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1 September 2013 Seasonal Abundance of Galling Insects (Hymenoptera) on Caryocar brasiliense (Malpighiales: Caryocaraceae) Trees in the Cerrado
Germano Leão Demolin Leite, Ronnie Von Dos Santos Veloso, José Cola Zanuncio, Geraldo Wilson Fernandes, Chrystian Iezid Maia Almeida, José Milton Milagres Pereira, José Eduardo Serrão, Marcus Alvarenga Soares
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Abstract

Caryocar brasiliense Camb. (Malpighiales: Caryocaraceae) trees have a wide distribution in the Cerrado, a tropical Brazilian savanna, with high diversity and endemism. This plant is protected by federal laws and is untouched in deforested areas of the Cerrado. This situation increases the damage to leaves from galling insects (Hymenoptera). We studied populations of galling insects and their natural enemies on C. brasiliense trees for 3 successive yr during each season in the Cerrado. A globoid gall-inducing Eurytoma sp. (Hymenoptera: Eurytomidae) and its parasitoid Sycophila sp. (Hymenoptera: Eurytomidae) adults and predator Zelus armillatus (Lepeletier and Serville) (Hemiptera: Reduviidae) on the leaves were most abundant in the winter. The numbers of vein galls correlated negatively with the numbers of discoid and spherical galls, and the numbers of spherical galls correlated negatively with the numbers of discoid galls on C. brasiliense leaflets. Increased percentages of defoliation were correlated with reductions in the percentages of leaflets with total galls and leaflet area with total galls. Increased numbers of Sycophila sp. and decreased numbers of Ablerus magistretti Blanchard (Hymenoptera: Aphelinidae) were correlated with reduction in the numbers of Eurytoma sp. Numbers ofQuadrastichus sp. (Hymenoptera: Eulophidae) and A. magistretti correlated negatively with the numbers of Sycophila sp. Increased numbers of Z. armillatus were correlated with reduction in the numbers of Eurytoma sp. and its galls and parasitoids. We concluded that this differential temporal distribution of galling insects and their natural enemies was influenced by plant phenology and time of colonization on C. brasiliense leaves.

The Cerrado occupies about 23% of the Brazilian territory (Da Silva & Bates 2002) and is characterized by high diversity of plants and insects and present a high degree of endemism (Bridgewater et al. 2004). Due to increasing threats to is biodiversity the Cerrado has been elected as a biodiversity hotspot (Myers et al. 2000). The Cerrado primary use is for grain and cattle production (Aguiar & Camargo 2004), as well as reforestation with exotic species, primarily Eucalyptus (Zanuncio et al. 2002). Through several governmental mechanisms and incentives the Cerrado has been devastated in the last five decades leaving only 20% of the land intact (Klink & Machado 2005). Naturally, the Cerrado is formed by a complex mosaic of phytophysiognomies that range from open Cerrado formations (campo limpo) up to tall and woody forests of 10-15 meters high, called Cerradão (Oliveira & Marquis 2002). In southeastern Brazil large patches of this rich Cerrado is seen immersed in a matrix of agriculture (primarily soybean and sugar cane), cattle farms and cities (urbanization). This is the case in Montes Claros in northern Minas Gerais state.

Caryocar brasiliense Camb. (Malpighiales: Caryocaraceae) is a flag species of the Cerrado, presents wide distribution (Brandão & Gavilanes 1992; Bridgewater et al. 2004; Leite et al. 2006a) and can reach up to 10 m high while the canopy may reach 6 m wide (Leite et al. 2006a, 2011a, 2012a). The leaves of C. brasiliense are alternate, trifoliate and have high trichome density; the flowers are hermaphrodite but mostly cross pollinated. Fruit production is annual, and C. brasiliense blooms between Jul and Sep (dry period) with fructification from Oct and Jan (rainy season) (Leite et al. 2006a). The fruit is a drupe with 1–4 seeds, weighing 158.49 ± 8.14 g (fresh weigh) and with a volume of 314.90 ± 20.93 cm3 (Leite et al. 2006a). Its fruits have an internal mesocarp rich in oil, vitamins, and proteins, and contain many compounds of medicinal importance. Not surprisingly, it is widely used by humans for food, production of cosmetics, lubricants, and in the pharmaceutical industry (Segall et al. 2005; Ferreira & Junqueira 2007; Garcia et al. 2007; Khouri et al. 2007).

This species represents the main source of income of many communities (Leite et al. 2006a). Caryocar brasiliense are protected by federal laws and hence are left in deforested areas of the Cerrado. Isolated individuals of this plant in the agro-landscape suffer from increased leaf, flower, and fruit damage from insect herbivorous (i.e. Coleoptera, Lepidoptera, and Hemiptera), which affects their natural enemies (i.e. predators) (Leite et al. 2012b, c, d, e). Among these insects, there are four types of galling insects (Hymenoptera) found on the C. brasiliense leaves (Leite et al. 2009, 2011c, d, e). These galls, principally galling