Assessment of pest insects of Capsicum annuum L.1753 (Solanaceae) in a cultivation cycle in Yaoundé

Pepper, Capsicum annuum is appreciated in tropical regions for its taste and its ability to increase the appetite level of food. This study aimed at investigating pest insects’ diversity of pepper right from pricking out to harvest. It also examined how aphids and whiteflies populations vary in the plant’s life cycle and specific fruit pests’ effects on the yield. During five months, individual plant organs were examined weekly. Insects encountered were captured, counted and identified. Immature stages were bred for identification purposes. Regular sampling allowed us to identify 28 species from 7 orders. During the pre-flowering phase, 5 orders were obtained: Hemiptera, Hymenoptera, Coleoptera, Lepidoptera and Orthoptera. The same orders were found at Flowering-fruiting phase, with appearance of one new order, the Thysanoptera. At this stage, exponentialgrowth of Hemiptera and Hymenoptera was also observed. During  maturation, Diptera and Lepidoptera were the most abundant pests. Ceratitis capitata and Cryptophlebia leucotreta were responsible for yield losses (20.46%). Aphids and whiteflies affected plant’s fitness, either directly through sap sucking or indirectly through viral transmissions. Ants’transport, disseminate and protect Hemipterans. Since plants phenology influences pest diversity, it should be taken into account in the efforts of developing IPM strategies.Keywords: Spice, phenology, yield, IPM

Biodiversity of Freshwater Shrimp of the Genus Macrobrachium (Decapoda Palaemonidae) in the Nyong Basin of Cameroon

The population of shrimps, especially the macrobrachium genus, has been affected with habitat pollution and overexploitation. Shrimps provide a major protein source to animals higher in the food chain. The importance of studying the ecology of shrimps in their different habitats helps in their preservation and provides possibilities of carcinoculture. This study examines diversity, ecology and reproduction parameters of fresh water shrimps of the genus macrobrachium in the basins of Lepmassoun and Ondoamedza rivers. Lepmassoun and Ondoamedza rivers form part of the larger Nyong river basin in Cameroon. In situ water physicochemical parameters were determined on site, preserved water samples used in mineral analysis and subsequent ecological health assessment. Shrimps were sampled using the scoop method with hand nets and analyzed. Sampling was done in 5 seasons distributed from January 2017 to February 2018. The results of physicochemical parameters indicate that water in the two rivers was slightly mineralized, sufficiently oxygenated and slightly turbid. It was generally a non-polluted ecological zone for shrimps. A total of 113 shrimps distributed among 14 species were collected. The shrimp population included Macrobrachium macrobrachion Macrobrachium idae, Macrobrachium rude, Macrobrachium niloticus , Macrobrachium dux Macrobrachium sp1, Macrobrachium sp2, Macrobrachium sp3,Macrobrachium sp4, Macrobrachium sp4, Macrobrachium sp5, Macrobrachium sp6, Macrobrachium sp7, Macrobrachium sp8 and Macrobrachium sp9.In the river Odoameza 11 species were collected among which Macrobrachium sp8 (26.02%) is abundant, though,in the river Lepmassoun we collected 10 species dominanced by Macrobrachium macrobrachion (22,5%). The species Macrobrachium macrobrachion is most ubiquiste throughout river Lepmassoun (%O = 83.33%) The river basin of Lepmassoun had a higher population of Macrobrachium macrobrachion with a percentage occurrence of 66.67%. then It is concluded that the water in the two river basins is of good ecological quality for shrimp survival with species Macrobrachium macrobrachion dominating in the river lepmassoun. In the river Ondoameza Macrobrachium sp8, Macrobrachium idea, Macrobrachium macrobrachion,Macrobrachium sp4 having all the percentage of occurrence (%O) of 66.67% are relatively represented. Only Macrobrachium dux have Ovigerous females in our study. This Ovigerous females ranged from 50.38 to 64.18 mm and egg size varied from 1.7 to 2 mm. The prawn attained a maximum total length and weight of 64,18 m and 2,96 g respectively. In our basins slope the Macrobrachium dux reproduces twice year during the big dry season and small dry season since production is early and the eggs are rather broad by consequence the larval development is shortened

Tephritid fruit fly species composition, seasonality, and fruit infestations in two central African agro-ecological zones

