No abstract

In Cameroon, fruit flies (Diptera: Tephritidae) represent a major constraint to fruit production in cucurbits. They are known to feed essentially on fruits, but some species are flower specialists. The present study aims to assess the oviposition preference of fruit flies on seven species of cucurbits along with two varieties (bitter and sweet) of Lagenaria siceraria (Molina) Standley at two locations namely Yaounde and Koutaba (Cameroon). The infested flowers and fruits were collected, examined and incubated individually under laboratory conditions. Dacus (Lophodacus) hamatus Bezzi (Diptera: Tephritidae) was recorded for the first time, from the male flowers of L. siceraria. Under field conditions, the females laid their eggs only on male flowers of both varieties of L. siceraria and no adult was obtained from their fruits and from both flowers and fruits of other six cucurbit species in this study. However, under laboratory conditions, larvae were able to develop on flowers and fruits of all cucurbits used in present investigation. The infestation rate and the mean number of larvae per male flower were significantly greater on the bitter variety than on the sweet of L. siceraria, suggesting specificity in the feeding preference of D. hamatus. This fly affects considerable the yield of L. siceraria at both the studied locations viz. Yaounde and Koutaba with mean infestation rates of 52.36 ± 5.72% and 57.63 ± 3.41%, respectively on male flowers of L. siceraria.

Though ant diversity was well documented, relations between ground-dwelling and arboreal ants were poorly known. It was in this mind that we compared species diversity and composition between ground-dwelling and arboreal ant in three type of habitats at Mfou, a suburban agglomeration of Yaoundé city in Cameroon. Ants were collected in secondary forests, cocoa farms, and palm groves using pitfall, baits and visual catch. Ant communities were characterised using species richness and Shannon diversity index. Nonmetric Multidimensional Scaling (NMDS) and Venn diagrams were used to determine respectively species composition and the number of exclusive and shared species between types of habitats. We recorded 144 ant species belonging to 39 genera and 6 subfamilies. Ground-dwelling ants were richest and diversified in secondary forests, while arboreal ant fauna was in cocoa farms. Arboreal ant community in palm groves was closed to that found on the ground in all type of habitats.Suggesting that, when a deep modifications occurred in a natural habitat, arboreal ant fauna could not establish permanent colonies. Therefore, trees canopies were colonised by some ground-dwelling ant species who progressively substituted arboreal ant on the trees. Consequently, arboreal ant became progressively rare with intensification of anthropogenic disturbance and habitat loss.

Leucinodes Orbonalis appears as the main constrain to Eggplant production. In Cameroon, many varieties of the genus Solanum (Solanaceae) are cultivated and their fruits compositions vary in terms of pH, carbohydrates, proteins, and polyphenols content. We investigated to see if primary and secondary metabolites content in the fruits could influence the preference of attacked due to Leucinodes Orbonalis. The damage due to Leucinodes Orbonalis were compared on two species of two cultivars each. These experimentations were carrying out both in the laboratory and on the field. On "zong", "inerme", "jakatu" and "F1 African beauty" varieties, the pH of the fruits was 5.22, 4.57, 5.4 and 5.02 respectively; the sugar content of the fruits was 6.45 mg/g, 4.79 mg/g, 7.92 mg/g and 7.85 mg/g respectively; the polyphenol content of the fruit was 5.74 mg/g, 6.79 mg/g, 5.26 mg/g and 4.63 mg/g and the protein content of the fruit was 3.02 mg/g, 1.66 mg/g, 4.48 mg/g and 4.25 mg/g respectively. The study on the susceptibility of the species/varieties of Solanum spp. showed that S. melongena var. inerme was the most resistant (with 47.8%) and that S. Aethiopicum var. jakatu, most susceptible (with 79.47%) to attacks due to Leucinodes Orbonalis. The study also showed that total sugars, total proteins and pH value levels were positively and significantly correlated with attacks due to Leucinodes Orbonalis (r=0.97*, r=0.86* and r=0.70* respectively) while the total polyphenols content in the fruits was negatively and significantly correlated with the same attacks due to the same fruit pests (r=0.76*). These informations can be of great importance in the varietal selections by farmers.