摘要:

Adult population fluctuations of wildAnastrephafruit flies were determined by McPhail trap captures in 5 orchards of different fruit species at the Soconusco region in Chiapas, Mexico. The main fruit fly hosts at these orchards were orange, guava (low and highlands), sapodilla,Achras zapotaL., and chalum,Inga michelianaHarms. All plant species exhibited different fruiting phenologies. Fruit fly species composition varied among the orchards with 1 or 2 predominant species representing from 43 to 86% of theAnastrephaindividuals. The predominant species were always associated with the main fruit host in the orchard. Adult populations varied strongly between and within orchards. In all cases, peak population numbers of predominant species were recorded shortly after the period of maximum host fruit availability. Simple regression analysis between fly numbers and rainfall showed that this environmental factor cannot explain population fluctuations, whereas host fruit availability can be considered the most important environmental factor affecting adult populations in these tropical orchard habitats.

DOI:10.1093/ee/24.4.861

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

The biology ofTyphlodromalus peregrinus(Muma) was studied in the laboratory at 26°C. Each of the following organisms was evaluated as suitable diet: all stages ofTetranychus urticaeKoch; immature stages ofPanonychus citri(McGregor) (Acari: Tetranychidae); and pollens ofMalephora crocea(Jaquin),Quercus virginianaMiller, andTyphalatifolia(L.). The combination ofT. urticaewith each pollen was also tested. Total developmental time ranged between 5.73 and 7 d for females and between 5.67 and 6.93 d for males. The percentage of females in the total population ranged between 53 and 61%. A diet ofT. urticaeprovided the shortest generation time (G), greatest female longevity, and mean total fecundity (F) which resulted in the highest net reproductive rate (R0) value (25.31 expected females per female), intrinsic rate of increase (rm= 0.224), and finite rate of increase (erm= 1.25) per day forT. peregrinl1s. Diets of onlyP. citriorM. crocearesulted in close values of G = 8.67, 8.91; F = 47.11, 49.47; R0= 24.00, 26.65; rill = 0.210, 0.219; anderm= 1.23, 1.24, respectively.Q. virginianaandTypha latifoliawere the least favorable food sources, with results of G = 8.78, 9.41; F = 30.38, 24.25; R0= 14.20, 12.04;rm= 0.193, 0.170, ander= 1.21, 1.18, respectively. Thermvalues were highly affected by generation time and mean total fecundity (R2= 0.947).

DOI:10.1093/ee/24.4.870

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

In its natural environment, the Colorado potato beetle,Leptinotarsa decemlineata(Say), colonizes plants that are distributed in patches. In such conditions, females must select oviposition sites that will provide sufficient resources for the survival of their offspring. The presence of conspecific eggs on the plant reduces the amount of resources available, so the density of conspecific eggs must be evaluated. In the laboratory, most females laid their eggs on the terminal leaflet of the highest of 3 leaves available to them. Feeding damage did not seem to modify the process of oviposition, and the presence of eggs did not change feeding patterns. In choice tests, egg clutches, hexane-washed eggs, yellow paper, and green paper reduced deposition of eggs on the treated leaflet, whereas hexane, white paper, and egg extract did not. Conspecific egg perception using visual cues, and possibly other stimuli, was demonstrated.

DOI:10.1093/ee/24.4.875

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Parasitoid assemblages associated withPhyllonorycterleaf miners (Lepidoptera: Gracillariidae) were examined on the 2 deciduous oaks,Quercus dentataandQ. mongolica, in Hokkaido, northern Japan, and those on 2 others,Q. acutissimaandQ. variabilis, in Nara, central Japan. To address to what extent interspecific competition is important in organizing parasitoid communities, I compared species richness, species composition, and levels of parasitism by guilds at different host immature stages among the parasitoid assemblages. Parasitoids were separated into 5 guilds according to parasitism modes (idiobiosis and koinobiosis) and host immature stages attacked and killed. Pooled data showed that the number of parasitoid species per host leafminer species in Japan (3.1) was similar to that in the United Kingdom (4.1) and that idiobionts (potential generalists) exceeded koinobionts (specialists) in species number (62.5%). A koinobiont guild and 2 idiobiont guilds had an inverse relationship in level of parasitism between 2 assemblages at each study area. These results may suggest that interspecific competition is important in organizing parasitoid communities. Nevertheless, dominant species and guilds varied among the assemblages, resulting in different patterns of percentage of parasitism by guilds in relation to host stage among the assemblages. This implies underuse of hosts at some stages by parasitoids, and interspecific competition is unlikely to be severe. Interspecific competition, therefore, seems to partially contribute to parasitoid community organization

