During the year 2000 I worked with a research team, lead by Dr. Sven-Erik Jacobsen, at the International Potato Center in Peru analyzing the pest problems in organic production of the andean quinoa grain (Chenopodium quinoa). I present here a brief synopsis of the crop and the related pest species, along with recommendations for integrated pest management of the crop.

Quinoa, Chenopodium quinoa Willdenow (Chenopodiaceae), is a crop that has been cultivated in dry and saline parts of Andean South America for thousands of years (Jacobsen et al. 2003). Due to an exceptional combination of vitamins, minerals, and a high protein quality, the grain is one of the most promising crops for increased production in Latin America and elsewhere (National Research Council 1989; Jacobsen 1997).

Several species of insects and birds causes economic losses for Peruvian and Bolivian quinoa farmers (Blanco 1982; Zanabria and Banegas 1997; Rasmussen et al. 2003; Robles et al. 2003). Part of the insects associated with quinoa are cosmopolitan polyphagous pests (e.g. Agrotis ipsilon (Hufnagel), Lepidoptera: Noctuidae), others are widespread pests endemic to the Andean region (e.g. Epicauta spp., Coleoptera: Meloidae) (Kranz et al. 1982; Zanabria and Banegas 1997). Yet the most damaging insect pests are Eurysacca quinoae Povolný and E. melanocampta (Meyrick) (Lepidoptera: Gelechiidae), two related moth species that apparently do not attack other crops than quinoa and its related kañiwa (Chenopodium pallidicaule) (Rasmussen et al. 2001a). For a more detailed review of the quinoa pests in Latin America and elsewhere, refer to Rasmussen et al. (2003).

The two species of quinoa moths are easily separated but has not been treated separately previous to 2000 (Rasmussen et al. 2001a), when it was found that in Puno and Huancayo of Peru E. quinoae would constitute the main pest of quinoa, rather than E. melanocampta as previously reported (e.g. Zanabria and Banegas 1997). According to the literature the moth will cause a 15 to 50% loss of production, and occasional they will destroy the entire production (Rasmussen et al., 2003). The moth has at least two or three generations throughout the vegetative period of the quinoa season from October to June in Peru and Bolivia, but knowledge on how the moth survives out of this period, has not been studied and is purely speculative (cf. Chacón 1963).

Organic quinoa production is in demand, and with the right management tools for native crop production, it is expected that quinoa will improve the economic well being of the poor rural populations and the small-scale Andean farmers of Peru and Bolivia (Jacobsen et al. 2003). Quinoa has been neglected international pest management interest, but it is the hope that several new initiatives will improve and expand the knowledge of the crop management and in particular the tools to manage the sometimes devastating pests in the crop.

The following four basic research areas have to be addressed in order to develop an IPM strategy for quinoa; (1) basic knowledge of the biology of the pest needs to be understood; (2) action and economical threshold levels should be determined; (3) continuous monitoring and evaluation of pest abundance should be initiated; and (4) lastly the existing control methods should be evaluated. The current knowledge of each of these areas are briefly reviewed below, and contrasted with the subjects that needs to be emphasized upon. The research is somewhat complicated by the fact that two different species – with apparently different biology – were recently differentiated, making it difficult to refer older biological studies to either of the two species as no voucher specimens were deposited in public Peruvian collections (Rasmussen et al. 2001a). The current knowledge of each of these areas are briefly reviewed below, and contrasted with the subject that needs to be emphasized upon.

Basic knowledge of the biology: The two species of quinoa feeding Eurysacca in Peru and Bolivia have been described and illustrated, but little is known for the phenology of the two species. Preliminary data suggests that E. quinoae is active during the first part of the cropping season, and only very late in the season E. melanocampta has been recorded from adjacent volunteer plants (Rasmussen, pers. obs.). Several previous studies of Eurysacca sp. (probably E. quinoae) demonstrated five instars and provide detailed description of the different instars reared in the laboratory (Quispe 1979; Ochoa 1990; Franco and Ochoa 1996; Flavio 1997). Attempts to rear E. quinoae in Puno, Huancayo, Lima, and Bolivia during the cropping season (2000) did not result in any adult oviposition, except for a very low number of eggs during the early part of the season in February 2000. Further biological studies of the pest are necessary to be able to rear both species under laboratory conditions. These studies are also needed to complete feeding trials (to determine host plant resistance and preference, see next), determine degree-days needed for development under controlled conditions, as well as observe copulating and oviposition behavior, and eventually also the diapausing behavior. Presently very little biological information for Eurysacca is available (Rasmussen et al. 2001b; Rasmussen et al. 2003, Rasmussen et al. in prep.).
Studies of moth population fluctuations over several years in different areas would help determine the edafoclimatic factors necessary for high population levels of the moth(s). Some preliminary data show that E. melanocampta was confined to volunteer quinoa plants after the cropping season, That host plant record should be further pursued, along with sampling of a wide range of wild Chenopdium species and other suggested wild host plants (Rasmussen et al. 2003), including a doubtful record for potato in Colombia (Povolny and Valencia 1986).

