Host specificity of the ragwort flea beetle Longitarsus jacobaeae (Waterhouse) (Coleoptera:Chrysomelidae)

Abstract

The ragwort flea beetle, Longitarsus jacobaeae, was tested for host specificity against representative species of native New Zealand Senecio. Adult feeding and oviposition tests were carried out under quarantine with and without a choice of host plants. Larval development was assessed using potted plants. It was concluded that L. jacobaeae is highly specific to Senecio jacobaea and that it is extremely unlikely to be damaging to native New Zealand Senecio species.     

椰子木蛾的产卵节律及其对寄主植物的产卵选择性

【背景】椰子木蛾是近年来新入侵我国棕榈科植物的害虫,研究其产卵习性可为监测和防治该虫提供参考。【方法】在室内条件下,观察、记录了椰子木蛾雌成虫的产卵节律及其对不同寄主植物的产卵选择性。【结果】椰子木蛾最高日产卵量可达34.4粒·头-1,且主要集中在羽化后4 d内产卵,占总产卵量的54.1%;产卵活动主要发生在夜间23:00到次日8:00;在椰子、蒲葵、大王棕、槟榔和散尾葵等寄主植物上的产卵量无显著差异,为89.3~147.7粒·头-1,但产卵位置存在差别。【结论与意义】椰子木蛾雌成虫具有较强的繁殖能力和产卵节律性,且在不同寄主植物上的产卵量一致。     

共生菌通过氧气浓度调控果蝇产卵偏嗜性

【目的】研究东方醋杆菌(Acetobacter orientalis)和短小乳杆菌(Lactobacillus brevis)通过氧气浓度调控黑腹果蝇(Drosophila melanogaster)产卵的偏嗜性,并研究其对后代存活率和发育历期的生物学意义。【方法】利用双相选择装置解析果蝇产卵行为。利用分光光度仪和pH计测量细菌的OD值与pH值。通过改变果蝇的视觉、味觉和嗅觉感官以检测介导果蝇产卵行为的感觉系统。用后代的发育历期与存活率评价其生物学意义。【结果】果蝇产卵对东方醋杆菌具有趋避性,产卵指数为–0.76,对短小乳杆菌具有趋向性,产卵指数为0.5,并且二者接种比例决定了果蝇的产卵选择。氧气作为一个调节因子,可改变果蝇对东方醋杆菌和短小乳杆菌的产卵偏嗜性。氧气是东方醋杆菌生长必需的条件,有氧培养的OD值为1.3,而无氧培养的OD值为0.4。氧气是短小乳杆菌生长非必需的条件,有氧和无氧培养的OD值均为2.2。破坏嗅觉可严重地影响果蝇对细菌的产卵偏嗜性。东方醋杆菌和短小乳杆菌均促进了果蝇的生长,分别提高存活率1倍和1.5倍,分别缩短果蝇发育历期1 d和2 d。【结论】东方醋杆菌和短小...     

Pollen beetle (Meligethes aeneus) oviposition and feeding preference on different host plant species

The oviposition and feeding preferences of the pollen beetle, Meligethes aeneus, were determined in choice and no-choice tests in field, semi-field and greenhouse trials. Plant species used were Brassica napus, B. campestris, B. juncea, B. nigra, B. carinata, Sinapis alba and Crambe abyssinica. With respect to number of eggs laid, S. alba and C. abyssinica were inferior to the other species. Pollen beetles laid fewer eggs on B. nigra than on the other Brassica spp. in no-choice tests, however this difference was partly due to fewer eggs laid per bud rather than fewer buds used for oviposition. Most eggs, for all plant species, were deposited in buds sized 2–3 mm. Feeding damage on all plant species was relatively similar. Pollen beetles seem to have a wider host range for feeding than for oviposition. There was good agreement in plant species ranking as oviposition hosts between the field, semi-field and greenhouse trials.     

