摘要:

The use of persistent OP insecticides made mite management practical in orchards since the predator,Neoseiulus fallacis(Garman), quickly becomes resistant to these chemicals. In developing a mite-management program, the effect of pesticides was investigated by full season plots, population samples of small, replicated pesticide plots, and at close intervals after single applications of pesticides to replicated plots. Many population samples from commercial orchards were studied in order to adapt management practices to the biology of the mites. Most fungicides have no effect on mites, but several suppress phytophagous mites while having little or no effect onN. fallacis. Applications of miticides at reduced dosage to low levels of phytophagous mites are more effective than a single full dosage on medium or high population levels in suppressing pest mites until predators can increase sufficiently to effect control. Several miticides kill phytophagous mites but are harmless toN. fallacis. An early application of plant spray oil plus a properly timed application of miticide 3–5 weeks after bloom comprise the main features of managing the mite populations. In about 25% of the orchards observed no miticide was required.

DOI:10.1093/ee/3.2.333

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Food collection and pairing habits of 3 Mexican species ofPhanaeusare examined. InPhanaeus, dung is usually buried near the animal dropping, butP. daphnisHarold,P. mexicanusHarold andP. palliatusSturm very often reduce the effects of inter-specific competition with other Scarabaeinae by rolling a piece of dung a considerable distance away from the animal dropping. This behavior assists in the formation of bisexual couples because males are attracted to females who are rolling a ball of dung. The newly formed couple works together in the construction and provisioning of a burrow, but their relationship is not sexual until ovarian maturation occurs. Most individuals ofP. palliatusand many of the other 2 species dig burrows under or near the edge of the dropping; such burrows are usually occupied by a single individual of either sex, not by a bisexual couple.Nidification is always distinct from the formation of burrows for shelter and food storage and seems to be stimulated solely by ovarian maturation. The construction of a burrow (“home”) by a bisexual couple in eitherP. daphnisofP. mexicanusis considered an example of incipient subsocial behavior. With the concurrent reduction in competition, more individuals can feed on a single dropping, the excrement is dispersed more rapidly and over a wider area, and flies do not have a chance to breed in the dung.

DOI:10.1093/ee/3.2.341

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

A strain of the entomogenous fungus,Entomophthozanr.thaxteriana(Petch), isolated from the green peach aphid,Myzus persicae(Sulzer) shows promise as a biological control agent for aphids. This isolate is intermediate in its morphology betweenE. thaxterianaandE. virulentaHall and Dunn. The spore sizes, i.e. conidia 24 × 19μ, resting spores 22μ, more closely approximateE. virulenta. Lack of rhizoid production, however, has caused us to call this strainE. thaxteriana. The resting spores produced by this isolate can be stored for long periods of time and when properly treated will give up to 98% germination. Greenhouse and field studies have shown this species to be both pathogenic and virulent, giving 100% control in 3 days. The resting spores of this fungus are currently under production in the laboratory and will be field tested against the potato aphid complex in Northern Maine. Effectiveness, however, is not the only criteria which determines an insect pathogen as a good candidate for biological control. It must also be demonstrated that it is safe for man.

DOI:10.1093/ee/3.2.346

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Four species of aphids commonly colonize cereal crops in South Dakota: greenbug,Schizaphis graminum(Ron dani); English grain aphid (EGA),Macrosiphum avenae(F.); corn leaf aphid (CLA),Rhopalosiphum maidis(Fitch); andR. padi(L). However, none of these aphids seem capable of overwintering in South Dakota, though anholocyclic populations may persist until mid-December on winter grains. No sexuales of any of these species have been found in samples of populations from the field, and no sexuparae ofR. padihave been taken in surveys of aphids onPrunus(Kieckhefer and Gustin 1967). The reappearance of aphids in cereal crops in South Dakota each April or May has been abrupt; initial populations consist exclusively of alate viviparae with no fundatrices or nymphs present. Appearance of alate populations on spouting grains in spring has frequently been so early as to preclude development from eggs because of insufficient time and unfavorable environment for development. Populations of alate viviparae of these species of aphids undoubtedly migrate from the south and become reestablished in South Dakota each spring. Surveys in Texas, Oklahoma, and Kansas in March and April have shown that greenbugs, EGA, andR. padisurvive the winter in portions of some or all of these states and that numbers increase early in spring (Cartier 1957, Plant Pest Control Division 1965, Wallin and Loonan 1971). Jensen and Wallin (1965) and Taylor (1965) suggested low-level jets as a vehicle for long-distance transport of aphids into the North Central states and Berry and Taylor (1968) took greenbugs and EGA in collections from an airplane in low-level jet winds (3,000 ft) over Kansas. Arrival of greenbugs and EGA in Iowa has been associated with low-level jet winds (Wallin et al. 1967, Wallin and Loonan 1971). The objective of our study was to determine the dates cereal aphids reach South Dakota in spring and to analyze weather patterns that were associated with this arrival.

