Oriental fruit moth (Lepidoptera: Tortricidae) phenology and management with methoxyfenozide in North Carolina apples

The phenology of oriental fruit moth, Grapholita molesta (Busck), on apple (Malus spp.) in North Carolina was studied using pheromone traps and egg sampling in abandoned and commercial orchards in 2000 and 2001, with subsequent development of an oviposition degree-day model and management studies in relation to codling moth, Cydia pomonella (L.), phenology. Oriental fruit moth eggs were found in greater numbers on leaves early and on fruit later in the growing season, on the top versus the bottom of the leaf surface, and on the calyx area versus the side or stem end of the fruit. A degree-day (DD) model to predict oriental fruit moth oviposition was developed based on temperature accumulations from peak moth trap capture of the first (overwintering) generation, by using 7.2 and 32.2 degrees C as the temperature limits. The model predicted four ovipositing generations of oriental fruit moth with the second beginning 507 DD after peak moth catch. Using predictions of the oriental fruit moth and codling moth degree-day oviposition models, an experiment was conducted to determine the level of second generation oriental fruit moth control with methoxyfenozide applied under different scenarios for first generation codling moth. Methoxyfenozide was equally effective in managing codling moth and oriental fruit moth for all treatment timings.     

Toxicity and residual activity of methoxyfenozide and tebufenozide to codling moth (Lepidoptera: Tortricidae) and oriental fruit moth (Lepidoptera: Tortricidae)

A series of studies were conducted to examine the residual activity and toxicity of the ecdysone agonists tebufenozide and methoxyfenozide to codling moth, Cydia pomonella (L.), and oriental fruit moth, Grapholita molesta (Busck), in North Carolina apple systems. Methoxyfenozide exhibited greater activity than tebufenozide against codling moth eggs in dose-response bioassays, with a 4.5- and 5.3-fold lower LC50 value to eggs laid on fruit treated before or after oviposition, respectively. Oriental fruit moth eggs were 57- and 12-fold less sensitive to methoxyfenozide than were codling moth eggs on fruit treated before and after oviposition, respectively. Methoxyfenozide was effective in reducing larval entries of both codling moth and oriental fruit moth in field residual activity bioassays, exhibiting activity for at least 28 d after application. Residue breakdown on fruit was approximately 80% at 28 d after treatment for both methoxyfenozide and tebufenozide, with the most rapid residue decline (60%) occurring during the first 14 d after application. Two applications of methoxyfenozide applied at 14-d intervals provided better canopy coverage and higher residue levels than one application. Spray volume (683 versus 2,057 liters/ha) did not affect the efficacy of methoxyfenozide. Leaf and fruit expansion during the season was measured to determine potential plant-growth dilution effects on residual activity. There was very little increase in leaf area after mid May, but increase in fruit surface area over the season was described by a second order polynomial regression. Implications for codling moth and oriental fruit moth management programs are discussed.     

Particle films for suppression of the codling moth (Lepidoptera: Tortricidae) in apple and pear orchards

Studies were conducted in 1997 and 1998 to evaluate the effects of three particle film formulations consisting of kaolin and adjuvants on neonate larvae, ovipositing adult females, and eggs of the codling moth, Cydia pomonella (L.). Neonate larval walking speed, fruit discovery rate, and fruit penetration rate on apple host plants coated with particle films were significantly lower than on host plants without particle films in laboratory assays. Females oviposited less on host plants covered with a particle film residue than on untreated plants in laboratory choice and no-choice tests. Hatch rate of codling moth neonate larvae was unaffected by particle films sprayed on host plants either before or after oviposition. Fruit infestation rates were significantly reduced on particle film-treated trees compared with untreated trees for both first- and second-generation codling moth in field trials in both apple and pear orchards. Particle films appear to be a promising supplemental control approach for codling moth in orchards where moth density is high, and may represent a stand-alone method where moth densities are lower.     

