6 - BM-2014v5n3页

Bioscience Methods 2014, Vol.5, No.3, 1-11

http://bm.biopublisher.ca

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Table 1 Sampling localities in northern Ghana with their

agroecological zones from which fruit samples were collected

for the study

Province/Region Collection site

Agro-ecology

Northern

Tamale suburbs

Salaga woodland

Damongo forest

Daboya valleys

Gushie bushland

Guinea savanna

Upper West

Wa suburbs

Wahabu forest

Daffiama bushland

Wechiaw woodland

Babille bushland

Sudan savanna

Upper East

Bolga suburbs

Sandema woodland

Navrongo bushland

Zebilla hills

Bawku bushland

Sudan savanna

Sahel savanna

The number of fruits in a sample varied according to

the species and their on-site abundance. Sampled

fruits were placed in plastic bags with the appropriate

labels. Each plastic bag was put inside a piece of

synthetic mesh and placed in a plastic container. The

ends of the synthetic mesh was pulled and tightened

over the rim of the container, lifting the fruits off the

bottom of the container. They were secured in this

position by fitting the plastic lid of the container over

the mesh. Elevating fruits over the bottom of the

container avoids physical damage to fruits on the

rough local roads. To ensure adequate ventilation, the

middle portion of each lid was cut out and replaced by

10 x 15 cm piece of tight-weave synthetic mesh

capable of retaining any emerged insects. During

transportation of fruits from field to laboratory, the

containers were covered with moistened cotton fabric

to avoid excessive heating.

Table 2 List of the main hosts of

B. invadens

and

C. cosyra

in northern Ghana from which fruits were sampled for the study

Fruit species

Common name

Habitat

Total no. Samples

Mangifera indica

L.

Mango

Cultivated

53

Sclerocarya birrea

A. Rich.

Marula plum

Wild

19

Annona senegalensis

Pers.

Sour sop

Wild

30

Terminalia catapa

L.

Tropical almond

Wild

53

Diospyros mespiliformis

A. DC.

Persimon

Wild

38

Ficus syncomosus

L.

Syncomore fig

Wild

25

Ziziphus mucronata

Willd.

Jujube

Wild

19

Sarcocepholus latifolium

Smith. Bruce

African peach

Wild

71

Vitellaria paradoxa

C.F. Gaertn

Sheanut

Wild

69

Capsicum anuum

L.

Green pepper

Cultivated

32

Icacina senegalensis

Juss.

Icacina, false yam

Wild

59

Ximenia americana

L.

Albarillo

Wild

41

1.2 Fruit incubation

In the laboratory, fruits in each sample were counted

and weighed before being placed in incubation units.

An incubation unit consisted of a 1.5-litre rectangular

plastic container with 0.5 cm ellipsoid holes cut into

the bottom. An ellipsoid-shaped hole (but not circular)

prevented fruits from clogging the holes during

incubation while at the same time allowing mature

larvae of fruit flies to fall through after they had exited

the host fruit. The lid of the container was cut open at

1.0 x 0.5 cm on the middle and covered with a

synthetic mesh. The container with holes was covered

with the lid and nested into a second container

(without holes at the bottom). A layer of sterilized

sand was placed at the bottom of the second container

to serve as pupation medium for the exiting larvae in

addition to soaking up fruit juice.

The incubation units were arranged on metal shelves,

the legs of which were placed in a water-filled

container, thus helping to supplement humidity while

simultaneously acting as a effective barrier to strange

insects. Each fruit sample was maintained for a

minimum period of 4 weeks at 25±3 ºC and 60±10%

RH. The 4-week holding period encompassed the

period of larval pupation, and most fruits were

shrunken and dry by the end of the period (Copeland

et al., 2002). During the holding period, fruit samples

were kept moist by spraying with fine mist of water as

needed, but spraying was avoided on fruits samples