Dr. Costancia P. Rugumamu Department of Zoology and Wildlife Conservation,

1. DEVELOPMENTS AND IMPLICATIONS IN THE MANAGEMENT OF INSECT PEST INFESTATIONS IN STORED MAIZE, ZEA MAYS (L.): A CONTRIBUTION TO INTEGRATEDPEST MANAGEMENT Dr. Costancia P. Rugumamu Department of Zoology and Wildlife Conservation, University of Dar es Salaam, P.O. Box 35064 DAR ES SALAAM, TANZANIA

2. Introduction • Insect pest infestations cause greater losses of stored maize crop in developing countries including Tanzania - hindering agricultural devpt. • In cases of pest outbreak, the stored crop is at high damage risk given the low EIL. • Devpts. in crop insect pest magt. technologies: applications of chemical pesticides, biological control, varietal resistance, traditional control, legislative strategies.

3. Introduction cont. • Food and agriculture policy in Tz is to achieve self-sufficiency in food and food security through increased food production as well as increased commodities for export. • It underscores the need to utilize S&T in order to maximize productivity:improved methods of farming, seed varieties & better methods of crop pest magt. in storage. • Some technologies are integrated and hence become components of IPM.

4. Introduction cont. • Regarding GMCs in Tz., preparations are underway and a National Biotechnology Advisory Committee (NBAC) has been established. • NBAC consists of policy makers, govt. agencies, R&D institutions, and the private sector. • Advisory on introduction & development of GMOs in the country= account human and environmental safety, public concerns, ethical, and socio-economic factors.

5. Maize and insect pest infestations • Maize, Zea mays was first introduced in Tz by Portuguese traders in the C16th and C17th and was initially suited to the coastal strip. • Technological devt. and introduction of many new maize varieties to farmers has triggered the crop propagation into the high and middle altitudes. • Maize as a staple food and cash crop is grown and stored in almost all the regions of the country. • The crop however, is mostly susceptible to insect pest infestations.

6. Maize and insect infest. cont. • Since the early 1980s problems associated with maize storage in Tz have been aggravated by the accidental introduction of a serious alien pest of drying maize in fields and in storage, the LGB, Prostephanus truncatus (Horn). • LGB was given various local names reflecting economic losses caused by both larvae and adults to on-farm stored maize. • It is imperative therefore to develop effective magt strategies against the pests especially in rural areas with agricultural based livelihoods.

7. Maize and insect pest infest. • Increases in maize yields have been facilitated by S&T advances in breeding for genotypes of greater resistance to field pests and diseases and by applic.of modern farm practices & implements. • However, greater storage losses may also result from some of the improved technologies. • Some grain physical and chemical/nutritional characteristics incorporated in breeding could result into its susceptibility to insects in storage.

8. Application of chemical pesticides • Historically, when synthetic chemical pesticides came into widespread use in the 1940s they promised an era of abundant agricultural yields, however, it didn’t take long to recognize that the miracle chemicals had also costs and risks. • Chemicals were highly toxic to most insect groups, broad spectrum and persistent. • However, despite their shortcomings current control of stored pests is mainly achieved by chem. pesticides eg. Permethrine; Pirimiphos -methyl.

9. Application of chem. pesticides cont. • Insect growth regulators (IGR) and juvenile hormones (JH) are included in the pesticides group, they are specific and have minimal disruptive effects on the environment. • JH if applied to full-grown larva disturbs metamorphosis and the insect dies as a deformed pupa/adult. • IGR - not as specific as JH but interfere with cuticle formation at ecdysis killing larvae.

10. Application of chem. pesticides cont. • Chemical pesticides in Africa, for example, are very expensive and most govts. have reduced subsidy to farm inputs especially to pesticides. • However, it is argued that many chem. pesticides may cost comparatively little, because the risks and social costs associated with their use are not included in their price. • Rational decision to use chemical pesticides mustbe based on cost – benefit analysis and EIA.