Quantifying pepper maggot (Diptera: Tephritidae) oviposition and infestation over time

In 1998 and 1999, pepper maggot flies, Zonosemata electa (Say), were excluded from pepper plants with row covers for 0-6 wk after initial oviposition was detected. The proportion of oviposition attempts (scars) and larval infestation that occurred each week and the cumulative oviposition and infestation over time were determined. Due to environmental factors, initial oviposition was delayed, and the numbers of oviposition scars on fruit and flies caught on traps were lower in 1998 than in 1999. The proportions of scarred or infested fruit were low (< 8% of total) during the first 7 d after the pest was detected each year. Oviposition peaked 8-14 d after beginning in 1998, but not until 21-28 d after the initial scar was detected in 1999. Because systemic insecticides tend to provide control of adults and most hatching larvae, it may be possible to delay the initial insecticide application for up to a week after oviposition commences and still minimize fruit damage. There was no association with either year between the proportion of flies captured on traps and the proportion of oviposition scars on fruit the same week or 1 and 2 wk later.     

Seasonal and cultivar-associated variation in oviposition preference of Oriental fruit moth (Lepidoptera: Tortricidae) adults and feeding behavior of neonate larvae in apples

The Oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae) has become a pest of tree fruits since its introduction to the United States in the early twentieth century. Oriental fruit moth has historically been a major pest problem in peach production, and outbreaks in commercial apple (Malus spp.) orchards in the eastern United States were rare until the late 1990s. Recent outbreaks in Mid-Atlantic apple orchards have lead researchers to investigate host-associated effects on oriental fruit moth biology, behavior, and population dynamics. Studies were designed to assess cultivar level effects in apples on oviposition and larval feeding behavior of oriental fruit moth. In a mixed cultivar apple orchard, total oriental fruit moth oviposition and oviposition site preferences varied between cultivars. These preferences also varied over time, when sampling was repeated at various times of the growing season. Although most adult female oriental fruit moth preferentially oviposited in the calyx and stem areas of apple fruit, noticeable numbers of eggs also were laid on the sides of fruit, contradicting some previous reports. Oriental fruit moth females exhibited a strong ovipositional preference for fruit that were previously damaged by oriental fruit moth or codling moth, Cydia ponmonella (L.). The majority of newly hatched oriental fruit moth larvae were observed to spend <24 h on the surface of apple fruit before entry, and this behavior was observed on several apple cultivars. Neonate larvae exhibited a preference for entering fruit at either the stem or calyx ends, regardless of their initial site of placement. Our findings underscore the importance of adequate spray coverage and accurate timing of insecticide applications targeting oriental fruit moth.     

Vertical distribution of codling moth adults in pheromone-treated and untreated plots

The vertical distribution of codling moth,Cydia pomonella (L.) within pheromone-treated and untreated apple and pear orchard canopies was determined using tethered virgin females, unbaited sticky traps, and blacklight observation of released moths. Mating of virgin females tethered at various heights in untreated orchard canopies increased with placement height from 1–4 m. Application of pheromone dispensers for mating disruption at 2 and 4 m above the ground greatly decreased mating. Greatest capture of males and females on unbaited sticky traps occurred at mid- and upper-canopy heights. Total capture of males and females in pheromone-treated plots was not statistically different than in untreated plots. The percentage of mated females captured on sticky traps did not vary with trap height or pheromone treatment. Released moths marked with flourescent powder and observed at dark with a blacklight indicated that moths are primarily distributed high in the canopy. However, males shifted to a position lower in the canopy when pheromone dispensers were placed 2.1 m above the ground. Results suggest that pheromone dispensers be placed in the upper canopy for optimal disruption of codling moth mating.     