Open Access Journal; Published online: 13 Nov 2022Bactrocera dorsalis and several Africa-native Ceratitis species are serious constraints to fruit production in sub-Saharan Africa. A long-term trapping and fruit collection study was conducted (2011–2016) in two contrasting agro-ecological zones (AEZs) of Cameroon to determine fruit fly species composition, seasonality, attraction to various lures and baits, and fruit infestation levels. Ten tephritid species from genera Bactrocera, Ceratitis, Dacus, and Perilampsis were captured in traps. Bactrocera dorsalis was the most dominant of the trapped species and persisted throughout the year, with peak populations in May–June. Ceratitis spp. were less abundant than B. dorsalis, with Ceratitis anonae dominating in the western highland zone and Ceratitis cosyra in the humid forest zone. Methyl eugenol and terpinyl acetate captured more B. dorsalis and Ceratitis spp., respectively than Torula yeast. The latter was the most effective food bait on all tephritid species compared with Bio- Lure and Mazoferm. Bactrocera dorsalis was the dominant species emerging from incubated fruits, particularly mango, guava, and wild mango. Four plant species—I. wombolu, Dacryodes edulis, Voacanga Africana and Trichoscypha abut—were new host records for B. dorsalis. This study is the first long-duration and comprehensive assessment of frugivorous tephritid species composition, fruit infestations, and seasonality in Central Africa

The Defensive Role of Volatile Emission and Extrafloral Nectar Secretion for Lima Bean in Nature

Lima bean (Phaseolus lunatus) features two indirect anti-herbivore defenses—emission of volatile organic compounds (VOCs) and secretion of extrafloral nectar (EFN)—which are both inducible upon herbivore damage. In a previous field study, Lima bean benefited from the simultaneous induction of the two defenses, yet it remained unclear whether both had contributed to plant protection. Our experimental approach aimed at studying the defensive role of both indirect defenses simultaneously. Tendrils were sprayed with jasmonic acid (JA) to induce both defenses, and performance was compared to that of others that were treated with a synthetic blend of either EFN or VOCs. Confirming earlier results, JA treatment and application of the VOC mixture induced EFN secretion in treated tendrils in quantitatively similar amounts. The composition of the applied synthetic blend of EFN was adjusted to match the concentration of EFN secreted from JA- and VOC-treated tendrils. Repeated application of either enhanced the performance of several fitness-relevant plant parameters such as growth rate and flower production. Tendrils treated with JA showed a similar trend, yet some fitness-related parameters responded less to this treatment. This suggests a minor importance of any putative JA-dependent direct defense traits or higher costs of JA-elicited responses as compared to VOCS and EFN, as otherwise JA-treated tendrils should have outperformed VOC- and EFN-treated tendrils. Moreover, the beneficial effect of applying synthetic EFN alone equaled or exceeded that of VOCs and JA. Ants were by far the dominant group among the arthropods that was attracted to JA-, VOC-, or EFN-treated tendrils. The results suggest that EFN plays a more important role as an indirect defense of lima bean than VOCs or any other JA-responsive trait

Phytogéographie tropicale : réalités et perspectives

Une enquête écologique portant sur le contenu des poches foliaires du myrmécophyte #Scaphopetalum thonneri a permis de mettre en évidence une relation entre cette plante et différentes espèces de fourmis. Les #Technomyrmex (#Dolichoderinae) sont les plus fréquentes. On trouve aussi des #Tetramorium et des #Crematogaster (#Myrmicinae). Ces poches abritent également des fondations de #Cataulacus, #Crematogaster, #Pheidole, #Tetramorium (#Myrmicinae) et de la #Ponerinae Discothyrea oculata. Les reines fondatrices de cette dernière s'installent dans des poches occupées par des pontes d'araignées. Elles approvisionnent ensuite leur couvain à partir des oeufs d'araignée. Des #Lombricidae$, de nombreux arthropodes et des gastéropodes ont également été recensés. En dehors des fourmis, les araignées dominent. Deux types d'arguments sur le rôle des fourmis sont discutés : protection contre les défoliateurs ; assimilation de minéraux provenant des détritus des fourmis accumulés dans certaines domaties. (Résumé d'auteur

