Leucoptera coffeella (Guérin-Mèneville & Perrottet, 1842 (Guerin-Meneville, 1842)

Fornazier, M. J., Martins, D. S., Fanton, C. J. & Benassi, V. L. R. M., 2019, INTEGRATED PEST MANAGEMENT IN CONILON COFFEE, Conilon coffee - The Coffea canephora produced in Brazil, Vitória, ES, Brasil: Incaper - Capixaba Institute for Research, Technical Assistance and Rural Extension, pp. 493-533 : 2021-2024

Leucoptera coffeella (Guérin-Mèneville & Perrottet, 1842 ( Lepidoptera : Lyonetiidae )

Description and Biology

The African continent is considered as the region of origin of the coffee leaf miner, which has spread throughout the world and is present in all regions where coffee is grown. In Brazil, the coffee leaf miner presence was observed from 1850 ( GALLO et al., 2002).

The moth is very small, presenting 6.5 mm of wingspan; the wings are silver-white in the dorsal part with a dark circular patch of yellow halo at the ends ( Figure 6A ). During the day, they hide on the lower part of the leaves and at dusk, leave the hiding place and begin their activities. The lay is performed on the upper face of the leaves ( MORAES, 1998), and the average per night is seven eggs. They do not usually put more than one egg in the same place. To this point, several points of the same leaf or different leaves are visited by the female. The hatching of the caterpillars takes, in average, from 5 to 21 days, according to the conditions of temperature and humidity. They penetrate directly into the leaf mesophyll without coming in contact with the external environment; lodge between the two epidermis, causing the parenchyma destruction, forming the "mine̎. The destroyed regions are drying up, and the attacked area increases with the caterpillars development and the junction of the various "mines̎. The dry parts are easily detachable, being common to find a large number of caterpillars being found on the same leaf ( Figure 6B and 6C ).

The larval stage lasts between 9 and 40 days. At the end of this period, the caterpillars leave the interior of the leaves,leaving the lower part, where they weave silk thread and descend to the downer part of the coffee tree, where they will make a characteristic "X̎ shaped cocoon ( Figure 6D and 6E ). In this place, which provides the insect with proper moisture, pupae transformation occurs in most of the caterpillars. The pupal stage lasts from 5 to 26 days. After its completion, new moths appear, whose average longevity is 15 days. The evolutionary cycle varies from 19 to 87 days, being able to obtain from 7 to 9 annual generations. The climate exerts a great influence on the coffee leaf miner population. Higher temperatures and summer periods favor its development. These factors cause a great variation of the pest infestations from year to year and in the same crop (SOUZA; REIS; RIGITANO, 1998).

Losses

Until 1970, the coffee leaf miner was considered a problem only in the dry season, and coffee farmers lived with the insect without major problems. However, from then on, the plague began to occur indiscriminately in the dry and rainy seasons.The insects arrived in certain areas of São Paulo, causing serious damage and became the main pest of coffee in some regions. Its losses result from the reduction of the photosynthetic capacity by the leaves destruction and, mainly, by their fall. The symptoms are more visible in the upper part of the plant, where great defoliation is observed when the attack is intense. The coffee tree drastic defoliation caused by high pest infestations can affect the fruiting, with malformation of the floral buds and low survival of the fruits. It is considered one of the main pests of robusta coffee in the State of Rondônia, where 77% of the upper third leaves were infested by the coffee leaf miner ( COSTA et al., 2001). However, conilon coffee is considered to be moderately resistant to the pest, and the level of economic damage, defined as 30% of mined leaves with live caterpillars, for arabica coffee ( REIS et al., 2010), is hardly reached in commercial coffee plantations (MEDINA FILHO; CARVALHO; MONACO, 1977; FERREIRA; MATIELLO; PAULINI, 1979; AVILÉS et al., 1983; PAULINO et al., 1984). Coffee trees conducted at wider spacing tend to be more infested. Increased infestations have been observed associated with intensive summers, common in the months of January and February. The hot, dry climate, characteristic of the northern region of Espírito Santo, may favor an increase in the pest population throughout the year, accentuating itself in the months of prolonged drought. But the densification of crops that are being adopted in the State favors the maintenance of higher humidity and may disadvantage the population development of this pest. However, until now no reports of economic damages caused by the coffee leaf mines in conilon coffee in Brazil have been found.

Methods of control

Cultural

Bands of vegetation between fields allow an increase in the population of natural enemies, and it is recommended the rational management of the weeds, the use of mulch and intercropping in the growth of conilon coffee plantations, among other guidance based on the principles of agroecology. Plant resistance is a genetic method of pest control and a factor that has been observed by Incaper in the evaluation of available genetic material of C. canephora for identification of resistance sources that can be used in the improvement of Capixaba conilon .

Biological

The coffee leaf mine has a great number of parasite insects. However, the indiscriminate use of insecticides can alter the complex of parasitoids and predators and, consequently, cause population explosions of L. coffeella .

The main parasitoids reported associated with the coffee leaf miner belong to the Braconidae families [ Colastes letifer (Mann) , Eubadizon punctatus (Redolfi) , Mirax sp. ] and Eulophidae [ Closterocerus coffeellae (Ihering) , Citrospilus sp., Horismenus aeneicollis (Ashemead) , Neochrysocharis coffeae (Ihering) and Tetrastichus sp. ] (REIS; SOUZA; VENZON, 2002).

The main predators are from the Vespidae family [ Brachygastra lecheguana (Latreille) , Eumenes sp. , Polybia occidentalis (Olivier) , P.paulista (Ihering) , P.scutellaris (White) , Protonectarina sylveirae (Saussure) and Synoeca surinama (L.)]. These species of predators are social insects that destroy the L. coffeella galleries to feed on their caterpillars. Brachygastra lecheguana is the most frequent species, and in certain places, does a good pest control (SOUZA; REIS; RIGITANO, 1998).

Chemical

To carry out any kind of chemical treatment in order to control the coffee leaf miner, it is necessary to know the pest infestation and its natural enemies in the area planted with coffee.

Population sampling:

• The area should be divided into homogeneous terrains of 3 thousand to 5 thousand plants and, fortnightly, mainly in the summer periods, the random collection of about 200 leaves in 20 holes between the second and fifth pairs of leaves of the middle and higher thirds of coffee trees;

• after the collection, one should count the total number of sampled leaves and the number of mined leaves, determining the percentage of those which have been attacked, with the presence of live caterpillars. Observe the number of preyed mines and the parasitism in the samples.

Spraying:

Growing crops should be monitored for identification of early pest outbreaks,which must be quickly fought.The control can be carried out using several insecticides after finding infestation index higher than 25-30% of leaves infested with live caterpillars. In seedling nurseries and in plantations up to two years old, the control of the coffee leaf miner must be initiated when the onset symptoms of live caterpillars appear in the foci where the initial development of the pest population is observed.

Systemic via soil:

The systemic granulated insecticides applied via soil have efficiency to control the coffee leaf miner; however, its use was extremely low with the emergence of the neonicotinoid insecticides group that have greater safety for the applicator and the environment and are efficient for several pests control associated with coffee. The WG formulation of these new products allows the application in drench, liquid way. The use of insecticides via soil in a preventive way requires a perfect knowledge of the pest history and its losses to the terrain to be treated, in order to avoid that its use becomes uneconomical. The minimum use of insecticides and in a localized way, will help the preservation of the beneficial entomofauna that acts efficiently in the natural control of the miner.

Figures

Figure 6. Moth (A); coffee leaf damage (B and C); caterpillar at the beginning of pupal stage (D); and the characteristic X-shaped cocoon of coffee tree miner (E).