Sprayable microencapsulated sex pheromone formulations for mating disruption of four tortricid species: effects of application height, rate, frequency, and sticker adjuvant

Several application parameters of microencapsulated (MEC) sex pheromone formulations were manipulated to determine their impact on efficacy of disruption for codling moth, Cydia pomonella (L.); oriental fruit moth, Grapholita molesta (Busck); obliquebanded leafroller, Choristoneura rosaceana (Harris); and redbanded leafroller, Argyrotaenia velutinana (Walker). Depending on the experiment, the formulations evaluated were those formerly manufactured by 3M Canada (London, ON, Canada) or those that are currently available from Suterra LLC (Bend, OR). The efficacy of MEC formulations applied by air-blast sprayer evenly throughout the entire canopy of 2-3-m-tall apple (Malus spp.) trees was equivalent to treatments in which targeted applications of MECs were made to the lower or upper 1.5 m of the canopy (at equivalent overall rates) for oriental fruit moth and both leafroller species. The realized distribution of deposited microcapsules within the tree canopy corresponded well with the intended heights of application within the canopy. The additional coapplication of the pine resin sticker Nu-Film 17 increased efficacy but not longevity of MEC formulations for oriental fruit moth; this adjuvant had no added effects for codling moth or leafroller formulations. Increasing the rate of active ingredient (AI) per hectare by 20-30-fold (range 2.5-75.0 g/ha) did not improve the disruption efficacy of MECs for codling moth or either leafroller species when both low and high rates were applied at equivalent frequencies per season. A low-rate, high-frequency (nine applications per season) application protocol was compared with a standard protocol in which two to three applications were made per season, once before each moth generation for each species. The low-rate, high-frequency protocol resulted in equivalent or better disruption efficacy for each moth species, despite using two-fold less total AI per hectare per season with the former treatment. The low-rate, frequent-application protocol should make the use of MEC formulations of synthetic pheromone more economical and perhaps more effective.     

The effectivenes of Trichotim in control of Cydia pomonella L. in western Romania

In the last years a significant attack increasing of codling moth was observed in the western part of Romania. In order to reduce the population of this pests a bioproduct was used named Trichotim based on entomophagous insect Trichogramma sp. Trichotim is a Romanian product certified in year 2000 with the purpose to control the pests present in various cultures such us cabbage, vineyards and fruits plantations. The study was expanded over two years (2008 and 2009), in a super intensive apple orchard of Didactical Experimental Station part of University of Agricultural Sciences Timisoara. In order to control the codling moth, the product Trichotim was used three times correlated to pest biology (two releasing of Trichogramma wasps in the time of first generation and one release in the time of second generation of the pest), releasing 300.000 wasps/ha in total, where 250.000 wasps in first generation time of the codling moth respectively 50.000 wasps in the time of second generation of the pest. The releasing of entomophagous species Trichogramma succeeded at two days after maximal flight values of Cydia pomonella L. The flight curves was realized based on pheromonal traps ATRAPOM placed in tree canopy in stage BBCH 69 (end of flowering, all petals fallen). In order to assess the efficacy of Trichotim the observation was conducted 14 days before fruit harvesting. In the plots where 300.000 wasps were released, the fruits were attacked in percent of 12,33% (efficacy 87,67%) in year 2008 and respectively 14,66% (efficacy 85,33%) in 2009. In untreated plots (control) the fruits were attacked in percent of 23% in 2008 respectively 27,33% in 2009.     

Seasonal susceptibility of 'Bartlett' pears to codling moth (Lepidoptera: Tortricidae) infestation and notes on diapause induction

Seasonal susceptibility of 'Bartlett' pear, Pyrus communis L., to codling moth, Cydia pomonella (L.), infestation, successful completion of larval development after infestation, and the induction of C. pomonella diapause was studied from 1992 through 1995. The seasonal variation in C. pomonella infestation and larval survival were effected by changes in fruit maturity. In late May through mid-June, pears were hard and were not as successfully infested by C. pomonella and produced less larvae compared with fruit later in the season. In late June to mid-July, pears became more suitable for infestation and a greater percentage of the larvae completed their development. In late July through mid-August, pears were susceptible to infestation, but the larvae were less likely to successfully complete development than in the late June to mid-July period due to pear tissue breakdown. From mid-August through September, pears are unsuitable for infestation, and few larvae were produced. When fruit were infested with neonate larvae in late May and mature larvae emerged from the fruit in July, a low percentage of the larvae entered diapause. However, when fruit were infested with neonate larvae in early July and mature larvae emerged from the fruit in early August, the majority of the larvae entered diapause. When fruit were infested with neonate larvae in late July through September and mature larvae emerged from the fruit after mid-August, nearly all C. pomonella larvae had entered diapause.     