Influence of habitat and seasonal variation on wild mammal diversity and distribution with special reference to the Trypanosoma brucei gambiense host-reservoir in Bipindi (Cameroon)

To evaluate the role of wildlife in the resurgence and perenisation of human African trypanosomiasis (HAT), we investigated the influence of habitat and seasonal variations on the diversity and spatial distribution of wild mammals, with special reference to those recognised as potential host-reservoirs of Trypanosoma brucei gambiense in Bipindi (southwestern Cameroon). To achieve this, we carried out transect surveys in four habitat types over two years. A total of 31 mammal species were recorded, of which 14 occurred in the undisturbed forest, 9 in cocoa plantations, 11 in farmlands and 11 in village-adjacent gallery forests. Among them, six species (Cephalophus monticola, Cephalophus dorsalis, Atherurus africanus, Cricetomys emini, Nandinia binotata and Cercopithecus nictitans), known as reservoir hosts of T. b. gambiense, occurred in all kinds of habitats suitable or unsuited to Glossina palpalis palpalis and in all seasons. These species are the most involved in the transmission cycle (human being/tsetse flies/wild animals). Cercopithecus cephus, Miopithecus talapoin and Heliosciurus rufobrachium host Trypanosoma brucei spp.; however, only C. cephus does not occur permanently in the suitable habitat of G. palpalis palpalis. In general, some species (C. monticola, Tragelaphus spekei and C. emini) showed a slight density increase from the long dry to the heavy rainy season within the undisturbed and farmland habitats, and a slight decrease within cocoa plantations and village-adjacent forests in the same period. The density of A. africanus increased greatly from the long dry season to the heavy rainy season in the undisturbed forest while, the density of primates in this habitat decreased slightly from the long dry season to the heavy rainy season. These variations indicate a permanent movement of wild mammal reservoir or feeding hosts from one biotope to another over the seasons. Thryonomys swinderianus needs to be investigated because it occurs permanently in the suitable habitat of G. palpalis palpalis and Potamochoerus porcus for its genetic similarities to domestic pigs, favourable feeding hosts of G. palpalis palpali

Ecology of an improbable association: The pseudomyrmecine plant-ant Tetraponera tessmanni and the myrmecophytic liana Vitex thyrsiflora (Lamiaceae) in Cameroon

Field surveys were conducted to: (a) examine the traits of Tetraponera tessmanni and/or its host that enables this ant to monopolize mature lianas; (b) identify insects which occupy Vitex thyrsiflora at different development stages, and how they interact with T. tessmanni; and (c) determine if the ant protects its host. The study was conducted in a forest on the slopes of Mont Kala in southern Cameroon. In young individuals of the obligate myrmecophytic liana V. thyrsiflora, several species of ants and other arthropods compete for resources offered by the plant. In mature individuals, the only inhabitant is the ant species T. tessmanni, which is completely restricted to Vitex lianas as its sole host. Established colonies of this ant provide effective defence against herbivores. The association between V. thyrsiflora and T. tessmanni is unusual in 2 respects. First, the climbing life form is rare among myrmecophytes. Secondly, it is surprising that a pseudomyrmecine should be the obligate associate of a liana. Pseudomyrmecine plant-ants often prune vegetation contacting their host plant. This behaviour functions in part to protect against invasion of the host by ecologically dominant ants. In contrast, T. tessmanni does not prune and is associated with a plant whose success, and thus that of its resident ant colony, depends on contacts with many other plants. Several traits of V. thyrsiflora and T. tessmanni combine to make the colonization of host plants by potential competitors very difficult. These include behavioural and morphological filters restricting entrance into the plant and exploitation of the resources it can supply; plant anatomical organization that enables T. tessmanni workers to carry out all activities, except leaf patrolling, within a single, branched private nesting space within which all food resources offered by the plant are produced; and polygyny, permitting the colony to monopolize a large, rapidly growing and long-lived territory

Diversity and spation distribution of vectors and hosts of T. brucei gambiense in forest zones of Southern Cameroon: Epidemiological implications

