苹果非疫区建设中的苹果蠹蛾监测与防控

为了保护我国苹果蠹蛾主产区免受苹果蠹蛾Cydia pomonella(L.)的危害、突破国际贸易技术壁垒,促进苹果这一我国优势农产品的出口,2004年,我国农业部开始在西北黄土高原、环渤海湾2个中国苹果优势产区建设苹果非疫区,总面积达133.3万hm2。在非疫区建设的8年时间中,已在全国范围内建立了完善的苹果蠹蛾监测网络;至2010年,监测点总数达8000余个,调查面积达133.3多万hm2。在苹果蠹蛾防控方面,主要通过建立完善的应急反应体系及非疫区档案管理制度,加强公众宣传以及提高苹果非疫区外围的检疫和防治力度等措施,阻止了苹果蠹蛾在我国的进一步扩散蔓延。     

Variability in the efficacy of sex pheromone lures for monitoring oriental fruit moth (Lepidoptera: Tortricidae)

Studies were conducted in Chile and the United States to compare the attractiveness of various commercial sex pheromone lures and two experimental lures for oriental fruit moth, Grapholita molesta (Busck), in peach orchards treated with or without sex pheromone dispensers. The experimental lures contained the three‐component sex pheromone blend of G. molesta: Z‐8‐dodecenyl acetate, E‐8‐dodecenyl acetate and Z‐8‐dodecenol (Z8‐12:OH), and the sex pheromone of codling moth, Cydia pomonella (L.), (E,E)‐8,10‐dodecadien‐1‐ol, (codlemone). Commercial lures varied in their substrate, initial loading and blend ratio of components. Significant differences in male catches were found among commercial lures in orchards treated with or without sex pheromone dispensers. Experimental lures with the addition of codlemone significantly increased the catches of G. molesta using lures loaded with 0%, 1% or 5% Z8‐12:OH in the G. molesta blend compared with the same ratio of components in just the G. molesta blend. The experimental lures were significantly more attractive than all commercial lures in the untreated orchard. However, moth catch with the experimental lures in the sex pheromone‐treated orchard was only intermediate among all of the lures tested. These findings highlight the need to develop more effective and standardized lures that can be used in trap‐based monitoring programme for this important pest.     

Synergism between aromatic compounds and green leaf volatiles derived from the host plant underlies female attraction in the oriental fruit moth

Blends of volatile compounds emitted by host plants are known to mediate the attraction of gravid female herbivores to oviposition sites, but the role of individual odor components is still little understood. We characterized the olfactory response of mated female Cydia (Grapholita) molesta (Busck) (Lepidoptera: Tortricidae) to synthetic mixtures of compounds emitted by peach shoot, a key host plant of this herbivore, and investigated the role of important constituents of bioactive mixtures in moth attraction. Relative ratios of constituents of the mixtures corresponded to the natural ratio of volatile compounds collected in the plant's headspace. A significant attractant effect was found for a comparatively complex 10‐compound mixture that included four green leaf volatiles [(Z)‐3‐hexen‐1‐ol, 1‐hexanol, (E)‐2‐hexenal, and (Z)‐3‐hexen‐1‐yl acetate], five aromatics (benzaldehyde, methyl salicylate, methyl benzoate, benzonitrile, and phenylacetonitrile), and a carboxylic acid (valeric acid). Using a subtraction approach, the number of compounds was progressively decreased, resulting in a bioactive 5‐compound mixture composed of two constituents, green leaf volatiles and aromatic compounds. Further evaluations revealed that benzaldehyde and benzonitrile must be present in association with three distinct green leaf volatiles to produce an attractant effect on the female moths. This 5‐compound mixture was as attractive as natural peach shoot volatiles, which are known to comprise over 20 compounds. Results are discussed in light of the documented synergistic effect between the three general green leaf volatiles and the two specific aromatic compounds.     

