The light-brown apple moth,Epiphyas postvittana (Walker): 5. Variability of demographic characteristics in field populations of southeastern Australia.

Studies of population samples of the light-brown apple moth (LBAM), Epiphyas postvittana (Walker), collected along a 1500 km north-south transect in southeastern Australia, revealed significant differences in demographic performance between cohorts of different origins reared under uniform conditions in the laboratory. Mean sample values for survivorship and rate of pre-imaginal development, notably, were found to vary according to the latitude and mean January temperature of collection sites, suggesting that specialized forms had evolved in LBAM as an adaptive response to the characteristics of local environments. Underlying this general trend, however, great differences were recorded between samples from neighbouring populations, in actual values manifested for specific properties affecting demographic performance which would support the hypothesis that LBAM might currently be in the process of diversification throughout the area surveyed, as a consequence of environmental changes resulting from European settlement. General inferences are drawn from the present findings, concerning feasible objectives and procedures for the practical study of pest insects.     

Effect of plant architecture and hail nets on temperature of codling moth habitats in apple orchards

Plant architecture of apple trees in commercial orchards was rapidly changed from traditional tall trees to dwarf trees to optimize yield and fruit quality. Additionally, hail nets are widely used to prevent yield loss by hail. These changes are expected to considerably influence the orchard microclimate and thus the developmental rates of pest insects in apple. However, these relationships have not yet been fully elucidated. The present study was conducted over the seasonal cycle to investigate the influence of plant architecture and hail nets on the habitat temperatures of the codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), in apple, Malus domestica Borkh. (Rosaceae). Within the canopies, leaf area index (LAI) and global site factor (GSF) were quantified using hemispherical photography. Temperature was analysed for the main habitats of the different codling moth stages, i.e., air within the canopy, bark of tree stems, and apple fruit. In dwarf trees, LAI was lower, leading to a higher GSF than in tall trees. Hail nets did not influence LAI and GSF. Results for dwarf trees compare as follows with those for tall trees: Average air temperatures within the canopy were 0.7 °C higher during daytime, whereas 0.4 °C lower at night. Mean surface temperatures of bark were 0.9 °C higher on sunny and 0.4 °C on overcast days. Mean surface temperatures of apple fruits were 1.8–2.7 °C higher on sunny days, but 0.6 °C cooler on overcast days. The effect of hail nets was confined to a reduction of the air temperature within the canopy by approximately 0.2–0.8 °C. Bark and apple surface temperatures were not significantly affected. Based on the temperature differences in the habitats considered, the calculated development of the codling moth in dwarf trees was on average 3 days faster than in tall trees. The calculations imply a negligible effect of hail nets on codling moth development.     

Aerial application of pheromones for mating disruption of an invasive moth as a potential eradication tool

Biological invasions can cause major ecological and economic impacts. During the early stages of invasions, eradication is desirable but tactics are lacking that are both effective and have minimal non-target effects. Mating disruption, which may meet these criteria, was initially chosen to respond to the incursion of light brown apple moth, Epiphyas postvittana (LBAM; Lepidoptera: Tortricidae), in California. The large size and limited accessibility of the infested area favored aerial application. Moth sex pheromone formulations for potential use in California or elsewhere were tested in a pine forest in New Zealand where LBAM is abundant. Formulations were applied by helicopter at a target rate of 40 g pheromone per ha. Trap catch before and after application was used to assess the efficacy and longevity of formulations, in comparison with plots treated with ground-applied pheromone dispensers and untreated control plots. Traps placed at different heights showed LBAM was abundant in the upper canopy of tall trees, which complicates control attempts. A wax formulation and polyethylene dispensers were most effective and provided trap shut-down near ground level for 10 weeks. Only the wax formulation was effective in the upper canopy. As the pheromone blend contained a behavioral antagonist for LBAM, 'false trail following' could be ruled out as a mechanism explaining trap shutdown. Therefore, 'sensory impairment' and 'masking of females' are the main modes of operation. Mating disruption enhances Allee effects which contribute to negative growth of small populations and, therefore, it is highly suitable for area-wide control and eradication of biological invaders.     

