摘要:

The flea beetleAphthona abdominalisDuftschmid was selected as a candidate for biological control ofEuphorbia esulaL.(leafy spurge) in North America, where this introduced plant is a serious weed. The insect was collected and studied in Italy, where it occurs naturally. As part of the study of its life history, the effect of temperature on embryonic development was investigated at constant temperatures of 12, 15, 20, 25, 30, 35, 38, and 41°C, and variable temperatures were used as well. Survival and developmental rates were obtained. The median values used to calculate the time required for embryonic development through the thermal summation, a linear regression, and the logistic equation are discussed. The experimental data gave a developmental zero between 12 and 13°C. Embryos completed their development at constant temperatures from 15 to 38°C. Development required from 32.6 d at 15°C to only 4.5 d at 35°C constant temperatures.A. abdominaliswas cleared and introduced into the United States during 1993.

DOI:10.1093/ee/24.3.720

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

The host-alternating life cycle ofMyzus lythri, an aphid of European origin that feeds on purple loosestrife (Lythrum salicaria), is detailed. The complex life cycle and low availability of primary host plants are hypothesized as limiting early-season development of aphid populations on purple loosestrife. Experiments were undertaken in 1993 to determine if large populations of this aphid could influence the growth and development of purple loosestrife. Two-year plants each inoculated with five aphids showed significantly lower root and shoot weight after a 7-wk period as compared with matched controls. Over half of 20 seedlings (3 mo old) inoculated with two or fiveM. lythriwere dead or clearly dying 11 wk after inoculation. Mass rearing for early-spring release and planting primary hosts are possible methods to augment the potential of this aphid to function as a biological control agent for purple loosestrife.

DOI:10.1093/ee/24.3.724

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Trioxys curvicaudusMackauer was imported into northern California in 1970 for control of the linden aphid,Eucallipterus tiliae(L.). In 1991, it was found no farther than 40 km from the release sites, but in this area it is the dominant primary parasitoid attacking the aphid. This limited distribution is attributed mainly to the scarcity of favored hosts; climatic conditions play a contributory role. In 1992,T. curvicauduswas introduced and established in San Rafael, partially displacing the previously dominantT. pallidus(Haliday); however, it did not provide satisfactory control of the aphid. Five other primary parasitoids were reared from the linden aphid:T. tenuicaudusStary,Aphelinus subflavescens(Westwood),A sp. nr.perpallidusGahan,A. automatusGirault, and an undescribedTrioxysspecies (the latter three are new host records). Ten hyperparasitoid species were recovered, with new host records forPachyneuron califonicumGirault andCoruna clavataWalkeronTrioxys, Alloxysta xanthopsis(Ashmead) onAphelinus,and a species from theAlloxysta megourae(Ashmead) complex onTrioxysand the subgenusAphelinus(Mesidia). Hyperparasitoid species ranged from patchy to well distributed.Syrphophagus aphidivonls(Mayr)was reared at a significantly higher rate from Aphelinus hosts thanTrioxyshosts.

DOI:10.1093/ee/24.3.730

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Single releases of the predacious mite,Euseius tularensisCongdon, and additions of apple pollen were made in the spring of 1991 in three citrus orchards in the San Joaquin Valley of California. Dusting citrus trees with apple pollen had no significant effect on the predacious mite populations at this time of year. In two of the three orchards, releases of 500 or 2,000E. tularensisper tree significantly increased the cumulative number of predacious mites found in the trees before or during the period of fruit susceptibility to citrus thrips. In 1992, single releases of 2,000 miles and four releases of 100 or 500 predacious mites were compared with nonrelease trees in two orchards. One site had relatively high natural densities of predacious mites and was not significantly affected by predacious mite releases. In the other site, the peak density ofE. tularensiswas improved 2-fold by releases ofE. tularensis. A single release of 2,000E. tularensisper tree was more beneficial than multiple releases of 500 or 100 mites. A greater cumulative number of predacious mites was significantly correlated with improved biological control of citrus thrips,Scirtothrips citri(Moulton), as measured by reduced heavy scarring of fruit in the 1992 orchards. This suggests thatE. tularensiscan be important in reducing citrus thrips in citrus groves managed under a selective pesticide program.

DOI:10.1093/ee/24.3.738

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Laboratory experiments were conducted to evaluate the voracity of adult and larval stages of the polyphagous predatorColemegilla maculataDeGeer on the Colorado potato beetle,Leptinotarsa decemlineata(Say), immature stages. After a period of 24 h at 25°C in 50-mm petri dishes, adult coccinellids attacked 11 eggs and killed 14 first instars and 4 second instars. Fourth-instar coccinellids attacked 9 eggs and killed 11 first instars and 3 second instars. Effect of temperature on predation effectiveness ofC. maculata adults, third and fourth instars was studied on potato stems infested withL. decemlineataeggs, first or second instars. No predation activity occurred at 7.5°C. Predator effectiveness increased linearly with temperature in the subsequent 10–30°C temperature range studied. At each temperature, no significant difference in the number of prey killed was observed betweenC. maculataadults and fourth instars. The use of potato stems in assessing predation byC. maculatasignificantly reduced the number of prey killed by introducing the need for searching by the predator. Results suggest that inundative releases of third-instarC. maculataagainst eggs and first instars of Colorado potato beetles could be of interest in the case where releases of adult coccinellids would fail because of their tendency to rapidly fly out of the field.

DOI:10.1093/ee/24.3.748

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

The effects ofBacillus thuringiensisBerliner in artificial diet on the feeding behavior of lalvae of the gypsy moth,Lymontria dispar(L.), were measured in both short-term (1 d) and long-term (10 d) tests. In short-term tests, reduced rates of feeding, growth, and digestive efficiency were caused byB. thuringiensisat concentrations that did not kill larvae within the duration of the tests. In long-term tests, larvae given a choice between treated and untreated diets avoided diet containingB. thuringiensisfor the first 7 d. After 7 d, increased movement by the larvae apparently obscured effects ofB. thuringiensison the distribution of the larvae. Effects ofB. thuringiensison the feeding behavior of gypsy moth larvae may, therefore, be one reason why high rates of mortality of gypsy moth are difficult to obtain withB. thuringiensisunder field conditions.

DOI:10.1093/ee/24.3.755

出版商:Oxford University Press    

年代:1995

数据来源: OUP

摘要:

Infective juveniles ofSteinernema carpocapsaeWeiser andSteinernema scapterisciNguyen&Smart infected nymphal grasshoppers under petri dish and simulated field conditions.S. carpocapsaecaused higher mortality and was more infective (number of nematodes gaining entry to host) thanS. scapterisci. Rate of mortality did not vary significantly among the nymphal instars, but nematodes were more infective in larger nymphs. For hatching grasshoppers digging to the soil surface, mortality and infectivity were positively correlated with soil moisture levels. Pathogenicity was especially enhanced by high humidity at the soil surface. Three sandy soils were also evaluated for effect on mortality and infectivity, but the influence of soil type, while significant, was small relative to soil moisture.

DOI:10.1093/ee/24.3.762

出版商:Oxford University Press    

年代:1995

数据来源: OUP