Quantitative trait locus mapping of resistance in apple to Cydia pomonella and Lyonetia clerkella and of two selected fruit traits

Apple, Malus×domestica, is the most important fruit grown within the temperate zonobiome. It is attacked by both fruit‐damaging and leaf‐damaging lepidopteran pest insects, which require regular control such as the carpophagous codling moth, Cydia pomonella, or frequent control such as the phyllophagous apple leaf miner, Lyonetia clerkella. As many environmentally friendly pest control tactics are only effective at low levels of infestation, host plant resistance is a promising future component of integrated pest management systems, but knowledge is still lacking on such genetically based approaches against lepidopteran pests. The aim of the study was to identify molecular markers linked to C. pomonella and L. clerkella resistance or susceptibility in commercial apple as well as markers linked to selected fruit traits. The number of C. pomonella‐infested fruits and the number of L. clerkella mines were quantified as measures of apple resistance or susceptibility to the studied moth species. Herbivore surveys on 160 apple genotypes, representing a segregating F₁ cross of the apple cultivars ‘Fiesta’ and ‘Discovery’, were carried out during two consecutive years and at two sites in Switzerland. Broad‐sense heritability was 29.9% (C. pomonella), 18.2% (L. clerkella), 21.9% (fruit number) and 16.6% (fruit diameter). A subsequent analysis identified a quantitative trait locus (QTL) associated to C. pomonella susceptibility on the Discovery linkage group 10. The closest marker to this QTL was the random amplified polymorphic marker Z19‐350. No significant QTL was identified for resistance to L. clerkella. A putative QTL associated to fruit number was identified on Fiesta linkage group 12. The presented QTL associated with C. pomonella susceptibility and the putative QTL linked to fruit number may facilitate marker‐assisted breeding of resistant apple cultivars with cropping traits desirable for optimal fruit production.     

Diel patterns of locomotor activity in Cydia pomonella: age and sex related differences and effects of insect hormone mimics

Abstract. The diel pattern of locomotor activity in the codling moth Cydia pomonella L. (Lepidoptera: Tortricidae) was investigated in the laboratory, using a computer-based infra-red actograph. The level of locomotor activity varied with sex and age. On the day of emergence, females were more active than males, but on days 2, 4, 6 and 12 males were approximately twice as active as females. Males reached their highest activity on day 4 and females on day 12. Both sexes were most active at dusk. Their activity patterns were fitted to a set of polynomial regression models. Treatment with 400 p.p.m. of Juvenile Hormone mimic, fenoxycarb, stimulated locomotor activity and provoked a marked activity peak at dawn in both virgin and mated females. A similar treatment with the ecdysone agonist tebufenozide showed a neutral effect on the locomotor activity of females. Possible implications of these findings are discussed in relation to the physiology of the moth and to its dispersal behaviour.     

Le rôle de l'olfaction dans l'attraction exercée par les pousses et les fruits de pêcher sur les larves néonées de tordeuse orientale Cydia molesta

Summary The behaviour of newly hatched Cydia molesta larvae was studied in Petri dishes, at 23°C, in darkness. The trials of varying duration, each consisted of 50 larvae (ten replicates of five larvae). The larvae were strongly attracted by either a recently cut piece of growing peach twig or a piece of a fresh peach skin. These were clearly preferred to equivalent wet papers. One hundred percent relative humidity was provided by covering the bottom of the dishes with wet paper. The proportion of larval attracted by the plant material reached or exceeded 84% inside 50–60 minutes.In other trials, the larvae were also attracted by concentrated extracts of peach twigs and fruits prepared with chloroform. The bottom of the dishes was covered with dry paper and the larvae continually observed with a video camera under a dim red light (10 lux). The extracts from growing peach twigs were more attractive than those of fruits and physiologically old twigs.The role of olfaction in the behaviour of larvae and the diffusion of semio-chemicals by the plant are demonstrated.