Transgenic Tobacco and Apple Plants Expressing Biotin-binding Proteins are Resistant to two Cosmopolitan Insect Pests,Potato Tuber Moth and Lightbrown Apple Moth,Respectively

Tobacco (Nicotiana tabacum cv. Samsun) and apple (Malus x domestica cv. Royal Gala) plants expressing avidin or strepavidin were produced using Agrobacterium tumefaciens-mediated transformation. ELISA assays showed that avidin expression ranged from 3.1 to 4.6 microM in tobacco and from 1.9 to 11.2 microM in apple and streptavidin expression ranged from 11.4 to 24.5 microM in tobacco and from 0.4 to 14.6 microM in apple. Expressed at these levels, both biotin-binding proteins conferred a high level of insect resistance on transformed tobacco plants to larval potato tuber moth (PTM), Phthorimaea operculella (Zeller) (fam. Gelechiidae) and on apple plants to larvae of the lightbrown apple moth (LBAM) Epiphyas postvittana (Walker) (fam. Tortricidae). More than 90% of PTM larvae died on tobacco plants expressing either avidin or streptavidin genes within 9 days of inoculation. Mortality of LBAM larvae was significantly higher (P < 0.05) on three avidin-expressing (89.6, 84.9 and 80.1%) and two streptavidin-expressing (90 and 82.5%) apple plant lines than on non-transformed control plants (14.1%) after 21 days. Weight of LBAM larvae was also significantly reduced by feeding on all apple shoots expressing avidin and on apple shoots expressing streptavidin at levels of 3.8 microM and above.     

The light-brown apple moth,Epiphyas postvittana (Walker): 3. Differences in susceptibility to a nuclear polyhedrosis virus

A nuclear polyhedrosis virus (NPV) was found to be widespread throughout the distribution of the light-brown apple moth (LBAM), Epiphyas postvittana (Walker), in southeastern Australia. Tests were done on sample cohorts drawn from laboratory strains and field populations to determine whether (i)susceptibility to NPV varied significantly in LBAM; and (ii) responses which exposure to the virus was known to elicit in the CAN Laboratory Strain (Geier & Oswald 1977) could be regarded as typical of the species. It was shown that discrete breeding groups could differ greatly in the relative mortality which they sustained following similar exposures to NPV. Whereas more females died than males in all virus-treated cohorts, as had been previously established in the CAN Strain, the demographic impairment typical of many individuals surviving exposure to NPV in that very tolerant strain (reduced weight of females, reduced fecundity and fertility) was not generally manifest in more susceptible forms of the species. Field surveys so far have not been detailed enough to reveal distribution patterns in the host-pathogen relationship. The epidemiology of the virus is unknown and its role in the life system of LBAM is not understood.     

Temporal dynamics of parasitoid assemblages parasitizing the codling moth

Population dynamics of parasitoid–host interaction is primary important knowledge to develop an efficient biological control strategy of insect pests. We analyzed the seasonal dynamic of the parasitoid community of the codling moth in two sites in South-Eastern France, which differed by the number of codling moth annual generations. Parasitism was estimated by sampling both young larvae collected within apple fruits and mature larvae in band traps wrapped around the trunk of the apple trees. Parasitism rates differed between sites and between young and mature larvae. Parasitism rate were higher in young larvae (29% in average) than in the mature ones (21% in average) and globally increased along the season among cohorts of mature codling moth larvae (from 4% to 34%). The three most abundant species in the parasitoid community – Ascogaster quadridentata, Pristomerus vulnerator and Perilampus tristis – were observed at both sites, in each codling moth cohort and in both young and mature larvae. Among all the parasitoids, the proportion of Perilampus – an hyper-parasitoid attacking both Ascogaster and Pristomerus primary parasitoids – increased among the codling moth cohorts (from 9% to 53%) whereas the proportion of Ascogaster decreased (from 82% to 35%). This shed light on the importance to characterize the dynamic of the whole trophic network (including hyperparasitism) to design biological control strategies.     

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.     

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.     

甘肃省苹果蠹蛾卵的空间分布格局

为准确掌握苹果蠹蛾Cydia pomonella(L.)的田间发生动态,本文对苹果园中苹果蠹蛾卵的空间分布格局和抽样技术进行了研究。结果表明:在第2代卵发生高峰期,苹果叶片上的苹果蠹蛾卵量显著高于果实上的卵量(叶片上着卵量占总卵量的58.2%,P<0.05),叶片上的卵主要分布于叶片正面(正面着卵量占叶片上总卵量的69.6%,P<0.05);在树冠不同方位上,东、南两面的着卵量最大,但在不同空间层次上分布的卵量没有差异。卵在叶片和果实上均呈聚集分布,且聚集强度随种群密度的升高而增加,其聚集是由环境因素造成的。文中还根据Taylor幂法则参数建立了苹果蠹蛾卵的理论抽样数模型。     