11. Application of chem. pesticides cont. • Chemicals rarely kill all the pests, the few survivors over generations develop slight genetic differences = biotypes resulting into serious problems= resistance to the chems. • If not well monitored, continued addition of chem. = general ecological disturbance. • In Tanzania, TPRI supervises & regulates the manufacture, importation, distribution, sale & use of pestic. & administer regulations made under the Act establishing it.

12. Biological control • Another IPM component which broadly includes all control types involving living organisms. • It reduces the necessity of using chem. poisons and gives long-term control from one introduction. • Hence biointensive IPM is advocated under far-sighted agricultural policies. • A natural predator, the histerid beetle Terestriosoma nigrescens Lewis was released for biological control of P. truncatus (Horn) in East Africa notably in Kenya.

13. Biological control cont. • Some limitations to this technology are that, most predators are not host-specific; • The enemy requires longer period to be effective in the control. • Further ecological research on specificity of agents to the pests may allow a wide introduction of more predators; pathogens; parasites and parasitoids of common insect pests.

14. Biological control cont. • Male sterilization - effective in restricted popns. & also in spps. where females only mate once and unable to discriminate against sterilized males. • Attractant pheromones used in P. truncatus pest popns. monitoring in Tz. = control measures may then be exercised with precise timing. • Pheromones employed in insect pest behavioural control = induced to fly to inappropriate hosts.

15. Biological control cont. • Genetic engin., Tz has ratified the Cartagena protocol on biosafety - Safe CFTs of GMCs principles are outlined. • Under GMO technology, many food plants are being genetically engineered to resist pests that include Bacillus thuringiensis, (Bt). • TPRI & NBAC - closely monitor the devt. & testing of GM products & provide scientific advices on their safety. • However, there are no laws in Africa at present requiring GM labels on food containers.

16. Biological control cont. • Main advantages of biological control evolve around: • - no development of resistance by the pests; • - no residual of poisons in the envt. • - no build-up of toxins in food chains; • - no killing of beneficial organisms; • - permanence of successful control; • - self-adjusting.

17. Biological control cont. • There can arise shortcomings, eg. most predators are not host-specific, attack beneficial organisms and the GM parasites or pathogens when misused cause disasters. • The dual-use nature of biological agents due to the ease with which they could be directed to antagonistic use against crops and animals raises concern.

18. Varietal resistance • It has adverse effect on the bionomics of the pest by causing its death or decreasing the rate of its development and reproduction. • It is environmentally safe, economically acceptable to farmers and most compatible with other IPM components. • A search to identify more insect pests resistant varieties is recommended as an initiative to significantly reduce losses.

19. Varietal resistance cont. • More methods for screening maize for varietal resistance are being developed. • These are intended to positively contribute to the welfare of communities. • And to be in line with the need to monitor possible misuse of breeding technologies which could lead to mass production and distribution of varieties with poor storage qualities causing great losses leading to famine and insecurity.

20. Application of traditional pesticides • Farmers’ ingenuity has enabled them through time to employ IK by applying botanical & non-botanical pesticide materials to protect their crops. • In some traditional beliefs seeds are “blessed” by local priests for high yields, protection from all types of pests including thieves. • There is need for further research on the efficacy, full potential & possible toxicological hazards associated with traditional pesticides use.

21. Legislative Control • Restrictions of movement of produce domestically & at international entry points are practiced in Tz. • This programme is adaptable as a model for other countries in Africa to prevent P. trucatus infestation from spreading to neighbouring countries. • The strategy, however, works with limited success given free movement of people in these areas.

22. A way forward in stored products IPM • Continued research in the field of IPM that will reduce reliance on only chemical control in farm stores is recommended. • Since IPM strategies are specific to each pest, climatic conditions and other local factors, they require long term multidisciplinary research programmes to develop successful methods which once formulated, IPM strategies unlike chemicals can’t be packed and sold everywhere.

23. A way forward cont. • It is advanced - instead of IPM “technology transfer” through training and visit (T&V) system, the “farmer first” paradigm of participatory nonformal edn. led by IPM extensionists in farmer field schools followed by community IPM activities emphasizing farmer-training-farmer & research by farmers had greater success in achieving IPM implementation. • When wisely used and in accordance with BTWC the S&T advances in stored products IPM would contribute to solving major development issues.

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