Diversity and infestation indices of fruit flies ( Diptera : Tephritidae ) in guava ( Psidium guajava L . )

The fruit flies are considered major pests in the world fruit production due to the direct damage they cause to fruits and the ability to adapt to areas where they are introduced. The objective of this research was to study the fruit fly diversity, the infestation indices in fruits and to characterize the tephritids community in a guava (Psidium guajava L.) cultivar "Paluma", in a commercial orchard located in São Luís, state of Maranhão, northeastern Brazil. In the survey, fly hunting bottles containing hydrolyzed protein in a ratio of 500 ml/10 L of water were used. To assess the infestation indices, fruits were collected, individualized in plastic containers with sterile sand, and kept in a climate-controlled chamber. 2,901 specimens of fruit flies were collected. From these, 2,328 were collected in traps and 573 in fruit samples. The species found belong to the genus Anastrepha, including Anastrepha striata, Anastrepha obliqua, Anastrepha fraterculus, Anastrepha sororcula, Anastrepha distincta, Anastrepha zenildae and Anastrepha pickeli. Considering the total tephritids collected in fruits and traps, a low diversity (H’ = 0.2689 and 0.4147, respectively) was found. A. striata predominated among the collected species. The largest number of insect pests captured occurred in May 2008, a period of increased guava fruit availability in the orchard. The infestation indices were 231.02 pupae/kg and 26.42 pupae/fruit.


INTRODUCTION
Fruit production in Brazil has grown significantly and the country holds a prominent position in the international market by increasing the position of fruit growing in the national economy.Brazil is the third largest fruit producer *Corresponding author.E-mail: rlemos@cca.uema.br.
Author(s) agree that this article remain permanently open access under the terms of the Creative Commons Attribution License 4.0 International License in the world and is a leading producer of tropical fruits (FAOSTAT, 2013).
The marketing of fresh fruit in the world is severely limited by the occurrence of fruit fly (Diptera: Tephritidae), which is considered as one of the main pests of the world fruit production, due to the direct damage they cause and the ability to adapt in other areas, where introduced (Godoy et al., 2011).Yield losses due to fruit damages caused by fruit flies is associated with high control costs, and affect international trade relations due to phytosanitary restrictions that are imposed (Godoy et al., 2011).The tephritids economic importance is due to the yield losses they cause in world fruit production, since they feed on fruits from several species.Moreover, they are quarantine pests (Araujo et al., 2013).
Guava (Psidium guajava L., Myrtaceae) is one of the most attacked fruits in Brazil by the fruit fly species Anastrepha spp.and Ceratitis capitata (Wied).
The population of fruit flies fluctuates due to a succession of primary or alternate hosts, the environment complexity and abiotic factors (Montes et al., 2011).The average temperature (°C) inversely influences the fruit fly occurrence, for example, lower temperatures favor an increase in the Tephritidae population (Araujo et al., 2008).With a population monitoring study, it is possible to follow the pest fluctuation in a specific area, to detect exotic or quarantine species, allowing for a more comprehensive characterization of the insect pest population in qualitative and quantitative terms.
Knowledge of fruit fly species of economic importance in a particular area, can only be obtained based on intensive surveys, made directly from host fruit, which enables detection of larvae present in the fruit, the degree of infestation in an orchard and the direct damage caused by the flies.Therefore, there is a need to determine the guava fruit infestation indices and to identify the fruit fly species that occur in the state of Maranhão, northeastern Brazil, in order develop low environmental impact strategies to control this insect.Thus, the aim of this work was to study diversity, the fruit infestation rates and to characterize the tephritid community in a commercial orchard of guava by faunal analysis.
The orchard was eight years old and was composed of 1,200 plants.The guava plant spacing was 6 × 5 m.The soil is from Itapecuru formation, classified as Latossol.The orchard was sprinkler irrigated with 6 mm water per plant every three days during the dry season.
Fourteen MacPhail model traps with attractive food (5% corn hydrolyzed protein, stabilized with borax), were installed under the tree canopies with 1.5 m height from the ground.Samples were collected every two weeks from February 2008 to January 2009.The captured insects were water sieved, separated by sex, counted and stored in bottles containing 70% alcohol solution for taxonomic identification, which was done based on the terminalia of female specimens, observing the aculeus.They were identified using a key from Zucchi (2000).
Mature fruits were collected at random on the top and from the ground under the trees to check the infestation rates.The fruits were weighed on a precision electronic scale in laboratory conditions and individually packaged in plastic containers with a thin layer of sterile sand (1.5 to 2.0 cm in height) on the bottom, to allow larvae to become pupae.These containers were covered and kept in a climate chamber of BOD type with temperature 25 ± 2°C and relative humidity 70 ± 10%, with photoperiod of 12 h and inspected every 48 h.
After 10 to 15 days, the substrate was sieved (1.5 mm mesh size) and the obtained pupae were counted and wrapped in transparent plastic containers with 6.5 cm in height and 4.5 cm in diameter, provided with a plastic cover pressure, for adult emergence observation.Thereafter, the adults were preserved in 70% alcohol solution for further identification.
Two parameters were used to obtain the infestation indices.The first was the number of pupae per fruit (pupae/fruit) and the second, the number of pupae per kg of fresh fruit (pupae/kg) (Araujo and Zucchi, 2003).Each infestation index refers to the average value obtained for the samples of infested host species.The maximum and minimum values indicate the indices variation according to the place of collection and the number of samples examined.
The fruit fly species faunal analyses was done by means of the software ANAFAU (Moraes et al., 2003).The tephritid community was characterized by the indices of frequency, constancy, richness, dominance and predominant species.The indices of evenness and the Shannon-Weaner diversity were also computed.The definition of extreme classes (super) was based on the class hierarchical classification (Silveira Neto et al., 1976).
A total of 273 female flies were identified in the guava fruits.A. striata was the major species reaching 94.5% of the total (Table 3).The presence of A. striata in this orchard suggests that there was a spread of this insect pest, since this species is more common in the north region of the country (Zucchi et al., 2011).A. striata was also the major species found in the traps, reaching 90.8%      (Spondias purpurea L.) in the municipality of Caxias and A. zenildae in guava (Oliveira et al., 2000) in the municipality of Santa Inês.Lemos et al. (2002), also found the predominance of A. striata in guava in the municipality of Itapecuru Mirim.Azevedo et al. (2010) and Santos et al. (2011), studying the main hosts of Anastrepha spp.found that A. fraterculus, A. sororcula, A. striata and A. zenildae focus on Myrtaceae, which has wide geographic distribution across the continent.This finding was possible due to to the fruit fly surveys carried out in the Cariri region, state of Ceará and the extreme south of the state of Bahia, respectively, both in the northeastern Brazil.Azevedo et al. (2010) Considering the total number of tephritids collected in fruits and traps, a low diversity (H' = 0.2689 and 0.4147, respectively) was found.The faunal analysis indicated that A. striata predominated among the species collected in fruits (Table 4) and traps (Table 5).Marsaro Junior et al. (2013) noted that A. striata, A. sororcula A. obliqua and A. fraterculus were the most frequent and predominant species found in a guava orchard in Boa Vista, state of Roraima, northern Brazil.These fruit fly species are reported as major insect pests of guava.
A. obliqua stood out as the dominant, very abundant and very common species whereas the others were only considered as frequent.Similarly, Oliveira et al. (2009) found that A. obliqua reached a very frequent rate in mango orchard in the coast of the state of Ceará.However, Zilli and Garcia (2010) and Alberti et al. ( 2012)  With regards to the Anastrepha spp.population fluctuation, there was a higher incidence of flies captured in May 2008, when fruits were found in abundance in the orchard (Figure 1).These results are similar to those reported by Araujo et al. (2008), Alberti et al. (2012), Santos et al. (2013) and Duarte at al. ( 2013) who explained that a high incidence of fruit flies can be related to the greater presence of fruit in the orchard.
A total of 304 guava fruit samples were obtained from February 2008 to January 2009.The average fruit weight varied from 0.072 to 0.165 kg.The average number of pupae obtained from these fruits varied from 9 to 370 individuals (Table 6).Infestation rates for guava commercial orchard in São Luis, state of Maranhão, northeastern Brazil, was higher in August and September 2008, reaching 231.2 pupae/kg and 26.42 pupae/fruit; and 125.8 pupae/kg and 9.43 pupae/fruit, respectively.Several factors may influence the fruit fly infestation indices in orchards.Azevedo et al. (2010) studying commercial orchards in the Cariri region noted that these tephritids population fluctuation is directly related to the availability of host fruits and the amount of rainfall in the

