Neochrysocharis formosa (Westwood) (Hymenoptera: Eulophidae), a newly recorded parasitoid of the tomato moth, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), in Argentina

MG Luna VI Wada J La Salle NE Sánchez About the authors

Abstract

We report the first record of Neochrysocharis formosa (Westwood) parasitizing larvae of the tomato moth, Tuta absoluta (Meyrick), in tomato crops in Northern Buenos Aires Province, Argentina. Tomato moth larvae were sampled during four consecutive growing cycles, between 2003 and 2005, in 10 sites. Neochrysocharis formosa was present only in organic outdoor and protected crops, and predominantly during the late season. Parasitism rates varied from 1.5% to 5%. The finding of this species is a new record for Argentina and South America, and T. absoluta is a new host record.

Lycopersicum esculentum; biological control


SCIENTIFIC NOTE

Neochrysocharis formosa (Westwood) (Hymenoptera: Eulophidae), a newly recorded parasitoid of the tomato moth, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), in Argentina

MG LunaI; VI WadaI; J La SalleII; NE SánchezI

ICentro de Estudios Parasitológicos y de Vectores CEPAVE, La Plata, Argentina

IICSIRO Entomology, Black Mountain Laboratories, Canberra, Australia

Correspondence

ABSTRACT

We report the first record of Neochrysocharis formosa (Westwood) parasitizing larvae of the tomato moth, Tuta absoluta (Meyrick), in tomato crops in Northern Buenos Aires Province, Argentina. Tomato moth larvae were sampled during four consecutive growing cycles, between 2003 and 2005, in 10 sites. Neochrysocharis formosa was present only in organic outdoor and protected crops, and predominantly during the late season. Parasitism rates varied from 1.5% to 5%. The finding of this species is a new record for Argentina and South America, and T. absoluta is a new host record.

Keywords:Lycopersicum esculentum, biological control

The tomato moth, Tuta absoluta (Meyrick), is a main pest of greenhouse and outdoor tomato crops in South America (Siqueira et al 2000, Vargas 1970). Recently, it has spread to Europe and North African countries, where significant damage was reported (Urbaneja et al 2009, Viggiani et al 2009).

The use of chemical pesticides is a common practice to control the pest. However, due to its concealed habit, it requires several treatments per growing season, which in turn can result in a decrease of efficacy by the development of insecticide resistance by this pest (Ecole et al 2000, Siqueira et al 2000, Lietti et al 2005, Strassera 2009). In the search for other pest management practices, biological control is a reliable alternative to be considered (Altieri & Nichollls 1999, van Lenteren & Manzaroli 2000).

In this paper we report the first record of Neochrysocharis formosa (Westwood), an eulophid parasitoid, parasitizing T. absoluta larvae in tomato crops in Northern Buenos Aires Province, Argentina. This finding is a new record for Argentina and South America, and T. absoluta is a new host record.

Tomato moth larvae were sampled during four consecutive growing cycles (two in spring, early season, and two in summer, late season), from 2003 to 2005, in an important horticultural region located in the surroundings of La Plata (Buenos Aires province, Argentina, 34º 58' S, 57º 59' W). Ten tomato fields (referred to as 'sites') were chosen, of which six were under organic and four conventionalpest control (i.e. Bt and / or purines vs. synthetic insecticide use by calendar applications, respectively). All of the conventional and half of the organic crops were protected (open-sided plastic greenhouses) and the remaining were outdoor-cultivated. Each sample consisted of 100 leaves with apparent T. absoluta damage randomly picked. Samples were taken once per cropping cycle, exceptionally twice. Leaves were placed in sealed plastic bags and transported to the laboratory. Mines were dissected under a stereoscope to determine the presence of T. absoluta larvae and parasitoids. Parasitized hosts were kept individually in glass vials (5 ml), provided with a piece of wet paper, in a walk-in rearing chamber (25 ± 2ºC; 70 % RH, 14:10 L:D photoperiod) until parasitoid pupation.

We recorded the number of preimaginal individuals of T. absoluta and the number of larvae and pupae of N. formosa. At each sample site, the percentage parasitism was calculated as the number of parasitized hosts/ total number of hosts collected × 100. Voucher parasitoid specimens were deposited in the Museo de La Plata (La Plata, Argentina) and in the Australian National Insect Collection (Australia).

