ECONEX PLUSIA (CHRYSODEIXIS) CHALCITES

Sexual pheromone diffuser of the species Plusia chalcites to attract males, with a duration of 40 days in normal field conditions.

Diffuser in the shape of a closed polyethylene vial. It is packaged individually in an aluminium sachet with labelled instructions. Once taken out of the sachet, the diffuser does not need any activation operation. Simply place it directly in the trap.

Plusia chalcites is a tropical-subtropical species that damages various crops including those of major economic importance.  It is found throughout the Iberian Peninsula, the Balearic and Canary Islands.  It is present in a more dispersed fashion in central and southern Europe, northwest Africa, Asia and Oceania. 

Crops affected: Aubergine, marrow, strawberry, beans, melon, cucumber, pepper, watermelon, tomato, bananas, etc.

MORPHOLOGY AND BIOLOGY

Egg: The eggs are generally laid in isolation and scattered on the plant surface. The egg is dome-shaped with a striated texture and is off-white in colour

Larva: The larva has a small, sharp, green head with a lateral, black stripe.  The body is an intense green colour with fine, white lateral dorsal lines on it.  The body is sharp and enlarges towards the end of the larval stage.  It has 3 pairs of thoracic legs and three pairs of false abdominal legs. At its final stage it can measure 3.5 cm in length.

Pupa: The pupa is found inside a silken cocoon on the leaves of the cultivated plant or on adventitious plants (weeds).  Initially it is an off-white colour, turning green later and gradually darkening by the end of its development.   It measures approx. 2 cm in length.

Adult: The adult has a wing span of 4 to 4.5 cm.  The front wings are golden-brown.  Its morphology is similar to that of Plusia (Autographa) gamma but differs from it in the front wings which have two oblique silver spots, ribbed with white that are characteristic of it.

The lifecycle is holometabolic. The caterpillar goes through stages of egg, larva, pupa and adult. The life cycle is continuous and there will be an overlap between the different stages.   They are able to winter in the larval form as it has a marked resistance to the cold.

Once the adults have reached sexual maturity the life cycle begins with reproduction which happens over 4 to 8 days.  After copulation the eggs are laid on the underside of the leaves.  The development of the eggs varies depending on temperature, ranging from 3 days at 26^oC to 18 days at 12^oC.  

Embryonic development lasts from 5 to 25 days (20^oC).  Once the eggs hatch they are in the first larval stage.  The larval stage lasts 44 to 45 days (20^oC) and the pupal stage lasts 15 to 25 days at the same temperature.

Females can lay 500 eggs.

The caterpillars reach the final larval stage when they weave a silk cocoon on the underside of the leaves or in the folds of the leaves.

The caterpillars can emerge throughout the year.  They more commonly emerge in late summer and autumn and coincide with the adult flights.  Different generations can overlap in the same crop and there are usually 2 to 3 generations a year.

SOURCE: Agricultural Council of Andalusia (Spain)

DETECTION AND MONITORING

1 to 2 traps should be set per hectare, placed at crop level. They can be placed on a support for this purpose. The traps should be set in spring.

MASS TRAPPING

Mostly the males of this species are captured, in order to reduce the mating, so that non-copulated females will have unviable eggs. This reduces the pest population

To carry out mass trappings the number of traps per area should be increased depending on the location and homogeneity of the crops. One trap can control an area of between 500 and 1,000 m². This entails a trap density of 10 to 20 traps per hectare.

NECESSARY MATERIAL

An ECONEX POLILLERO, ECONEX GREEN POLILLERO or EOSTRAP® trap.

A pheromone diffuser ECONEX PLUSIA (CHRYSODEIXIS) CHALCITES as attractant, which is placed in a small cage located in the center of the trap lid.

PERIOD OF USE

To achieve good control of Plusia (chrysodeixis) chalcites, it is advisable to combine the two methods: detection and monitoring and mass trapping.

In spring you can place 1 or 2 traps per hectare to detect the pest and observe the level of their populations. Through established thresholds of tolerance in each area, the control measures are later defined, in this case mass trapping.

The threshold of tolerance for Plusia (chrysodeixis) chalcites is very low and varies according to the area. Generally it is around 3 captures per trap and per week. Moment in which we recommend to set traps all over the crop for mass trappings.

DAMAGES

DIRECT DAMAGE: The caterpillars are active both day and night. When they are small they feed on the parenchyma of the leaves as can be seen by the holes on underside of the leaves. They become more voracious in later larval stages, making larger holes that are spread across the entire leaf.

The presence of small larvae do not cause any appreciableharm to a fully grown crop.  However in a newlytransplanted crop the larvae can get to 'blind' the plant affecting the apical bud.

The main damage to the crop is through defoliation, particularly in young plantations.  Although their eggs are not laid in clusters, their rapid growth   favours the concentration of many larvae on a single plant or on nearby plants, thereby increasing its degree of impact.

INDIRECT DAMAGE:  The wounds caused by this pest allow other pathogens (fungi, bacteria, etc.) to enter the plant.

FACTORS THAT INFLUENCE THE NUMBER OF TRAPS REQUIRED

Pest population, adjoining crops, level of control required, etc.

An important factor is crop size. More traps are needed in small and irregular sized crops than in uniform plots with a larger surface area. Another important factor is the distance from other plots that have the same pest. In such cases plot boundaries should be consolidated, so a trap density of up to 20 traps per hectare may be needed. More traps may be needed in the case of mass trappings

RESULTS

f technicians or farmers use the traps and pheromones as described here and when the first generation of adults emerges, then the effectiveness of this control system is very good, as proved by data from many organic farms. When large crop areas are covered, more than 95% of the pest is often controlled.

A factor limiting this system is where there are small farms in many places with neighbouring plots that have a high level of pest infestation. Apart from some important basic rules in controlling Plusia (chrysodeixis) chacites effectively, each farmer/technician should find his/her own system of achieving this and he/she may experiment with this system, even establishing his/he own tolerance thresholds.

STORAGE OF THE DIFFUSERS

The diffusers must be kept in their original container and in a refrigerator at 4^oC, or in the freezer at -18^oC, in which case they will remain valid for 2 and 4 years respectively.