Endemic Parasitoids Associated with Anastrepha spp. (Diptera: Tephritidae) Infesting Guava (Psidium Guajava) in Southern Bahia, Brazil

Abstract

Brazil harbors a very high diversity of Anas trepha species that infest a wide variety of hosts. Out of the 195 Anastrepha species currently de scribed, 95 species are known from Brazil, and these infest fruits in 31 plant families (Zucchi 2000). Many Myrtaceae are important fruit fly hosts, and approximately 25 species in the genera Psidium, Eugenia, and Syzygium are infested (Hernandez-Ortiz 2000). Guava (Psidium gua java L.), endemic to the Neotropical region, is the most valuable cultivated species in the Myrtaceae (Thaipong & Boonprakob 2005) and is one of the preferred fruit fly hosts in Brazil (Araujo & Zuc chi 2003; Raga et al. 2006). It is also noteworthy that fruit from the family Myrtaceae is particu larly attractive to parasitoids in the family Figiti dae. This suggests a long-standing tritrophic rela tionship among these parasitoids, fruit flies, and myrtaceous fruit (Guimar?es & Zucchi 2004; Guimar?es et al. 1999, 2003). Recent studies conducted in Central and South America revealed the presence of a large guild of native tephritid parasitoids (Ovruski et al. 2004, for review). Even though native parasitoids are potentially useful biological control agents of fruit flies, the available information on their diversity and abundance is still relatively scant for Brazil, where most systematic parasitoid surveys are re stricted to a few locations in the southern and southeastern regions (Canal & Zucchi 2000; Guimar?es et al. 2000; Uch?a-Fernandes et al. 2003). There is a considerable gap in these sur veys, especially in the northeastern region, which is responsible for significant fruit production in Brazil (Canal & Zucchi 2000; Gon?alves et al. 2006). In the state of Bahia, previous studies have focused on the eastern region, Rec?ncavo Baiano (between 38?30' and 40?09'S latitude and 12?18' and 13?36'W longitude), approximately 500 km to the north of the current study site (Matrangolo et al. 1998; Canal & Zucchi 2000, for review; Car valho 2005; Gon?alves et al. 2006). We present the results of a survey in which we systematically sampled guava fruits in Una, southern Bahia, a region in the coastal zone sur rounded by one of the few and largest remnants of the highly endangered mature coastal rainforest in Brazil (Faria et al. 2006). The Brazilian Atlan tic rainforest is considered one of the richest biomes on earth, and southern Bahia harbors high levels of endemism and diversity of plants and animals (Thomas et al. 1998; Faria 2006). Lit tle is known regarding tephritid species and their associated parasitoids in southern Bahia wet for est or in agricultural ecosystems surrounded by or next to it. However, it is noteworthy that studies carried out in Mexico confirmed that native host plants in the rainforest area provide an important reservoir of native Anastrepha parasitoids (L?pez et al. 1999; Aluja et al. 2003). Our study repre sents the first report describing the Anastrepha parasitoid guild and the tritrophic relationships among these organisms in southern Bahia. Our study site was a guava orchard of 0.5 ha within a 30-ha farm located in Una, Bahia, 40 m above sea level at 15?17'36S latitude and 39?04'31 W longitude. The farm is located in an area surrounded by mature coastal rainforest and the native vegetation is classified as tropical low land rainforest. Climate is defined as Af (tropical wet) with a mean annual temperature of 24.7?C and 1,827 mm rainfall. There is no distinct rainy season although rainfall is more concentrated from Feb to Apr and a dry period of 1-3 months may occur from Dec to Mar (Faria et al. 2006). The orchard comprised 100 trees of P. guajava cv Paluma and has been free of any pesticides for over 3 years. Fruit samples were collected weekly from Feb 2004 to Jan 2005. Samples of 10 ripe or ripening fruit were collected randomly both from the tree canopies and fallen fruit at the ground level. Sample sizes varied due to fruit availability throughout the year. The collected fruit were counted, weighed, and individually placed in plas tic containers with a layer of vermiculite and cov ered with voile cloth until larvae emerged and pu pated. All pupae obtained were placed in 30-mL plastic containers with a layer of vermiculite at the bottom and covered with voile cloth until adults emerged. Voucher specimens were depos