Approximately 2,403 T. absoluta larvae were collected and reared from early crops and another 3,208 from late crops. Neochrysocharis formosa was only present in organic outdoor and protected crops, and predominantly in late season (Table 1). Thus, it was found in five out of six sites, at 1.5% to 5% percentage of parasitism. Exceptionally, N. formosa was registered in one early organic site, where it reached approximately 11% of parasitism (Table 1). Interestingly, it was found coexisting in most sites with the native eulophid Dineulophus phtorimaeae de Santis. However, when N. formosa was found at early season, the proportion of parasitism was much higher (92%) than that of D. phtorimaeae, but closer to equal rates (46%) in late crops. Neochrysocharis formosa could develop earlier during the cropping cycle, probably due to its wider host range that would allow to use alternative hosts and crops (both outdoor and greenhouse) throughout the year (Bene et al 1985, Cabello et al 1994), and also because one of its competitors, D. phtorimaeae, apparently finds better habitat conditions in late non-protected crops (Luna et al 2010).

Neochrysocharis formosa is now known from all continents except Australia, and has an extremely varied biology (Noyes 2003). It is currently considered cosmopolitan after several introductions for biological control. In Argentina, there are no reports of any intentional introduction of this species; however, lack of previous records may be more an indication of a poor knowledge of its distribution than its absence (Hansson 1995).

Neochrysocharis formosa is a quite polyphagous species known to attack a wide variety of leafmining and gall forming insects. It has been recorded as a primary parasitoid from well over 100 species of hosts in four different orders (Coleoptera, Diptera, Hymenoptera, Lepidoptera) and it is also known to practice non-concurrent host feeding and acts as a hyperparasitoid. It has been reported in horticultural crops as tomato, eggplant, celery, several Fabaceae and Brassicaceae, and melon, and in floral as chrysantemum and gerbera. It is present in cultivated and non-cultivated plant species and, in total, it has been recorded from over 60 different plant species in 25 families (Noyes 2003). Neochrysocharis formosa is an endoparasitoid, which usually emerges from its host in its last larval stage and pupates externally. There are reports describing high natural levels of control (> 50%) of of Liriomyza spp. larvae by N. formosa (Tryon & Poe 1981, Bene et al 1985, Cabello et al 1994).

Considering its spontaneous presence in tomato crops in the region and its proved efficacy as a biological control agent, it would be worth continuing studies to assess the potential of N. formosa against T. absoluta. This fits in well with the strategy proposed to control generalist herbivore species (like leafminers), which recommends conservation biological control of indigenous natural enemies as a starting point rather than the introduction of exotic natural enemies (Murphy & La Salle 1999). A pest management programme that includes regular monitoring and use of selective pesticides was previously demonstrated to be suitable to preserve N. formosa in tomato crops (Schuster et al 1979). Further biological studies on N. formosa, as well as another T. absoluta parasitoid species, would establish a foundation for such a conservation biological control program.

Acknowledgments

We thank the tomato producers I. Abán, M. Del Pino, M. Maita, R. López, S. Parrillo, P. Peralta and M.E. Senattori. To M.E Strassera (AER-INTA Gran Buenos Aires) and E. Nieves (CEPAVE) for technical assistance. A. Salvo (UNCor, Argentina) kindly provided useful suggestions and bibliography. This research was funded by ANPCyT (IM 40-2000), CONICET (PIP 2000), and UNLP (Nº 396, 01/01/2002-2006).

  • Correspondence:
    M Gabriela Luna
    Centro de Estudios Parasitológicos y de Vectores - CEPAVE (CCT La Plata CONICET y UNLP)
    Calle 2 nº 584 (1900), La Plata, Argentina
  • Received 21 May 2010 and accepted 05 October 2010

    Edited by José R P Parra - ESALQ/USP

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    Correspondence: M Gabriela Luna Centro de Estudios Parasitológicos y de Vectores - CEPAVE (CCT La Plata CONICET y UNLP) Calle 2 nº 584 (1900), La Plata, Argentina lunam@cepave.edu.ar

    Publication Dates

    • Publication in this collection
      21 June 2011
    • Date of issue
      June 2011

    History

    • Received
      21 May 2010
    • Accepted
      05 Oct 2010
    Sociedade Entomológica do Brasil Sociedade Entomológica do Brasil, R. Harry Prochet, 55, 86047-040 Londrina PR Brasil, Tel.: (55 43) 3342 3987 - Londrina - PR - Brazil
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