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Browsing by Author "Roininen, Heikki"

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Active restoration facilitates bird community recovery in an Afrotropical rainforest
(Biological Conservation, 2016) Latja, Pirita; Valtonena, Anu; Malinga, Geoffrey M.; Roininen, Heikki
Active restoration of rainforests is essential in enhancing the recovery of biodiversity in many tropical regions suffering from deforestation. However, the value of actively restored rainforests for birds is still relatively poorly understood because of the short history of active restoration programs. Here, we studied the recovery of bird communities in Kibale National Park, Uganda.Wesampled birds along a restoration gradient consisting of six restoration areas (3–16 years old) and used five primary forests as reference areas. We found that bird community compositions changed in an orderly fashion along the restoration gradient. The abundance of arboreal insectivore frugivores and forest specialists increased, while that of foliage-gleaning insectivores, granivores and forest visitors decreased towards older sites. The similarity of the bird communities of the restored forests to those of the nearby primary forests increased linearly with time. If this recovery rate is extrapolated to the future, the bird communities could reach a pre-disturbance state after only approximately 20 years of active restoration. However, previous studies have shown that recovery is typically a non-linear process, and the time needed for bird communities to recover is more likely longer than this. Nevertheless, our study provides evidence that bird communities benefit from active rainforest restoration after human-induced deforestation.
Artificial diets determine fatty acid composition in edible Ruspolia differens (Orthoptera: Tettigoniidae)
(Journal of Asia-Pacific Entomology, 2018) Rutaro, Karlmax; Malinga, Geoffrey M.; Opoke, Robert; Lehtovaara, Vilma J.; Omujal, Francis; Nyeko, Philip; Roininen, Heikki; Valtonen, Anu
There are increasing interests in rearing edible insects in Africa, but information on how the feeds modify their fatty acids is largely lacking. In this work, the influence of artificial diets on the fatty acid contents and composition in the edible Ruspolia differens (Serville, 1838), in Uganda was assessed. R. differens was reared on the mixtures of six gradually diversified diets of two, three, four, six, eight and nine feeds. The diets were formulated from rice seed head, finger millet seed head, wheat bran, superfeed chicken egg booster, sorghum seed head, germinated finger millet, simsim cake, crushed dog biscuit pellet and shea butter. Fatty acid methyl esters were prepared using direct transesterification method, and analysed using gas chromatography. The contents of saturated, monounsaturated and polyunsaturated fatty acid differed significantly among the diets. The more diverse diets resulted in increased content of the polyunsaturated fatty acids. The n6:n3 ratio differed significantly among the diets and between the sexes, with R. differens fed on the four-feed diet having a higher n6:n3 ratio than those fed on other diets. Also, the fatty acid composition differed significantly among the diets, and diet diversification corresponded with the proportions of polyunsaturated fatty acids, especially linoleic acid. Overall, our results demonstrate that higher levels of essential fatty acids can be achieved by rearing R. differens on highly diversified diets. These findings are important in informing the design of future mass-rearing program for this edible insect
Bottom-up manipulations alter the community structures of galling insects and gall morphs on Neoboutonia macrocalyx trees in a moist tropical rainforest
(Agricultural and Forest Entomology, 2014) Malinga, Geoffrey M.; Valtonen, Anu; Nyeko, Philip; Roininen, Heikki
The effects of bottom-up forces on the community structure of tropical insect gallers and within species variation in gall morphotype assemblages are not well understood. We tested the roles of increased nutritional quality and density of host plants with respect to structuring the galling insect communities and gall morphotype assemblages on Neoboutonia macrocalyx trees in Uganda. Plant nutritional quality and resource concentration were manipulated with four levels of fertilization and the group size of trees, respectively. After applying these treatments in May 2011, gallers established naturally on experimental replicates. Fivemonths later, we sampled gallers and recorded their numbers and the different morphotypes. We analyzed the effects of treatments on the structures of galler communities and gall morphotype assemblages. We recorded 5237 individuals, representing four galler species. One species, Cecidomyiid leaf galler, was represented by three morphologically distinct galls. Fertilization, host tree density and their interactions significantly changed the structures of galler species communities and gall morphotype assemblages. The results of the present study demonstrate the important role of bottom-up factors in structuring galler communities and the gall morphotype assemblages. These changes are likely caused by differential responses of different galler species and gall morphs to plant quality or quantity changes.