我国启动重大入侵害虫苹果蠹蛾基因组测序

苹果蠹蛾Cydia pomonella (L.)属鳞翅目卷蛾科,具有极强的适应性和抗逆能力,是仁果类果树的毁灭性害虫。1953年首次在我国新疆库尔勒发现,并迅速扩散危害,1987年随旅客携带物传入甘肃敦煌,造成了重大经济损失,是我国重点防控的检疫对象。近日,由中国农业科学院植物保护研究所、南京农业大学等科研单位联合启动了苹果蠹蛾的基因组测序工作。研究团队对苹果蠹蛾进行了10余代的纯化,建立了纯化品系。利用流式细胞分析和小片段文库前期测序等方法,对苹果蠹蛾基因组进行了初步的基因组前期分析。结果显示,苹果蠹蛾基因组大小约为650 Mb, 17-mer和SNP分析显示杂合度大约在0.3%-0.6%之间。经协商拟定了详细的全基因组鸟枪法测序方案后,基因组测序已经全面启动。苹果蠹蛾的基因组测序,对阐明其入侵机制、抗逆机理及防控等研究具有重要的推动意义。     

Effects of fertilizer and herbicide application on Nantucket pine tip moth infestation (Lep., Tortricidae)

A study of fertilizer and herbicide effects on Nantucket pine tip moth (NPTM), Rhyacionia frustrana (Comstock) infestations was conducted in loblolly pine ( Pinus taeda L.) plantations in Nacogdoches Co., Texas, from 1988 to 1989. Both fertilizer and herbicide applications had effects on NPTM infestation level, pupal weight and host tree oleoresin production. Nitrogen fertilization increased infestation levels; whereas, phosphorus applications tends to decrease infestation rate. Herbicide treatment had a negative effect on NPTM infestations possibly because of decreased moisture stress and increased tree vigour. This is in contrast to general observations of increased NPTM infestations associated with reducing competing vegetation. Fertilizer application alone did not significantly improve pine growth due to competing vegetation. A combination of fertilizer and herbicide achieved the best growth.     

Male oriental fruit moth response to a combined pheromone-based attracticide formulation targeting both oriental fruit moth and codling moth (Lepidoptera: Tortricidae)

Combined attracticide formulations targeting Oriental fruit moth, Grapholita molesta (Busck), and codling moth, Cydia pomonella (L.), were tested in a field trapping experiment. Capture of male codling moths in traps baited with the combined formulation was reduced compared with traps baited with the codling moth formulation alone, whereas capture of male Oriental fruit moth was increased compared with traps baited with the Oriental fruit moth formulation alone. Subsequent wind tunnel experiments showed that a single locus of the mixed attracticide formulation or close parallel presentation of the two formulations enhanced source contact by male Oriental fruit moths but did not influence earlier behaviors. However, the two formulations presented in a serial arrangement to Oriental fruit moth males in the wind tunnel resulted in enhanced lock-on, upwind flight, and source contact behaviors. In addition, male Oriental fruit moths remained on mixed pheromone droplets of the paste matrix longer than on droplets of the Oriental fruit moth formulation alone. The increased time spent on the mixed droplet was correlated with a more rapid poisoning and a greater proportion of poisoned males compared with males exposed to the Oriental fruit moth attracticide alone. These results demonstrate that a combined attracticide formulation will have different effects on each of the targeted species. It is anticipated that, due to decreased attractiveness, a combined formulation would be less effective against the codling moth. However, a mixed formulation, due to increased attractiveness and toxicity, could be more effective against the Oriental fruit moth under field conditions.     