DOI:10.1093/ee/3.2.347

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

In screening for insect resistance, free-choice methods have frequently been used to determine behavioral responses of insects to plant stimuli. As insects often orient to light, temperature, humidity, gravity, and substratum texture (Currie 1932; Roth and Willis 1951; Henson 1964; Green and Morrill 1970; Weseloh 1971), it is desirable to design screening techniques so that each host is presented to the insects in as similar a manner as possible. This is to avoid misinterpreting plant effect on insect behavior with responses elicited by the abiotic environment. The work presented here emphasizes the importance of plant height uniformity within cages when assessing cotton genotypes,Gossypiumspp., for ovipositional response byLygus hesperusKnight.

DOI:10.1093/ee/3.2.350

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Occasionally, large numbers of simuliids suddenly invade a formerly untroubled area. Detailed reports strongly suggest that the invading blackflies are brought flom their source by a traveling frontal system (Millar and Rempel 1944. Rempel and Amason 1947, Webster 1901). To be transported, however, the flies must first have been sufficiently active to be drawn up into the moving system. Insects clinging to vegetation are not vulnerable to updrafts.

DOI:10.1093/ee/3.2.351

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

The alfalfa weevil,Hypera postica(Gyllenhal), is a serious pest of alfalfa and occurs in all 48 conterminous United States (USDA 1972). In the southern part of its range, females oviposit on warm days throughout the fall and winter, and the damage done to early spring plant growth in these areas is generally attributed to larvae from these eggs (Evans 1959, Campbell et al. 1961). The literature pertaining to survival and over-wintering of alfalfa weevil eggs and their importance to spring damage of alfalfa in different geographic regions has recently been reviewed by Blickenstaff et al. (1972).

DOI:10.1093/ee/3.2.353

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

Increased emphasis in recent years on integrated control strategies has resulted in much research dealing with natural enemies of the greenbug,Schizaphis graminum(Rondani). One of these natural enemies, the hymenopterous parasitoidLysiphlebus testaceipes(Cresson) was found by Hunter and Glenn (1909) and Fenton and Fisher (1940) to be very active during greenbug out-breaks.

DOI:10.1093/ee/3.2.355

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

In a feedlot in Lancaster County, NB, in 1968, the authors observed adults ofPhilonthus thevenetiHorn feeding on dipteran eggs in breeding areas of the stable fly,Stomoxys calcitrans(L.), and the house fly,Musca domesticaL. Subsequent surveys of several feedlots in Lancaster and Saunders Counties determined that the beetles were present in all fly-breeding areas within the feedlots.

DOI:10.1093/ee/3.2.356

出版商:Oxford University Press    

年代:1974

数据来源: OUP

摘要:

The impact of grasshoppers on rangeland forage production, especially during years of high population levels, has been well documented by previous authors (Pfadt 1949, Nerney 1960, Putnam 1962). Most of this work, however, has concerned itself with measuring reductions in yield of various herbage species and/or grassland communities. With the recent surge of the concept of the ecosystem and its resultant impact upon ecological research (Watt 1966, Van Dyne 1969), it has become increasingly essential for research workers to adopt more holocoenotic approaches to the analyses of these relationships. Such is especially the case if the role of insects in ecosystem function is to be investigated.This study has taken unpublished data and examined them in the context of determining what is the most “important” ecological effect that grasshoppers have on the structure and function of a shortgrass prairie eco-system

DOI:10.1093/ee/3.2.358

出版商:Oxford University Press    

年代:1974

数据来源: OUP