Bottom‑up impact on the cecidomyiid leaf galler and its parasitism in a tropical rainforest
(Oecologia, 2014) Malinga, Geoffrey M.; Valtonen, Anu; Nyeko, Philip; Vesterinen, Eero J.; Roininen, Heikki
The relative importance of host-plant resources, natural enemies or their interactions in controlling the population of galling insects and their parasitism is poorly known for tropical gallers. In this study, we assessed the impacts of plant quality and density of host trees in regulating the densities of a galler species, the cecidomyiid leaf galler (Cecidomyiini sp. 1EJV) and its parasitoids and inquilines on Neoboutonia macrocalyx trees in Uganda. We manipulated the nutritional quality (or vigour) and the resource concentration with four levels each of fertilization and the group size of host tree. We then recorded the effects of these treatments on the growth rate and total leaf area of host plants, the density of gallers and their mortality by parasitoids and inquilines. Higher levels of fertilization and host density resulted in significantly higher total leaf area than did ambient nutrient levels, and lowest tree densities, respectively. Fertilization also caused significant change in the growth rate of leaf area. Both higher fertilization and host density caused higher density of gallers. Total leaf area was positively associated with galler density, but within galled replicates, the galled leaves were larger than the ungalled leaves. Although highest levels of fertilization and density of host trees caused significant change in the densities of parasitoids, the rate of parasitism did not change. However, tree-density manipulations increased the rate of inquilinism, but on a very low level. Our results demonstrate a trophic cascade in the tropical galler and its parasitoids as a response to bottom-up effects.
Developing Mass Egg-Laying Medium for the Edible Ruspolia differens (Orthoptera: Tettigonidae)
(Journal of Economic Entomology, 2019) Malinga, Geoffrey M.; Lehtovaara, Vilma J.; Valtonen, Anu; Nyeko, Philip; Roininen, Heikki
The edible katydid, Ruspolia differens (Serville), is an economically and nutritionally important insect species that is common and widespread in Africa. Currently, there are aims to develop mass-rearing methods suitable for this species, but a critical first step would require a suitable oviposition medium to ensure economic and easy production of eggs with high hatchability. The objective of the present study was to determine the oviposition preference and egg hatchability in different oviposition media. Based on preliminary testing of a wide range of different materials, two oviposition media, namely, artificial (folded plastic cloth) and natural medium (leaf sheath of Pennisetum purpureum Schumach attached to a stem), were selected for a detailed experiment. A two-choice laboratory experiment was conducted in which R. differens females were able to select between the folded plastic cloth (one side covered with short fleece) and a leaf sheath of P. purpureum (wrapped in polyester fiber). The results show that R. differens laid almost three times more eggs on the plastic cloth (mean ± SE, 169.3 ± 18.0) than on the natural substrate, P. purpurem (69.0 ± 13.9). However, the hatchability (overall mean% ± SE, 56.5 ± 4.7) of eggs in the two media did not differ. Folded plastic cloth, therefore, provided a more effective medium for egg laying by R. differens, and is thus a promising oviposition medium for getting natural populations to start laying eggs in future mass rearing.
The Edible Katydid Ruspolia Differens Is A Selective Feeder On The Inflorescences And Leaves Of Grass Species
(Entomologia Experimentalis et Applicata, 2018) Valtonen, Anu; Malinga, Geoffrey M.; Junes, Petra; Opoke, Robert; Lehtovaara, Vilma J.; Nyeko, Philip; Roininen, Heikki
Ruspolia differens (Serville) (Orthoptera: Tettigoniidae, Conocephalinae) (its common names including ‘African edible bush-cricket’, ‘edible grasshopper’, and ‘nsenene’) is an important source of food for humans in East Africa, but its ecology and biology are poorly understood. We explored the host plants of R. differens with a series of no-choice and multiple-choice laboratory experiments using 18 local common grass and sedge species in Uganda. In no-choice experiments, the degree of acceptance differed significantly among the studied plant species, but in only three species were leaves rejected and in one species were inflorescences rejected. The pattern of acceptance among plant species was different in the local vs. swarming populations. Leaves were generally more accepted by the local population, whereas inflorescences were generally more accepted by the swarming population. Both leaves and inflorescences were more readily accepted by males than by females. According to the multiple-choice experiments, R. differens preferred inflorescences over leaves. Our results demonstrate that R. differens is a facultatively oligophagous grass-specialist, which has a clear preference for certain grass or sedge species (especially inflorescences), but it accepts many host plants if the preferred ones are not available. To preserve viable natural populations of R. differens in East Africa in the long term, our results draw special attention to the availability of grasslands where accepted and preferred host plants are available year-round.
