Averrhoa carambola, fruit fly

Pasinato, Joel, Redaelli, Luiza Rodrigues, Botton, Marcos & Jesus-Barros, Cristiane Ramos de, 2019, Biology and fertility life table of Bactrocera carambolae on grape and acerola, Revista Brasileira de Entomologia 63 (3), pp. 217-223 : 218

Biology of carambola fruit fly on grape and acerola

The experiments were conducted from October 2016 to May 2017, with insects originating from the rearing. The adults used in the experiments with the grape cv. Itália and the acerola var. Junko were the sixth and the seventh generation reared in the laboratory, respectively .

The grapes used came from the São Francisco valley (Petrolina, Pernambuco, Brazil), whose insecticide applications ended 60 days before harvest and were collected at the harvest point. A sample of 20 berries was separated. They were measured, weighed, and the soluble solids (◦ Brix) were quantified using a digital refractometer (Hanna model – HI 96801) with the mean values recorded of 2.14 ± 0.03 cm, 0.008 ± 0.0003 g, and 15.1 ± 0.61 ◦ Brix, respectively. The grapes were first offered approximately seven days after harvesting .

Six groups of 20 couples from one of the sexually mature breeding cages (20–28 days old) were separated into plastic jars (21 × 14 × 12 cm), with the same food used during rearing and water. For each group, ten berries of V. vinifera were offered, so that the fruit flies acquired a previous contact with this oviposition substrate (experiment), for a period of 24 h. Before being offered to the flies, the grapes were inspected to ensure the absence of oviposition punctures from the field and remained immersed in hypochlorite solution at 0.005% for 1 h, according to Menezes and Assis (2004), then washed and dried. After this period, ten grapes were offered daily for nine days to each group of couples, for a period of three and a half hours (11 AM to 2:30 PM), for a total sample of 540 berries. Soon after exposure, all berries were observed under binocular stereomicroscope, to record the oviposition punctures, which were marked with a ballpoint pen. Subsequently, each berry was individually wrapped in a plastic pot (200 mL) containing a 0.5 cm thin-layer of vermiculite (type B) sterilized in the bottom and kept in an air-conditioned room (28 ± 1 ◦ C; 80 ± 10% RH; without photophase) .

Five days after exposure, a sample of 270 berries, five of each exposed set, were opened to count the number of viable and unviable eggs. The remaining 270 berries remained in the pots with vermiculite in the same chamber until the thirtieth day and were examined daily for larvae and/or puparia. Each puparium was weighed in a precision scale (AdventurerTM, model – AR3130-3L0) and placed individually in flat-bottom glass tubes (8.5 × 1.5 cm), containing sterilized vermiculite and moistened filter paper, and closed with parafilm (Parafilm M ®). The flasks with puparia were kept in an incubator (26 ± 1 ◦ C; 12 h photophase) until emergence.

The puparia were observed daily to record the emergence, sex the percent of deformed adults. Couples were formed with adults without deformation and separated into plastic containers (21 × 14 × 12 cm), receiving water and the same diet used for rearing. For each couple, beginning the seventh day of life, an artificial oviposition substrate was offered according to Bariani et al. (2016) and a mixture of water and grape pulp of the same cultivar was placed inside. Each day, the substrates were replaced and the eggs counted. Each day, 20 eggs (or all the egg when there was less than twenty) were placed on sponge fabric moistened with distilled water and kept in an incubator (26 ± 1 ◦ C; 12 h photophase) for hatching. This procedure was repeated throughout the oviposition period. The eggs were evaluated daily for six days by recording the number of larvae each day. The couples were kept to death.

The variables recorded were the number of punctures, total eggs, viable eggs and puparia, puparium weight, duration of egg–pupae, pupa, and egg–adult phases, sex ratio, longevity, fecundity, fertility, and length of pre oviposition, oviposition and post oviposition periods. The acerolas came from an organic orchard located in the rural area of Macapá , Amapá, Brazil. The fruits, about 0.5 cm in diameter, two to three days after flowering, were protected by bags made with voile type fabric. At the beginning of maturation (when the color of the pericarp turned from green to yellow), the fruits were harvested every two days and taken to the laboratory. A sample of 20 fruits was separated. Then they were measured, weighed, and the soluble solids (◦ Brix) quantified, using a digital refractometer (Hanna, model – HI 96801 ), and the mean values recorded were 2.5 ± 0.03 cm; 0.008 ± 0.0002 g; and 6.8 ± 0.09 ◦ Brix, respectively .

The method used to disinfect, infest, and evaluate acerola was the same as the grapes. For acerola, the punctures and the number of eggs deposited could not be recorded, because the color and consistency of the pulp made it impossible reliably evaluate. Therefore, the evaluations of this fruit were carried out beginning in the pupa stage.