DOI:10.1093/ee/24.4.879

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Life history of immatureLyctocoris campestris(F.), a predator of stored-product insects, was investigated at 17, 21, 25, and 29°C and ≍43, ≍58, and ≍75% RH in the laboratory. Most life history traits of L.campestriswere influenced by temperature, but none of the traits was influenced by relative humidity. The egg incubation period was ≍7 d at 25-29°C, but increased sharply at temperatures<25°C. An equation was developed to predict egg incubation period over a range of temperatures. Egg hatch rate did not vary with temperatures nor with the relative humidities. The mean hatch rate ranged from 78 to 86% across different temperatures summed across 3 relative humidities. The instar-specific nymphal development also varied with temperature. The 2nd stadium was the shortest followed by the 3rd, 1st, and the 4th, and the 5th stadium was the longest across all 4 temperatures. However, the ratios of duration of nymphal stadia remained constant across all 4 temperatures tested. Total nymphal durations were 20.5, 27.6, 40.1, and 66.2 d at 29,25,21, and 17°C, respectively; all 4 were significantly different from one another. The relationships between temperature and instar-specific nymphal durations and total nymphal durations were described by the same equation for both females and males; total nymphal durations did not vary with sex. Nymphal survival rates ranged from 0.60 to 1.00 and did not vary significantly with temperature or relative humidity. Sex ratio (proportion of males) of emerging adults ranged from 0.40 to 0.70, but did not differ from 1:1. These life history data are reported in a manner useful for developing a computer model for simulatingL. campestrispopulation dynamics.

DOI:10.1093/ee/24.4.889

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

The azalea lace bug,Stephanitis pyrioides(Scott), is a primary pest of azaleas throughout the eastern United States. We tested the hypothesis that azaleas growing under high light intensity and low water availability are stressed and consequently promote outbreaks of lace bugs. Azalea plants were grown under four light levels (0, 25, 50, and 75% shade) and two water treatments (high and low). Lace bugs preferred to feed and ovipositon shade-grown instead of sun-grown plants. Similarly, lace bug fitness (adult fecundity and longevity),survivorship, and inflicted plant damage were higher on shade-grown plants, with natural enemies excluded. Lace bug fitness did not differ on azaleas receiving high and low application rates of water. However, plants in the low-water treatment incurred more damage from lace bug feeding, perhaps as a result of increased feeding rate. These data on lace bug preference and fitness are inconsistent with reports in the literature that azaleas in sunny habitats are more prone to lace bug attack. Patterns of lace bug survivorship in exposed (0% shade) and woodlot (>75% shade) habitats rectified the apparent paradox. The survival of uncaged lace bugs was significantly poorer on plants placed in shaded woodlot habitats compared with their survival on plants placed in open settings. Although natural enemy effects were not explicitly tested, we suggest that higher rates of arthropod predation in the shaded woodlot habitat may be responsible for the reduced survival of lace bugs in this habitat. Thus, lace bugs are caught between two opposing environmental constraints and are relegated to sunny habitats, where although their performance is reduced on light- and water-stressed plants, overall survival is greatest. From a management perspective, lace bug infestations in urban landscapes could be minimized by planting azaleas in shaded areas with mixed vegetation and by preventing water deficit.

