Academic literature on the topic 'Light brown apple moth'

Trichogramma carverae Oatman and Pinto is mass-released for biological control of the leafroller pest, light brown apple moth, Epiphyas postvittana (Walker) in Australian vineyards. Parasitoid performance can, however, be constrained by a lack of suitable adult food and no information is available on the effect of nectar on the parasitism and longevity of T. carverae. To address this, the effect of alyssum, Lobularia maritima (L.) flowers on E. postvittana parasitism was studied in a vineyard experiment with and without releases of T. carverae. Egg parasitoid activity was assessed with E. postvittana egg �sentinel cards� and no parasitism was recorded in plots without T. carverae releases. Where T. carverae were released, there was no significant enhancement of parasitism by the presence of L. maritima flowers. Three hypotheses were subsequently tested to account for the lack of an effect: (i) T. carverae does not benefit from L. maritima nectar, (ii) T. carverae was feeding on nectar from other flowering plants (weeds) present in the vineyard, (iii) T. carverae was feeding on sugars from ripe grapes. A growth-cabinet experiment using potted L. maritima plants with and without flowers did not support hypothesis one. No parasitism was recorded after day two for T. carverae caged without flowers whilst parasitism occured until day eight in the presence of flowers. A laboratory experiment with common vineyard weeds (Trifolium repens, Hypochoeris radicata, Echium plantagineum) as well as L. maritima did not support hypothesis one but gave partial support to hypothesis two. Survival of T. carverae was enhanced to a small but statistically significant extent in vials with intact flowers of L. maritima, white clover (T. repens) and catsear (H. radicata) but not in vials with flowering shoots of these species from which flowers and flowering buds had been removed. Paterson�s curse (E. plantagineum) flowers had no effect on T. carverae survival. In a laboratory study, punctured grapes significantly enhanced T. carverae survival compared with a treatment without grapes, supporting hypothesis three. Trichogramma carverae performance in the field experiment was probably also constrained by relatively cool and wet weather. Further work on the enhancement of T. carverae efficacy by L. maritima and other carbohydrate sources is warranted. Greenhouse and field experiments were conducted to investigate whether T. carverae benefit from different groundcover plant species. Ten T. carverae adults (<24h after eclosion) were caged with different groundcover species and a control with no plant materials. Epiphyas postvittana egg sentinel cards were used to measure parasitism and longevity was recorded visually. Survival and realised parasitism of T. carverae was significantly higher in L. maritima than in Brassica juncea, Coriandrum sativum, shoots of these species from which flowers had been removed and nil control treatments. A similar experiment with Fagopyrum esculentum (with- and without-flowers) and a control treatment showed that survival was significantly higher in intact F. esculentum than in without-flower and control treatments. There was no significant treatment effect on parasitism in the early stages of that experiment, though parasitism was recorded in the presence of F. esculentum flowers for 12 days, compared with 6 days in other treatments. Higher parasitism was observed in intact Borago officinalis than in the flowerless shoot, water only and no plant material control treatments in a third experiment. There was no significant treatment effect on parasitism. Fitted exponential curves for survival data differed significantly in curvature in the first, second and third experiments but the slope was a non-significant parameter in the second and third experiments. In a second series of laboratory experiments, one male and one female T. carverae were caged with groundcover species to investigate male and female longevity and daily fecundity. Both male and female longevity in F. esculentum and L. maritima treatments were significantly higher than on shoots of these species from which flowers had been removed, and than in the control treatments. Daily fecundity was significantly greater in the intact L. maritima treatment than in all other treatments. Fitted exponential curves for daily fecundity differed significantly in position and slope but not in curvature. There was no significant treatment effect on longevity or parasitism when a male and female were caged with intact B. juncea, B. officinalis or without-flower of these species, nor in the treatment with no plant materials. No parasitism was observed in a survey of naturally occurring egg parasitoids on two sites close to Orange and Canowindra in New South Wales, illustrating the importance of mass releases of T. carverae in biological control of E. postvittana. In an experiment on the Canowindra site, parasitism was significantly higher on day one and day two after T. carverae release when with-flower treatments were compared with without-flower treatments. Parasitism was significantly