摘要:

Cotton plant phenology and bollworm,Heliothis zea(Boddie), populations were monitored in Arkansas and Texas during 1972–75. The purpose was to determine the influence of food supply and food age on population development and damage. Our data indicate that bollworm establishment is markedly reduced when the number of squares ≥ 6 mm in diam drops below 160 thousand/ha. Sixty-four percent of the squares which were tagged after mid-July were ≥ 12 days old when damaged by bollworms. Eighty-nine percent of the bolls receiving injury were damaged within 5 weeks after bloom, and 95% of the yield was produced from 1 mm squares formed during the 1st 6 weeks of squaring.

ISSN:1754-5692    

DOI:10.1093/ee/7.1.144

出版商:Oxford University Press    

年代:1978

数据来源: OUP

摘要:

Young adults ofT. castaneumleft their habitats sooner at higher adult densities and In the presence of large larvae. The rate of emigration by adults ofT. confusumwas not strongly influenced by initial density, and cohorts tended to cease emigration at ca. the same level in all density treatments. However, emigration byT. confusumcontinued as long as large active larvae were present. Actual numbers of progeny were more uniform than could be explained by differential emigration alone. The trend toward uniformity is discussed with respect to the facultative reduction in fecundity by crowded adults, and the cannibalism of eggs by non-emigrant adults and their developing larval progeny.

ISSN:1754-5692    

DOI:10.1093/ee/7.1.149

出版商:Oxford University Press    

年代:1978

数据来源: OUP

摘要:

The objective of this study was to evaluate the applicability of procedures for sampling and estimating within-tree populations ofDendroctonus frontalisin North Carolina. The procedures developed under epidemic conditions in Texas were applied to declining populations in North Carolina. Despite the differences in total population numbers, the within-tree distributions of allD. frontalislife stages were similar for both states. Infested surface area estimates using tree geometry tables developed from the Texas data base were satisfactory for North Carolina. Hence the “tree geometry-proportional density function” procedures for estimating total within-tree life stages are applicable in 2 widely separated regions ofD. frontalis' range and under extremely different population sizes.

ISSN:1754-5692    

DOI:10.1093/ee/7.1.157

出版商:Oxford University Press    

年代:1978

数据来源: OUP

摘要:

H. M. Flint et al. wish to amend the caption to their Figure 2 on page 59 in this issue as follows:Test 1 exposed 5/18–7/17 (T1/2= 106 days).Test 2 exposed 6/30–10/27 (T1/2= 133 days).

ISSN:1754-5692    

DOI:10.1093/ee/7.1.164

出版商:Oxford University Press    

年代:1978

数据来源: OUP

摘要:

Extracts from hydrated bean seeds (Phaseolus vulgarisL.) deterred the ovipositional response ofHylemya antiquaMeig. to volatile attractants released by cut pieces of mature onion bulbs. Experiments using choice bioassays with gravid female adult flies indicated that the active principle(s) is a non-volatile, non-polar constituent of hydrated bean seeds that functions via a contact stimulus.

ISSN:1754-5692    

DOI:10.1093/ee/7.1.165

出版商:Oxford University Press    

年代:1978

数据来源: OUP

摘要:

Japanese gypsy moth,Lymantria dispar japonicaMotschulsky, in low population densities in northern Japan's mixed species forests, oviposited almost exclusively on the white bark ofBetula platyphyllaSukatschev: in plots totaling 3.3 ha, 88 of 90 egg masses were on white birches, which comprised<30% of the stand composition.Likewise, high densities of the moth in a planting ofLarix leptolepis(Sieb. and Zucc.) Gord. preferred to oviposit onB. platyphylla:3 white birches among 154 trees (0.09 ha) held 84% of the egg masses, and one birch that had a DBH of 17 cm held 482 masses. These findings have practical application for field workers who wish to collect gypsy moth eggs in northern Japan where white birch is found.

ISSN:1754-5692    

DOI:10.1093/ee/7.1.168

出版商:Oxford University Press    

年代:1978

数据来源: OUP

摘要:

The innate capacity of increase was calculated for cohorts and isolated individuals of the green cloverworm,Plathypena scabra(F.). Colony and midseason field-collected cohorts were similar, as were early-season and late-season field-collected cohorts. Similarities were: percentage individuals in prereproductive and reproductive periods, age-distribution patterns, realized sex ratio, and seasonal abundance records for field-originated cohorts.Calculated rates of increase were used to estimate numbers of females needed at initial invasion of Iowa agroecosystems to cause economic losses later in the season. Two methods of simulating ovipositional pattern were advanced to contribute to predictive population models.

ISSN:1754-5692    

DOI:10.1093/ee/7.1.171

出版商:Oxford University Press    

年代:1978

数据来源: OUP