DOI:10.1093/ee/24.4.898

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

The relationship between oviposition preference and offspring performance is critical to the evolutionary ecology of the interactions between herbivorous insects and plants, but is not well understood. To improve our understanding of this relationship we must critically evaluate the relative importance of the selective forces or causes of mortality that affect developing larvae. We documented a strong relationship between oviposition preference and larval performance for 2 species of galling tenthredinid sawflies, a petiole galler,Euurasp., and a leaf galler,Pontaniasp., nearP. pacificaon the arroyo willow,Salix lasiolepis. There was a correlation between attack and survival on different ramet ages for both sawfly species. Mortality caused by plant resistance by ramet age primarily explained the pattern of attack of both sawflies. The effect of plant resistance was strongest on willow shoots on very young ramets. This effect decreased rapidly as ramet age increased and then increased relatively slowly as ramets aged, becoming very strong on the oldest ramets. Mortality caused by plant resistance was 8-fold greater than mortality caused by natural enemies forEuuraand 3.2-fold greater for Porltania. Natural enemies may playa lesser role in the population dynamics of the sawflies that may be subsidiary to the plant-herbivore interaction. We reason that selection has resulted in ovipositing females flying primarily in the upper parts of willow clones and avoiding the highly resistant younger ramets common in the lower parts of clones. Within the upper parts of clones, the evolution of female behavior that discriminates against shorter, slower growing shoots on older ramets would be selected for by the decreasing survival of offspring on these shoots.

DOI:10.1093/ee/24.4.909

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

The bionomics ofEuxesta stigmatisLoew were studied in the field and laboratory. Different features of life stages of this insect are described. Eggs were laid on the tip of corn ears inside silks, and larval development took place inside com ears. Abundance ofE. stigmatiseggs was lower in June than in other months in 1989, and higher in April than in other months in 1990. The sex ratio of adult flies on corn ears favored females, whereas the sex ratio did not vary significantly on other plant parts.

DOI:10.1093/ee/24.4.917

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

A two-component pheromone blend containing a 1:1 (vol:vol)ratio of isomeric 5,1l-dimethylheptadecane and isomeric 2,5-dimethylheptadecane was tested in high-capacity Unitraps to monitor populations of the western hemlock looper,Lambdina fiscellaria lugubrosa(Hulst), throughout the coastal western hemlock and interior cedar hemlock biogeoclimatic zones of British Columbia. Rubber septa were loaded with each component at doses of 10, 100, 1,000, and 10,000 μ (1992) and 1 and 10 μ (1993). Males demonstrated a dosedependent response, except that captures in traps with the 2 highest doses (1,000 and 10,000μ) did not differ. Unitraps with 10-μ lures captured significantly more males than similarly baited sticky traps at the beginning of the flight and with 1- and 10-μ-baited lures at midflight. Both 1- and 10-μ lures maintained their attractiveness over the 3-mo flight season, which extends from mid-August through October, but catches in traps with l-μ lures were low. In all cases,>80% of the males were captured by the beginning of October. Seasonal trends in trap catches were not closely related to temperature. This research suggests that traps baited with 10-μ lures could be used to monitor populations and detect incipient outbreaks of the western hemlock looper.

DOI:10.1093/ee/24.4.923

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Eggs, larvae, and pupae of the western hemlock looper,Lambdina fiscellaria lugubrosa(Hulst), were sampled and related to the numbers of male moths captured in pheromone-baited Unitraps at 27 (1992) and 34 (1993) study sites throughout the coastal western hemlock and interior cedar hemlock biogeoclimatic zones of British Columbia. Male moth catches in traps baited with 10 μg of both isomeric 5,1l-dimethylheptadecane and 2,5-dimethylheptadecane on a rubber septum lure were significantly correlated with larval and pupal counts within the same generation and were predictive of egg counts in the subsequent generation, suggesting that pheromone-baited traps could be used to monitor populations and predict future outbreaks.

DOI:10.1093/ee/24.4.933

出版商:Oxford University Press    

年代:1995

数据来源: OUP