Eupoecilia ambiguella

Eupoecilia ambiguella

The vine moth (Eupoecilia ambiguella (Hübner, 1796)) is a moth belonging to the Tortricidae family.

Systematics –
From a systematic point of view it belongs to:
Eukaryota domain,
Kingdom Animalia,
Subkingdom Eumetazoa,
Superphylum Protostomia,
Phylum Arthropoda,
Subphylum Tracheata,
Superclass Hexapoda,
Class Insecta,
Subclass Pterygota,
Endopterygota cohort,
Superorder Oligoneoptera,
panorpoid section,
Order Lepidoptera,
Glossata suborder,
Infraorder Heteroneura,
Ditrysia division,
Superfamily Tortricoidea,
Family Tortricidae,
Subfamily Tortricinae,
Cochylini tribe,
Genus Eupoecilia,
Species E. ambiguella.
The term is basic:
– Tortrix ambiguella Hübner, 1796.
The terms are synonymous:
– Clysia roserana Frölich, 1828;
– Clysia turbinaris Meyrick, 1928;
– Cochylis roserana (Frölich, 1828);
– Conchylis ambiguella (Hübner, 1796);
– Eudorea ambiguella (Hübner, 1796);
– Eupoecilia ambiguella Walsingham, 1900;
– Loberia omphaciana Bruand, 1850;
– Tinea ambiguella Hübner, 1796;
– Tinea omphaciella Faure-Biguet de Simonest, 1801;
– Tortrix roserana Frölich, 1828.

Geographic Distribution and Habitat –
Eupoecilia ambiguella is a small moth that lives and reproduces in a vast territory that Europe, China (Anhui, Fujian, Gansu, Guizhou, Hebei, Heilongjiang, Henan, Hubei, Hunan, Jiangxi, Shaanxi, Shanxi, Sichuan, Tianjin, Xinjiang, Yunnan, Zhejiang), India, Japan, Korea, Mongolia and the Russian Far East.
In Italy it is widespread in the northern areas where it carries out two generations a year which often coincide with those of Lobesia botrana, for which control is often combined.
The larvae of Eupoecilia ambiguella feed mainly on dogwood, Rhamnus frangula, Hedera helix, Rhamnus cathartica, grapes and honeysuckle. The species is considered a pest to grapes.

Morphology –
Eupoecilia ambiguella is a small moth with a wingspan of 12-15 mm in the adult state.
The fore wings have the typical shape of the generality of the Tortricids, that is they are subtrapezoidal, with a convex costal margin and tendentially parallel to the anal one and a distal margin falling in an anteroposterior direction.
It differs from the other Tortricids and, therefore, also from Lobesia botrana due to the conformation of the cubit: the posterior cubitus (Cu2) is absent (present in the moth) and the posterior branch of Cu1 (C1b) originates from the last quarter of the discal cell (about three-quarters of the way down the disc cell in the moth).
Macroscopically, the design of the fore wings emerges more evidently: in Lobesia botrana the wings are marbled, in E. ambiguella they are yellowish-white in colour, with a brown sub-trapezoidal transversal band which extends in the intermediate zone from the costal margin to the anal and with a wider base in the costal margin. The hind wings are greyish in color and have a lighter colored fringe at the edge.
The egg has a lenticular and elliptical shape, 0.6 mm wide and 0.8 mm long; it has a yellowish color when it has just been laid, but then bearing an orange or reddish-brown speckle.
The larva, about 1 mm long at birth, is very similar to that of L. botrana, whitish in color with a dark head. At the end of the development it reaches 10-12 mm in length, of variable color from dark red to hazelnut-greenish, brown in the head and in the back of the first thoracic segment.
The chrysalis is reddish-brown in colour.

