摘要:

The aggregation pheromone ofCarpophilus hemipterus(L.), previously isolated and identified using wind-tunnel bioassays, was field tested in California. A 4-d preliminary study in plantings of figs and stone fruits was followed by long-term studies in a date garden (12 mo) and a stone fruit orchard (11 wk). The pheromone was most effective in combination with host-related coattractants such as fermenting whole wheat bread dough or fermenting fig juice. In the date garden, for example, traps baited with pheromone plus bread dough caught an overall mean of 1,152C. hemipterus, but those baited with only the pheromone or dough caught only 23 and 3 per trap, respectively. A semisynthetic volatile mixture of methanol, methyl butyrate, propanal, and apple cider vinegar was nearly as effective as fermenting dough as a coattractant and is a practical, longer-lasting alternative to dough. The pheromone was formulated on rubber septa, which were replaced every 2 wk. There was a 45% decrease in trap catch due to aging of septa from wk 1 to wk 2, but the septa retained activity into the second week despite daily maximum temperatures<40°C. In the date garden, peak response to the traps occurred during June (65% of the total catch), although temperatures were favorable for beetle flight throughout most of the year. In all experiments, both sexes responded similarly. Four other nitidulid species responded significantly to the pheromone ofC. hemipterus:C. mutilatusErichson,C. lugubrisMurray,C. obsoletusErichson, andC. (Urophorus) humeralis(F.). Two other nitidulid species in the study plots,C. freemaniDobson andHaptoncus luteolus(Erichson), responded poorly or not at all to the pheromone.

ISSN:0046-225X    

DOI:10.1093/ee/21.5.1143

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

A green papaya fruit or an extract of green papaya fruit peel increased unmated female papaya fruit fly (Toxotrypana curvicaudaGerstaecker) attraction to male pheromone at low pheromone release rates. Green papaya peel extract also increased mated female attraction to male pheromone, but only at the highest pheromone release rates tested. Such enhanced responses may aid the ability of females to locate hosts by responding to a combination of male pheromone released from host fruit and fruit odor.

ISSN:0046-225X    

DOI:10.1093/ee/21.5.1154

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Biology of the parasiteCotesia flavipesCameron and rearing procedures appropriate for small-scale laboratory production of the parasite are described. Unfed female parasites had a type I survivorship curve and lived an average of 23.8 h. Parasites accepted and used third- to sixth-instarDiatraea saccharalis(F.) as hosts. The sex ratios and number of parasite progeny were independent of host instar. Increasing parasite/host ratios increased the proportion of hosts parasitized; the increase in proportion parasitized was curvilinear, apparently reaching an upper limit at parasite/host ratios>2:1. Parasites had low attack rates, with a maximum of 1.6 attacks per parasite at a 1:4 parasite/host ratio. Some host larvae exposed to parasites died, whereas others failed to pupate. Exposed larvae that failed to pupate either contained encapsulated parasite larvae or molted to the immaculate, diapausing form. Results suggested that rearing is achieved best by exposing females to hosts as soon after mating as possible, and that the parasite/host ratios used for rearing depend on whether the objective is to maximize the total number of parasites produced or produce the most progeny per adult parasite. Parasite encapsulation and host death are likely caused by the noncoevolved association between the Old World parasite and the New World host.

