Biological control by tachinid flies (Diptera: Tachinidae) in Venezuela has been highly successful, mainly against sugarcane borers of the genus Diatraea. The parasitoid Amazonian fly, Lydella (=Metagonistylum) minense exerted a significant reduction of the percentages of infestation/internodes perforated by sugarcane borers in the plantings areas of Venezuela for more than 50 years, obtaining the consequent economic benefit. After the introduction of the braconid wasp Cotesia flavipes (Cameron), it was possible to control all Diatraea species, since L. minense showed a preference over D. saccharalis and a lesser extent over the other species.

Keywords: biological control, sugarcane, benefits, tachinids, Cotesia displacement, pest population reduction

Between 1949 and 1951, Box (1952),^1-3 studied the indigenous parasites of Diatraea in Venezuela which consisted of 19 species of Hymenoptera, 6 Diptera and 2 Cryptogams plants. He mentions the presence of Billaea (Paratheresia) claripalpis (Wulp), Myobiopsis (Leskiopalpus) diadema (Wiedemann), Palpozenillia (Zeniliia) palpalis (Aldrich) y Jaynesleskia (Leskiomima) jaynesi (Aldrich), in different places in Venezuela. The species B. claripalpis, M. diadema, P. palpalis and J. jaynesi were reported parasitizing different species of Diatraea in different plants and environments.

The history of the introduction and initial success of the Amazonian fly, Lydella (=Metagonistylum) minense in Venezuela, is described by Box (1956)⁴ as follows: it was discovered by J. G. Myers parasitizing larvae of D. saccharalis in aquatic grasses in the lower Amazon River and at the same time by O. Monte in southern Brazil, also attacking D. saccharalis.

Myers considered this parasite very promising in resolving the high infestations of the borer D. saccharalis in British Guiana. In a second expedition by Myers with L. C. Scaramuzza in 1933 and after several months of hard work, they sent 6 shipments of a total of 3,000 puparia, which were reproduced in the Georgetown laboratory.

The releases were made in the sugarcane fields of Guiana and the control results were surprising. In view of this successful experience, Box recommended this dipteran for Venezuela and between October 1950 and November 1951, shipments of the Amazonian breed began to be received from Trinidad and Sao Paulo, Brazil sent by L. C. Scaramuzza from Cuba.

Dyar and Heinrich,⁵ studied the American Moths of the Genus Diatraea and related species. Of the 14 species identified by Box in Venezuela (1948, 1951), 5 were considered important for sugarcane: D. saccharalis, D. impersonatella Guilding, D. centrella (Moschler), D. busckella Dyar & Heinrich and D. rosa Heinrich.^6-8

The different technical and scientific studies of various tachinid species, promoted by H. Box, were widely supported by the El Palmar Sugar Mill in 1953 and the results obtained showed that it was worth, following a biological control program. Between the 60s and 80s of the last century, the Amazon fly was released in all areas of the sugar mills through the production of their own laboratories, being the best example of that the El Palmar Mill where the fields least infested by Diatraea in Venezuela were observed, thanks to the perseverance of the people involved.

This work shows the success of the Amazonian fly, Lydella (=Metagonistylum) minense in the areas of influence of the Sugar Mills of Venezuela for more than 50 years, observing the reduction of the percentages of infestation or perforated internodes by Diatraea spp. (% I.I.), with the consequent economic benefit.^9,10

After the introduction of the braconid wasp Cotesia flavipes (Cameron),¹¹ it was possible to control all Diatraea species, since L. minense has preference over D. saccharalis and to a lesser extent over the other species.

In 1975, the Integrated Control Service laboratory (SERCOIN) was inaugurated in Acarigua, Portuguesa State, a company that undertook the production the Amazonian fly for the state Sugar Mills (CENAZUCA), using breeding technology through artificial diets, proposed by King et al.^12,13 and successively modified.^14,15

As an example of the effect of the Amazonian fly in the Sugar Mill El Palmar area, between 1953 and 1980, the % I.I. was dropped from 14.7% to 1.7%, and the percentage of average parasitism ranged between 22 and 68% (Figure 1). These results were achieved thru the release of 1,492,075 Amazonian flies.⁹ This trend continued through the years, until Servicio Biológico, C.A¹⁶ and the Fundación Azucarera para el Desarrollo, la Productividad y la Investigación (FUNDACAÑA) introduced C. flavipes, since 1988 and 1999, respectively, thus reducing the infestations to a minimum level.

Figure 1 Effect of the parasitism of L. minense and percent of intensity of infestation since the initial releases. Central El Palmar, (Aragua State).

In the sugar mill Azucarera Rio Turbio (Figure 2), it can be seen that L. minense lowered the percentage of D. saccharalis from 81% to 15.63% between 1959 to 1981 and in the same period the % I.I. dropped from 22.4 to 7.73. Practically since the introduction of C. flavipes in 1988,¹¹ C. flavipes prevailed over L. minense, and the effect of both parasitoids was important, reducing the % I.I. from 15.04 to 1.68 between the years 1962 and 2011, which translated into a benefit-cost of 41.25:1, (with the investment of 1 dollar in biological control, 41.25 benefit in sugar was recovered). In total, 4,090,245 L. minense were released from 1951 to 1999 and 115,334 gr. of C. flavipes (approximately 115,334,000 wasps) from 1988 to 2011, with a recovery of 157,345.23 MT of sugar.^17-19

The success was obtained through the biological control of sugarcane borers using releases of L. minense and later of C. flavipes, and an organized monitoring system in which the % I.I., and the percentage of parasitism in the different species were observed. Also, thanks to the establishment of the laboratory of the sugar mill El Palmar.

Since the 50’s of the last century, the production of these parasitoids was always available. From this beginning, laboratories were established in all the sugar mills and institutions such as the Instituto para el Fomento de la Produccion Azucarera (IFPA)²⁰ and private groups such as Servicio Biológico C.A., and FUNDACAÑA, companies that developed a mass production for the breeding of the hosts thru artificial diets and thus reach mass productions of the parasitoids, which allowed constant releases on a large scale. In this way, it has been possible to have a very important benefit-cost in the sugarcane industry in Venezuela.

None.

The authors declare that there are no conflicts of interest.

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