How to safely compost Cameraria ohridella-infested horse chestnut leaf litter on private compost heaps

Abstract:  The horse chestnut leafminer Cameraria ohridella (Lep., Gracillariidae) is a recently introduced invasive pest, which frequently defoliates horse chestnut trees Aesculus hippocastanum already in summer. Currently, the removal of leaf litter, in which pupae of C. ohridella hibernate, is the only effective short-term control measure available. In the past the deposition of pest-infested litter on private compost heaps was dissuaded because of the risk of leafminer emergence in the following spring. Thus, the aim of this study was to test safe ways to compost pest-infested horse chestnut leaf litter on small heaps so that private gardeners can save the costs for leaf disposal. The number of C. ohridella adults emerging from heaps covered with either soil or uninfested foliage was reduced by 96% compared with controls. Only single leafminers emerged from the top covered heaps and there was no difference between the use of soil or uninfested foliage as cover. However, cover did not prevent the emergence of a few leafminers over the sides of the heaps. Overall, we conclude that it is relatively safe to compost C. ohridella -infested A. hippocastanum leaf litter on small compost heaps provided they are properly covered.     

Using hosts of mixed sizes to reduce male-biased sex ratio in the parasitoid wasp, Diglyphus isaea

Overproduction of males in mass rearing of parasitic Hymenoptera contributes to higher costs for biological control because only females directly kill pests. We present a technique, based on manipulating host composition, to generate less male‐biased sex ratios in parasitoid species that adjust their sex allocation in response to relative host size. Our system consisted of chrysanthemum, Dendranthema grandiflora Tzvelev var. ‘Miramar’; a leafminer, Liriomyza langei Frick (Diptera: Agromyzidae); and a commercially available parasitoid, Diglyphus isaea (Walker) (Hymenoptera: Eulophidae). We compared the offspring sex ratios of D. isaea females presented with different compositions of L. langei larvae on chrysanthemum. Presenting individual females with only large hosts increased mean sex ratio from 32 to 67% male over 2 days. However, presenting individual females with progressively larger hosts over 1 or 2 days reduced mean sex ratio from 90 to 100% male to less than 30% male. Groups of females produced sex ratios around 58% male if presented with both plants infested by only small hosts and plants infested by only large hosts. In comparison, groups of females produced sex ratios around 48% male if presented with plants infested by both small hosts and large hosts. We compared the use of both small hosts and large hosts to only large hosts for simulated mass rearing of wasps over 8 weeks. Using both small hosts and large hosts produced similar numbers of wasps as using only large hosts, but reduced mean sex ratio of weekly cohorts from 66% male to 56% male. The two techniques produced females of similar size, but using both large hosts and small hosts produced slightly smaller males than using only large hosts. The use of both small hosts and large hosts for mass rearing of D. isaea could reduce actual costs of females by 23%.     

Trophic web associated with the South American tomato moth Tuta absoluta: implications for its conservation biological control in Argentina

相似文献   

Cameraria ohridella: 10 years of sex pheromone and kairomone research

This review traces the identification and use of sex pheromone of the horse chestnut leafminer Cameraria ohridella Deschka et Dimi? (Lepidoptera, Gracillariidae, Lithocolletinae) to monitor population density and discuss its potential for direct control. Host volatiles endogenously emitted from Aesculus hippocastanum L. leaves are described in terms of their ability to control conspecific females.     

Mortality fecundity and longevity of parasitoids of the spotted tentiform leafminer,Phyllonorycter blancardella [Lep.: Gracillariidae] at constant temperatures in the laboratory

The results of laboratory tests showed that mortality of adult eulophids, primarily,Sympiesis sericeicornis (Nees),S. marylandensis Girault andPnigalio flavipes (Ashmead), was significantly (P<0.05) lower than that of adultPholetesor ornigis (Weed) when exposed to temperatures between 20° and 36°C for 48 h. However, adultP. ornigis lived longer than those of the eulophids at 15°C, but were shorter liver at 33°C. The fecundity ofP. ornigis was little affected at temperatures of 15°, 20°, 24° and 33°C. Exposure of adultP. ornigis to 30°C for 16 h resulted in reduced longevity of both sexes but did not affect fecundity or the proportion of females ovipositing. Mortality of pupae of the eulophids was significantly lower than that of pupae ofP. ornigis at temperatures of 20°, 30° and 33°C. The sex ratio of surviving adults was not affected by temperature.      

Establishment and spread of two introduced parasitoids (Ichneumonidae) of the birch leafminer, Fenusa pusilla (Lepeletier) (Tenthredinidae)

Lathrolestes nigricollis(Thomson) and Grypocentrus albipes Ruthe,Palearctic specialist parasitoids of thebirch-leafmining sawfly Fenusa pusilla(Lepeletier), were imported from central Europe andreleased at three locations in Edmonton, Alberta,Canada during 1994–1996. Parasitoids becameestablished at two locations, L. nigricollis atboth and G. albipes at one, and were recoveredfor 3–5 years after release. Lathrolestesnigricollis has dispersed throughout most ofEdmonton, and at least 13 km from release sites, butG. albipes has been recovered only 400–500 mfrom one release site. Five years after introductionat one site, percent parasitism by L.nigricollis was 78% and 84% for the first andsecond generations, respectively, and about 48% ofparasitoid eggs were encapsulated.     