ISSN:0046-225X    

DOI:10.1093/ee/21.5.1160

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Biological control of European red mite,Panonychus ulmi(Koch), and apple rust mite,Aculus schlechtendali(Nalepa), varied in 1991 in 20 prey-predator treatment plots after Single and mixed releases ofMetaseiulus occidentalis(Nesbitt) andTyphlodromus pyriScheuten were made in 1990. Control of spider mites in 1991 was better in mixed-species than in single-species release plots.M. occidentaliswas the dominant phytoseiid in mixed-species release plots in 1990, butT. pyriwas more common in 1991. In fall, eggs ofM. occidentalisdisappeared before eggs ofT. pyridid. In spring, eggs ofT. pyriappeared first. Oviposition byM. occidentalismay have been slowed by cool weather and limited use of pollen as food. With few prey present, competition favoredT. pyri, andM. occidentaliseventually disappeared from mixed-, but not from single-species plots.M. occidentaliswas more affected byZetzellia mali(Ewing) than wasT. pyri, butT. pyrihad more impact on populations of this stigmaeid mite. Competition byZ. maliwith the phytoseiids may cause negative and pOSitiveeffects on biological control. The two phytoseiids have complementary traits that allow them to control pest mites together, but their management may be complicated by interspecific competition.

ISSN:0046-225X    

DOI:10.1093/ee/21.5.1168

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Natural predation on nymphs and adults of the cotton fleahopper,Pseudatomoscelis seriatus(Reuter), was assessed during 108 h of visual observation in an insecticide-free cotton field in central Texas. Predaceous arthropods of 13 species (from nine families) were observed to forage on the fleahopper. More than 80% of the predation events observed were attributable to spiders. The striped lynx spider,Oxyopes salticusHentz, was dominant among the predators observed eating fleahoppers (15 records of feeding in action). Cotton fleahoppers composed ≈25% of the total prey ofO. salticusduring June and July. It was estimated during midseason that once every 4 d, one O.salticuswould kill one cotton fleahopper. The assessment of the killing power ofO. salticus,based on the predation rate and the predator-to-prey ratio (i.e., number ofO. salticusindividuals per fleahopper), suggests that these spiders are important mortality agents of the cotton fleahopper (≥15% prey mortality per day in the middle of the growing season). Additional fleahopper mortality is attributable to other predaceous arthropods such asPeucetia viridans(Hentz) (Oxyopidae), jumping spiders (Salticidae), crab spiders (Thomisidae), web-building spiders (Araneidae, Dictynidae, Theridiidae), damsel bugs (Nabidae), and ants (Formicidae).

ISSN:0046-225X    

DOI:10.1093/ee/21.5.1178

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Visual and olfactory stimuli used by adult, insectary-reared larval parasitoids,Diachasmimorpha longicaudata(Ashmead), of tephritid fruit flies were examined in the context of host microhabitat location. Mated female parasitoids used the odor of ripe, uninfested fruits to orient toward sticky traps simulating host-habitats (fruits) in field-cage studies. Females showed a significant preference for some fruits (e.g., orange, guava) over others (e.g., apple). All fruit odors tested except apple were significantly more attractive to females than odorless controls. Male parasitoids, in contrast, were not attracted to any of the fruit odors tested. Males, however, readily distinguished between traps of different colors, with preferences reflecting an interaction of the colors' hue and intensity. Females' discrimination among colors was related to the presence or absence of fruit odors.

ISSN:0046-225X    

DOI:10.1093/ee/21.5.1189

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Effects of host age during each of the 5 d of the last host instar were determined by exposing larvae ofHelicoverpa(=Heliothis)zea(Boddie) to newly larviposited maggots of the larval-pupal parasitoidArchytas marmoratus(Townsend). Based on determinations made in host pupae, lower percentages of older hosts were parasitized and lower percentages of maggots from older hosts developed to the second ins tar. Weights of maggots that parasitized older hosts were lower in 1-d-old host pupae. For older hosts, mean length of the larval stage ofA. marmoratusafter host pupation was longer; weights of youngA. marmoratuslarvae revealed that maggots developed very slowly until just before the host pupated. Surviving maggots developing from older hosts used the longer developmental times to overcome the weight differentials, and weights ofA. marmoratuspupae were the same regardless of host age and parasitoid weight at the beginning of the host's pupal stage. These and other data indicate that complex behavior allows theA. marmoratusmaggot to evade host defenses and grow to a size that enables the parasitoid to avoid encapsulation when it finally enters the host hemocele.