Specialist pollinating seed predator exhibits oviposition strategy consistent with optimal oviposition theory

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Feeding and oviposition preference of the Sakhalin pine sawyer Monochamus saltuarius (Coleoptera: Cerambycidae) for various tree species

Monochamus saltuarius was recently identified as an important vector of Bursaphelenchus xylophilus, the cause of pine wilt disease. In this study, M. saltuarius adults preferred different species of tree based on the longevity, ingested amount and wounded area that were determined for 90 d. Among eight tree species, the longevity of feeding by M. saltuarius was not significantly different except when feeding in Sciadopitys verticillata. However, the highest ingested amounts with the largest wounded areas were associated with Pinus koraiensis. The highest oviposition preference was in P. densiflora for the first 20 d. However, after 40 d, the oviposition highest preference was noted in P. koraiensis. For oviposition activities, M. saltuarius preferred the tree species in the following order: P. densiflora > P. koraiensis > P. rigida > Larix leptolepis. Although many oviposition scars were observed, M. saltuarius laid fewer eggs in P. rigida than other species of pine, which was related to the bark thickness. The oviposition frequencies were highest with bark 2.0–2.5 mm thick and with tree diameters of 110–130 mm. The current study increased understanding of the ecology of M. saltuarius by identifying specific tree preferences.     

Trade-offs of host use between generalist and specialist <Emphasis Type="Italic">Helicoverpa</Emphasis> sibling species: adult oviposition and larval performance

Much attention has been paid to the question of the relative importance of female behaviour versus larval feeding capacities in determining the host range of herbivorous insects. Host-use trade-offs displayed by generalist and specialist sister species of the genus Helicoverpa were evaluated to examine the relationship between maternal choice and offspring performance. The prediction of optimal oviposition theory, that females will choose to lay eggs on plants on which their offspring perform best as larvae, was tested by measuring oviposition preference and larval performance of Helicoverpa armigera and H. assulta on tobacco, sunflower, and hot pepper. These two measures were more highly correlated in the specialist H. assulta. Both species exhibited the same oviposition preference ranking: tobacco > sunflower > hot pepper. H. armigera larvae preferred sunflower, followed by tobacco and hot pepper; while H. assulta larvae preferred tobacco to sunflower and hot pepper, consistent with their mothers’ oviposition preference. Duration of the total period from egg to adult emergence for each species was significantly shorter on the host plant preferred by the larvae. H. assulta had shorter larval duration and higher relative growth rate than H. armigera on tobacco and hot pepper, and vice versa for sunflower, indicating species differences in host utilization. Thus, while only the specialist H. assulta displayed the predicted optimal oviposition pattern, females of both species show the least preference for the plant on which their offspring perform worst. Selection for optimal oviposition may be stronger on the specialist, which has fewer choices and lower lifetime fecundity than the generalist.     

GENETIC VARIATION IN CACTOPHILIC DROSOPHILA FOR OVIPOSITION ON NATURAL YEAST SUBSTRATES

Theory predicts that environmental heterogeneity in space or in time can maintain genetic polymorphism. Stable polymorphisms are expected to be more readily maintained if there are genotype specific habitat preferences. Genotype specific preferences for oviposition sites in Drosophila could be a major factor promoting habitat selection, and thus the maintenance of genetic variation. This hypothesis is being tested using the cactophilic species, D. buzzatii and D. aldrichi, where available evidence indicates a potential for such habitat selection, the habitats (oviposition sites) being yeast species found in the natural environment of these flies (cactus rots). Genetic variation for oviposition preferences was tested using isofemale lines—for D. buzzatii, a total of 60 lines from seven localities widely distributed through the species range in Australia, and for D. aldrichi, 21 lines from three of these localities. Females were given a choice of five yeast species as oviposition sites. Genetic variation for oviposition preferences on these natural substrates was demonstrated. There was significant variation among isofemale lines within populations in their patterns of preferences for oviposition on the five yeast species. However, analyses of preferences for each yeast species separately showed that the genetic variation for preferences relates to only three of the five species. Heritabilities of individual female preferences for these three species were low, ranging up to 9%. Little geographic differentiation was apparent among populations, most likely due to similar selection regimes within each population. Within populations, this kind of habitat selection could act to maintain polymorphisms, both at loci determining the habitat preferences and at other loci in linkage disequilibrium with them.     

