摘要:

Diapausing adults ofChrysoperla carneaStephens were stored at low temperature (5°C) under short daylengths (10:14 [L:D] h) for 31 wk with little maintenance. Rates of survival were very high (≈97%), and both males and females retained high reproductive potential. Shortly after transfer to warm, long-day conditions,>90% of the pairs produced fertile eggs: initiation of oviposition after storage was synchronous and predictable. Subsequently, depending on the duration of storage, females oviposited an average of 230–350 eggs during the first 30 d of oviposition (≈50–70% of the eggs produced by unstored females). Except for one group that was stored for 31 wk, high levels of fertile oviposition persisted for ≈45 d after storage. Cold storage ofC. carneabenefits biological control efforts by providing flexibility and efficiency in mass-production to meet peak seasonal demands for eggs or young larvae; an alternative method of shippingC. carneato distributors who choose to harvest eggs (or young larvae) for sale; and a reserve supply of stock if insectary colonies fail or dwindle. It also makes standardized stock available for use in long-term ecological, physiological, or genetic research.

DOI:10.1093/ee/22.4.843

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

The functional response of the parasiteCotesia flavipes(Cameron) was measured at low densities of the hostDiatraea saccharalis(F.) in field cages containing corn plants. Hosts were exposed to parasites by allowing host larvae to bore into the corn stalks and create the natural microhabitat associated with parasite foraging. Of 992 hosts exposed, 785 were recovered, of which 689 produced adult moths. In total, 96 hosts were considered attacked byC. flavipes. Thirty-four (35.4%) of the attacked hosts were successfully parasitized and producedC. flavipesprogeny, and an additional 62 attacked hosts (65.6%) did not pupate or produce parasites, as a result of encapsulation of parasite progeny by the hosts. The 34 successfully parasitized hosts produced an average of 41.2 parasite progeny per host, of which 29.3 were female, giving a sex ratio (females-males) of 2.33: 1. Use of linear and nonlinear regression to describe the functional response gave nearly equal predictions of attack rates and fit the data equally well. The functional response was indistinguishable from a linear response over the range of host densities tested, whether parasitization was defined as the number of hosts producing parasite progeny, or the total number of hosts attacked. The two different measurements of the functional response ofC. flavipesare important for estimating the success of parasite search inferred from the data, because attack rates that include only the number producing parasite progeny greatly underestimate the number of parasites finding hosts. The near linearity of the functional response is likely due to measurement of parasite success at realistic host densities, which avoids the limitations caused by measurement at artificially high host densities.

DOI:10.1093/ee/22.4.849

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

Combining two species of entomopathogenic nematodes with different search strategies suppressed two pest species of soil insects when they occurred in the same habitat. The majority of individuals ofSteinernema carpocapsae(Weiser) have a sit and wait (ambusher) strategy and tend to be near the soil surface. This species was effective against larvae of the black cutworm,Agrotis ipsilon(Hufnagel) (Lepidoptera: Noctuidae), which feeds near or at the soil surface.Heterorhabditis bacteriophoraPoinar has an active foraging (cruiser) strategy and occurs deeper in the soil profile. It was effective against larvae of the black vine weevil,Otiorhynchus sulcatus(F.) (Coleoptera: Curculionidae), which occurs near roots. Soil temperature influenced the results. At 22°C, both nematode species killed their respective target insect within 1 wk. At 16°C,S. carpocapsaekilled black cutworm larvae, butH. bacteriophorawas not effective against black vine weevil larvae 2 wk after treatment. A few black vine weevil larvae were infected withH. bacteriophoraat that temperature, and a longer exposure of the black vine weevil larvae to the nematode may have increased efficacy. In addition to search strategies, the susceptibility of the insects to the nematode species plays an important role in pest suppression.

DOI:10.1093/ee/22.4.859

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

Zetzellia mali(Ewing) feeds on and is fed upon byTyphlodromus pyriScheuten andMetaseiulus occidentalis(Nesbitt), especially when phytophagous mites are scarce on apple foliage. These mites interact indirectly through competition for prey. Probably because of both indirect and direct effects,T. pyriwas less dense andM. occidentaliswas much less dense in plots withZ. malithan in plots whereZ. maliwas suppressed by endosulfan.M. occidentalisalso had less effect onZ. malithanT. pyri. Biological control ofPanonychus ulmi(Koch) andAculus schlechtendaliNalepa was effective whereZ. malioccurred alone at high levels or with either or both phytoseiids. Plots that received mixedT. pyri–M. occidentalishad effective control of pest mites with or withoutZ. mali. Z. malidisplacedM. occidentalisand controlled pest mites in plots withM. occidentalisonly. In plots withT. pyrionly, dominance ofT. pyriorZ. maliwas mixed—most often near equal levels occurred, but sometimes one or the other dominated. In mixed plotsT. pyridisplacedM. occidentalisin 1991, but interactions betweenT. pyriandZ. maliin 1992 were like those in plots withT. pyrionly. Releases of 25–50M. occidentalisand 200–300P. ulmiinto trees with manyZ. malidid not allow for establishment ofM. occidentalis, but establishment readily occurred where fewZ. maliwere present. Management ofM. occidentalis, T. pyri, Z. mali, and pest mites is discussed in relation to long-term biological control.

DOI:10.1093/ee/22.4.865

出版商:Oxford University Press    

年代:1993

数据来源: OUP

摘要:

Ten-d-old apterae of Russian wheat aphid,Diuraphis noxiaKurdyumov, (25 per treatment) were inoculated with conidial suspensions (106conidia per ml) ofBeauveria bassiana(Balsamo) Vuillemin, isolate SGBB 8601, or with sterile water, then caged individually on wheat seedlings. Temperature was maintained at 22 ± 3°C, and relative humidity was kept at ≥95% for 24 hand ≈85% subsequently. Each aphid was monitored daily over 14 d for mortality and nymph production. All newborn nymphs and dead adults were removed and plated. The experiment was performed four times.B. bassianasignificantly increased aphid mortality (mean mortality due to mycosis, 82%). Over the 14-d period, untreated adults produced significantly more nymphs (37.8 ± 4.5) (mean ± SE) than didBeauveria-treated adults (14.3 ± 1.6). However, the pathogen did not affect nymph production by individual aphids (mean, 3.3 nymphs per d per aphid for both treatments). Thus, treatment differences in total reproduction were caused by differential mortality rather than differential reproduction rates of individuals. Most (>99%) nymphs produced from infected adults were uninfected.

DOI:10.1093/ee/22.4.874

出版商:Oxford University Press    

年代:1993

数据来源: OUP

DOI:10.1093/ee/22.4.879

出版商:Oxford University Press    

年代:1993

数据来源: OUP

DOI:10.1093/ee/22.4.881

出版商:Oxford University Press    

年代:1993

数据来源: OUP