摘要:

General properties of crop colonization by herbivores and their predators and parasites are discussed using soybeans as an example and the theory of island biogeography as a conceptual basis. Crop development is described and contrasted to typical island situations. In the crop, resources for herbivores are sufficient, but for predators and parasites they are deficient. This difference was seen in the colonization curves for the 2 groups. There was a lag between colonization by herbivores and their enemies with no appreciable increase in the latter until the soybean canopy was developed. Colonization and extinction rates were higher at the field edge than in the center, but an equilibrium number of species did not develop at either site in time to be of predictive value in developing pest management strategies. Methods for counteracting the destabilizing influences of current agricultural practices on arthropod communities are discussed.

ISSN:1754-5692    

DOI:10.1093/ee/5.4.605

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

Strip spraying, the technique of applying narrow bands of a moderately persistent pesticide to control active arthropods, is developed and evaluated for the use of malathion against cereal leaf beetle adults. Field and laboratory experiments quantified beetle movement, pesticide degradation on plants, accumulation and degradation of pesticide in the insects, and behavioral and mortality effects from the pesticide.The inclusion of these factors into a model allowed computer simulations of experiments involving a variety of strip configurations, insecticide concentrations and movement rates. A field validation experiment showed strip spraying to be very effective in reducing adult cereal leaf beetle densities and gave results reasonably close to the model predictions. Computer simulations show the most economical means of achieving various levels of mortality while reducing cost and insecticide actually applied.

ISSN:1754-5692    

DOI:10.1093/ee/5.4.612

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

Percent hatch and number of days to hatch were determined for eggs ofDiabrotica virgiferaLeConte separated in salt and sucrose solutions of various specific gravities (1.03–1.17). Eggs were found to decrease in specific gravity during post-chill development. A linear regression of mean number of days to hatch on specific gravity was highly significant and accounted for 94.7% of the variability. Eggs with specific gravities less than 1.08 had a significantly higher percent hatch than eggs with specific gravities 1.08–1.10.

ISSN:1754-5692    

DOI:10.1093/ee/5.4.621

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

A procedure for storingAphelinus asychis(Walker) adults at reduced temperatures was developed. Storage of adults was studied at 15, 30, 60, 90, 105, and 120 days at temperatures of 10, 7.2, 4.4, and 1.7°C. The effects of weekly and monthly feeding schedules on survival and reproduction were studied. The optimum temperature was 4.4°C. Adults survived longest when fed weekly, but the feeding schedule did not influence reproduction. Females survived storage longer than males and were able to produce a normal proportion of ♀ offspring without additional mating after storage. Adults stored for 15 days reproduced at the same level as unstored adults, but reproduction declined as the length of storage increased.

ISSN:1754-5692    

DOI:10.1093/ee/5.4.623

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

Diapause in bothManduca sexta(L.) andApanteles congregatus(Say) was inhibited by high temperatures (30–31°C) during the scotophase when the photoperiods would normally induce diapause. The same high temperatures during the photophase did not inhibit diapause.

ISSN:1754-5692    

DOI:10.1093/ee/5.4.626

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

Adult bollworms,Heliothis zeaBoddie, and tobacco budworms,H. virescens(F.) emerging from overwintering populations were difficult to detect when covers were placed over the soil in fields planted the previous year in corn, cotton, soybeans, or tobacco, but later generations were easily detected. Counts of larvae taken weekly in these fields and subsequent identification of the larvae indicated that blacklight traps detected the presence of bollworm moths but not budworm moths.

ISSN:1754-5692    

DOI:10.1093/ee/5.4.628

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

Spatial distribution of chironomid midges in relation to the various substrate types in a concrete-lined flood control channel system carrying domestic and industrial waste water was studied. Bare concrete surfaces, filamentous algae, detritus, fine sand, and coarse sand and gravel were the 5 types of substrates in this drainage system. A minimum of 10 benthic samples from each of the 5 substrates prevailing in different sections of the channel system were collected, using a modified Surber sampler (0.09 m2frame and 500μpore net). The study was repeated on 4 different occasions.Midges belonging to 5 genera were taken.Chironomusspp. andCricotopusspp. were the 2 most abundant groups forming 97.4% of the total midges taken on any occasion.Chironomusspp. larvae predominated in fine sand, whereasCricotopusspp. larvae were associated with detritus. On all 4 sampling dates, fine sand contained 42–80% of the totalChironomusspp. larvae taken from all 5 substrates. Similarly, substrate composed of detritus supported 58–78% of the totalCricotopusspp. larvae. Midge larval densities in some parts of the channels exceeded 3000/0.09 m2on some occasions. During sampling, a number of drift-borneChironomusspp. andCricotopusspp. larvae and pupae contributed to the benthic collections.

ISSN:1754-5692    

DOI:10.1093/ee/5.4.631

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

Studies conducted for 3 yr demonstrated that significant differences in pecan leaf phylloxera,Phylloxera notabilisPergande, infestations occurred among 3 cultivars of pecans grown in an orchard that had not been subjected to any insect control practices for over 20 years. Observations during the studies revealed that 8 other cultivars in the same orchard remained virtually uninfested.Sampling data obtained indicated that the distribution of phylloxera galls around a tree was random; however, the density of galls was greater in the lower portions of the trees.

ISSN:1754-5692    

DOI:10.1093/ee/5.4.637

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

The methodology of a topological mapping procedure for estimating the total number of insects inhabiting a tree trunk is presented. Data necessary for using the procedure are insect densities at measured intervals on the bole. The procedure minimizes errors resulting from smoothing, regression or extrapolation and provides estimates suitable for evaluating bias and variability of other sampling plans.

ISSN:1754-5692    

DOI:10.1093/ee/5.4.640

出版商:Oxford University Press    

年代:1976

数据来源: OUP

摘要:

When added to liquid media, malathion, MGK®264(N-octyl bicycloheptene dicarboximide), and naled, at concentrations of 100μl/l (insecticide:media), completely inhibited the production of zearalenone (F-2) byFusarium graminearum. F-2 production was completely inhibited in cultures treated with 30 and 10μl/l naled and was reduced by 53% in cultures treated with one μl/l naled. All insecticides except methoxychlor inhibited growth and/or F-2 production by at least 38% at concentrations of 10 and/or 30μl/l. In cultures treated with insecticides at levels of 30–100 μl/l and in those treated with diazinon, naled, dichlorvos, ethion, and pyrethrins at concentrations of 1–10 μl/l, the reduced level of F-2 production was a consequence of reduced mycelial growth. At lower concentrations of one and/or 10 μl/l, azinphosmethyl, malathion, allethrin, Rabon® (2-chloro-1-2,4,5-trichlorophenyl) vinyl dimethyl phosphate), piperonyl butoxide, MGK®264, and mevinphos reduced F-2 production without reducing mycelial growth. Naled was fungicidal at concentrations of 100 μl/l and fungistatic at levels of 1, 10, or 30 μl/l.

ISSN:1754-5692    

DOI:10.1093/ee/5.4.644

出版商:Oxford University Press    

年代:1976

数据来源: OUP