The average recorded duration of A. exotica development was 2.0, 7.4 and 5.7 days for eggs, larvae and pupae respectively, and 15.04 days from egg to adult emergence. i. It is essential to know the peak period of aphid migration before application of insecticides. A yellow to brown discolouration, and weight loss occurs as a result. Shew (1988) found slightly more infection at 20°C than at 24°C. Since S. rolfsii does not produce spores, dissemination depends on movement of infested soil and infected plant material. Upon isolation from diseased tissue, the fungus will grow on a variety of media, most optimally at 25°C, producing large black conidial heads (up to 700-800 um in diameter). In culture, the whole area of a Petriplate is rapidly covered with mycelium, including aerial hyphae which may cover the lid of the plate. Effects of six host plants on the biology of black bean aphid, C.M.I.IA.A.B. A cereal-cereal-groundnut crop rotation and removal of volunteer groundnut plants from the field will help to check rust inoculum build-up. Pour confirmer ces résultats sur 15 acquisitions sélectionnées, la croissance de la population de pucerons a été mesurée après dix jours. Ring Nematode. The second stage of juveniles invade roots at or close to the tip and migrate to the site of differentiating vascular tissues. We use cookies to distinguish you from other users and to provide you with a better experience on our websites. The percentage of conidia that germinate is known to decrease with increasing temperature above 20°C and at 20°C it takes about 12 h for 50% of the conidia to germinate. The occurrence of pod rots may be severe due to attacks of nematodes, termites, and millipedes on pods, thus predisposing the invasion by fungi and bacteria. Old lesions are characterized by their blotchy appearance and indistinct margins. Published online by Cambridge University Press: URL: /core/journals/international-journal-of-tropical-insect-science. i. Privacy Policy3. Solarize the soil during the hot dry season. The vulva is in the posterior portion of the body. Images by E. Arcaya. A very small amount (10-20 ppb) can produce fatal liver cancer in young animals. Aspergillus flavus is responsible for the disease of peanuts and corn commonly known as yellow mould. The older leaflets are dark green and reduced in size with their margins rolled outward. Often one or more elongate males are present in an egg sac. How are waste products excreted in amoeba? Life cycle: In the Middle East the cowpea aphid reproduces by parthenogenesis the year around and no sexual forms have so far been found. Use resistant/tolerant cultivars: ICGS 11, ICGS 44, ICGV 87141, ICGV 87187, ICGV 87119, ICGV 87121, ICGV 87160, ICGV 87157, or ICGV 86590. What is the reserve food material in red algae? Plants infected late, show typical leaf symptoms without the marked stunting and bushy appearance. ii. However, this schedule could be modified using a suitable disease forecast system based on temperature, humidity, cloudy weather, and rainfall pattern to save the fungicide and reduce the spray cost. iv. It is essential to know the peak period of aphid migration before application of insecticides. Sclerotia forming on a host tend to have a smooth texture, whereas those produced in culture may be pitted or folded. Later infected plants may only show bud necrosis on a few branches and axillary shoot proliferations may be restricted to the terminal portion. Feed prepared with this meal caused the death of 100 000 turkeys in Great Britain. We use cookies to help provide and enhance our service and tailor content and ads. Pod rot tends to be severe in sandy soils and in fields intensively cropped to peanuts. The virus survives in these hosts and acts as a source of inoculums for the vector. In their study on the influence of rainfall, temperature and relative humidity on groundnut leaf rust epidemiology, Lokhande (1998) observed that rainfall of about 200 mm, temperature between 23.5 to 29.4°C and relative humidity in the range 67 to 84% are congenial weather conditions for initiation and development of this disease. Subsequently terminal bud necrosis occurs especially when day temperatures exceed 30°C. A crop rotation of cereal-cereal-groundnut can significantly decrease the level of root-knot nematode infestation in soils. Images by E. Arcaya. Although no worldwide compilation of host genera has been published, over 270 host genera have been reported in the United States alone. Avoid damage to the testa while decorticating. iv. The vulva is located posteriorly, close to the anus. The fungi that cause pod rot are normally found at some level in most peanut soils. Moreover, in the present study different levels of aphid densities 10, 30, 40, 50, 60, 70, 80 and 100 were used to calculate the functional response. In early infection, pods are seldom produced. Following harvest, further infections may develop, with fungal growth covering the seed surface and invading the seed itself. An egg sac often protrudes posteriorly from the female to the exterior of the gall. Cook (1981) observed germ tube growth of P. personata towards stomata from the first day after inoculation of detached groundnut leaves. It develops small necrotic flecks that enlarge and become light to dark brown. Aflatoxin contamination in groundnut can occur in the stems of seedlings, pods and seeds. The spray combination of carbendazim at the rate 0.1% + Mancozeb at the rate 0.1% effective in reducing leaf rust disease. GRDC. Life history, life table and functional response of A. exotica were determined using the cowpea aphid Aphis craccivora Koch, 1854 as prey under controlled conditions of temperature, humidity and light.

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