苹果蠹蛾成虫产卵特性

苹果蠹蛾Cydia pomonella(L.)是全球温带地区果园主要害虫之一,是中国的重要检疫性有害生物,对我国苹果、梨等水果的安全生产造成极大危害及威胁。为详细了解苹果蠹蛾的产卵特性,从而为进行有效的监测与防控提供基础信息,作者于2006年在甘肃省山丹县梨果园中对树冠不同高度与朝向的蛀果率进行了调查,并于2010在内蒙古阿拉善左旗对梨树果枝上不同部位的产卵量进行了详细调查。主要研究结果如下:1)树冠2.5m以上的蛀果率显著高于2.5m以下的蛀果率,树冠东面的蛀果率最高,南面的蛀果率最低;2)在整个果园中,靠近北侧的果树上果实受害程度要高于南侧果树上的果实受害程度,整个果园中蛀果率由北向南逐渐降低;3)叶片上的卵数最多,占总卵数的73.1%,果实上的卵数次之,占总卵数的14.6%,枝条上的卵数最少,占总卵数的12.2%;4)在产卵的叶片上,卵主要产在叶背面,叶片背面卵量是叶正面的6.65倍。鉴于以上研究结果,在开展化学防治或颗粒体病毒防治时,应注意充分喷施果树上层树冠,且在对果实进行处理的同时,叶片和枝条也需要充分喷药。     

Ovipositional preferences amongst navel sweet orange types by the false codling moth, Cryptophlebia Ieucotreta

Five different navel sweet orange cvs or cv. selections, planted in the Citrusdal area of the western Cape Province, South Africa, were evaluated for their susceptibility to false codling moth infestation. The proportion of yield lost by two of them, cv. Bahianinha and the 'Buffelspoort' cv. selection, was lower than losses from the others evaluated. Damage due to other factors causing fruit abscission was also lowest in the cv. Bahianinha. The greatest number of eggs laid throughout the season was on the 'Addo' cv. selection, and losses due to the false codling moth were also greatest on this orange type. Rate of oviposition was significantly (P > 0.05) lower on the cv. Bahianinha than on all the other types. Parasitism by a trichogrammatid egg parasitoid appeared to have no impact on overall egg mortality and did not account for any of the observed differences in fruit loss. The relationship between egg deposition and fruit loss was not clear and many factors require further investigation. Nevertheless, the distinct difference in rate of oviposition on the 'Addo' cv. selection, on the one hand, and on the cv. Bahianinha, on the other, indicates some consistent response to positive or negative stimuli.     

Host status of fresh prunes by potential quarantine pests in laboratory tests and evaluation of packinghouse culls.

The status of fresh prunes, Prunus domestica L., as a host for codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae); peach twig borer, Anarsia lineatella Zeller (Lepidoptera: Gelechiidae); omnivorous leafroller, Platynota stultana Walshingham (Lepidoptera: Tortricidae); oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae); navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae); and walnut husk fly, Rhagoletis completa Cresson (Diptera: Tephritidae), was investigated in laboratory tests and by examination of packinghouse culls. In laboratory no-choice tests, the mean number of adults reared per fruit was 0.01 for codling moth, 0.08 for omnivorous leafroller, 0 for oriental fruit moth, and 1.6 for navel orangeworm. In choice tests the mean number of adults reared per apple or fresh prune was for codling moth, 0.78 and 0.02 (significantly different); for omnivorous leafroller, 0.05 and 0.02; and for oriental fruit moth, 2.07 and 0 (significantly different), respectively. Walnut husk fly oviposited in fresh prunes in no-choice tests but pupae did not develop from the fruit. In choice tests, walnut husk fly did not oviposit in fresh prunes when caged with its normal host, green walnuts, in which large numbers of pupae developed. Inspection of packinghouse culls for immature insects showed that fresh prunes with possible larval feeding sites in the form of frass or fruit gum extrusions were lighter in weight, significantly less firm, similar in color, and had significantly higher soluble solids than noninfested fruit. Based on packinghouse cull samples, 1 fresh prune per 133 harvested fruit would be expected to show possible insect damage. Eleven peach twig borer larvae were found in fresh prune cull samples (213.9 kg) removed from a 16,744.5-kg harvest. The calculated level of infestation was 1 infested fruit per 8,501.8 fruit harvested or per 21.7 cartons of medium-sized packed fruit. Based on our results, the risk of infestation of fresh prunes by the insects in this study would be minimal in fruit exported from the San Joaquin Valley of California.     

