摘要:

Frankliniella occidentalis(Pergande) oviposition was examined in ‘Granny Smith’ apple bud and fruitlet clusters under different adult population densities throughout bloom. Samples of bud clusters of different maturation stages taken throughout bloom in 1989–1990 indicated that egg densities and egg infestation rates within a sample date were generally higher on more mature clusters. However, rather than thrips preferentially ovipositing on the more mature blossom cluster stages, most eggs were laid on buds by early-pink to early-bloom state during 1989 and 1990 with little to no accumulation later in bloom. Cohorts of clusters maturing later in bloom had few to no eggs. Egg densities did not increase with rising thrips densities within clusters either across bloom states or across treatments with different population densities. Clusters sampled during late bloom in 1990 had the highest thrips densities but had very low egg densities. Eggs were often laid (12–100%) on sepals and on the stems of apple buds rather than on the area around the ovary that would result in scarred fruit. Within apple bud clusters, more eggs were laid and egg densities were higher on king buds (central apical bud, which opens first) compared with lateral buds (those buds within a cluster surrounding the king).

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1568

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The bruchid beetleStator vachelliaeBottimer will sometimes oviposit on seeds of the nonhostParkinsonia aculeata(Leguminosae = Fabaceae), but most larvae do not survive. Of 1,118 eggs onParkinsoniaseeds, 86% occurred in a narrow zone where seeds ofParkinsoniaand the normal leguminous hostAcacia flexuosawere mixed on the ground beneath overlapping canopies. A field experiment indicated that females use nonseed cues associated withAcacia(pod valves and cow and horse dung) to locateAcaciaseeds, and when seeds of both hosts are encountered, females oviposit equally on seeds of both plants. Other factors that were not controlled in the experiments (amount of daylight, temperature, humidity) may also affect discrimination between seeds of different hosts. Survivorship onParkinsoniawas<0.1% in the field, whereas onAcaciait was 15%. Most (53%) mortality onParkinsoniawas attributable to inability of larvae to penetrate seed coats. Enemy-free space was available onParkinsonia:only 3% of bruchid eggs on its seeds were parasitized, but on the normal hostAcacia,24% were parasitized. We suggest three steps for S.vachelliaeto includeParkinsoniain its host range or for a host shift: (1) oviposition on the potential host in proximity to cues associated with the normal host, which does not appear to require a genetic change in search or oviposition behavior; (2) larvae of S.vachelliaemust evolve the ability to complete development in the new host; and (3) the adult beetles must be able to track the new host. Only step 1 has occurred in this system. The results support previous suggestions that the initial colonization of new hosts may be behavioral.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1577

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

First instars of the eucalyptus longhorned borer,Phoracantha semipunctata(F.), were not capable of colonizing bark of vigorous standing trees of twoEucalyptusspecies. The lack of a kino gum reaction after the introduction of larvae into the bark ofE. grandisHill ex Maiden andE. tereticornisSmall strongly indicates that this gum does not play an important role in the initial defense against borer attack. Larvae were also not able to colonize the bark of logs that were maintained at high moisture content but were able to colonize the bark of dry logs and artificially water-stressed trees that had reduced bark moisture content. We propose that bark moisture content plays a critical role in the resistance of eucalyptus trees against colonization by eucalyptus longhorned borer larvae.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1583

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Preference among, and relative consumption and use of several legumes by third instars of the cabbage looper,Trichoplusia ni(Hübner)(Lepidoptera: Noctuidae), were studied under laboratory conditions. Leaf disks of the relatively insect-resistant ‘PI 227687’ and insect-susceptible ‘Davis’ soybean,Glycine max(L.) Merrill; and of snap bean,Phaseolus vulgarisL.; and ‘Henderson's Bush’ lima bean,P. lunatusL. were preferred to sucrose-treated elderberry-pith disks; thus, the phagoexcitant effects of primary and secondary substances from the leaves of all plants exceeded those of sucrose alone. Leaf disks of ‘PI 227687’ were significantly less preferred than those of ‘Davis’ soybean and lima bean. Consumption and utilization of ‘Henderson's Bush’ lima bean and ‘Davis’ soybean leaves were most efficient, and of ‘PI 227687’ soybean leaves were least efficient. A lower rate of food intake on snap bean was associated with a higher efficiency of conversion of ingested food into body matter. Efficiency of conversion of digested food (ECD) into body matter was significantly and positively associated with the growth rate (GR) of larvae on the most suitable host plant, lima bean, but was negatively associated in larvae on ‘PI 227687’, the least suitable host. The relatively high consumption index (CI) on ‘PI 227687’ indicated significant antibiotic effects from secondary substances in ‘PI 227687’. Relative preference observed in leaf disk assays was not reflected in host-plant suitability based on consumption and utilization of foods. To understand better the insect-plant interrelationships, both insect preference for, and consumption and utilization as food should be studied.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1589

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Daily parous rates were determined over a period of 31 d forAnopheles quadrimaculatusSay adults from three locations in the eastcentral rice-growing region of Arkansas. Estimates of the average parous rate, oviposition cycle length, and survival rate per oviposition cycle were determined for mosquitoes from each site. Collections from site 1, a rural site where cattle supplied a source for mosquito blood meals, exhibited a parous rate of 32% and an engorgement rate of 97%. The average oviposition cycle was 4 d with a survival rate of 30%. Collections from site 2, a rural site with few blood hosts, exhibited a parous rate of 17% and the engorgement rate was only 2%. The average oviposition cycle and survival rate at this site could not be reliably estimated. Collections from site 3, an urban site where blood hosts were highly available but where an integrated mosquito control program was in effect, yielded a parous rate of 17% and the engorgement rate was 85%. The average oviposition cycle was 4 d with a survival rate of 17%. These data demonstrate the ability of mosquito control to reduce parous and survival rates ofA. quadrimaculatusby altering the age structure of abated mosquito populations.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1595

