Browsing by Author "Yarro, Jacob G."

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    Anatomic Morphometrics of the “Senene” Tettigoniid Ruspolia differens Serville (Orthoptera: Conocephalidae) from North-West Tanzania
    (2013) Matojo, Nicodemus D.; Yarro, Jacob G.
    The morphometrics of Ruspolia differens (order: Orthoptera; family: Conocephalidae), the longhorn grasshopper that is widely known as senene by its Kiswahili name, was largely unclear although the species serves broadly as a delicacy relish snack. In this study, the anatomic morphometrics of this insect was critically inferred based on the samples that were collected from North-west Tanzania in April-May 2009. R. differens was revealed to have a number of unique anatomic features that can essentially serve in its diagnosis. These include the paired male metathoracic flaps, finger-like prosternal protuberances, hind femoral spines, subequal tibial black markings, and an obvious male biased antennal dimorphism.
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    An Assessment of Methods for Sampling Carabid Beetles (Coleptera: Carabidae) in a Montane Rain Forest
    (2007) Nyundo, Bruno A.; Yarro, Jacob G.
    Pitfall trapping is the traditional method for sampling carabid beetles and other grounddwelling invertebrates. Tests were carried out in the Udzungwa Mountains National Park between March 1999 and July 2000. Results indicated that pitfall traps were less efficient compared to manual searching methods, both in terms of relative abundance and species richness of carabid beetles. The results are discussed in the context of biodiversity inventories in the Eastern Arc Mountains
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    Comparative Biology of Mallada Desjardinsi (Navas) and Chrysoperla Congrua (Walker) (Neuroptera: Chrysopidae), Predators of Helicoverpa Armigera (Hubner) (Lepidoptera: Noctuidae) and Aphis Gossypii (Glover) (Homoptera: Aphididae) On Cotton in Eastern Tanzania
    (Taylor and Francis, 1995) Kabissa, Joe C.B.; Kayumbo, H. Y.; Yarro, Jacob G.
    The developmental biology of Mallada desjardinsi (Navas) and Chrysoperla congrua (Walker) on the American bollworm, Helicoverpa armigera and the cotton aphid, Aphis gossypii was studied in the laboratory at 28–32°C. Total larva! periods of M. desjardinsi and C. congrua on H. armigera eggs were 14.4 and 14.8 days respectively. However, when reared on A. gossypii larval periods of M. desjardinsi and C. congrua were 14.9 and 13.5 days respectively. When reared on H. armigera 52.9% and 25% respectively of third instars of M. desjardinsis and C. congrua sp. died before pupation. However, when reared on A. gossypii 82.6% and 46.9% respectively of third instars of M. desjardinsi and C. congrua died before pupation. Thus, H. armigera eggs and A. gossypii nymphs were both adequate but not optimal diets for chrysopid larval development. The number of prey consumed by M. desjardinsi and C. congrua increased with instar. Total larval consumption of H. armigera by M. desjardinsi and C. congrua was determined to be 135.5 and 169.8 eggs respectively. However, total larval consumption of A. gossypii by M. desjardinsi and C. congrua was found to be 189.0 and 171.8 nymphs respectively. Because of its longer larval period, and higher consumption of A. gossypii, M. desjardinsi would be better suited for use against A. gossypii than C. congrua. In contrast, C. congrua whose consumption of H. armigera was higher than that of M. desjardinsi although their larval periods were similar, would appear promising for control of H. armigera.
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    Dwarf Variety of Coconut, Cocos Nucifera (Palmae), a Hostplant for the African Armyworm, Spodoptera Exempta (Wlk.) (Lepidoptera, Noctuidae)
    (Cambridge University Press, 1981) Yarro, Jacob G.; Otindo, B. L.; Gatehouse, A. G.; Lubega, M. C.
    The dwarf variety of coconut, Cocos nucifera L. (Palmae), was found to be eaten by the larvae of the African armyworm, Spodoptera exempta (Wlk.). The comparison of the armyworm infestation on the leaves of the coconut seedlings and the adjacent grass species revealed lower larval density and growth rate on coconut seedlings. This observation suggests that a small population of the African armyworm can survive and develop on the leaves of the dwarf variety of coconut.
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    Functional Response of Two Chrysopid Predators Feeding on Helicoverpa Armigera (Lep: Noctuidae) and Aphis Gossypii (Hom; Aphididae)
    (Springer, 1996) Kabissa, Joe C. B.; Yarro, Jacob G.; Kayumbo, H. Y.; Juliano, Steven A.
    Predation onHelicoverpa armigera (Hubner) eggs andAphis gossypii (Glover) nymphs by 3rd instar larvae ofMallada desjardinsi (Navas) andChrysoperla congrua (Walker) was studied under laboratory conditions. Single predators that had been starved for 24 hours were isolated for 1 hour in 9 cm Petri dishes containing prey at densities of 5, 10, 15, 20 and 25 per dish. A type II functional response model gave a satisfactory fit to the data in case ofM. desiardinsi preying onH. armigera. However, with C.congrua, a type III model gave a slightly better fit. ForA. gossypii, functional responses of both predators did not differ from type II, withM. desjardinsi showing a significantly lower search rate and shorter handling time thanC. congrua. Implications of these findings are discussed
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    Life and Fertility Tables for Spodoptera Exempta (Wlk.) (Lepidoptera, Noctuidae)
    (Cambridge University Press, 1984) Yarro, Jacob G.