Host and vector distribution of Trypanosoma brucei gambiense was studied in relation to habitat types and seasons. Six (19.35%) of the 31 mammal species recorded in Bipindi were reservoir hosts. Cercopithecus nictitans was confined to the undisturbed forest and the low intensive shifting cultivation zones, while Cephalophus monticola, Cephalophus dorsalis, Cricetomys gambianus, Atherurus africanus and Nandinia binotata occurred in all the habitat types. As for vectors of human African trypanosomiasis (HAT), Glossina palpalis palpalis, was the most abundant (99.13%) among tsetse fly species. It occurs in all biotopes with its highest density recorded in the village-adjacent forest. The village-adjacent forest is therefore the most risky transmission zone for HAT mainly during the short rainy season when G. palpalis palpalis’ density is highest (2.91); while, the high and low intensive shifting cultivation zones are the most important contact zones between humans, G. palpalis palpalis and wild mammals in all season

Fruit preference, parasitism, and offspring fitness of Fopius arisanus (Hymenoptera: Braconidae) exposed to Bactrocera dorsalis' (Diptera: Tephritidae) infested fruit species

Fopius arisanus (Sonan) (Hymenoptera: Braconidae) is a koinobiont solitary parasitoid of various fruit flies, particularly those in the genus Bactrocera. Researchers introduced F. arisanus into Africa for the biological control of Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), a pest of a wide range of fruit trees and vegetables. However, the suitability of host fruit species as egg-laying substrates for parasitoid development remains poorly investigated in tropical Africa. The present study examines the preference and performance of F. arisanus on B. dorsalis reared on eleven fruit species through laboratory choice-test trials. We assessed the oviposition activity, parasitism rate, developmental time, and offspring fitness of F. arisanus on nine cultivated and two wild host fruits species. Oviposition attempts were higher on Psidium guajava (L.) (Myrtales: Myrtaceae) and Mangifera indica (L.) (Sapindales: Anacardiaceae) than on the other host fruits tested. The wasp parasitized host eggs in P. guajava in no-choice experiments. Psidium guajava, Irvingia wombulu (Vermoesen) (Malpighiales: Irvingiaceae), and Irvingia gabonensis (Aubry_Lecomte) Baill (Malpighiales: Irvingiaceae) were suitable for parasitism in choice tests. Of all host fruits tested, the body and hind tibia lengths of both parasitoid sexes emerging from M. indica were longer than on the others. The female ovipositor was long on Annona squamosa (L.) (Magnoliales: annonaceae) and short on Eribotrya japonica ([Thunb.] Lindl.; Rosales: Rosaceae). We obtained the longest preimaginal developmental time for both sexes on E. japonica and the shortest for females and males on Carica papaya (L.) (Brassicales: Caricaceae). These results demonstrate the ability of some tested fruit species to serve for the permanent establishment of F. arisanus in the field

Multi-locus phylogenies of the genus Barteria (Passifloraceae) protray complex patterns in the evolution of myrmecophytism.

The four species of the central African genus Barteria show variation in habitat and in degree of association with ants. Whereas B. solida, restricted to submontane forests, attracts opportunistic ants to extrafloral nectar, the three other species, found in lowland rainforests (B. fistulosa, B. dewevrei) and in littoral scrub (B. nigritana), possess stem domatia of varying shapes and degrees of specialisation, hosting either non-specific arboreal ants (B. nigritana, some B. dewevrei) or two large species of ants of the genus Tetraponera Smith, 1852 that are specific to some species of Barteria (B. fistulosa, some B. dewevrei). We aimed to investigate whether this variation represents an evolutionary trend toward increasing specialisation of mutualism or the reduction or loss of myrmecophytic traits. For this, we determined phylogenetic relationships within the genus using DNA sequences (primarily nuclear ITS) and microsatellite genotypes (11 loci) on a large sample of individuals, mostly from Cameroon and Gabon. The two types of markers support an initial dichotomy that groups B. dewevrei with B. nigritana and B. fistulosa with B. solida respectively. Within these pairs, species do not appear reciprocally monophyletic. At microsatellite loci, B. nigritana forms a clade embedded within B. dewevrei; and within both B. solida and B. fistulosa, geographical populations show levels of differentiation similar to that observed between populations of B. solida and B. fistulosa. Geographic distance alone does not account for genetic differentiation between species, which indicates reproductive isolation. Divergence in each of the two pairs implies evolutionary transitions in habitat and in myrmecophytism. Specialised mutualism with specific ant species of the genus Tetraponera has been lost in species found in more marginal habitats