Lepidoptera, Linnaeus, 1758

Bustillo, Alex, 2015, Part II. Pests, Compendium of Coffee Diseases and Pests, United States of America: The American Phytopathological Society, pp. 45-60 : 55-56

Leucopteracoffeellum (Guérin-Méneville) ( Lepidoptera : Lytiidae)

is amicro-lepidopteran, with a crepuscular nocturnal habit.The moths have a 6.5-mm wingspan and are brownish white withfrilledfore and hind wings. The larvae live in tuntheyconstruct within the leaf ( Fig. 94 ). Completely developedlarvaeare3.5 mm long.There is sexual dimorphism, a 1: 1sexratio. The eggs ofL. coffeellum , deposited by the malesontheuppersurface of the coffee leaves, have a gelatinousaspectand are difficultto see with the naked eye. The stageis4-6 days long. After eclosion, the L. coffeellum trpillarsenterthe leaftissue through the lower part of the whichisincontact withtheleafepidermis, without touching the outside. The coffee leaf miner has four larval instars. The larval stage lasts 16-26 days at temperatures around 20°C. After completing the larval period, larvae are transformed into pupae. They abandon the tunnels and weave a cocoon, normally at the axial part of the leaves ( Fig. 95 ). In general, more pupae are found on the lower third of the plant. Some larvae may fall onto the soil, where they pupate. The pupal stage lasts about 14 days at 20°C.

In the field, adult coffee leaf miners feed on honeydew. They mate mainly at night, although they can also mate in the morning after the dew dries. Preoviposition time is 3.6 days at 20°C. Oviposition does not occur below 18°C. The number of eggs laid per female is quite variable. On average, females place 75 eggs in 13 days on the leaves of susceptible coffee plants, with the largest number of eggs laid on day four.

Damage

Outbreaks of L. coffeellum are common on coffee plantations located at low altitudes and in warm areas and during dry seasons in areas where pesticides are frequently used. Right after eclosion, the caterpillars perforate the upper epidermis of the leaf and enter the mesophyll, feeding on palisade parenchyma cells. The lesions that form between the epidermis, also called galleries or tunnels, have irregular margins, are pale yellow, and later become brownish ( Fig. 96 ). The necrosed leaf surface reduces photosynthesis because the flux of water, minerals, and organic matter is limited. Nevertheless, the loss in production is mainly due to defoliation, provoked by the increase in the level of ethylene, principally when the lesions are near the petiole.

More tunneled leaves fall from the upper third of the plant, and the production losses are directly related to the intensity of attack and the period over which it takes place. Besides the direct damage, an intense attack by L. coffeellum weakens the plant and incites a 61% loss of the leaves, a 70% loss in the dry matter of the trunk, a 60% loss of the roots, and a 50% reduc ­ tion in the photosynthetic activity of the remaining leaves.

Population Management

Coffee leaf miners are now important pests in parts in Africa and the Americas, mostly as a result of heavy use of pesticides, which has eliminated many of the pest’s natural enemies within coffee groves. Abundance of coffee leaf miners is favored during dry seasons in areas of high temperatures. Monitoring can be facilitated with pheromone traps. Populations are reduced by the combined action of rainy seasons and a complex of natural enemies. Among the predators recorded are Polybia spp. , Polistes spp. , Chrysoperla externa (Hagen) , and parasitoids of the genera Closterocerus, Horismenus, Pnigalio , and Chrysocharis .

Figures

Fig. 94. Leucoptera coffeellum larva removed from its mine. (Courtesy J. C. Ortiz, Cenicafé)

Fig. 95. Leucoptera coffeellum cocoon. (Courtesy J. C. Ortiz, Cenicafé)

Fig. 96. Leaf damage caused by Leucoptera coffeellum. (Courtesy A. Bustillo, Cenicafé)