Kwame Afreh-Nuamah

Abundance and distribution of the Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae), in Late Valencia citrus orchards in Ghana

The abundance and distribution of Ceratitis capitata (Wiedemann) in Late Valencia citrus orchards and other alternative host crops was investigated using trimedlure-baited traps at the University of Ghana’s Agricultural Research Centre in the Eastern region of Ghana. The effect of some climatic factors on the population dynamics of the pest was also studied. The population of C. capitata increased from September to October 2006 and from February to March 2007, when Late Valencia citrus fruits were ripening or ripened. The fruit fly population was the lowest from November 2006 to January 2007 when citrus fruits were in the immature green stage. Ceratitis capitata was not trapped in mango, pawpaw and pepper fields and did not emerge from fruits of these crops. Multiple regression analyses also revealed that rainfall and temperature significantly influenced the pest population. The results of this study have important implications on the decision-making process for the safe, effective monitoring and management of C. capitata in Late Valencia citrus orchards in the study area in Ghana and probably in other areas as well.

Farmers' perceptions of constraints to plantain production in Ghana

SUMMARY Plantain (Musa AAB), a primary food crop in Ghana, is a key component in sustainable agricultural systems in high rainfall zones. Recently, there has been a substantial yield decline and reduction in plantation life. To elucidate the context in which intervention strategies should be developed, a Participatory Rural Appraisal (PRA) was conducted at five villages in the major plantain-producing belt of Ghana. The importance of plantain as a preferred food was confirmed, although farmers tended to sell plantain for cash income, using cheaper, less preferred alternatives for home consumption. Farmers identified decreasing soil fertility, the high cost of labour for weeding, pests and diseases, lack of good quality planting material and marketing-related issues as the major production constraints. Due to declining productivity in less fertile regions, plantain has been replaced with other food crops such as cassava and maize. Farmers overestimated the importance of insect pests but were unaware of the extensive damage that could be caused by nematodes and the foliar disease, black sigatoka. They observed, however, that pest damage is more severe when soil fertility is poor. Clearly, integrated pest management is likely to be most effective when practiced within the context of cropping systems management; sustainable strategies that are being developed for resource-limited plantain farmers in Ghana are discussed.

Species composition and host range of fruit-infesting flies (Diptera: Tephritidae) in northern Ghana.

An important aspect of fruit fly management is accurate information on the species and their host spectrum. Studies were conducted between October 2011 and September 2013 to determine the host range and species diversity of pest fruit flies in the northern savannah ecology of Ghana. Fruit samples from 80 potential host plants (wild and cultivated) were collected and incubated for fly emergence; 65 (81.5%) of the plant species were positive to fruit flies. From records in Africa, 11 plant species were reported to be new hosts to the African invader fly, Bactrocera invadens (Drew, Tsuruta and White, 2005). This study documented the first records of Dacus ciliatus (Loew) and Trirhithrum nigerrimum (Bezzi) in northern Ghana although both species have been previously reported in other parts of the country. Infestation by B. invadens was higher in the cultivated fruits; Ceratitis cosyra dominated in most wild fruits. Cucurbitaceae were mainly infested by three species of Dacus and Bactrocera Cucurbitae, a specialized cucurbit feeder. Among the commercial fruit species, the highest infestations were observed in mango, tomato, sweet pepper and watermelon, whereas marula plum, soursop, tropical almond, sycamore fig, African peach, shea nut, persimmon, icacina and albarillo dominated the wild host flora. The widespread availability of host plants and the incidence of diverse fly species in the ecology call for particular attention to their impact on commercial fruits and the development of sustainable management strategies against these economically important pests in Ghana.

Species composition of fruit flies (Diptera: Tephritidae) in the Citrus Museum at the Agricultural Research Centre (ARC), Kade, Ghana

To determine species composition of fruit flies on six cultivated varieties of citrus (Late Valencia orange, Pineapple orange, Ovaleto, Mediterranean sweet lemon, Satsuma tangerine and Ortanique orange), a study was conducted at the Agricultural Research Centre, Kade, Ghana. Improvised Lynfield baited traps (methyl eugenol (ME) and citrus juice (CJ)) and McPhail baited traps (trimedlure (TML)) were used. Ripe infested fruits from the selected varieties were also collected and incubated. Tephritid fruit fly species from trapping were identified as Bactrocera invadens Drew, Tsuruta & White, Bactrocera Cucurbitae (Coquillet), Ceratitis ditissima Munro, C. anonae Graham, C. capitata (Wiedemann), C. bremii Guerin-Meneville, Dacus bivittatus (Bigot), D. punctatifrons Karsch and Trirhithrum Bezzi. A total of 35,247 fruit flies were collected from the traps, with densities of 10.38, 1.00 and 0.27 flies/trap/day for ME, CJ and TML traps, respectively. All incubated fruit varieties showed co-habitation of three different species (C. ditissima, C. anonae and B. invadens) in each of them. In addition, one Dacus vertebratus was obtained from dropped Late Valencia fruits. Moreover, three individual Fopius caudatus (Szèpligeti) parasitoids were recorded from the infested incubated fruits. Ranking of the different fruit fly species from infested incubated host fruits was as follows: C. ditissima (476) > C. anonae (74) > B. invadens (71) and D. vertebratus (1). Competitive ability among the invasive flies in their process to infest the six citrus varieties was observed. These findings could serve as a useful starting point for the development of a reliable catalogue of host diversity, fruit fly species diversity and associated natural enemy records in Ghana.

Preliminary inventory of hymenopteran parasitoids associated with fruit-infesting flies (Diptera: Tephritidae) in Northern Ghana

ABSTRACT Baseline studies were conducted to determine the parasitoids associated with fruit flies in the northern savanna ecology of Ghana. Fruit fly puparia obtained from incubation of 17 host fruit species were maintained in rearing cages for the emergence of parasitoid wasps. Four species of braconid parasitoids namely, Fopius caudatus (Szépligeti), Psyttalia cosyrae (Wilkinson), Psyttalia concolor (Szépligeti) and Diachasmimorpha fullawayi (Silvestri) were recovered. F. caudatus was the most abundant parasitoid (61.0%) reared from most host fruits while D. fullawayi was the least abundant (7.7%). The overall mean parasitism rate was 7.1% with the highest record in Annona senegalensis Pers., Sarcocepholus latifolium S. Bruce and Icacina senegalensis Juss. Ceratitis cosyra and Bactrocera invadens were the fruit fly species most commonly reared that produced F. caudatus, and to a lesser extent, P. cosyrae. The peak occurrence of the parasitoids coincided with the peak of the rains and the maturity period of many of the host fruits. This first inventory of tephritid parasitoids in Ghana provides critical baseline data for biological control efforts in the future.