摘要:

Two trap designs and eight formulations of potato tuberworm,Phthorimaea operculella(Zeller), sex pheromone,trans-4,cis-7-tridecadien-l-ol acetate (PTM 1) and PTM 1 +trans-4,cis-7,cis-10-tridecatrien-l-ol acetate (PTM 2) were tested in the field during 1982 in Lima, Peru. No significant differences (P>0.05) in trap capture were observed between the water pan trap at ground level and the funnel trap set at ground level and at 40 and 80 cm of elevation. All eight ratios of PTM 1 and PTM 2 tested were significantly superior to the use of virgin-female traps. Highest capture was obtained by using a 9:1 ratio of PTM 1 to PTM 2. Ratios of 1:1.5 and 3:1 were as effective as a 9:1 ratio of PTM 1 to PTM 2. PTM 1 alone had significantly lower captures than these ratios. The attractiveness of a 9:1 ratio appears to drop after 90 days of field use. The 1:1.5 ratio remained attractive for 90 days and beyond. Storage at −5°C for 2 months did not diminish the attractiveness of this pheromone blend.

ISSN:1754-5692    

DOI:10.1093/ee/13.1.61

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Population counts ofZetzellia mali(Ewing) and its prey,Aculus schlechtendali(Nalepa),Panonychus ulmi(Koch), andTetranychus urticaeKoch on ‘Delicious’ apple trees were studied to determine what factor(s) regulates predator-prey oscillations. Four interrelated factors were considered: leaf nutrients, soil moisture, leaf conditioning, and growth of the apple leaves. It was observed that prey populations initially increased when the trees added new leaves. Soon thereafter, the predator,Z. mali, increased its numerical response. The combined effect of predation and leaf conditioning caused a decline in the prey populations. With fewer prey available, the numerical response ofZ. malidecreased. Leaf nutrients, soil moisture, and leaf conditioning affected the number of phytophagous mites on the trees. The overall predator-prey cycle, however, was not affected.

ISSN:1754-5692    

DOI:10.1093/ee/13.1.65

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Eight insecticides were identified from 43 samples of honey bees obtained from 35 beekeepers in 1981 and 1982. A total of 268 colonies were documented to have been contaminated from May through early October. Carbaryl was detected in 65% of the samples. Methyl parathion and methoxychlor were found in 30 and 14% of the samples, respectively. Other insecticides in honey bees included endosuIfan, chlordane, malathion, diazinon, and acephate. Two simultaneously occurring insecticides were present in 28% of the samples. Residues in brood-nest comb tended to be higher than in dead bees. Most colonies contaminated only by carbaryl recovered, though 9% succumbed. Of the colonies experiencing methyl parathion or dual methyl parathion and carbaryl or endosulfan poisonings, 77% were killed or severely weakened. The majority of incidents involving carbaryl and methoxychlor were reported in May and June, when extensive ground spraying of trees for gypsy moth control occurred. Commercially grown crops treated with carbaryl may have been the principal sources of contaminated bees in July and August. Bees died from methyl parathion from July through September, when its application to orchards and sweet cornfields was common.

ISSN:1754-5692    

DOI:10.1093/ee/13.1.70

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Relative-density estimates from two insect-sampling devices (sweep-net and shake cloth) were compared with absolute-density estimates for three size classes of the corn earworm,Heliothis zea(Boddie) (Lepidoptera: Noctuidae), and the fall armyworm,Spodaptera frugiperda(J. E. Smith) (Lepidoptera: Noctuidae), in peanuts. Linear regression analysis indicated that medium and large larvae of corn earworm and all size classes of fall armyworm were consistently recovered by both devices (r2≥ 0.80). Small corn earworm estimates were poor for both devices (r2≤ 0.38).

ISSN:1754-5692    

DOI:10.1093/ee/13.1.75

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Five stages of malathion-resistant Indianmeal moth (IMM),Plodia interpunctella(Hübner), larvae were tested for their susceptibility to a granulosis virus. The virus was applied as a lactose coprecipitate at concentrations of 0 to 250 mg/kg of IMM diet in increments of 25 mg. At a significance level ofP= 0.01, the 1st- and 2nd-instar larvae were highly susceptible; 3rd instars had an intermediate level of susceptibility; 4th and 5th instars demonstrated relatively little susceptibility. First-instar offspring from IMM that survived treatment suffered 100% mortality in virus-contaminated media.

