摘要:

In statistical analyses of simulated insecticide efficacy trials it was found that changes in distribution of target insects caused by reductions in abundance may result in incorrect inferences. The severity of the problem is directly related to the index of aggregation from Taylor's power law. Thus, highly aggregated species, such as many pests, are likely to be inconsistently sampled, with the result that insecticide efficacy trials may suggest an incorrect conclusion with far higher probability than the nominal significance level. Transformation of the data and the use of measures of mortality such as Abbott's method do little to alleviate the problem. A simple enumeration of test reports inInsecticide&Acaricide Tests(Entomological Society of America, College Park, Md.) suggests that a large proportion of tests in the literature may be erroneous, some completely incorrect.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.1

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Loblolly and shortleaf pines on one study site in the North Carolina piedmont were subjected to attack by varying numbers of southern pine beetle (SPB),Dendroctonus frontalisZimmermann. Shortleaf pines appeared to be the more susceptible host on this site. Resin flow rate was significantly lower and length of the hypersensitive lesion resulting from inoculation of the trees with the blue-staining fungusCeratocystis minor(Hedgecock) Hunt was significantly longer in shortleaf pines successfully attacked by 2,000 SPB compared with shortleaf pines unsuccessfully attacked by 2,000 SPB. Loblolly pines attacked by ca. 2,000 SPB had similar resin flow rates and longer hypersensitive lesions than did shortleaf pines unsuccessfully attacked by 2,000 beetles. Overall, shortleaf pines either had a high resin flow rate or a long hypersensitive response, whereas in loblolly pines, the two variables were positively correlated.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.9

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Major hypotheses on the adaptive significance of insect gall formation are reviewed: nonadaptive, plant protection, mutual benefit, nutrition, microenvironment, and enemy hypotheses. We evaluate the validity of each, and find the first three to be without merit because galls clearly have adaptive features for the insect, but few if any for the plant, and the galler has negative impact on the plant, making the relationship parasitic. Predictions are developed to enable testing of hypotheses, and tests are discussed. Nutrition and microenvironment hypotheses are supported, while the enemy hypothesis remains with several uncertain issues to be resolved. The evolution of the galling habit has followed two pathways, one via mining plant tissues and the other from sedentary external herbivores that then modify plant growth. In each route the sequence of selective factors was probably different, but improved protection from hygrothermal stress and improved nutrition are of primary importance, and protection from enemies probably reinforced the galling habit.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.15

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Activity patterns of fifth-instar tobacco budworms,Heliothis virescens(F.), and cabbage loopers,Trichoplusia ni(Hübner), were determined in the laboratory with an ultrasonic actograph and in the field by visual observations of marked larvae. Field data correlated well with laboratory data and showed that larvae of both species were active predominantly during periods of illumination. Activity patterns of larvae and timing of pesticide treatments for increased efficacy are discussed

ISSN:1754-5692    

DOI:10.1093/ee/16.1.25

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

At least 6 species of herbivorous mites, 18 species of predatory mites, and>5 species of detritus- and fungus-feeding mites were found on apple foliage during 2 yr of sampling in 17 southern Michigan apple orchards. Species with the greatest volume (biomass) included the stigmaeid predatorsAgistemus fleschneriSummers andZetzellia mali(Ewing), the phytosdeiid predatorNeoseiulus fallacis(Garman), and the tetranychid herbivorePanonychus ulmi(Koch). Volume of mite species in abandoned orchards was correlated with their volume in commercial orchards. However, several species with high volume in abandoned orchards had a low volume or were absent in commercial orchards. A shift in predator species took place rapidly over a single season when orchards were not sprayed. Predator volume was less than herbivore volume in commercial orchards, but the reverse was true in abandoned orchards.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.30

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Greenhouse and laboratory studies showed that each instar and adult of tarnished plant bug (TPB),Lygus lineolaris(Palisot de Beauvois), may feed on eggs and the first three instars ofHeliothisspp. Under greenhouse test conditions, significantly moreHeliothisspp. eggs were destroyed in a 24-h period by third- and fourth-instar TPB than by adult TPB. However, adult TPB preyed on significantly larger numbers of second- and third-instarH. virescens(F.) larvae during 24- and 48-h periods than any of the five instars. Under laboratory conditions, significantly higher percentages ofHeliothiseggs were destroyed in 24 and 48 h by the TPB adult and by each instar, two through five, than were destroyed by the first instar.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.37