Oviposition site selectivity of some stream-dwelling caddisflies

Population dynamics depends upon the spatial distribution of individuals in heterogeneous environments. The various processes surrounding insect oviposition are central to understanding their population dynamics because the choice of oviposition site ultimately influences the survivorship and spatial distribution of their progeny. Aquatic insects are often assumed to have non-selective oviposition habits, but empirical data are scarce and selective oviposition may be quite common. We quantitatively sampled egg masses of stream-dwelling caddisflies (Trichoptera) that specialise in egg-laying on hard substrata underwater, in order to characterise oviposition site selectivity and test for communal oviposition. In a field survey of two Scottish streams, we sampled egg masses of three species, Polycentropus flavomaculatus, Hydropsyche siltalai, Rhyacophila dorsalis, with the aim of testing whether egg mass abundance varied with current (riffles vs. pools), location within the channel (margins vs. centre) and rock exposure (emergent vs. fully submerged). In one stream, we captured adults landing on emergent rocks and assessed whether females were modified morphologically for swimming. The egg masses of two species (P. flavomaculatus, H. siltalai) occurred primarily on submerged rocks in pool margins, and adult females had legs modified for swimming. In contrast, egg masses of R. dorsalis were most abundant on the underside of emergent rocks in riffles, and females were not modified for swimming. Communal oviposition was evident for all three species, with most egg masses aggregated on the minority of potential rocks. How females locate oviposition sites and the consequences of these highly specialised oviposition behaviours to the survival and spatial distribution of larvae now require investigation. The effects of these behaviours on population dynamics are likely to differ from terrestrial herbivores because oviposition sites are not food resources for these aquatic species.     

Influence of induced water stress in ponderosa pine on pine sawflies

Summary Three levels of water stress were induced on pole-size ponderosa pine (Pinus ponderosa) to determine the influence of plant moisture stress on oviposition, survival, and growth of two species of pine sawfly (Neodiprion fulviceps and N. autumnalis). It was found that water stress affected oviposition and subsequent egg survival but not larval development or survival. Stress had a negative effect on early season oviposition (N. fulviceps) and a positive effect on late season oviposition (N. autumnalis). Egg hatch was different between species and years and among treatment levels. Larval development, feeding, and survival were not affected by water stress. Overall, the effect of stress was not sufficient to explain population outbreaks of sawflies. Several hypotheses are presented as possible explanations for the observed experimental results.     

Aspects of the biology of Xanthocnemis zealandica and Austrolestes colensonis (Odonata: Zygoptera) at three ponds in the South Island,New Zealand

Abstract

Both Xantnocnemis zealandica McLachlan and Austrolestes colensonis White were univoltine, and emerged asynchronously. At Woodend Pond, in 1971, larval growth was divided into cohorts by the drying up of some larval habitats in summer and autumn. Larval development was continuous in the other (permanent) habitats. A. colensonis differed from X. zealandica in its oviposition sites and its ability to survive the winter in the egg stage. There were differences in the larval food of the two species reflecting their differing agility.     

Oviposition substrate selection by Florida mosquitoes in response to pathogen‐infected conspecific larvae

The impact of the presence of larval mosquito pathogens with potential for biological control on oviposition choice was evaluated for three mosquito species/pathogen pairs present in Florida. These included Aedes aegypti infected with Edhazardia aedis, Aedes albopictus infected with Vavraia culicis, and Culex quinquefasciatus infected with Culex nigripalpus nucleopolyhedrovirus (CuniNPV). Two‐choice oviposition bioassays were performed on each host and pathogen species with one oviposition cup containing infected larvae and the other cup containing uninfected larvae (control). Both uninfected and E. aedis‐infected female Ae. aegypti laid significantly fewer eggs in oviposition cups containing infected larvae. Uninfected gravid female Ae. albopictus and Cx. quinquefasciatus oviposited equally in cups containing uninfected larvae or containing larvae infected with V. culicis or CuniNPV, respectively. Gravid female Ae. albopictus infected with V. culicis did not display ovarian development and did not lay eggs. The decreased oviposition by gravid Ae. aegypti in containers containing E. aedis‐infected larvae may indicate that the infected larvae produce chemicals deterring oviposition.     