higher in the F. esculentum treatment than in C. sativum, L. maritima, vegetation without-flowers and control treatments on these dates. On day five, parasitism was higher in C. sativum than in all other treatments. There was no significant increase in parasitism in a second experiment conducted on the Orange site. Coriandrum sativum, F. esculentum and L. maritima appear to be suitable adult food sources for T. carverae and offer some scope for habitat manipulation in vineyards The adults of many parasitoid species require nectar for optimal fitness but very little is known about flower recognition. Flight cage experiments showed that the adults of T. carverae benefited from L. maritima bearing white flowers to a greater extent than was the case for light pink, dark pink or purple flowered cultivars, despite all cultivars producing nectar. Survival and realised parasitism on non-white flowers were no greater than when the parasitoids were caged on L. maritima shoots from which flowers had been removed. The possibility that differences between L. maritima cultivars were due to factors other than flower colour, such as nectar quality, was excluded by dyeing white L. maritima flowers by placing the roots of the plants in 5% food dye (blue or pink) solution. Survival of T. carverae was lower on dyed L. maritima flowers than on undyed white flowers. Mixing the same dyes with honey in a third experiment conducted in the dark showed that the low level of feeding on dyed flowers was unlikely to be the result of olfactory or gustatory cues. Flower colour appears, therefore, to be a critical factor in the choice of plants used to enhance biological control, and is likely to also be a factor in the role parasitoids play in structuring invertebrate communities. Provision of nectar producing plants to increase the effectiveness of biological control is one aspect of habitat manipulation, but care needs to be taken to avoid the use of plant species that may benefit pest species. Greenhouse experiments were conducted to investigate whether the adult E. postvittana and larvae benefit from nectar producing groundcover species. Newly emerged E. postvittana adults were caged with different groundcover species and a honey-based artificial adult diet. The longevity of male and female E. postvittana when caged with shoots of borage (B. officinalis) and buckwheat (F. esculentum) bearing flowers was as long as when fed a honey-based artificial diet. This effect was not evident when caged with shoots of these plants from which flowers had been removed. Longevity was significantly lower than in the artificial diet treatment when caged with coriander (C. sativum) or alyssum (L. maritima) irrespective of whether flowers were present or not. There was no significant treatment effect on the lifetime fecundity of E. postvittana. A second experiment with mustard (B. juncea) (with- and without-flowers), water only and honey-based artificial adult diet showed no significant treatment effects on the longevity of male and female E. postvittana or on the lifetime fecundity of E. postvittana. The anomalous lack of a difference between the water and honey-based diet treatments precludes making conclusions on the value of B. juncea for E. postvittana. Two greenhouse experiments were conducted to evaluate the effects of groundcover species on the larval development of E. postvittana. In the first experiment, larval mortality was significantly higher in C. sativum, and L. maritima than in B. juncea, B. officinalis and white clover (T. repens) a known host of E. postvittana. Coriandrum sativum and L. maritima extended the larval period. In B. juncea and B. officinalis, mortality did not differ from that in T. repens. In F. esculentum, larval mortality was significantly higher than in T. repens. A short larval period was observed on B. juncea, B. officinalis and F. esculentum. Fitted exponential curves for larval mortality differed significantly in curvature between plant treatments. Similarly, successful pupation was significantly lower in C. sativum, F. esculentum and L. maritima than in T. repens. The percentage of successful pupation in B. juncea and B. officinalis did not differ from F. esculentum and T. repens. Fitted exponential curves for pupation differed significantly in curvature. A similar trend was observed in a second experiment with potted plants. The overall results suggest that C. sativum and L. maritima denied benefit to E. postvittana adults and larvae, so could be planted as vineyard groundcover with minimal risk of exacerbating this pest. Overall results suggest that T. carverae require nutrients to reach their full reproductive potential and flowers provide such nutrients. Lobularia maritima and C. sativum may be considered �selective food plants� for T. carverae whereas F. esculentum appears to be a �non-selective food plant�; both T. carverae and E. postvittana benefited from it. Fruits such as grapes can be used as food resources in habitat manipulation and this merits further research. This result also suggests that within species flower colour is an important factor for flower selection in habitat manipulation.