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Daily periodicity of preovipositional behavior and egg deposition by the onion fly,Delia antiqua(Meigen), was monitored hourly under laboratory conditions with a photoperiod of 16:8 (L:D) and a female density of 30 per 1,260 cm3. Although preovipositional behaviors occurred in appreciable frequency throughout a day, most eggs were laid 10–12 h after lights on. When flies were tested in a chamber with photoperiod shifted 6 h from the solar photoperiod, periodicity in egg deposition remained strictly entrained with chamber photoperiod. This ovipositional periodicity corresponds well with the afternoon peak of catches in flight traps in the field. These results suggest that behavioral observations in the field and short-term control measures (e.g., volatile insecticides) directed against ovipositing flies may be performed best during the late afternoon

ISSN:1754-5692    

DOI:10.1093/ee/16.1.41

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

The plant bug,Lygus hesperusKnight, was reared on five common bean,Phaseolus vulgaris(L.), genotypes, three of which were previously identified as resistant (‘BAT 1081’, ‘BAT 1299’, and ‘CIAT 5979’) and two as susceptible (‘Red Kidney’ and ‘CIAT 5683’). Age-specific life-table parameters were estimated as a means to measure plant resistance toL. hesperus. Under both field and laboratory conditions, fewer bugs survived to the adult stage on the resistant cultivars than on the susceptible cultivars. Female lygus bugs reared on the resistant genotypes also had lower gross reproductive rates, net reproductive rates, and intrinsic rates of increase than those bugs held on the susceptible genotypes. These life-table values for CIAT ‘;5683’ were significantly greater than for all other cultivars. Resistance had no effect on mean generation time. Finite rates of increase and population doubling times were significantly lower on resistant cultivars. These life-table results confirm resistance to lygus bugs in common bean cultivars based on reduced survivorship to adulthood, fecundity, and longevity of females.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.45

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

An ecological study of the European corn borer (ECB),Ostrinia nubilalis(Hbn.), was conducted in Boone County, Iowa, from 1950 through 1965. The average date of the beginning of first-generation pupation was 12 May, with completion 8 June. Moth flight usually began in late May, peaked during the 2nd and 3rd weeks of June, and ended in early July. First-generation oviposition was greatest during the last half of June. Most (69.0%) first-generation ECB eggs hatched; a significant number (25.5%) were lost, probably due to heavy rains and violent winds. Greatest total numbers of first-generation ECB egg masses and larvae occurred in maize planted 6–10 d after the first planting date. The average date of the beginning of second-generation pupation was 16 July, with the average completion 14 August. Peak second-generation moth flight was during the first half of August. Peak oviposition was in early to mid-August. Percentage of second-generation eggs missing was less than that of the first generation, probably because severe storms were less frequent during August than in June. Heavy second-generation infestations often occurred in early-planted maize; more than 65% of second-generation larvae were found in maize planted during the first 10 d of the planting period. Heaviest infestations were in maize planted 21–30 d after the first planting date. A small third-generation moth flight occurred in some years. Predators were much more numerous during the second-generation oviposition period than during the first-generation oviposition. More second-generation eggs were eaten by predators than were first-generation eggs. The most common parasitoid of the ECB wasLydella thompsoniHerting; this species was uncommon after 1959. Other parasitoids were recorded but were not numerous.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.50

出版商:Oxford University Press    

年代:1987

数据来源: OUP

摘要:

Larva sampling and a pheromone trap grid with 103 traps spaced 200 m apart were used to assess overwintering and movement of the tortricid,Argyrotaenia citrana(Fernald), in a region of caneberry,Rubusspp.; filberts,Cordaylus aveliana(Walsingham); open fields; and woods in the northern Willamette Valley, Oreg.A. citranaoverwintered primarily in marionberry fields, within compact masses of dead leaves tied to canes on wire trellises.A. citranadid not overwinter on red raspberries, and survivorship on evergreen blackberries was low. Over 70% of the total catch in early season occurred in five traps located in marionberry fields. In 1984, cool temperatures had a direct effect on catch by reducing both numbers of traps catching moths and total moths trapped. Peak catch in spring occurred 3 wk after peak male emergence. Following peak male emergence, the number of traps catching moths increased dramatically, indicating that males were moving throughout the region. As emergence of summer adults began, however, moths were once again trapped primarily in marionberries. During the remainder of summer, the number of traps catching moths increased weekly. Peak emergence coincided with peak catch in August. Summer larva samples indicated that females dispersed into raspberry and blackberry fields adjacent to overwintering sites in marionberries. In 1985, catch in the spring was lower than in 1984, but was similarly restricted to moths on marionberries.

ISSN:1754-5692    

DOI:10.1093/ee/16.1.59

出版商:Oxford University Press    

年代:1987

数据来源: OUP