The fatty acid composition of edible grasshopper Ruspolia differens (Serville) (Orthoptera: Tettigoniidae) feeding on diversifying diets of host plants
(Entomological Research, 2018) Rutaro, Karlmax; Malinga, Geoffrey M.; Lehtovaara, Vilma J.; Opoke, Robert; Valtonen, Anu; Kwetegyeka, Justus; Nyeko, Philip; Roininen, Heikki
Ruspolia differens (Serville) (Orthoptera: Tettigoniidae) is a highly valued edible grasshopper species in Africa. However, the effects of plant diets on lipid content and fatty acid composition of R. differens are not well understood. We tested the effects of four diets on the total lipid content and fatty acid composition of R. differens. Sixth instar nymphs of R. differens were reared on one, and mixtures of two, three, and six natural plant inflorescences. Individuals collected from the field constituted a control treatment.We extracted lipids and analyzed the fatty acidmethyl esters using gas chromatography–mass spectrometry. We analyzed if the total lipid content, body weight, and fatty acid composition differed among diets and between the sexes using two-way ANOVAs and a PERMANOVA model, respectively. The total lipid content and weight of R. differens did not differ among the diets. The nine common fatty acids were palmitic (mean across treatments, 26%), oleic (22%), palmitoleic (18%), linoleic (13%), stearic (7%), myristic (6%), myristoleic (4%), α-linolenic (2%) and arachidic acid (1%). The composition of fatty acids and the proportion of essential fatty acids significantly differed among the diets. The proportion of essential fatty acids was highest in the control treatment (21%) but low in less diversified (one to three feed) diets (12–13%). This study demonstrates that the fatty acid composition in R. differens can be influenced through diet. Thus, with dietary manipulations, using local plants in Africa, it is possible to produce R. differens with preferred high quality essential fatty acids for human consumption.
Fatty acid content and composition in edible Ruspolia differens feeding on mixtures of natural food plants
(BMC Research Notes, 2018) Rutaro, Karlmax; Malinga, Geoffrey M.; Lehtovaara, Vilma J.; Opoke, Robert; Nyeko, Philip; Roininen, Heikki; Valtonen, Anu
To develop successful mass-rearing programs of edible insects, knowledge of the feeds and their influence on nutritional content is critical. We assessed the influence of natural food plants (grass inflorescences) and their mixtures on fatty acid profiles of edible Ruspolia differens. We reared neonate nymphs to adult on six dietary treatments consisting of one, and mixtures of two, three, five, six and eight plants. Results: The contents of saturated, monounsaturated and polyunsaturated fatty acids, omega-6/omega-3 ratio, and adult body weight did not differ among dietary treatments. However, the composition of fatty acids differed significantly among insects fed on six dietary treatments, but only for the rare fatty acids. Our results demonstrate that even if natural diets (grass inflorescences) do not strongly modify fatty acid contents or compositions of R. differens, when reared from neonate nymphs to adults, their n − 6/n − 3 fatty acid ratio is generally low and thus good for a healthy human diet.
Host plants of the non‐swarming edible bush cricket Ruspolia differens
(Ecology and Evolution, 2019) Opoke, Robert; Nyeko, Philip; Malinga, Geoffrey M.; Rutaro, Karlmax; Roininen, Heikki; Valtonen, Anu
The edible Ruspolia differens (Orthoptera: Tettigoniidae) is a widely-consumed insect in East Africa but surprisingly little is known of its host plant use in the field. We studied host plants used by non-swarming R. differens for 15 months, in central Uganda. In particular, we assessed the use of host plant species with respect to host cover in the field and host parts used by R. differens, also recording their sex, developmental stages, and colour morph. Ruspolia differens were found on 19 grass and two sedge species and they were observed predominantly (99% of 20,915 observations) on seven grasses (namely, Panicum maximum, Brachiaria ruziziensis, Chloris gayana, Hyparrhenia rufa, Cynodon dactylon, Sporobolus pyramidalis, and Pennisetum purpureum). Ruspolia differens was most frequently observed on the most common grass of each study site but P. maximum, and S. pyramidalis were used more frequently than expected from their cover in the field. Furthermore, R. differens were observed predominantly on inflorescences (97% of feeding observations) and much less frequently on the leaves (3.0%), stems (0.1%), and inflorescence stalks (0.1%) of grasses and sedges. Host use was not independent of sex, developmental stage, or colour morph. Panicum maximum was the preferred host of the youngest nymphs of R. differens. Overall, our findings indicate that a continuous supply of diverse grass resources with inflorescences is necessary for the management and conservation of wild populations of R. differens.