ISSN:1754-5692    

DOI:10.1093/ee/13.1.79

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Thermal summation studies of the development of the navel orangeworm,Amyelois transitella(Walker), on almonds were carried out during 1981 and 1982. An upper developmental threshold of 34.4°C was determined from field data. New crop nuts were caged while still attached to the tree and inoculated after hullsplit with 1st-instar larvae. Mean developmental times from egg to adult when reared on new crop nuts were 424 and 427 degree-days C in 1981 and 1982, respectively. Nuts from previous years' crop (“mummies”) were also caged in the field and inoculated with 1st-instar larvae. The mean time required for navel orangeworm development on mummy almonds was 623 degree-days C.

ISSN:1754-5692    

DOI:10.1093/ee/13.1.81

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Eggs of the Mexican bean beetle,Epilachna varivestisMulsant (Coleoptera: Coccinellidae), were exposed for durations of 1/30, 1/10, 1/4, 1/2, 2, 4, 6, and 24 h to temperatures of 30, 35, 38, 40, 42, and 44°C and then were hatched at 25°C. Unexposed controls were maintained at 25°C. Survival as a percentage of that for unexposed eggs decreased with increasing exposure times at temperatures above 30°C, but developmental periods did not differ for any temperature-exposure combination at which hatch occurred. From the survival-exposure relationship for each temperature, the exposures that resulted in 90, 70, 50. 30, and 10% survival were determined, and the reciprocals of the exposures (× 100%) gave the rates of injury accumulation required to cause mortality of 10, 30, 50, 70, and 90% of the eggs, respectively. The injury accumulation rate-temperature relationships for those five mortality levels were used successfully to simulate the survival of nine egg cohorts under fluctuating temperature conditions in the greenhouse and to predict the abundance of 1st-instar larvae from observed oviposition in one soybean field.

ISSN:1754-5692    

DOI:10.1093/ee/13.1.86

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

The incidence ofErynia phytonomi(Arthur) andBeauveria bassiana(Balsamo) in southern-California populations of the Egyptian alfalfa weevil,Hypera brunneipennis(Boheman) (Coleoptera: Curculionidae) was determined during 1979 and 1980.E. phytonomiinfection normally occurred as a single epizootic in March or April after latewinter rains, and was typified by the results in the 1979 survey. Although incidence was relatively high, the epizootic occurred too late to prevent damage to the crop by feeding larvae. Abnormally heavy rainfall early in the year, such as occurred in 1980, initiated an earlier, longer epizootic, and seemed correlated with lower larval densities.E. phytonomisurvived temporary dry periods occurring during the epizootic in dried host larvae, called resting larvae, on which the fungus sporulated when suitable conditions resumed.B. bassianaincidence was less affected by rainfall. Harvesting of the field, resulting in exposure of surviving larvae to soil-borne inoculum, increased the incidence ofB. bassiana. Complete harvesting of the field seemed to have an immediate adverse effect on incidence ofE. phytonomi, but levels of the fungus later reached new peaks.

ISSN:1754-5692    

DOI:10.1093/ee/13.1.95

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Larvae of the corn earworm,Heliothis zea(Boddie), and the fall armyworm,Spodoptera frugiperda(J. E. Smith), were reared under laboratory conditions on a diettreated withAspergillus flavusLink orA. parasiticusSpeare. Results indicate A.parasiticusis more toxic to the corn earworm than A.flavuswhen larvae are not transferred daily. The larval stage of the corn earworm sustains more toxic effects than either the pupal or adult stages. When larvae were transferred to fresh diet daily after initial exposure to treated diet, neither the corn earworm nor the fall armyworm showed any significant pathogenic effects (P= 0.01). Overall, toxicity was more evident than pathogenicity.

ISSN:1754-5692    

DOI:10.1093/ee/13.1.100

出版商:Oxford University Press    

年代:1984

数据来源: OUP

摘要:

Two generations of seedcorn maggots (SCM)occurred in central Iowa in 1980 and 1981. In both years, overwintering flies appeared in late April (at 181/198°Dc; 1980–1981) and the F1generation appeared in early June (at 494/490 degree-days C; 1980–1981). SCM were uncommon or absent in the summer and fall, strongly suggesting aestivation by flies in the F2. Air temperatures were useful in predicting SCM development in the field; however, both air and soil temperatures overestimated SCM development. Our results indicate that low-risk planting periods could be identified with additional knowledge of SCM population biology.

ISSN:1754-5692    

DOI:10.1093/ee/13.1.105

出版商:Oxford University Press    

年代:1984

数据来源: OUP