摘要:

In a field cage, the responses of females of the polyphagous ichneumonid ectoparasitoidExeristes roborator(F.) to a natural host and microhabitat were reduced by prior experience with the same host in an artificial microhabitat. Learning of the artificial microhabitat probably interfered with females' normal responses to the natural system. Parasitoids that had previously attacked hosts in the artificial microhabitat contacted the natural system in fewer numbers and performed host-seeking and host-attacking activities on it with lower intensity than control females. They also killed fewer host larvae than controls. Thus, rearing procedures that permit parasitoids produced for release as biological control agents to gain experience with nontarget hosts and microhabitats could impair these insects' effectiveness against target pests. Prior experience with the natural host and microhabitat did not increase females' responses to them. This result could reflect the way in which learning functions forE. roboratar. Learning might allow the parasitoid to use unusual or less preferred hosts when its normal hosts are rare but not to enhance its responses to hosts for which it has a strong innate preference. Learning may have causedE. roboratorto respond almost exclusively to the natural host and microhabitat when it was familiar with them. Fidelity to a target system caused by prior exposure to it might enhance a biological control agents' performance over a longer term than was examined here.

ISSN:0046-225X    

DOI:10.1093/ee/20.3.889

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The weevilTrichobaris bridwelliBarber is a natural enemy of jimsonweed (Datura stramoniumL.) in the southern United States. The temporal distribution of all life stages showed thatT. bridwelliis bivoltine in central Texas and overwinters principally in the adult stage inside the seed capsules of jimsonweed. Females oviposited in the leaves, flowers, and capsules. Subsequent development occurred both in the stems and capsules of its host plant. All life stages ofT. bridwelliwere attacked by hymenopterous parasitoids;Anaphessp. andMicroctonussp. are new host records. In the laboratory, adult females lived an average of 16.1 wk and deposited an average of 324 eggs. Development in the laboratory required 37.8 d: egg 5.9 d, larval stage 20.2 d, prepupal period about 3 d, and pupal stage 8.7 d. The intrinsic rate of increase (Tm) ofT. bridwelliwas calculated from laboratory life table data to be 0.41 at 24°C.T. bridwelliwas evaluated for its potential effectiveness as a biological control agent of jimsonweed and possibly chinese thornapple,Datura feroxL. AlthoughT. bridwellidid not complete development on a critical test plant (tobacco) under laboratory conditions, extensive host specificity testing should be conducted to determine the limits of its host range.

ISSN:0046-225X    

DOI:10.1093/ee/20.3.899

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The effect of scarab beetle activity on the breeding of coprophilic insects in cattle dung was investigated in a pasture in central Queensland. On seven occasions, natural dung pats were covered with one of two types of wire mesh cages: fine mesh was used to exclude scarabs, and coarse mesh protected an equal number of other pats from trampling by cattle. Pats under the coarse mesh were colonized by the usual range of dung arthropod fauna including scarabs. Populations of scarabs and other dung arthropods also were sampled on each occasion using pitfall traps baited with cattle dung. Fewer adult predaceous insects were collected from pats beneath the coarse mesh. These pats also yielded fewer Diptera, hymenopterous parasitoids, and coprophagous Coleoptera than the pats beneath the fine mesh.