Mixed Artificial Diets Enhance The Developmental And Reproductive Performance Of The Edible Grasshopper, Ruspolia Differens (Orthoptera: Tettigoniidae)
(Applied Entomology and Zoology, 2018) Malinga, Geoffrey M.; Valtonen, Anu; Lehtovaara, Vilma J.; Rutaro, Karlmax; Opoke, Robert; Nyeko, Philip; Roininen, Heikki
Diet mixing is a common feeding habit among polyphagous insect herbivores and is believed to be advantageous for performance-related factors like growth, survival and oviposition. However, relatively little is known about the influence of artificial diet or their mixtures on the performance of edible insects. We examined the effects of artificial diet mixtures on the developmental and reproductive performance (survival, developmental time, fresh adult weight and female fecundity) of an edible grasshopper, Ruspolia differens (Orthoptera: Tettigoniidae). We raised individuals from eggs and reared newly hatched nymphs to adult stage on six different dietary treatments consisting of a single diet, and mixtures of two, three, five, six and eight artificial diets. More diversified diets resulted in shorter development time and greater adult fresh weight and female fecundity compared to the single diet or less diversified diets. Even with slight diet diversification, survival to adult stage was greatly improved. Overall, these results highlight the potential of diet mixtures in achieving maximum adult weights and female fecundity and shortening development time, information which could be used when designing mass-rearing programs for this edible grasshopper.
Performance of the African edible bush-cricket Ruspolia differens on single and mixed diets containing inflorescences of their host plant species
(Entomologia Experimentalis et Applicata, 2020) Malinga, Geoffrey M.; Valtonen, Anu; Hiltunen, Minna; Lehtovaara, Vilma J.; Nyeko, Philip; Roininen, Heikki
The African edible bush-cricket, Ruspolia differens (Serville) (Orthoptera: Tettigoniidae), is an economically valuable insect in sub-Saharan Africa. For its mass-rearing, suitable diets that can sustain its performance need to be identified. This study aimed at finding inflorescence diets of 10 host plant species and their mixtures that result in the highest R. differens production. We reared newly hatched nymphs to adults on inflorescences of single host species, and also on a gradient of five diversifying dietary mixtures consisting of one and mixtures of two, three, five, and seven host plant species. For the single host-plant diets, the developmental time was shortest on Pennisetum purpureum, Chloris gayana, and Brachiaria ruziziensis (approximately 63 days), whereas the fresh weight was highest on B. ruziziensis and P. purpureum (approximately 0.383 g). Survival was highest (>65%) on C. gayana, P. purpureum, B. ruziziensis, Setaria sphacelata, and Sporobolus pyramidalis, and lowest on Panicum maximum, Hyparrhenia rufa, Cynodon dactylon, and Paspalum scrobiculatum (<40%). With respect to diet mixtures, the developmental time was significantly shorter (on average 16 days shorter), and survival was higher, in the most diversified diets compared to the least diversified diets. The contents of polyunsaturated fatty acids (PUFA) and fatty acid composition did not differ significantly among the diets. However, the content of monosaturated fatty acids (MUFA) differed significantly among the diets and there was a significant diet*sex interaction. From the applied point of view, based on our results, for maximal weight and survival plus fast development, we recommend rearing on P. purpureum, C. gayana, B. rizuziensis, and S. sphacelata, and on dietary mixtures of inflorescences. These findings are important in designing large-scale rearing programs for this species.
Recovery of bird communities after selective logging and clear-cutting in Kibale National Park, Uganda
(Ostrich, 2016) Latja, Pirita; Malinga, Geoffrey M.; Valtonen, Anu; Roininen, Heikki
In the face of the continuing destruction of tropical rainforests, a major challenge is to understand the consequences of these habitat changes for biodiversity and the time scale at which biodiversity can recover after such disturbances. In this study, we assessed the patterns in communities of birds among forests of varying age consisting of clear-cuts of former coniferous plantations, selectively logged compartments and primary forests in Kibale National Park, Uganda. Birds were surveyed by 10-minute point counts at 174 randomly located points in nine forest areas during September–October 2011. A total of 2 688 birds representing 115 species were recorded. The species density, diversity and dominance of all birds, and dominance of forest specialists showed no differences between forest areas, whereas the species density and diversity of forest specialists differed significantly between forest areas. The composition of communities of all birds and of forest specialists varied significantly among the forest areas. Our results show that even after 19 and 43 years, respectively, communities of birds in clear-cuts of former coniferous plantations and selectively logged forests have not fully recovered from the disturbances of logging, highlighting the need to preserve primary forests for conservation of birds.
