Cacoecimorpha pronubana (Hübner, [1799]) and Epiphyas postvittana (Walker, 1863) are economically important polyphagous pest species. The larvae of these moths affect a wide range of horticultural crops. We evaluated the seasonal abundance and population dynamics of these two species, hypothesising that both species of moth exhibit similar patterns in their seasonal abundance and respond to abiotic factors. The study was carried out on a wide range of protected ornamental crops grown on a total area of 1 ha at a commercial nursery. The study was completed over five consecutive years from 2015 to 2019, where both populations were monitored weekly during the months of moth activity, from April to November, using sex pheromone traps to trap the males of both species. The timing and abundance of catches were analysed in relation to local meteorological data. The mean yearly abundance of adult males was 604 ± 23.89 (mean ± SE; C. pronubana) and 1706 ± 167.18 (E. postvittana) also differing significantly between years for both species. There was no influence of any weather measures on the abundance of E. postvittana, but sunshine duration (4.84 ± 0.26 hr) and temperature (13.04 ± 0.57°C) affected the mean seasonal abundance of C. pronubana. There was an overall difference in the seasonal pattern of abundance between the species studied. While we demonstrate a seasonal abundance difference between years for C. pronubana, we found no significant seasonal differences for E. postvittana. Improved understanding of seasonal abundance, phenological patterns and inter‐seasonal variations in population dynamics of these two species may be useful in developing forecasting models that can be used in improving integrated pest management strategies for these two pests.

The carnation tortrix moth, Cacoecimorpha pronubana, and the light brown apple moth, Epiphyas postvittana (Walker, 1863) (Lepidoptera: Tortricidae) are two important polyphagous pest species affecting a wide range of plant species many of which are horticultural crops. Crop damage is caused by the larvae of these two moths rolling leaves together and feeding on the foliage. In order to understand how these two species are affected by a host plant through transgenerational dietary changes, we hypothesised that larval parental pretreatment diet affects growth and reproduction of offspring. We tested the performance of developmental traits of C. pronubana and E. postvittana on three host plant species (larval diet treatment) – Prunus (Rosaceae), Choisya (Rutaceae) and Griselinia (Griseliniaceae). For the experiment, we used larvae from a second generation of C. pronubana and E. postvittana reared either exclusively on Prunus, or reared exclusively on Griselinia (pretreatment). Regardless of whether moths had been reared on Prunus or Griselinia both species of host plant had a significant average effect on the duration of larval development and the pupal size of both species of moth, for E. postvittana, and for C. pronubana. Although, neither pretreatment, nor treatment had a significant overall effect on fecundity (number of eggs per clutch laid) in either species of moth, there was a significant interaction effect observed between the pretreatment and post‐treatment on fecundity for both species of moth. Our results suggest that changes of host plant species composition can affect the performance of offspring of both these polyphagous pest species intergenerationally in complex ways which are relevant to agroecosystems. Such phenomena may be important when developing new strategies for the integrated pest management of these two important pest species.

The carnation tortrix moth, Cacoecimorpha pronubana (Hübner, [1799]) (Lepidoptera: Tortricidae), is one of the most economically important insect species affecting the horticultural industry in the UK. The larvae consume foliage, flowers or fruits, and/or rolls leaves together with silken threads, negatively affecting the growth and/or aesthetics of the crop. In order to understand the polyphagous behaviour of this species within an ornamental crop habitat, we hypothesized that different host plant species affect its life history traits differently. This study investigated the effects of the host plant species on larval and pupal durations and sizes, and fecundity (the number of eggs and the number and size of egg clutches). At 20°C, 60% RH and a 16L:8D photoperiod larvae developed 10, 14, 20 and 36 days faster when reared on Christmas berry, Photinia (Rosaceae), than on cherry laurel, Prunus laurocerasus (Rosaceae), New Zealand broadleaf, Griselinia littoralis (Griseliniaceae), Mexican orange, Choisya ternata (Rutaceae), and firethorn, Pyracantha angustifolia (Rosaceae), respectively. Female pupae were 23.8 mg heavier than male pupae, and pupal weight was significantly correlated with the duration of larval development. The lowest and the highest mean numbers of eggs were produced by females reared on Pyracantha (41) and Photinia (202), respectively. Clutch size differed significantly among moths reared on different host plants, although the total number of eggs did not differ. This study showed that different ornamental host plants affect the development of C. pronubana differently. Improved understanding of the influence of host plant on the moth's life history parameters measured here will help in determining the economic impact that this species may have within the ornamental plant production environment, and may be used in developing more accurate crop protection methodologies within integrated pest management of this insect.