Action and economical threshold levels: Threshold levels should be established to help farmers decide when application or other control methods should be applied. Good preliminary data exists from Villanueva (1978), Blanco (1994), and Hidalgo (1999) on the damage caused by the larvae and economic thresholds. Action thresholds and general recommendations for the evaluation of moth abundances should be modeled based on previous work and eventually additional studies, including a wider range of variables than previously recorded (soil, climate, cultivars, rotation cycles, etc.). The farmer?s perspective on the impact of Eurysacca on the crop has never been gathered in a systematic way, perhaps through questionnaires. This would give additional background information for elaborating models for either of the threshold levels.

Monitoring and prediction of the pest: So far there has not been a standardized method for monitoring the pest, either as adults or larvae. A method for quantifying pest abundances would aid both to compare pest incidence in different regions of Peru and Bolivia, and to follow pest population fluctuations during different years. Studies so far have used different methods (Saravia and Calle 1984; Saravia and Germán 1988; Ruíz 1995), based on average larvae count per plant. The monitoring could include additional sampling methods, i.e. light trapping, sweep-netting, and other trapping methods to determine presence of adults (and consequently feeding larvae). An important step toward this would be the development of a pheromone for either of the two species. Efforts in 2000 to send wild collected pupae to the Institute for Plant Protection (IPO-DLO), Wageningen, The Netherlands, to determine of pheromone attractants was not successful. The pheromone would be a most important tool for devising a simple monitoring strategy for the moths, and a method control through mating disruption.

Control methods should be evaluated: If organic production is the research goal, chemical controls should not be included as a component of an overall IPM strategy for quinoa. However, most IPM programs will allow and recommend the use of insecticides based on action threshold and overall IPM strategies for the crop. Plant resistance in quinoa has been described in part by Castillo (1978) and elsewhere (Instituto Nacional de Investigación Agraria (INIA), seed protocols), recommending the use of cultivars with high saponin content and lax inflorescence against the Eurysacca moth. Unfortunately this resistance is insignificant for other pests of quinoa (Yábar et al. 2002). Cultural control and practices to avoid high pest populations remain to be tested using the above mentioned monitoring approaches. In quinoa production, crop rotation with potato, cereals (oat and barley), and legumes such as tarwi (Lupinus mutabilis) or beans (Vicia faba), is recommended to break the continuity of the food chain for oligophagous pests (Mujica 1993). For small-scale farming intercropping in the field with beans, tarwi, and corn is also recommended in Peru and Bolivia (Tapia 1997; Zanabria and Banegas 1997). Other recommendations include aspects of sowing date, nutrient management, irrigation, planting density/thinning, phytosanitation, and tillage practices (Dent 1995; Sharma and Nwanze 2000). Using corn as a trap plant was studied by Ruíz (1991). Pathogens have not been characterized from the moth(s), but may be of potential importance, along with biopesticides like botanical extracts (natural repellents) that has been effective for small-scale farmers (Gallegos et al. 1982; Saravia 1998). The last and maybe most promising control strategy is biological control from parasitoids. This has been reported several times, as there are some very efficient natural control agents associated with the quinoa moth (Delgado 1989; Ormachea and Quispe 1993; Rasmussen et al. 2001c), in particular Phytomyptera sp.n. (Diptera: Tachinidae), Gen.n. sp.n. (Hymenoptera: Ichneumonidae) and Copidosoma spp. (Hymenoptera: Encyrtidae), as well as other species of Ichneumonidae and Braconidae (Hymenoptera). An average pest control of 30% was found in all regions during the start of the cropping season for E. quinoae, and a much higher control rate (above 90%) late in the season of E. melanocamopta (Rasmussen, unpublished). To focus on some of these natural control agents could contribute significantly to the control of the Eurysacca moths. With additional focus on the biology of the parasitoids, massive rearing of these, their population fluctuations, abundance, etc., could contribute to pest control.

As previously stressed, some of the components are currently not very well known or standardized, along with references to past research on the Eurysacca moths. It is found that there is no ?good? method for monitoring the pest population, and only limited biological data for the pest, except for immature development (but not under controlled conditions). It is also stressed that action thresholds should be re-estimated based on current conditions. With more information, in particular with respect to the monitoring and prediction of the pest, as well as biological data, treatment effectiveness can be better evaluated, from this information. From those findings an IPM strategy can be developed. With the knowledge distributed out to farmers and extension workers, the moth population should be kept low and therefore severe production loss thus avoided.

Resumen en español
Se menciona los siguientes cuatro componentes para desarrollar una estrategia de manejo integrado de plagas (MIP) en quinua; (1) conocimiento básico de la biología de la plaga; (2) identificación del umbral de acción y el umbral económico; (3) iniciar un monitoreo continuo de la plaga en todas las regiones de producción; y (4) último evaluar los métodos de control existente. Con mas información, en especial al respecto de monitoreo y predicción de la plaga, tanto como datos biológicos, será posible mantener un nivel bajo de la población de polillas y así evitar perdidas de producción.

Se registra también las áreas poco estudiados y en especial se menciona la falta de monitoreo y modelos para predicción de la plaga, junto con datos de sobrevivencia de la polilla y los umbrales de acción actuales.

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