Browsing by Author "Mphuru, Athanasius N."

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    Comparative biological and ecological studies of callosobruchus species in Tanzania with particular emphasis to Callosobruchus Chinensis (L.)
    (University of Dar es Salaam, 1983) Mphuru, Athanasius N.
    Comparative biological and ecological studies of Callosobruchus species in Tanzania with particular emphasis to Callosobruchus chinensis are presented. Five species of Callosobruchus were found to be associated with various types of stored legumes in Tanzania. These include C. analis. The morphological characters of taxonomic value of these species are described and illustrated and emphasis is placed on structures in the male genitalia. Distinct differences occurred between the various species of Callosobruchus. The shape, size, and number of chitinized plates in the saccus region of the genitalia varied greatly between different species. The number of these chitinized plates in C. chinenis, C. rhodesianus, C. analis and C. phaseoli were two six, four, and two, respectively. Similarly the length, width, and the number of setae at the tip of parameres of different species showed significant differences. The number of setae at the tip of lateral parameres of C. chinensis, C. rhodesianus, C. analis and C. phaseoli were 20, 7, 15, and 26, respectively. In C. maculatus the genitalia occurred in two forms. These two forms are described and the significance of this polymorphism is discussed.Samples collected from different parts of the country showed that they contained only one species and mixed populations were very rare. The significance of this and possible reasons for it are discussed. Distribution and host plants data of all the species are described. Studies on the distribution and relative abundance of Callosobruchus species in Tanzania indicate that C. phaseoli in that order. C. maculatus was the most abundant species in the drier areas of Tanzania especially in Morogoro, Dodoma, Singida, Tabora, Shinyanga and Mwanza regions while C. chinenis was the most important species in the high altitude areas including Mbeya, Iringa, Moshi and Arusha regions. Studies on host-plant relationships showed that C. phaseoli was found associated mainly with lablab (Labla niger), while C. analis was found associated mainly with chickpea (Cicer arietinum). C. chinensis was found associated with a wide range of legumes including Pigeon peas (Cajanus cajan), chick peas (cicer arietinum), Cowpeas (Vigna unguiculata) and green gram (Vigna aureus). C. maculatus showed food preference similar to those of C. chinensis except that this species also attacked Bambaranut (Voandzeia subterranea). The distribution of these pests is discussed in relation to the origin of the host plants. Studies on the life history of C. chinensis at 300C and 80% R.H. are also described. Measurements of the width and length of head capsule and length and width of larvae indicate that there are four distinct larval instars. The total developmental period from egg to adult averaged three weeks. The egg stage, the first, second, third and fourth larval and pupal stages lasted 4 to 5, 2 to 3, 2 to 3, 3 to 4, 5 to 6 and 5 to 6 days, respectively. From the measurements of the length and width of each successive instar the development of the larvae followed a geometric pattern. Longevity in C. chinensis adult was also measured in absence of food and presence of glucose solution and water at different temperatures. The adult was short-lived, living for only about a week. Food and water had little influence on the adult longevity. Temperature on the other hand greatly influenced the life span of adult. The significance of this is discussed. The weight losses, pattern of bruchid damage and the relationship between damage and losses are reported in these investigations. The weight loss due to one bruchid varied from 20 to 30mg. Bruchid damage had little influence on percentage germination. However, it greatly influenced the seedling vigour