Integrated control of apple pests in New Zealand 10. Population dynamics of codling moth in Nelson

Abstract

Sampling methods are described for estimating the population density, mortality, and natality of a univoltine population of codling moth attacking mature apple trees (cv. ‘Delicious’) at Nelson, New Zealand. These methods were used to construct life tables for the species over eight generations (1967–68 to 1974–75) on trees variously sprayed and not sprayed with ryania in an integrated control programme. Bait traps provided a sensitive measure of seasonal adult population density. Analysis of the life tables shows that migration of adults was the main key factor and that overwintering larval mortality (particularly that due to bird predation), fecundity, and ryania also made a major contribution to variation in generation mortality. In the absence of ryania the resident population usually increased between generations, whereas it usually decreased when ryania sprays were applied. The density dependence of overwintering larval mortality was due to bird predation, and the inverse density dependence of larval mortality from ryania was due to changes in the site of fruit entry with larval population density. Fecundity was density independent, and inconclusive evidence was obtained on the density dependence of migration. The wide variation in fecundity is attributed primarily to weather conditions. The impact on control strategy of the above key factors, density dependence, and total natural mortality is discussed. Ryania is found to be uneconomic, whereas the granulosis virus of codling moth and male removal with pheromone traps show promise as future control methods. The need to eliminate reservoirs of codling moth close to orchards under integrated pest control is emphasised. Regulation of codling moth populations at Nelson on neglected, unsprayed trees appears to result from intraspecific competition for fruits and cocooning sites, and weakly density-dependent mortality of mature larvae when seeking cocooning sites and while overwintering in their cocoons. Variation in fecundity also cohtributes to fluctuations in abundance of the species. In contrast, at low density in an integrated control programme no intraspecific competition was evident; migration, winter mortality, and fecundity were the main determinants of abundance. This illustrates the need to study pest populations at densities similar to those tolerable commercially.     

Fine-scale abundance and distribution of wild silk moth pupae

Although several factors influence herbivore insect distributions at any particular scale, the most important determinants are likely to differ between species with different life histories. Identifying what these factors are and how they relate to life history forms an important component of understanding the population dynamics of species, and the habitat requirements necessary for their conservation. The pupal stage of two wild silk moth species, Gonometa postica Walker and G. rufobrunnea Aurivillius (Lepidoptera: Lasiocampidae), is the target of harvesting practices that are totally dependent on the availability of pupae from natural populations. Consequently, and partly due to poor knowledge of the species' biology, there is substantial interest in the distribution of pupae among and within trees for both these species. It was investigated whether between- and within-tree pupal distributions in these two species are non-random, and if so, whether there are relationships between pupation site use and tree characteristics such as tree size, available pupation space and branch position. Between-tree patterns in pupal abundance were random in terms of absolute spatial position, but markedly non-random with respect to tree characteristics. The apparent G. postica pupae were aggregated on large larval host plants, whereas the cryptic G. rufobrunnea pupae were aggregated on non-host plants. These patterns reflect the life history differences of the two species. In contrast, at the within-tree scale, branch position, aspect and tree shape influenced pupation site choice similarly for both species. These patterns might be related to microclimate. Documenting between-tree and within-tree patterns in Gonometa pupal distributions is the first step towards explaining pupation site selection, as well as identifying possible evolutionarily selective factors in the species, and generating testable hypotheses from these.     