ISSN:0046-225X    

DOI:10.1093/ee/21.5.1196

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Initial resting spore germination for two isolates (RF 150 and RF 250) ofEntomophaga calopteni(Bessey) Humber [=Entomophaga grylli(Fresenius) Batko, pathotype 2], a fungal pathogen of grasshoppers (Acrididae), was recorded for five different buffer systems: orthophosphate (OPHO), citrate-phosphate (CPHO), tris (hydroxymethyl) aminomethane (THMM), glycine-NaOH (GLYC), and tris-maleate (TMAL). For each buffer system, eight pH levels were tested ranging from 4 to 11. GLYC at pH 7–9 supported the highest germination percentages compared with the other combinations tested. In general, highest germination levels for all buffer systems occurred in the pH range of 6–8, although they were skewed toward the basic side of the pH scale in OPHO, THMM, and GLYC for isolate RF 150. THMM supported germination better than any other buffer system under highly alkaline conditions. Soil pH may be an important factor in disease transmission under natural conditions. The combined effects of temperature, photoperiod, pH, and buffer medium should be considered when reporting and comparing spore germination levels.

ISSN:0046-225X    

DOI:10.1093/ee/21.5.1202

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

Delaying infestation of potatoes by overwintering Colorado potato beetlesLeptinotarsa decemlineata(Say) by either 10 or 20 d following plant emergence increased damage to the potatoes. The egg deposition period was reduced from 5 to 3 wk; both increased rates of egg deposition and feeding occurred over a shorter period of time. Potatoes infested at plant emergence by Colorado potato beetle had fourth instars feeding during a 4-wk period of time while infestation 20 d after plant emergence reduced this feeding period to 2 wk and resulted in significantly greater defoliation than those infested at plant emergence. Delayed infestation by either 10 or 20 d had a negative effect on predation byPerillus bioculatus(Fabr.). Potato plants infested by Colorado potato beetles at plant emergence with releases ofP. bioculatus4 d later had the greatest percentage reduction in fourth instars and provided significantly greater foliage protection than plants infested at 10 or 20 d after plant emergence. Based on population levels of fourth instar Colorado potato beetles, multiple releases ofP. bioculatusandP. maculiventriswere not significantly more effective than a single release based on population comparisons of beetles. However, three releases (three predators per plant each release) of both species of predators provided greater potato foliage protection than a single release (three predators per plant).

ISSN:0046-225X    

DOI:10.1093/ee/21.5.1212

出版商:Oxford University Press    

年代:1992

数据来源: OUP

摘要:

The effects of host plant foliage on the susceptibility ofHelicoverpa zea(Boddie) toHeliothisbaculovirus (HzNPV) was examined in three separate laboratory bioassays. Larvae were administered viral suspensions, equivalent to three polyhedral inclusion bodies per insect, within 6 h of molting to the third instar for all bioassays. In the first bioassay,H. zealarvae were fed one of the following: artificial diet, cotton, grain sorghum, soybean, or tomato foliage for 24 h before and after administration of a viral suspension on the respective foliage. Larvae fed cotton were significantly less susceptible (36% mortality) than those fed either tomato or artificial diet (75% and 65% mortality, respectively). In the second bioassay, larvae were reared on artificial diet, dosed on plant foliage disks, and returned to artificial diet. No significant differences in virus-induced mortality were observed among the cotton (61%), tomato (61%), or artificial diet (63%) treatments. In a final bioassay, larvae, reared on artificial diet, were fed foliage 24 h before and after receiving virus on artificial diet disks. No differences in virus-induced mortality were observed among the cotton (69%), tomato (66%), or artificial diet (69%) treatments in the final bioassay. Overall results suggest that interaction(s) involving host plant foliar constituents and larval midgut conditions were responsible for the reduced mortality of insects fed and dosed on cotton.

ISSN:0046-225X    

DOI:10.1093/ee/21.5.1220

出版商:Oxford University Press    

年代:1992

数据来源: OUP