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Entomophaga maimaigaHumber, Shimazu&Soper was recovered from gypsy moth,Lymantria dispar(L.), populations from Massachusetts, Connecticut, New Hampshire, Vermont, eastern New York, northeastern Pennsylvania, and New Jersey in 1989 and 1990. NoE. maimaigawas recovered from cadavers of gypsy moth larvae collected in western New York, western Pennsylvania, West Virginia, or Virginia in either year despite high levels of rainfall in these regions in May of both years. In 1990,E. maimaigawas recovered in many areas that bordered the 1989 distribution (Maine, central Pennsylvania, central New York, Delaware, and northeastern Maryland) where it had not been recovered in 1989, possibly due to spread of the disease. In 1989, mortality of gypsy moth larvae from sites in Massachusetts was correlated with rainfall, but not with population density.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1601

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Parasitoids associated withBruchophagus platypterus(Walker) were collected in 1988 and 1989 in Wisconsin. Included wereAprostocetus (=Tetrastichus) bruchophagi(Gahan),Mesopolobus bruchophagiGahan,Habrocytus medicaginisGahan, andEupelmella vesicularis(Retzius).A. bruchophagiandM. bruchophagiwere the most abundant parasitoids found. Parasitism ranged from 0 to 62% and seed damage ranged from 2 to 39%. Diapause was initiated inB. platypterusandA. bruchophagibetween 1 August and 5 September in northern Wisconsin. The postdiapause developmental thresholds forB. platypterus,M. bruchophagi, andA. bruchophagiwere 12, 15, and 12°C respectively. Degree-day accumulations above those thresholds for adult emergence were 454, 86, and 559 forB. platypterus,M. bruchophagi, andA. bruchophagi, respectively. Sweep sample data from 3 yr agree with degree-day predictions for adult emergence.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1606

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The temporal, climatic, and physiological factors mediating dispersal of a naturally occurring population of horn flies,Haematobia irritans(L.), were examined. Resident (nondispersing) horn fly populations increased from late spring through early fall and decreased in late October. Fly-free herds 0.4 km from the source herd were reinfested from the source population at a significantly slower rate in June (4.6 flies per side per animal per day) than in August or October (7.1 flies per side per animal per day). Given that the greatest increase in the resident population occurred in June, it would appear that horn fly dispersal is not density-dependent. However, the rate of reinfestation was greatest in cattle treated with a larvicidal bolus and a daily application of a short-residual insecticide, indicating that reinfestation may be a function of competition for hosts, with the most rapid colonization occurring when few horn flies are present. The rate of reinfestation did not differ as a consequence of bolus treatment, suggesting that newly emerged flies rapidly disperse or replace older, dispersing adults. Physiological age-grading showed that the age structure of the dispersing flies did not differ significantly from that of the resident population. Moreover, all age classes were included in the dispersing population, with the largest proportion being parous adults. The dispersing population was primarily female, which emerged earlier and in greater numbers than males.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1612

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

In mango trees (Mangifera indicaL.), eggs ofPenicillaria jocosatrixGuenée were laid predominantly on or near inflorescences or new leaves. Some eggs were laid on spider webs near young growth. At 26°C, the development rate was: eggs, 2–3 d; larvae 9.5 d; pupae, 11 d. Developmental and survival rates were affected by host plant, plant part, and leaf age. On mango, larvae survived better and developed faster on young leaves10 d old. These leaves were reaching full size and were tougher. The unsuitability of older leaves was probably not related to protein levels, as survival and development rates on inflorescences, which had comparatively low levels of nitrogen, were higher. Larvae survived better and developed faster on young leaves of ambarella (Spondias dulcisForster f.) than on older, more mature leaves. Larvae were randomly distributed over the tree canopy on branches with young leaves with respect to height and compass direction in both wet and dry seasons. The behavior of larvae varied with age. First and second instars remained on the young leaves at all times. Third through fifth instars fed on young leaves at night and moved to the undersides of old leaves beneath the new shoot during the day. Adult females oviposited more frequently on leaves aged from budbreak to 4 d old. On a tree, the majority of the buds opened about the same time. Late breaking buds were fewer, and received proportionally higher numbers of eggs, causing more defoliation of these shoots.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1619

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Honey bee,Apis melliferaL., drones and workers were used to examine how differences in morphology, physiology, and behavior affect heat exchange and thorax temperature (Tth) during flight. Drones had twice the body mass (Mb) of workers (199.4 ± 2.5 versus 101.8 ± 3:3 mg) and exhibitedTth>2°C higher. Drones were unable to lowerTththrough regurgitation or through shunting heat to the abdomen. Heat production during hovering increased withMbwhereas total heat loss increased withMband with flight speed (V). Despite their larger size and higherTth, drones flew slower than workers. A heat budget model predicted thatTthwould decrease sharply withV, increase with body mass, and increase with the ratio of thorax mass to body mass. The model closely predicted theTthdifference between drones and workers and demonstrated that the higherTthof drones is primarily (75%) an effect of largeMh, somewhat (15%) a result of the high ratio of thorax to body mass and, to a lesser degree (10%), a result of slowerV. These morphological and behavioral traits are sufficient to account for the difference inTthbetween drones and workers.

ISSN:1754-5692    

DOI:10.1093/ee/20.6.1627

出版商:Oxford University Press    

年代:1991

数据来源: OUP