Extrafloral nectar in an apple ecosystem to enhance biological control

A common goal of conservation biological control is to enhance biodiversity and increase abundance and effectiveness of predators and parasitoids. Although many studies report an increase in abundance of natural enemies, it has been difficult to document increases in rates of biological control. To enhance parasitism of the tufted apple bud moth, Platynota idaeusalis (Walker) (Lepidoptera: Tortricidae), alternate food was provided by interplanting peaches bearing extrafloral nectaries into apple (Malus spp.) orchards. Laboratory studies showed that the presence of nectar increased longevity and parasitism rates by Goniozus floridanus (Bethylidae), the dominant parasitoid of tufted apple bud moth in West Virginia. In orchard studies, we found the total number of hymenopteran parasitoids was higher on peach (Prunus spp.) trees than on adjacent apple trees. Abundance of parasitic Hymenoptera also was significantly higher on the side of traps facing away from rather than toward peach trees, indicating attraction to peach trees. However, total parasitism rates of tufted apple bud moth were not affected by the presence of peach extrafloral nectar in any field studies. Insect injury to fruit at harvest showed that fruit from orchards with interplanted peach trees had less injury from San Jose scale, Quadraspidiotus perniciosus (Comstock) and stink bugs (Pentatomidae) than fruit from an apple monoculture. Although interplanting with peach trees did not produce the hypothesized result of increased biological control, the experiment did have beneficial results for pest management. These results demonstrate the importance of collecting data on variables beyond the targeted species when evaluating habitat manipulation experiments to fully assess the impact on the ecosystem.     

Natural mortality at different population densities of a pine shoot moth,Evetria cristata

A field population of Evetria cristata was studied in 10 plots in 1962 and in 6 plots in 1963. These plots were divided into 2 or 3 groups of different population levels of the shoot moth in respective years. The survival of the insect was then analysed in these different groups of plots. The survival rate of E. cristata from eggs to adults in the first generation was found always higher in the group with low population density, which indicates the existence of some factors that affect the population more severely when the insect is more abundant. Lissonota evetriae and Pediobius sp. seemed to have killed more proportion of the hosts where the shoot moth density was high. However, the total effect of the all natural enemies was not always great in the plots with high density of the moth. The survival of the second generation of the moth in 1963 was observed to be much higher at any population level than in the other generations.     

Delayed density-dependent parasitism of eggs and pupae as a contributor to the cyclic population dynamics of the autumnal moth

Many populations of forest Lepidoptera exhibit 10-year cycles in densities, with impressive outbreaks across large regions. Delayed density-dependent interactions with natural enemies are recognized as key factors driving these cyclic population dynamics, but emphasis has typically been on the larval stages. Eggs, pupae and adults also suffer mortality from predators, parasitoids and pathogens, but little is known about possible density relationships between mortality factors and these non-feeding life stages. In a long-term field study, we experimentally deployed autumnal moth (Epirrita autumnata) eggs and pupae to their natural enemies yearly throughout the 10-year population cycle in northern Norway. The abundance of another geometrid, the winter moth (Operophtera brumata), increased in the study area, permitting comparisons between the two moth species in predation and parasitism. Survival of autumnal moth eggs and pupae was related to the moth abundance in an inverse and delayed manner. Egg and pupal parasitoids dominated as density-dependent mortality factors and predicted the subsequent growth rate of the host population size. In contrast, effects of egg and pupal predators were weakly density dependent, and generally predation remained low. Parasitism rates did not differ between the autumnal and winter moth pupae, whereas predators preferred winter moth pupae over those of the autumnal moth. We conclude that parasitism of the autumnal moth by egg and pupal parasitoids can be related to the changes of the moth density in a delayed density-dependent manner. Furthermore, egg and pupal parasitoids cannot be overlooked as causal factors for the population cycles of forest Lepidoptera in general.     

Effects of Contact and Ingestion Exposure to Formulated CheckMate® LBAM-F and Unformulated LBAM Mating Pheromones on Adult Worker Honeybees,Apis mellifera (Hymenoptera: Apidae)