柑桔潜叶蛾对柑桔的为害及经济阈值的研究

调查福州市郊柑桔园柑桔潜叶蛾（Ｐｈｙｌｏｃｎｉｓｔｉｓｃｉｔｒｅｌａ）在雪柑、芦柑、蕉柑、福桔４个品种上的为害情况．根据其为害特性和柑桔果实产量大小年份可能给经济阈值带来的误差,采用同一树上以秋梢为计量单位,环割被测枝条（避免枝条间养分重新分配而带来误差）的方法,研究了为害秋梢的叶片光合作用强度,当年和翌年春夏梢的生长量,翌年果实品质和重量,以及叶片被害程度与柑桔潜叶蛾幼虫密度的关系．结果表明,柑桔受潜叶蛾为害后具有一定的光合补偿及组织愈伤的补偿能力;根据福州地区１９９４年柑桔生产力,以雪柑为品种确定经济阈值为１．２１头１龄幼虫／嫩叶;缩小了经济阈值受果实产量大小年份差异而带来的误差;同时考虑品种、柑桔园水热条件、产量水平、天敌作用等多种生态因子,建立了多因子经济阈值模型     

Volumes of petroleum spray oil required for control of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) in mature citrus orchards

Studies on the relationship between volume of spray and suppression of citrus leafminer ( Phyllocnistis citrella ) oviposition by petroleum spray oil on 4 m-high mature orange trees showed a negative exponential relationship between spray volume and the number of mines per leaf. Significant reductions in the number of mines per leaf compared to unsprayed trees was achieved at spray volumes of ≥ 3300 L/ha using oscillating boom and at ≥ 3200 L/ha using rotary atomiser sprayers. However, improvements in efficacy at volumes over 3200–3300 L/ha were not significant and so of little practical value. The optimal spray volumes for citrus leafminer control are therefore suggested to be 3000–3500 L/ha. No significant difference in effectiveness was found between the oscillating boom at 3300 L/ha and a rotary atomiser at 3200 L/ha. The effect of oil spray on the citrus leafminer parasitoid Semielacher petiolatus (Girault) (Hymenoptera: Eulophidae) was inconsistent. Improved droplet deposition and coalescence may enhance the coverage of new growths and increase the efficacy of oil spray for protection of plants from oviposition.     

Antagonism between herbivore‐induced plant volatiles and trichomes affects tritrophic interactions

We used tomato genotypes deficient in the jasmonic acid (JA) pathway to study the interaction between the production of herbivore‐induced plant volatiles (HIPVs) that serve as information cues for herbivores as well as natural enemies of herbivores, and the production of foliar trichomes as defence barriers. We found that jasmonic acid‐insensitive1 (jai1) mutant plants with both reduced HIPVs and trichome production received higher oviposition of adult leafminers, which were more likely to be parasitized by the leafminer parasitoids than JA biosynthesis spr2 mutant plants deficient in HIPVs but not trichomes. We also showed that the preference and acceptance of leafminers and parasitoids to trichome‐removed plants from either spr2 or wild‐type (WT) genotypes over trichome‐intact genotypes can be ascribed to the reduced trichomes on treated plants, but not to altered direct and indirect defence traits such as JA, proteinase inhibitor (PI)‐II and HIPVs levels. Although the HIPVs of WT plants were more attractive to adult insects, the insects preferred trichome‐free jai1 plants for oviposition and also had greater reproductive success on these plants. Our results provide strong evidence that antagonism between HIPV emission and trichome production affects tritrophic interactions. The interactions among defence traits are discussed.     

Primer design for identifying economically important Liriomyza species (Diptera: Agromyzidae) by multiplex PCR

Leafminer flies, especially, Liriomyza huidobrensis, Liriomyza sativae and Liriomyza trifolii, are quarantine species in many countries. Their morphological similarity makes identification difficult. To develop a rapid, reliable, sensitive and simple molecular identification method using multiplex PCR, we newly sequenced the mitochondrial cytochrome oxidase I (COI) genes of Liriomyza bryoniae, Liriomyza chinensis, L. huidobrensis, L. sativae, L. trifolii, Chromatomyia horticola and four parasitoid species. We aligned them with all the COI sequences of the leafminer flies found in the international DNA nucleotide sequence databases (DDBJ/EMBL/GenBank). We then designed species‐specific primers to allow us to differentiate between L. bryoniae, L. chinensis, L. huidobrensis, L. sativae, and L. trifolii.