Seasonal Pattern In Population Dynamics And Host Plant Use Of Non‐Swarming Ruspolia Differens Serville (Orthoptera: Tettigoniidae)
(Journal of Applied Entomology, 2019) Opoke, Robert; Malinga, Geoffrey M.; Rutaro, Karlmax; Nyeko, Philip; Roininen, Heikki; Valtonen, Anu
The edible Ruspolia differens (Serville) (Orthoptera: Tettigoniidae) is an important source of food in East Africa, but the seasonality of its population dynamics and host plant use are not fully understood. We studied seasonal patterns in the population density and relative frequency of developmental stages, sexes, colour morphs and host plants of the non-swarming R. differens at two study sites in central Uganda over 15 months. Linear mixed models were used to study how precipitation and Enhanced Vegetation Index (EVI) predict population density and relative frequency of developmental stages, sexes, colour morphs and host plants. The results showed that all developmental stages of non-swarming R. differens were found in the field throughout the year. The population densities of R. differens were high in wet seasons and low in dry seasons and were best predicted by the EVI of the previous month. The sex ratio of the non-swarming R. differens populations was female biased. The proportion of males and green colour morphs increased during and after the rainy season. The use of host plants fluctuated seasonally so that during the greener seasons individuals used the more preferred host Panicum maximum more frequently. Overall, our work indicates that R. differens has a seasonal dynamic so that vegetation greenness can be used to forecast non-swarming R. differens population densities. Our results also suggest that source populations for swarming individuals might have a local origin. This is important for the management of habitats for reproduction and conservation of viable populations of R. differens in East Africa.
The successional pathway of the tree community and how it shapes the fruit-feeding butterfly community in an Afrotropical forest
(Journal of Tropical Ecology, 2017) Valtonen, Anu; Malinga, Geoffrey M.; Nyafwono, Margaret; Nyeko, Philip; Owiny, Arthur; Roininen, Heikki
The relative importance of different bottom-up-mediated effects in shaping insect communities in tropical secondary forests are poorly understood. Here, we explore the roles of vegetation structure, forest age, local topography (valley vs. hill top) and soil variables in predicting fruit-feeding butterfly and tree community composition, and tree community composition in predicting fruit-feeding butterfly community composition, in different-aged naturally regenerating and primary forests ofKibaleNational Park, Uganda.Wealso examinewhich variables are best predictors of fruit-feeding butterfly species richness or diversity. Butterflies (88 species) were sampled with a banana-baited trap and trees (98 taxa) with a 40 × 20-m sampling plot at 80 sampling sites. The environmental variables explained 31% of the variation in the tree community composition, the best predictors being local topography, forest age and cover of Acanthus pubescens (a shrub possibly arresting succession). The fruit-feeding butterfly community composition was better predicted by tree community composition (explaining 10% of the variation) rather than vegetation structure, local topography or soil factors. Environmental variables and tree species richness (or diversity) were poor predictors of butterfly species richness (or diversity). Our results emphasize the importance of tree community to recovery of herbivorous insect communities in tropical secondary forests.
Tree communities of different aged logged areas in an Afrotropical rainforest
(African Journal of Ecology, 2016) Owiny1, Arthur A.; Valtonen, Anu; Nyeko, Philip; Malinga, Geoffrey M.; Roininen, Heikki
Predicting the recovery processes in tree communities after logging is critical when developing conservation strategies. We assessed the patterns in tree communities in logged and primary forests in Kibale National Park, Uganda, representing 9- to 19-year-old clear-cuts of former conifer plantations, 42- to 43-year-old logged forests and primary forests. Species density and diversity were lower and dominance higher in the 9- to 19-year-old forests compared to the 42- to 43-year-old forests or primary forests. The tree species density, diversity and dominance of 42- to 43-year-old forests did not differ significantly from primary forests. However, they had a lower stem density, and higher cover of Acanthus pubescens, a shrub known to arrest the succession in Kibale. The tree community compositions of 9- to 19-year-old, 42- to 43-year-old and primary forests differed from each other. A large group of tree species (21) were primary forest indicators, that is, they were either missing or relatively rare in logged forests. The results of this study show that even after four decades of natural recovery, logged Afrotropical forests can still be distinguished from primary forests in their tree community compositions, emphasizing the slow community recovery and the important role of primary forests when preserving the tree communities in tropical rainforests.

Browsing by Author "Roininen, Heikki"

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