Acute 7-day toxicity tests evaluating adverse effects from contact and ingestion exposure to light brown apple moth (LBAM) pheromones and time-released microencapsulated LBAM pheromones in CheckMate® LBAM-F (Checkmate) were conducted on newly emerged honeybees (less than 24 h old). Contact studies exposed bees to 1× and 10× the CheckMate label application rate. Ingestion studies exposed bees to CheckMate formulations, and active (pheromone) ingredients (a.i.) at 0.1%, 1.0%, and 10% concentrations by weight in solid food. Bees ingested approximately 39% of their body weight during the tests. Mortality ranged from 2–10% in three of four contact and ingestion exposure trials. Trial 1, which utilized a different feeding design, showed higher mortality in both control and test replicates (9–28%). One-way ANOVA tests indicated no significant difference in mortality between control and treatment replicates in the four trials. Bees were subjected to one-time CheckMate contact exposures of up to 0.49 mg/kg-bee, and average pheromone and formulation ingestion exposures of up to 56 (0.1%), 611 (1.0%), and 6,282 (10%) mg/kg-bee-day. LBAM pheromones and microencapsulated pheromones proved to be non-toxic to honeybees when sprayed with 10× the field application rate, or when ingested in food at concentrations of up to 10% by weight.     

Limits to the potential distribution of light brown apple moth in Arizona–California based on climate suitability and host plant availability

The highly polyphagous light brown apple moth (LBAM) (Epiphyas postvittana (Walk.): Tortricidae) is indigenous to Australia and was first found in California in 2006. It is currently found in 15 coastal counties in California, but nowhere has it reached outbreak status. The USDA projects the geographic range of LBAM will include much of Arizona and California and the southern half of the US, which together with economic estimates of potential crop losses have been used as the rationale for an eradication program in California. We report a temperature-driven demographic model to predict the likely distribution and relative abundance of LBAM using the detailed biology reported by Danthanarayana and colleagues, and climate data from 151 locations in California and Arizona for the period 1995–2006. The predictions of our model suggest that the near coastal regions of California are most favorable for LBAM, the northern Central Valley of California being less favorable, and the desert regions of Arizona and California being unfavorable. The model also predicts that LBAM populations can develop at two of the hottest locations in SE Australia where it is has long been known to occur. This reassessment of the potential distribution of LBAM in California and Arizona suggests that its likely ecological and economic impacts would be less than previously assessed by USDA and that its current pest status warrants re-evaluation.     

Cuticular hydrocarbon profiles of codling moth larvae,Cydia pomonella (Lepidoptera: Tortricidae), reflect those of their host plant species

The cuticular hydrocarbons (CHCs) of codling moth larvae collected in the field from their host plant species, apple and walnut, were analyzed and compared with the CHCs of fruits from these two phylogenetically distant hosts. The CHC profiles of the larvae consisted solely of n‐alkanes (C₂₃–C₃₁) and differed quantitatively between host populations. Amounts of the CHCs from the walnut‐collected larvae were shifted towards longer‐chain alkanes compared to those from apple‐collected larvae. A similar shift was observed for the CHC profiles of walnut and apple fruits. Analysis of the CHCs of larvae reared on artificial diet, in comparison with hydrocarbons from the diet, confirmed that larval CHCs scarcely reflect hydrocarbons from the food source. This finding indicates that the larval hydrocarbons must be biosynthesized to a large degree by the insect, rather than being gained directly from its diet. Hence, codling moth populations from apple and walnut each synthesize their own CHC profiles, which largely resemble those of their respective host plant, yielding a potential tool of chemical camouflage from certain natural antagonists of the larvae. The findings of the present study, together with recent molecular population analyses, provides evidence for a process that might ultimately lead to sympatric speciation of this herbivore species. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 101 , 376–384.     

Influence of native ants on arthropod communities in a vineyard

• 1 Ants can have a range of effects on arthropods in crops, including suppressing herbivores such as caterpillars. However, ants can also increase hemipteran densities while reducing natural enemy numbers. In vineyard ecosystem, the effects of native ants and their interactions with other arthropods are poorly understood.
• 2 An ant‐exclusion experiment was designed to test the impact of native ants on both canopy and ground arthropods concurrently. The potential influence of ants on predation and parasitism of light brown apple moth (LBAM) eggs, a grape pest, was also examined. Adult grapevine scale insects and earwigs under bark were counted after a season of ant‐exclusion.
• 3 Among 23 ground ant species collected, six were found to forage in the canopy, with two Iridomyrmex species being the most commonly encountered.
• 4 There was no difference in the abundance of most arthropod orders and feeding groups between ant‐excluded and control vines, although ground spiders were more abundant under ant‐excluded vines, despite increased ground ant foraging pressure. LBAM egg parasitism and predation were low and probably affected by weather and other arthropods. Ant exclusion did not reduce survival of scale insects, although the distribution and abundance of scale insects were negatively associated with earwigs.
• 5 In conclusion, native ants did not consistently suppress arthropod assemblages, including natural enemies, and they did not promote the survival of scale insects. Interactions among native ant species within a vineyard might minimize their effects on other arthropods, although this needs further study.