Olfaction or the sense of smell is one of the major modes of communication in moths, playing an integral part in the moths' ability to locate mates for reproduction, location of host plants and oviposition sites. Some of the key players of the moths' olfactory system include general odorant binding proteins and olfactory receptors (OR). The aim of this study was to investigate the molecular mechanisms of olfaction in the light brown apple moth, Epiphyas postvittana. These data will contribute to the development of new pest control strategies for the moth and the development of olfactory biosensors. E. postvittana OR1 (EpOR1) is closely related to the pheromone receptors (PR) of other lepidopterans, but is expressed at similar levels in male and female antennae. Functional analysis in Sf9 cells demonstrated that it binds important plant semiochemicals but not pheromone. EpOR1 is sensitive to methyl salicylate, recognising this odorant to a low concentration of 10-15M. EpOR1 also binds a range of terpenes which showed Hill slopes ranging from 0.33--3.2. E. postvittana GOBP2 (EpGOBP2) was expressed in bacteria and purified to homogeneity. Binding analysis revealed it was able to bind octanol, α-farnesene, methyl salicylate, nerol, eucalyptol, geranyl acetate and pentyl acetate, but not citral, geranial and geraniol. EpGOBP2 was able to replace DMSO as a solubilising agent for methyl salicylate and geranyl acetate in a functional assay of EpOR1 in Sf9 cells. The sensitivity of EpOR1 for these two ligands in vitro was enhanced in the presence of EpGOBP2 [EC50 of EpOR1 with methyl salicylate in DMSO is (1.8 ± 0.9) x 10-12M and EC50 of EpOR1 with methyl salicylate in the presence on EpGOBP2 is (1.19 ± 0.82) x 10-13M], suggesting that EpGOBP2 might not only be acting as a solubilising agent but also as an activated ligand. Forty-nine new ORs were identified by deep transcriptomic sequencing and light coverage genome scanning of E. postvittana bringing the total number of ORs identified to date for this species to 52. Phylogenetic analysis revealed that associated with lineage, 24 ORs had one-to-one orthologs with ORs from the silkworm, Bombyx mori, while 28 E. postvittana ORs were expansions compared with B. mori. EpOR1 and EpOR6 are the most closely related E. postvittana ORs to other moth pheromone receptors. However, EpOR1 binds plant semiochemicals and not pheromone components and EpOR6 remains to be functionally annotated. Tissue expression analysis of 26 of the ORs revealed that three (EpOR30, 33 and 34) are more than 600 times more highly expressed in male than female antennae, making them good candidates for being the pheromone receptors of E. postvittana. Functional analysis of these ORs will reveal their role(s) in E. postvittana olfaction.

The light brown apple moth, Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae), is a key insect pest that belongs to one of the largest families of Lepidoptera, the Tortricidae, which has over 10,000 described species. This family includes numerous major pests of crops, forests, and ornamental plants. Hence an understanding of factors that affect parasitism of E. postvittana is potentially relevant to many other pest species and agroecosystems. Although a number of species are known to parasitise E. postvittana, only few of them were recorded attack E. postvittana in vineyards. Moreover, little is known about the interactions between E. postvittana and the parasitoids that are associated with it in crop and non-crop habitats. Therefore，this study addressed the question, “why are some parasitoids that attack light brown apple moth so uncommon in vineyards?” My thesis presents an investigation of the activities of parasitoids in vineyards and adjacent native vegetation in the Adelaide Hills wine region, and provides insights into the contribution they make towards natural biological control of the light brown apple moth. This project aimed to investigate: (1) parasitism rates of E. postvittana in vineyards and adjacent native vegetation; (2) competitive interactions between parasitoids that attack E. postvittana; (3) the influence of host plants on foraging behavior and parasitism by parasitoids that attack E. postvittana; and (4) temperature dependent development of Therophilus unimaculatus (Turner) (Hymenoptera: Braconidae), a common parasitoid species that attacks E. postvittana. Field experiments showed that T. unimaculatus was most active in non-crop native vegetation, whereas Dolichogenidea tasmanica (Cameron) (Hymenoptera: Braconidae) was the most common parasitoid of larval E. postvittana in vineyards. Molecular identification of larval tortricids that were parasitised by either of the two parasitoids species indicated these two parasitoids share a range of tortricid hosts in both vineyards and natural habitats. These results indicated that the two key parasitoids have different patterns of habitat use between vineyard and adjacent fields. In order to investigate why parasitoids are not equally distributed between vineyards and native vegetation, two further series of studies were conducted. The first investigated the extent of interspecific differences in host discrimination and the outcome of interspecific competition between D. tasmanica and T. unimaculatus. Both wasp species did not show differential behavioural responses to un-parasitised hosts or those that were parasitised by the other species. But immature D. tasmanica out-competed immature T. unimaculatus, irrespective of the order or interval between attacks by the two species. The