Habits of Mocis latipes in grassland ecosystems.

Dear readers, in the previous issue we dealt with aspects of the life cycle of Mocis latipes, an insect that is detrimental to pastures, in this opportunity we will describe the habits and damage it can cause. Regarding the habits of the insect, it can be said that it tends to proliferate sporadically and explosively in pasture areas, since, according to some researchers, the arthropod does not proliferate in periods of water deficit or when rainfall increases, This is why in tropical areas with intermittent rains this type of insects can be observed, as occurs in the pastures of the Municipality of Colon, Zulia State, where they have been detected in June and December, when rainfall is intermittent.

On the other hand, when the eggs hatch, the larvae appear and in their first instars cause scratches on the tender parts of the leaves, presenting small translucent areas, because they only leave the lower cuticle of the leaves almost intact. Similarly, as the larvae develop, they begin to cause greater damage to the leaves, since it is observed as a kind of cut or perforations in the leaf lamina, sometimes leaving only the midrib of the leaf if it is not controlled in time.

1ST, 2nd and 3rd instar:these instars have an approximate duration of 8 days (2,3,3 days consecutively), during this period the small larvae begin to feed on the host plant, they tend to perform a kind of scraping of the leaves leaving translucent areas, because they only leave the lower cuticle of the leaves almost intact.

4th, 5thand 6th instar: one way to know if the larvae have already passed the 3rd instar when diagnostics are performed, is to take the larva and verify if they have two transverse spots on the back of dark color very similar to Spodoptera, when they are in these instars they begin to defoliate the leaves until leaving the midrib but if not controlled opportunely, a lava in the last instar well developed can reach an approximate length of 5 cm. On the other hand, it is necessary to emphasize that the present instars 4,5 and 6 have an approximate duration of 10 days (4,2,4 respectively).

The first thing to do is an inspection of the surfaces cultivated with grasses, since experience teaches that the control of a pest is based on a complete evaluation of the same, performing field reviews to identify the type of pest, determining whether we are in front of a sucking or chewing insect, so we can conduct a thorough investigation on the biological cycle, in addition to the phases and times when it causes damage, this will determine a suitable time for control, in addition to planning the most appropriate control method.

In the case of Mocis latipes, when there are susceptible pasture species and there is a history of attacks by these insects in neighboring areas, it is recommended that pastures be monitored frequently, especially if there are changes in climatic conditions, specifically when there is rainfall, since humidity will increase and combined with high temperatures in tropical areas, ideal conditions are created for the proliferation of the arthropod.

At present microbiological control methods are widely used, for preventive control it is recommended to apply Bacillus thuringiensis (wettable powder) at a rate of 0.5 - 0.75 kg /ha mixed with sufficient water at the beginning and at the end of the rains, It can also be applied when larvae are observed with very little development, i.e. in their first instars, the application should be made uniformly on the foliage of grass and weeds, preferably in the morning or late afternoon.

Another way to avoid the high presence of the insect in forage surfaces, is to use agroecological alternatives such as forage associations, either with herbaceous or shrub species, as it contributes to the balance of the ecosystem, since it would break the conventional management of the use of monocultures and can attract a variety of organisms (predators, entomopathogenic organisms) that can contribute to the control of certain pests.

Another way to keep paddocks with low possibilities of being attacked by the insect, is to carry out an adequate zootechnical management adjusting the animal load, this will avoid overgrazing and will keep the pastures physiologically active with a quick recovery after each cut, which translates into an active competition for space, light and nutrients with weeds, reducing the presence of these that can become hosts of the false meter worm.

If the economic threshold is exceeded, observing a high insect population in the paddocks, the application of synthetic pesticides such as emulsifiable Malathion 1.0 kg a.i./ha is recommended when the larvae are small; pesticides whose active ingredient is carbaryl and carbofuran can also be used, but they become extremely toxic, which can generate a decrease in the beneficial biota. If these types of chemical products are used, it is recommended to remove the animals from the pasture for a period of approximately 21-30 days, in order to prevent possible intoxication. Before this situation, neem extract could be tried for its control, since good results have been observed in some experimental trials for the control of the corn budworm.

Dear readers, as has been observed during the different publications related to insect pests, it has been reflected that the biodiversity present in the pastures depends on many factors that intervene directly in the ecosystem, therefore the management to which the agroecosystem is subjected can bring both positive and negative consequences. Currently the effects of climate change have generated an imbalance in agroecosystems, since the amount and distribution of rainfall in the year have varied greatly, which has influenced the intermittent presence of pests, so we must know their biological cycles and follow up in our pastures when we consider that there are ideal conditions for the proliferation of any of them.

- Aguilar, M. (2016). Diagnosis of the damage caused by the false meter (Mocis latipes) in the sugarcane crop (Saccharum officinarumL.) in Finca San José Buena Vista. Unpublished graduate work. University of San Carlos de Guatemala: Mazatenango Guatemala.

- Yepez , F. (2000). Lepidoptera masticadores de los pastos importance and management. Medellín: Universidad Nacional de Colombia.