Induced emissions of apple fruit volatiles by the codling moth: changing patterns with different time periods after infestation and different larval instars

The changes in the emission of volatiles from mature apple fruits in response to larval feeding by the codling moth (Cydia pomonella) under laboratory conditions are reported. A time course experiment investigated the emission of volatiles throughout the period of larval development following infestation. The volatiles consisted mainly of esters, a few aldehydes, and the terpene alpha-farnesene. Infested apples emitted the same compounds as healthy apples. The quantities of volatiles released were much higher for infested as compared to healthy fruits for an initial three day period. Following this period there was a decrease in volatile emissions (days 6-9), eventually declining back to the levels emitted from healthy apples or below by 9-21 days after infestation. In a separate experiment, the volatile emissions from healthy and artificially damaged fruits were compared to those from herbivore damaged fruits for each of the five larval instars of C. pommonella. The results from the discriminant analysis indicate that the most effective induction of volatiles occurred when fruits were infested with first instar larvae. Induction by first instar larvae was generally higher than after infestation by later instars, and for most compounds it also exceeded the emission from artificially damaged fruits.     

Comparison of pheromone-mediated mating disruption and conventional insecticides for management of tufted apple bud moth (Lepidoptera: Tortricidae)

Large-plot studies were used to compare pheromone-mediated mating disruption and conventional insecticide applications for management of tufted apple bud moth, Platynota idaeusalis (Walker), in North Carolina in 1993 and 1994. Pheromone trap catches were reduced in mating disruption blocks, and traps placed in the lower stratum of the canopy had a higher level of trap capture reduction compared with traps placed in the upper stratum. First-generation tufted apple bud moth exposure to either pheromones for mating disruption or insecticides affected second generation pheromone trap catches in the lower and upper canopy. More second generation male moths were caught in pheromone traps placed in the upper compared with the lower canopy in blocks treated with pheromones for mating disruption during the first generation, whereas the opposite was true in blocks treated with insecticides during the first generation. Despite reduced trap catches in pheromone-treated blocks, egg mass densities were not reduced in these blocks compared with insecticide-treated blocks. Furthermore, fruit damage was not significantly different between mating disruption blocks and conventionally treated blocks in orchards with relatively low populations of tufted apple bud moth, but damage was greater in mating disruption blocks in orchards with higher moth densities.     

Egg adhesion of the codling moth Cydia pomonella L. (Lepidoptera,Tortricidae) to various substrates: II. Fruit surfaces of different apple cultivars

In the late growing season of apples, most eggs of the codling moth, Cydia pomonella L. (Lepidoptera, Tortricidae), of the second and third generations are deposited directly on fruits. The apple fruit surface is densely covered by three-dimensional micro- and nanoprojections, the epicuticular wax crystals, emerging from an underlying wax film. These epicuticular waxes render the apple fruit surface hydrophobic, which could affect the attachment of insect legs and eggs to it. A better survival of the codling moth offspring is expected to be ensured by the selection of suitable oviposition sites by females, as well as by a proper adhesion of deposited eggs to these sites. In this study, we investigated egg adhesion of the codling moth to the fruit surface of different cultivars of the domestic apple, Malus domestica Borkh., by measuring the pull-off force required to detach eggs from fruits. Since surface characteristics may influence insect egg adhesion, the information about morphological and physicochemical properties of the fruit surface is crucial for understanding oviposition site selection by females. In the present study, surface morphology, wettability, and free surface energy of the apple cultivars ‘Boskoop’, ‘Elstar’, ‘Golden Delicious’, ‘Jonica’, and ‘Topaz’ were analyzed. Eggs adhered tightly to the fruit surface of all apple cultivars tested: pull-off forces averaged 63.9 mN. These forces are four- to tenfold stronger than those previously measured on adaxial and abaxial leaf surfaces of the identical apple cultivars. The mechanisms used by the moth to fix its eggs on the waxy surface of apple fruits, and the influence of fruit surface properties on egg glue adhesion are discussed. Furthermore, the results are debated in the context of the oviposition site selection by females, and its role in offspring survival of the second and third generations of the codling moth.