Attitude and biological cycle –
Eupoecilia ambiguella overwinters as a chrysalis, often under the bark of the plant or in other ravines of the vineyard, such as wooden posts, old stumps, etc.
Arrived in the spring period, between April and May (exceptionally in March-April) the adults and females appear on the flower clusters; this is the first generation of larvae that are anthophagous. The emergence of the males precedes those of the females on average.
The larval development takes place in about a month and nymphosis follows, with pupation starting from the second half of June. Nymphosis of the first generation lasts 9-12 days.
These larvae inchrysalidate in the cluster of flowers and the new adults that will follow the second generation appear between June and July. These ovipose on clusters already formed, the larvae that are born are carpophagous.
The larvae of this second generation have a slower growth rate than those of Lobesia, so much so that, at times, it lasts until October.
When ripe, the larva leaves the bunch and moves to the branches and stump where it pupates. The second generation larvae will then originate the chrysalises which will overwinter.
In this way the butterfly completes two generations a year; in warmer climates a 3rd generation can be had, but rarely, at the end of summer which, however, is often partial and incomplete.
The climate has a good impact on the biology of this moth which shows different behaviors in relation to both the climatic conditions and the phase of the cycle. The activity of the adults is favored by a mild climate and a fairly high relative humidity. The thermo-hygrometric optimum is placed at a temperature of 22-25 °C and a humidity of 70-100%, therefore torrid summers and hot and dry ones are clearly unfavourable. Furthermore, a marked mortality of the chrysalises of the wintering generation is noted in springs with strong temperature ranges, exceeding 20 °C.
Furthermore, the fertility of the females differs in the two generations: the females unfurled from the wintering chrysalis lay an average of 40-60 eggs, while those unearthed from the anthophagous generation lay an average of 30 eggs. The duration of the incubation is conditioned by the temperature and tends to decrease with higher temperatures. The eggs of the anthophagous generation hatch after 1-2 weeks, those of the carpophagous generation after just 3-4 days.
However, the flight period is more concentrated from May to August.

