The Present and Future Role of Insect-Resistant Genetically Modified Maize in IPM

Commercial, genetically-modified (GM) maize was first planted in the United States (USA, 1996) and Canada (1997) but now is grown in 13 countries on a total of over 35 million hectares (\u3e24% of area worldwide). The first GM maize plants produced a Cry protein derived from the soil bacteriumBacillus thuringiensis (Bt), which made them resistant to European corn borer and other lepidopteran maize pests. New GM maize hybrids not only have resistance to lepidopteran pests but some have resistance to coleopteran pests and tolerance to specific herbicides. Growers are attracted to the Btmaize hybrids for their convenience and because of yield protection, reduced need for chemical insecticides, and improved grain quality. Yet, most growers worldwide still rely on traditional integrated pest management (IPM) methods to control maize pests. They must weigh the appeal of buying insect protection “in the bag” against questions regarding economics, environmental safety, and insect resistance management (IRM). Traditional management of maize insects and the opportunities and challenges presented by GM maize are considered as they relate to current and future insect-resistant products. Four countries, two that currently have commercialize Bt maize (USA and Spain) and two that do not (China and Kenya), are highlighted. As with other insect management tactics (e.g., insecticide use or tillage), GM maize should not be considered inherently compatible or incompatible with IPM. Rather, the effect of GM insect-resistance on maize IPM likely depends on how the technology is developed and used

DISTRIBUTION AND SPECIES COMPOSITION OF CEREAL STEMBORERS IN THE EASTERN ZONE OF TANZANIA

A survey was conducted in the four regions of Tanga, Morogoro, Coast and Dar es Salaam in eastern Tanzania to determine the distribution and species composition of cereal stemborers and their natural enemies. A total of 22 fields were sampled in Tanga, 28 in Morogoro, 17 in Coast and one in Dar es Salaam. Chilo partellus was found to be the predominant species, accounting for 80 % of all stemborers collected. Busseola fusca, Sesamia calamistis and Chilo orichalcociliellus made up 15, 4 and less than 1 % of the stemborers collected respectively. Infestation levels varied with the age of the plants, whereby younger plants were more severely infested (infestation ranging from 20 - 40 %) than mature plants (infestation ranging from 5 - 15 %). Two larval parasitoids, Cotesia sesamiae and Cotesia flavipes, were the main natural enemies collected. However, the levels of parasitism of the stemborers were very low. The exotic natural enemy Co. flavipes may have spread from the Kenya coast (where it is established) into eastern Tanzania. RÉSUMÉ Une enquête a été menée dans les quatre régions de Tanga, Morogoro, Coast et Dar es Salaam dans l'est de la Tanzanie afin de déterminer la distribution et la composition en espèces des foreurs de tige de céréales et de leurs ennemis naturels. Au total, 22 champs ont été échantillonnés dans Tanga, 28 dans Morogoro, 17 dans Coast et un dans Dar es Salaam. Chilo partellus est l'espèce dominante, il représente 80% de tous les foreurs des tiges récoltés. Busseola fusca, Sesamia calamistis et Chilo orichalcociliellus représentent respectivement 15, 4 et moins de 1 % des foreurs de tige récoltés. Les niveaux d'infestation varient avec l'âge des plantes; ainsi les plantes les plus jeunes sont plus sévèrement infestées (l'infestation est comprise entre 20 - 40%) que les plantes mûres (l'infestation est comprise entre 5 et 15%). Deux parasitoïdes larvaires, Cotesia sesamiae et Cotesia flavipes, sont les principaux ennemis naturels récoltés. Cependant, les niveaux de parasitisme des foreurs des tiges sont très bas. L'ennemi naturel exotique Co. flavipes a dû s'étendre de la côte kenyanne (où il est établi) vers la côte tanzanienne

Abundance and diversity of lepidopteran stemborers and their parasitoids on selected wild grasses in Uganda

Surveys were conducted in four agroecological zones in Uganda to catalogue wild host plants of lepidopteran stemborers. Among those sampled, Panicum maximum, Pennisetum purpureum, Pennisetum polystachion and Sorghum arundinaceum were selected for further studies on stemborer diversity and density. Overall, stemborer incidence was low (< 10.8%) with the highest infestations on S. arundinaceum. Among the 11 borer species identified, there were seven noctuids, two crambids, one pyralid and one unidentified cossid. The economically important crambid Chilo partellus and the noctuid Busseola fusca were mostly found on S. arundinaceum and were rare on the other three grass species. Braconid larval parasitoids were commonly obtained from C partellus on S. arundinaceum and parasitoids of Sesamia spp. were most often found on P. purpureum. We concluded that in Uganda, with the exception of S. arundinaceum, wild grasses play a minor role in the seasonal persistence of C partellus and B. jusca

Diversity of lepidopteran stem borers on monocotyledonous plants in eastern Africa and the islands of Madagascar and Zanzibar revisited

Surveys were completed in Eritrea, Ethiopia, Kenya, Madagascar, Mozambique, Tanzania, Uganda and Zanzibar to assess the lepidopteran stem borer species diversity on wild host plants. A total of 24,674 larvae belonging to 135 species were collected from 75 species of wild host plants belonging to the Poaceae, Cyperaceae and Typhaceae. Amongst them were 44 noctuid species belonging to at least nine genera, 33 crambids, 15 pyralids, 16 Pyraloidea species not yet identified, 25 tortricids and three cossids. The noctuid larvae represented 73.6% of the total number of larvae collected, with 66.3, 3.5 and 3.8% found on Poaceae, Cyperaceae and Typhaceae, respectively. The Crambidae, Pyralidae, Tortricidae and Cossidae represented 19.8, 1.9, 2.5 and 0.1% of the total larvae collected, respectively, with 90.4% of the Crambidae and Pyralidae collected from Poaceae, and 99.7% of the Tortricidae collected from Cyperaceae. The lepidopteran stem borer species diversity in the wild host plants was far more diverse than previously reported