     

Trichogramma platneri (Hym.: Trichogrammatidae): Host choices between viable and nonviable codling moth,Cydia pomonella,and three-lined leafroller,Pandemis limitata (Lep.: Tortricidae) eggs

In laboratory host-preference studies,Trichogramma platneri Nagarkatti (Hym.: Trichogrammatidae) females, reared on viable codling moth,Cydia pomonella (L.) (Lep.: Tortricidae) eggs, parasitized significantly more viable than nonviable codling moth eggs produced by cobalt 60 irradiated adults. This ovipositional preference was maintained when competition increased per host egg. Similarly, one, three and fiveT. platneri females consistently oviposited more eggs into viable versus nonviable host eggs. A single femaleT. platneri parasitized a similar number of viableC. pomonella and three-lined leafroller,Pandemis limitata (Robinson) (Lep.: Tortricidae) eggs. However, as the number of females per host eggs increased, a significantly larger number of codling moth versus leafroller eggs were parasitized. One, three and fiveTrichogramma females parasitized significantly moreP. limitata versus nonviableC. pomonella eggs. NonviableC. pomonella eggs deflated to less than 25% of their original volume in four and ten days when held under dry and humid conditions respectively. The blackened prepupal stage of the parasitoid generally occurred in the nonviableC. pomonella eggs four days post-parasitization whereas the parasitized viable eggs blackened zero to one day earlier. Incubation under dry or humid conditions did not appear to influence the number of parasitized eggs that were able to blacken and show evidence of parasitism. Summerland Research Centre Contribution No. 938.     

Uptake of Granulovirus from the Surface of Apples and Leaves by First Instar Larvae of the Codling Moth Cydia pomonella L. (Lepidoptera: Olethreutidae)

Cydia pomonella granulovirus (CpGV) has received considerable attention as a potential microbial insecticide for the control of the codling moth (Cydia pomonella L.) , a worldwide pest of apples. Laboratory experiments were established to investigate virus uptake by first instar larvae, using a novel leaf disc bioassay technique. Virus uptake was found to be independent of active feeding and larvae became infected simply by walking or browsing on sprayed leaf disc surfaces in as little time as 3.5 min. Infection increased as a function of time spent on the leaf disc surface and a linear log time/probit mortality relationship could be fitted. The bioassay technique used has potential for the realistic laboratory testing of virus spray formulations. A field experiment showed that virus infection could be contracted by newly hatched codling moth larvae both from the surface of sprayed leaves and sprayed fruit. The potential for exploiting this knowledge for improving spray formulations is discussed.     

Antennal response of codling moth males, Cydia pomonella L. (Lepidoptera: Tortricidae), to the geometric isomers of codlemone and codlemone acetate

Single sensillum recordings from Cydia pomonella male antennae showed three different types of receptor neurons. The most abundant type was most sensitive to the main pheromone compound (E,E)-8,10-dodecadienol, while its response to the geometric isomers E,Z, Z,E and Z,Z was comparable to a tenfold lower dose of (E,E)-8,10-dodecadienol. This neuron type also responded to the four behaviorally antagonistic isomers of (Δ,Δ)-8,10-dodecadienyl acetate, among which it was most sensitive to the E,E isomer. Cross-adaptation studies showed that these compounds were all detected by the same receptor neuron type. Receptor neurons specifically tuned to (E,Z) or (Z,Z)-8,10-dodecadienol were not found, although these two compounds are behaviorally active. A second type of receptor neuron responded to all isomers of (Δ,Δ)-8,10-dodecadienyl acetate and was most sensitive to the E,E isomer. This neuron type did not respond to any of the isomers of (Δ,Δ)-8,10-dodecadienol. A third receptor neuron type was highly sensitive to the plant compound α-farnesene. The finding that the receptor neuron type tuned to the main pheromone compound responded even to strong behavioral antagonists aids the interpretation of ongoing behavioral studies for the development of the mating disruption technique in codling moth. Accepted: 3 March 2000