     

Integrated control of apple pests in New Zealand

In a study at Appleby Research Orchard, Nelson, examination of the fruit from mature ‘Delicious’ apple trees sprayed with ryania over 5 years showed that less than 10% of 5th‐instar larvae of the codling moth (Laspeyresia pomonella) seeking cocooning sites originated from fruit on the ground. In 1972 and 1973 the survival of such larvae was studied by tagging with cobalt‐58 and releasing them beneath mature trees. In both years about 25 % of the tagged larvae returned to the tree to spin cocoons. Larvae released on bare ground 0–1 m from the tree trunks were more successful than those released in the sward 1–2 m away. Once on the trees, most larvae spun cocoons beneath exfoliating bark on the lower parts of the leaders and the trunk. Fifty‐two percent of the cocoons located were formed on the ground, and overwintering mortality of these was estimated to be near 100%. The pre‐cocooning mortality of larvae released on the ground was similar to that of larvae released on the trees in the same year. It was concluded that larvae from windfalls could be ignored in estimating 5th‐instar larval mortality of codling moth on ‘Delicious’ trees. On the cultivars ‘Dunn's Favourite’ and ‘Cox's Orange Pippin’, however, the higher percentage of larvae in windfalls made their inclusion in mortality estimates essential.     

Evaluation of mating disruption for control of lightbrown apple moth (Lepidoptera: Tortricidae) in citrus

Three large-scale mating disruption (MD) trials were conducted from 2001 to 2004 in an organic citrus orchard in inland southeastern Australia to evaluate the effectiveness of the MD dispenser Isomate LBAM Plus in controlling lightbrown apple moth, Epiphyas postvittana (Walker), in citrus. At the application rate of 364-728 dispensers per ha, the dispensers reduced pheromone trapping of E. postvittana to almost undetectable levels for approximately 6 mo in the treated area. During this period, most sentinel females in the treated area failed to mate. Infestation by E. postvittana in the treated area was reduced by >50%. If distributed in citrus orchards in late winter (August), the dispensers can be expected to remain effective until next February in southeastern Australia, covering the period when most fruit scarring caused by its larvae occurs.     

Phacidiopycnis washingtonensis,Cause of a New Storage Rot of Apples in Northern Europe

Phacidiopycnis washingtonensis was identified by morphology and ITS sequence analysis as the cause of rubbery rot, a new storage disease of apples in northern Germany. Infected fruits had an unusually firm texture and pale appearance after storage in ultra‐low oxygen conditions, but turned dark brown to black in ambient atmosphere. Ultimately, the surface of rotted fruits became covered by black pycnidia producing cream‐coloured conidial exudates. Rubbery rot affected several apple varieties, including the commercially important ‘Jonagold’ and ‘Elstar’. Losses during storage were commonly below 1% but reached 5–10% in a few cases. Fruits of ‘Golden Hornet’ crab apple trees planted as pollinators in commercial orchards became heavily infected by P. washingtonensis in October. Conidia were released throughout the following season from infected fruit mummies, which remained attached to the crab apple tree.     

Larval performance of the oriental fruit moth across fruits from primary and secondary hosts

A common characteristic of many invasive herbivorous insects is their ability to utilize a broad range of host plants. By using various hosts in phenological succession, multivoltine herbivores may increase the number of successful annual generations, at the same time as potentially increasing their overall fitness. To achieve such success, herbivores must be able to develop efficiently on the nutritional resources offered by their hosts. The oriental fruit moth Cydia (= Grapholita) molesta (Busck) (Lepidoptera: Tortricidae) is one of the most damaging invasive insect species. Peach (Prunus persica) is its primary host, whereas the pome fruits apple (Malus × domestica Borkh) and pear (Pyrus communis) are considered as secondary hosts. In many parts of its geographical range, including southern Europe, populations of the moth switch from peach to apple or pear orchards during the growing season. The present study tests whether this temporal switch is supported by the physiological capability of the larvae with respect to developing efficiently on fruits of these taxonomically‐related host plants. Larvae are reared on peach, apple or pear fruits; several life‐history traits are measured; and correlations between the traits are calculated. The results obtained show that larvae do not have the same physiological capability with respect to using apple or pear fruits as hosts compared with using peach fruit. Pear fruit in particular is a sub‐optimal diet. These findings suggest that, in the case of continuous geographical expansion, concomitantly with global warming, apple orchards might support oriental fruit moth populations better than pear orchards, and that the switch onto novel hosts might be accompanied by restricted population growth.