ISSN:0046-225X    

DOI:10.1093/ee/20.3.909

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Four dairies in southern California were sampled weekly from April 1987 through June 1988 to determine the distribution and relative abundance of stable fly,Stomoxys calcitrans(L.), and house fly,Musca domesticaL., pupal parasites. Seven parasite species represented ≍90% of the parasites recovered from stable fly and house fly pupae, and includedSpalangia endiusWalker,Spalangia cameroniPerkins,Spalangia nigroaeneaCurtis,Muscidifurax raptorGirault and Sanders,Muscidifurax zaraptorKogan and Legner,Urolepis rufipes(Ashmead), andAleocharaspp.U. rufipeshad not been previously recorded to parasitize these hosts in California. Most of theU. rufipesrecoveries were between April and June. The relative abundance of parasites recovered from stable flies and house flies on four southern California dairies varied slightly for some species, but the overall rate of parasitism only ranged from 13.4 to 19.9%. A limited number of stable fly and house fly pupal collections from dairies in central California revealed a much lower proportion ofS. cameroniand a higher proportion ofS. endius, when compared with southern California dairies. The majority of stable fly and house fly pupae sampled at four southern California dairies were associated with pure manure substrates. There was no significant difference between the relative abundance of parasites recovered from stable fly pupae sampled from manure, manure plus hay, or wet-hay substrates. Significantly fewerS. nigroaeneaand significantly moreM. zaraptorwere recovered from house fly pupae developing in brewer's grain when compared with manure, manure plus hay, and wet-hay substrates. In pupal samples which contained both stable flies and house flies,S. cameroniwas recovered significantly more often from stable fly pupae. In general, there were no significant differences between stable fly and house fly in parasitism by the seven parasite species.

ISSN:0046-225X    

DOI:10.1093/ee/20.3.915

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

We conducted a mark–recapture study in which drag-collected ticks were removed from some park trails weekly from April to July. Weekly survival rates (probability of surviving and remaining on the trails) were significantly lower on trails used heavily by hikers, horses, and pets than on trails used less frequently. Although usage was the only obvious difference among these trails, differences in weekly survival rate estimates may be attributable to differential success in acquiring hosts. The estimated probability of capturing a host-seeking tick located along a trail on a single drag was 0.20 on the drag alone, and 0.25 including the person dragging. When routes parallel to the trails and of equal lengths were dragged immediately after sampling the trails, only ≍5% as many ticks (including ticks on the person dragging) were found off the trails as on them. We found no evidence of reduced tick numbers on removal trails, but this result should be considered inconclusive because the power of the discerning test was low. However, the data reported here provide insights into turnover rates of the adultDermacentor variabilispopulation and effectiveness of the drag as a sampling device.

ISSN:0046-225X    

DOI:10.1093/ee/20.3.922

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

The pheromone (E,Z)-2,13-octadecadien-1 ol acetate [called (E,Z)-2,13-ODDA] or (Z,Z)-3,13-octadecadien-1 ol acetate [called (Z,Z)-3,13-ODDA; the main component of the peachtree borer,Synanthedon exitiosa(Say), sex pheromone and mating disruption dispenser] was released into the air from Shin-Etsu ropes (254 per hectare [100 per acre]) in whole bunch grape vineyards and compared with untreated vineyards using a randomized block design (four replicates). Pherocon IC traps baited with a 99:1 blend of (E,Z)-2,13-ODDA:(Z,Z)-3,13-ODDA were used to monitor the seasonal number of grape root borer males,Vitacea polistiformis(Harris). These trap captures were significantly reduced by 99.1 and 87.5% in the vineyards treated with (E,Z)-2,13-ODDA and (Z,Z)-3,13-ODDA, respectively, compared with the untreated vineyard mean capture of 134.0 males. The (Z,Z)-3,13-ODDA-treated vineyards realized a mean grape root borer pupal skin reduction of 92.7% over a 2-yr period (life cycle), which was significantly different than the mean count from the untreated vineyards (17.2% increase). The mean pupal skin count reduction of 65.7% from the (E,Z)-2,13-ODDA-treated vineyards was not significantly different from either the (Z,Z)-3,13-ODDA-treated or untreated vineyards. This lower mean reduction was attributed to only one (E,Z)-2,13-ODDA-treated vineyard that probably experienced immigration of mated feral females from an untreated vineyard 200 m to the southwest. It appears that placement of 254 ties per hectare per season of either compound alone in isolated vineyards with a low to moderate population of grape root borers may be an effective and environmentally safe alternative to insecticide treatments for control of the grape root borer.