second series of experiments examined the effects of host plants on the behaviour of D. tasmanica and T. unimaculatus. The effects of selected native and non-native host plants on the foraging preferences and efficiency of the two parasitoids were investigated through behavioural observations in a wind tunnel, and an experiment in the field. The results indicated that plants play a role that affects the habitat preferences of the two parasitoid species by influencing their foraging behaviour, and contribute to their distributions among habitats. By studying the temperature dependent development of T. unimaculatus under constant temperatures, its mean developmental time from egg to adult emergence was found to be shortest at 24.4 days at 28.9 ℃. The data were fitted to a non-linear model, which showed that the number of generations of T. unimaculatus is equal or greater than E. postvittana in three out of four locations in Australia, and the development of T. unimaculatus is faster when the temperature is above 16.0 ℃. Thus temperature affects the extent of synchronization between populations of T. unimaculatus and E. postvittana. Overall, this research contributes to understand the contributions that parasitoids make to natural biological control of E. postvittana. I concluded that native vegetation adjacent to vineyards is not always a reliable source of natural enemies for control of E. postvittana in vineyards and, more generally, that native vegetation is not always a reliable source of natural enemies in crops. Based on the results, the different habitat preference of the two parasitoid species is likely to be influenced by different degrees of host-species and habitat preferences, including responses to plants, and possibly specific life history differences between the two parasitoid species. The results of this research are also expected to be useful for understanding natural biological control of many other pest species.
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food and Wine, 2015

This study investigated the role that native insectary plants can play in promoting predatory arthropods, and thereby to enhance biological control of vineyard pests in Australia. I also set out to clarify if light brown apple moth (LBAM), Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae) is the main lepidopteran pest of grapevines in vineyards. Economic damage is caused to grapevines each season by pest species and E. postvittana is considered the dominant insect pest in Australian vineyards. However, recent observations suggested that species of tortricids other than E. postvittana may also act as pests. I investigated which tortricids are present in local vineyards, and whether the diversity of tortricids varied significantly among vineyards. I used molecular methods to determine the species of tortricids present in the canopies of grapevines over two growing seasons. This study confirms that E. postvittana is the most common tortricid pest in South Australian vineyards. Acropolitis rudisana (Walker) (Lepidoptera: Tortricidae), lucerne leafroller, Merophyas divulsana (Walker) (Lepidoptera: Tortricidae), and cotton tipworm, Crocidosema plebejana (Zeller) (Lepidoptera: Tortricidae) are also present in grapevine canopies but have not been reported previously. I also sought to determine if three native candidate native insectary plants, Christmas bush, Bursaria spinosa (Cav.) (Apiales: Pittosporaceae), prickly tea-tree, Leptospermum continentale (Forst. and G.Forst) (Myrtales: Myrtaceae), and wallaby grasses, Rytidosperma ssp. (DC) (Poales: Poaceae) have the capacity to support populations of predatory arthropods throughout the year, and if they may also provide habitat for economically damaging vineyards pests. Surveys were conducted in Adelaide Hills, Barossa Valley and Eden Valley vineyards over a 12-month period. The data were analysed to answer the following questions. What is the biological and functional diversity associated with each plant species? What are the features of an effective, functional native insectary plant assemblage for use in and around vineyards? What is the level of similarity and dissimilarity between the arthropod faunas of each plant species? Each plant species was found to support diverse predator species, which should attack a range of other arthropod pests across their life stages. It may also be possible to increase the functional diversity of predatory arthropods by more than three times when B. spinosa or L. continentale is incorporated into a landscape containing vineyards. Rytidosperma ssp. provides valuable complementary habitat for predatory species other than those commonly found in association with the woody perennials. When Rytidosperma ssp. are included in a viii plant assemblage with each woody plant species, this could result in an average net increase in predator morphospecies richness of at least 27%. Species distribution modelling was used to examine the potential range of each plant species under different climatic conditions. The insectary plants are naturally adapted to all of the major wine growing regions within Australia. Vineyard managers are encouraged to explore the use of B. spinosa, L. continentale and Rytidosperma ssp. as insectary plants in their vineyards. This information could help wine grape growers to manage pests like LBAM, save time and money by producing grapes with lower pest incidence, while enhancing the biodiversity of their vineyards.
Thesis (Ph.D.) -- University of Adelaide, School of Agriculture, Food & Wine, 2019