Micro‐climate determines oviposition site selection and abundance in the butterfly Pyrgus armoricanus at its northern range margin

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Plant‐mediated effects of butterfly egg deposition on subsequent caterpillar and pupal development,across different species of wild Brassicaceae

1. Herbivory can change plant quality, which may have consequences for interactions between the inducing herbivore and other insect community members. 2. Studies investigating the effects of plant quality on herbivore performance often have neglected the egg stage, and instead introduced larvae onto the plant. Recently, we reported that herbivore oviposition by Pieris brassicae (Linnaeus) (Large Cabbage White Butterfly) reduced the plant quality of Brassica nigra L. (black mustard) for subsequent herbivores. 3. It remains unclear how persistent and common these plant‐mediated effects of oviposition are. Here, five species of wild Brassicaceae were used (B. nigra L., Brassica oleracea L., Sinapis arvensis L., Moricandia arvensis L., and Moricandia moricandioides Boiss). The response to oviposition by the specialist P. brassicae was determined by following the natural sequence of events: oviposition, egg, larval, and pupal development. All tested plant species are known to interact with P. brassicae in nature. Caterpillar, pupal mass, and development time on plants exposed to butterfly eggs were assessed compared with egg‐free plants. 4. It was shown that the plant‐mediated effects of oviposition are not specific for B. nigra but occur in most of the tested plant species except for M. arvensis. However, the strength of the plant‐mediated effect on caterpillar growth depended on plant species. Thus, across different members of the Brassicaceae family, oviposition can influence plant quality and has negative consequences on P. brassicae growth. Further studies are needed to assess to what extent this trait might be phylogenetically conserved.     

Indirect effects mediated by compensatory shoot growth on subsequent generations of a willow spittlebug

 We investigated whether oviposition by the spittlebug Aphrophora pectoralis on Salix miyabeana and S. sachalinensis in fall 1998 affected shoot growth pattern and further oviposition by subsequent generations of the willow spittlebug in early September 1999 and 2000. Spittlebug oviposition enhanced the growth of current-year shoots on 1-year shoots with oviposition (O-shoots) compared to those without oviposition (N-shoots): the length of current-year shoots increased in 1999 and 2000, the number of current-year shoots increased in 2000 despite a decrease in 1999, and the shoot abscission rate decreased during the 1999 winter. The number of egg masses per current-year shoot was greater on O-shoots than on N-shoots in 1999, and this tendency was reinforced in 2000. The total number of egg masses was greater on O-shoots than on N-shoots in 2000, although there was no significant difference in 1999. There is thus a positive feedback system between spittlebug attack and compensatory growth on willow. Received: April 11, 2002 / Accepted: July 30, 2002 Present address: Center for Ecological Research, Kyoto University, Otsu, Japan Acknowledgments We thank Masanori J. Toda and Andrew Davis for valuable comments and critical reading on this paper. Financial support was provided by a Japanese Ministry of Education, Science, Sports, and Culture Grant-in-Aid for Creative Basic Research to Takayuki Ohgushi. Correspondence to:A. Nozawa     

Within- and among-population variation in oviposition preference for urea-supplemented food inDrosophila melanogaster

Oviposition preference for ureasupplemented food was assayed by simultaneous choice trials on five pairs of closely related laboratory populations of Drosophila melanogaster.Each pair of populations had been derived from a separate ancestral population about 85 generations prior to this study. One population in each pair had been subjected to selection for larval tolerance to the toxic effects of urea; the other population served as a control. Considerable variation in oviposition preference was seen both within and among populations, with four of the ten populations showing a significant mean preference for ureasupplemented food. The degree of specificity shown by individual females was surprisingly high, leading to a bimodal distribution of oviposition preference in some populations. Overall, selection for larval tolerance to urea did not significantly affect oviposition preference. However, the data indicated that pairwise comparisons between randomly selected populations from the two larval selection regimes would lead to a range of possible outcomes, suggesting, in several cases, that selection for larval urea tolerance had led to significant differentiation of adult oviposition preference for urea in one or the other direction. The results, therefore, highlight the importance of population level replication and caution against the practice, common in ecological studies, of assaying oviposition preference in two populations that utilize different hosts in nature, and then drawing broad evolutionary inferences from the results.     