ISSN:0046-225X    

DOI:10.1093/ee/20.3.930

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Trap captures and species-specific responses (trap specificity) with four different, blends composed of four components of synthetic western obliquebanded leafroller,Choristoneura rosaceana(Harris) (Lepidoptera: Tortricidae) sex pheromone were assessed in British Columbia, using seasonal trap catches of obliquebanded leafroller and the ratio of obliquebanded leafroller toArchips rosanus(L.) (Lepidoptera: Tortricidae). A four-component blend containingZ11-14:0Ac,E11-14:0Ac,Z11-14:ALD, andZ11-14:0H in a 100:2:1:0.75 ratio captured the greatest number of obliquebanded leafrollers and had a degree of trap specificity. In addition, differences in trap captures and the degree of trap specificity also were assessed for eastern (Quebec) and western (British Columbia) populations of obliquebanded leafroller. Comparisons were made using three different blends composed of either three or four components of the obliquebanded leafroller sex pheromone with the ratios 100:2:1:1.5, 100:5:0:5, and 100:2.5:0:2.5ofZ11-14:0Ac,E11-14:0Ac,Z11-14:ALD, andZ11-14: OH. In British Columbia, the four-component blend (100:2:1:1.5)captured the greatest number of obliquebanded leafrollers and had a high degree of trap specificity. In Quebec, no differences in trap captures among the blends were observed. These results suggest that qualitative differences may exist between the sex pheromone of eastern and western populations of obliquebanded leafroller and indicate the need for considering regional differences when monitoring obliquebanded leafroller with commercial synthetic pheromone blends.

ISSN:0046-225X    

DOI:10.1093/ee/20.3.935

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Over a range of densities from 15 to 140 grasshoppers per m2, six persons counted grasshoppers in subsamples delineated by wire rings that encompassed 0.05, 0.10, or 0.25 m2per ring. Results did not differ significantly between personnel. The smallest ring size was the most accurate. Each increase in area per ring yielded a decrease in accuracy; the proportion of error increased with ring size but was constant over the observed range of densities. The 0.10- and 0.25-m2rings detected only 80 and 58%, respectively, of available grasshoppers. The larger rings obviously encompassed more area than an observer could simultaneously comprehend. A random spatial distribution was confirmed for grasshoppers on rangeland. Poisson confidence intervals therefore are appropriate. The precision of Poisson confidence intervals is essentially a function of the total number of insects detected in a sample. Precision can be improved rapidly by adding subsamples to assure detection of 40–50 total grasshoppers per sample; improvement after about 200 total grasshoppers per sample is imperceptible.

ISSN:0046-225X    

DOI:10.1093/ee/20.3.939

出版商:Oxford University Press    

年代:1991

数据来源: OUP

摘要:

Experiments were conducted in 1988 and 1989 to determine the effect and potential interaction of height of semiochemical–insecticide bait placement and within-canopy adult corn rootworm vertical distribution on beetle mortality in baited traps. Results of an experiment utilizing semiochemical–insecticide baited traps, and unbaited yellow sticky traps placed in a corn (Zea maysL.) field at 0 m and corn ear height indicated thatD. virgifera virgiferaLeConte mortality was significantly higher at ear height baited traps. In addition, moreD. v. virgiferafemales were distributed near ear height than at 0 m. Results of subsequent experiments with baited, and unbaited traps placed at 0, 0.6, 1.2, 1.8, and 2.4- m height intervals within the canopy indicated that efficacy of starch baits increases with height of bait placement and the vertical distribution of corn rootworm beetles interacts with height of semiochemicaln–insecticide bait placement. Data from all experiments strongly indicate that semiochemical–insecticide granules placed at ground level will not effectively attract and kill femaleD. v. virgiferabeetles. To optimize the effectiveness of corn rootworm semiochemical–insecticide baits, application of formulations should be restricted as much as possible to regions at or above the ear. Formulations need to be developed that will adhere to plants at the time of application.

ISSN:0046-225X    

DOI:10.1093/ee/20.3.945

出版商:Oxford University Press    

年代:1991

数据来源: OUP