey types can influence their initial preference.