Physical factors influencing the oviposition behaviour of European grapevine moths Lobesia botrana and Eupoecilia ambiguella

Uncovering the entire process of oviposition could enable the development of innovative pest control strategies. The European grapevine moth Lobesia botrana as well as the European grape berry moth Eupoecilia ambiguella are serious insect pests, which still threaten viticulture in many parts of the world. By creating an artificial semiochemical emitting surface, in form of a card, we tried to develop an egg‐monitoring tool for the oviposition of these two species in vineyards. The idea was to create a decision support system that facilitates timing and necessity of insecticide treatments. This article deals exclusively with the initial step towards the development of this tool: the influence of physical factors (colour, shape or texture) of a surface on the oviposition behaviour of L. botrana and E. ambiguella under laboratory conditions. The acceptance of different artificial substrates as oviposition site was analysed exclusive of volatile organic compounds emitted by a host plant. We investigated particular colours of the surface, which could be a visual stimulus to trigger the oviposition of both species. Apparently, the colour green, the texture of the material and the light conditions turned out to be highly important stimuli for oviposition.     

Whether ideal free or not,predatory mites distribute so as to maximize reproduction

Ideal free distribution (IFD) models predict that animals distribute themselves such that no individual can increase its fitness by moving to another patch. Many empirical tests assume that the interference among animals is independent of density and do not quantify the effects of density on fitness traits. Using two species of predatory mites, we measured oviposition as a function of conspecific density. Subsequently, we used these functions to calculate expected distributions on two connected patches. We performed an experimental test of the distributions of mites on two such connected patches, among which one had a food accessibility rate that was twice as high as on the other. For one of the two species, Iphiseius degenerans, the distribution matched the expected distribution. The distribution also coincided with the ratio of food accessibility. The other species, Neoseiulus cucumeris, distributed itself differently than expected. However, the oviposition rates of both species did not differ significantly from the expected oviposition rates based on experiments on single patches. This suggests that the oviposition rate of N. cucumeris was not negatively affected by the observed distribution, despite the fact that N. cucumeris did not match the predicted distributions. Thus, the distribution of one mite species, I. degenerans, was in agreement with IFD theory, whereas for the other mite species, N. cucumeris, unknown factors may have influenced the distribution of the mites. We conclude that density-dependent fitness traits provide essential information for explaining animal distributions.     

Comparison of oviposition behavior of a solitary and a gregarious parasitoid (Hymenoptera: Mymaridae)

Anaphes victus Huber andAnaphes listronoti Huber (Hymenoptera: Mymaridae) are respectively solitary and gregarious egg parasitoids of the carrot weevil,Listronotus oregonensis (LeConte) (Coleoptera: Curculionidae). We made detailed ethograms of the oviposition behavior on unparasitized and parasitized hosts for the two species. We then compared the behavior of virgin and mated females for the oviposition of male and female progenies. The two species did not always oviposit after insertion of the ovipositor, but these punctures without oviposition could be readily differentiated from oviposition.A. victus oviposited only once by puncture, whileA. listronoti deposited one to three eggs during the same sequence. The variability of the duration of the various components was generally lower for a given female than between females. Two components, the abdominal vibrations and the pause, were significantly shorter in ovipositions that resulted in male progency for the two species. However, an important overlap in duration prevents using these differences to sex the progeny at oviposition. Virgin females of both species, although capable of producing only males, exhibited both behaviors. Parasitized hosts were recognized through internal and external markings that were used in host discrimination.