    Laboratory reared populations of Spodoptera exempta (Wlk.) had higher net reproductive rate and capacity for increase on maize, Zea mais L. and star grass, Cynodon dactylon (L.) Pers. than on Kikuyu grass, Pennisetum clandestinum Chiov., Guinea grass, Panicum maximum Jacq. and Setaria plicatilis (Hochst.) Hack. These parameters were greatly influenced by the larval mortality, but in all cases they were greater than one demonstrating that S. exempta populations can multiply on all the host plants tested. Since no populations with stable age distributions are known for S. exempta the net reproductive rate is more appropriate than the capacity for increase in estimating its population growth.
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    Reduced Hatchability of Anopheles Gambiae S.S Eggs in Presence of Third Instar Larvae
    (2014) Godfrey, Gilbert M.; Urasa, Fausta M.; Katunzi, Gerald; Yarro, Jacob G.; Munga, Stephen; Kweka, Eliningaya J.
    Background: We investigated the hatchability rates of freshly laid Anopheles gambiae s.s. eggs in presence of thirdinstars larvae. These experiments were conducted using 30 eggs in larval densities of 20, 60 and 100 larvae inmicrocosms. These experiments were designed to evaluate the eggs hatchability in habitats with late larvae instarsof the same species (experimental) or no larvae at all (control). Freshly laid eggs of An.gambiae s.s. were washed inmicrocosms containing larvae of third instars in different three densities (20, 60 and 100) and likewise in controlmicrocosms (without larvae). Eggs hatchability was monitored twice daily until no more first instar larvae emerged.The numbers of first instars larvae were record ed daily and lost eggs were considered preyed upon by third instars.Findings: The findings of this study showed that egg hatchability was significantly influence d by larval density.Conclusion: The findings of this study suggest that presence of larvae in habitats may significantly reducehatchability of eggs.
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    Seasonal Abundance of Chrysopids (Neuroptera: Chrysopidae) Preying on Helicoverpa Armigera (Hubner) (Lepidoptera: Noctuidae) and Aphis Gossypii (Glover) (Homoptera: Aphididae) on Cotton in Eastern Tanzania
    (Elsevier, 1996) Kabissa, Joe C. B.; Kayumbo, H. Y.; Yarro, Jacob G.
    The occurrence of chrysopids on cotton in relation to Helicoverpa armigera and Aphis gossypii was studied between 1988 and 1991. By the 8th week after germination predators and their prey were already established on the crop. Among the chrysopid species observed on cotton, only Mallada desjardinsi (Navas) and Chrysoperla sp. occurred on cotton when both H. armigera and A. gossypii were present. Chrysopids and A. gossypii were most abundant on cotton between the 12th and 15th weeks after germination. However, peak abundance of eggs and larvae of H. armigera on cotton occurred earlier between the 8th and 13th weeks. Parasitism in populations of field collected larval, pupal and imaginal chrysopids was noted. Activity of adult H. armigera and chrysopids monitored by light traps showed two peaks of abundance coinciding with short and long rains. Prospects of manipulating chrysopids for biological control of H. armigera and A. gossypii are discussed.
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    Survival and Development of the African Armyworm Spodoptera Exempta (Wlk.) (Lepidoptera, Noctuidae) on Some Grass Species (Graminae
    (Cambridge University Press, 1984) Yarro, Jacob G.
    At 25°C and 70% r.h. larvae of Spodoptera exempta develop faster and pass through five instars on star grass, Cynodon dactylon (L.); Pers. maize, Zea mais L.; and Kikuyu grass, Pennisetum clandestinum Chiov. whereas on guinea grass, Panicum maximum Jacq.; and Setaria plicatilis (Hochst.) Hack, the development is not only slower, but the larvae pass through six and seven instars, respectively. Samples of larvae reared on the former grass species suffer high mortality only at the first and the last instar stages so that the distribution of per cent mortality is U-shaped. On the latter host plants, the mortality during the first instar stage is equally high and continues through the subsequent instars with no obvious peak towards the end of the larval life. The samples on C. dactylon and Z. mais had much higher growth indices than those on P. maximum and S. plicatilis. C. dactylon is a preferred natural food plant of S. exempta in the field, and these investigations demonstrate its value and importance.
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    Variability in Polymorphism and Sex Ratio of the Conehead Ruspolia Differens Serville (Orthoptera: Conocephalidae) in North-West Tanzania
    (2010) Matojo, Nicodemus D.; Yarro, Jacob G.
    We scrutinized variability in colour polymorphism and sex ratio of the cone-headed tettigoniid Ruspolia differens (Orthoptra: Conocephalidae) in north-west Tanzania during periods of swarms and of non-swarming phase. Six key colour morphs were characterized together with their continuous and discontinuous sub-morphs. Seasonal weather alterations evidenced to alter the relative frequency and sex-ratio biasness of these morphs. During dry season the equilibrium of colour polymorphism favours the frequency of the browns and the population is chiefly male-biased, but during wet season the greens are favoured and the population is female-biased. This implies that these traits are directly governed by weather conditions and are subjects to vary with geographical regions. Tegmina coloration showed to be a sex-linked trait as brownness was associated with maleness whereas greenness was associated with femaleness. Further, tegmen speckles are a useful biomarker of inheritance of the browns and the greens are dominant over the browns. It was apparent that the distinct variability in colour polymorphism and sex ratio of this insect is its interactive strategy for inhabiting different weather and environments.