Table 2 .
Number of pupae and adults of Anastrepha spp.(Diptera: Tephritidae) obtained in fruits of guava cv.Paluma in São Luis, state of Maranhão, northeastern Brazil.

Table 3 .
Number of females of Anastrepha spp.(Diptera: Tephritidae) collected in a guava cv.Paluma commercial orchard in São Luis, state of Maranhão, northeastern Brazil.
of the total (Table3).Some fruit fly species associated with their hosts have been recorded in the state of Maranhao including A. obliqua in starfruit (Averrhoa carambola L.), A. striata in both guava and hog plum

Table 4 .
Faunal analysis of the Anastrepha spp.(Diptera: Tephritidae) collected in fruits in a guava cv.Paluma commercial orchard in São Luis, state of Maranhão, northeastern Brazil.
, found four Anastrepha spp.including A. zenildae, A. sororcula, A. fraterculus, A. obliqua and Ceratitis capitata associated with guava in the Cariri region, state of Ceará.Duarte et al. (2013) noted greater diversity of Anastrepha spp. in guava fruits in the state of São Paulo, southeast Brazil.Lima et al. (2012) observed that A. striata and A. obliqua predominated among the four species observed in mango orchards (Mangifera indica L.), in Boa Vista, state of Roraima, northern Brazil.Among the species collected in traps, there was the species A. pickeli, not yet recorded in the state of Maranhao.Araujo et al. (2009) recorded A. pickeli for the first time in the municipality of Mossoró, state of Rio Grande do Norte.Azevedo et al. (2010) also found A. pickeli in a study carried out in Cariri, state of Ceará, both states are located in northeastern Brazil.