Ecological Role –
Together with Lobesia botrana, Eupoecilia ambiguella forms the group of carpophagous pests of greatest importance in the field of grapevine adversity. While occupying the same ecological niche as the first, its attacks never occur simultaneously.
The damage occurs both on the flower cluster (the first generation) and on the berries in the enlargement and veraison phase (second generation), causing the same negative effects as Lobesia.
However the E. ambiguella has an area that tends to extend further north, compared to that of L. botrana), as locations with a cooler and more humid climate are preferred.
From an ethological point of view, the adults of E. ambiguella have crepuscular and nocturnal habits, while during the day they rest by stationing themselves in shady and cool sites. Sexual activity is mediated by the attractive action exercised on males by the pheromone emitted by females.
The eggs of the females of the carpophagous generation are deposited singly, generally on the side of a flower bud, more rarely on the pedicels and on the rachis. The eggs of the females of the anthophagous generation are deposited, also singly, on the berry near the pedicel.
The larvae show a more pronounced voracity than those of L. botrana. A single anthophagous larva destroys 50-60 flowers, a carpophagous larva destroys about 20 berries. The anthophagous larvae wrap the flowers in glomeruli by means of silky threads and attack the flowers by piercing them from the outside. During development they build a small case which will eventually be used as a cocoon to protect the chrysalis. Pupation takes place within the infested glomeruli. The carpophagous larvae envelop globerules of berries in a dense web after which they penetrate inside the berries, partially emptying them of the contents.
Even if associated with the vine (for the obvious greater economic repercussions) the Eupoecilia ambiguella has a marked polyphagia which is poured on a wide species of plants, which under the taxonomic aspect, concern herbaceous or woody plants, generally with fruit berry or similar, belonging to genera such as Ribes, Lonicera, Viburnum, Rhamnus, Ligustrum, Juniperus, Hedera, etc. This polyphagia manifests itself, in particular, in the regions located beyond the vine cultivation area.
As far as the agronomic control systems of this moth are concerned, they can be divided into two main methods, namely, abiotic and biotic.
The natural control factors are of the abiotic or biotic type.
Among the first we remember, as mentioned, the thermo-hygrometric regime. The most effective action is performed by the temperature: thermal regimes above 30-32 °C can cause a high mortality of adults even in conditions of high relative humidity. The action of the climate can therefore be such as to determine the disappearance or modest activity of the moth in entire regions. This is what occurs in most of the Italian territory, where hot and dry summers disfavor the moth and the attention of winemakers is concentrated on the moth.
The biotic factors are instead represented by a high number of natural antagonists, whose overall incidence, however, is modest compared to that of the biological control of the moth. Among the parasitoid insects, we mention the genus Pimpla (Hymenoptera: Ichneumonidae) and the chalcidoid Colpoclypeus florus (Hymenoptera: Eulophidae). Among the active predators are the crisopes (Neuroptera: Chrysopidae) and the hoverflies (Diptera: Syrphidae). Finally, among the parasites, there are some entomopathogenic fungi (Beauveria bassiana, Spicaria farinosa).
In any case, the fight against E. ambiguella follows the criteria already expressed for the fight against L. botrana, above all because the moments of the interventions coincide; the intervention thresholds, obtained either by monitoring or by sampling, are cumulative of the damage and the flight of the two Moths. If we want to consider only E. ambiguella, the sampling and evaluation criteria of the intervention thresholds are the same seen for L. botrana; only the pheromones, the sex traps and the number of captures change to determine the intervention threshold. The traps must be placed in mid-April and the intervention threshold, for some types of traps (eg: traptest), is approximately 10 males captured per trap per week.
Sampling is carried out by checking the bunches (about 100 per hectare of vineyard), randomly selected on the branch, on a certain number of randomized stumps in the field.
The samplings must be carried out in three pre-established periods which more or less correspond to the three generations; in particular to flowering (the generation), from the thumbnail to the pre-closing of the bunch (2nd generation) and from veraison to the first half of September (3rd generation). With sampling, the intervention thresholds are:
– 1st generation: 35-50% of infested bunches;
– 2nd generation: it is possible to intervene at the first attacks on the grapes, in areas at risk; or with a threshold of 5% of bunches infested with larvae or in the presence of eggs or with penetration holes;
– 3rd generation: we intervene at a threshold of 5% of infested bunches.
To determine the intervention threshold can also be performed by the use of sex traps for monitoring. These must be installed (1 or 2 per hectare or per company) at the beginning of April; the hormonal capsule, and possibly also the fund, must be changed about 10 days before the expected flight of the next generation.
Generally the catches of the first generation are only indicative of the existing population (it is not advisable to negotiate).
For the other generations, the indicative threshold proposed in some environments is 10 males caught per trap per week (eg: traptest).
If you don’t want to consider the intervention threshold, you can treat it about 10-12 days after the first catches, if only one treatment is sufficient; or it can be treated after 9-13 days, with a subsequent intervention after 7 days, from the moment in which the capture phase of the males is growing.
The intervention is also activated when the threshold of infested bunches is exceeded, or at the first damage to the berries.
The guided fight can also be carried out with biotechnological products, in fact you can use biological formulations based on Bacillus thuringiensis ssp. kurstaki.
This biological insecticide, in consideration of its characteristics, must be distributed before the larvae have entered the berries; it is used with good results against the larvae of the second generation, distributing it twice (the first at 7-9 days and the second at 15-16 days from the beginning of the growing phase of the catches) or once only between the 19th and the 13th day from the beginning of the growing phase of the catches. Against the third generation (of the moth), it is applied 2 and 3 weeks after the start of the captures of the males. In these interventions it is advisable, to improve the effect of the treatment, to add about 500-1000 g of sugar per hectolitre of water.
In recent times, some research has been interested in preparations based on viruses and fungi (microbiological control), which seem to have activity against some tortricides including Lobesia, and sexual confusion techniques.
Finally, it should be remembered that agro-ecological techniques, with grassing, intercropping with other plants, the presence of hedges delimiting the plots, dry stone walls for the refuge of parasites or antagonists greatly improve the infestations of these insects until they are reduced below the threshold of intervention. Obviously, in the latter case it is necessary to make use of the advice of an agronomist with specific skills in agroecology.

Guido Bissanti

Sources
– Wikipedia, the free encyclopedia.
– GBIF, the Global Biodiversity Information Facility.
– Russo G., 1976. Agricultural entomology. Special Part. Liguori Publisher, Naples.
– Pollini A., 2002. Handbook of applied entomology. Edagricole, Bologna.
– Tremblay E., 1997. Applied entomology. Liguori Publisher, Naples.
Photo source:
– https://observation.org/photos/29146316.jpg