Range and Occurance of Pigeonpea Pests in Central Uganda

A study was carried out at the Makerere University Agricultural Research Institute, Kabanyolo over four cropping seasons (1990-1992) to determine the range of pests attacking pigeonpeas ( Cajanus cajan (L) Millsp.) in Uganda, and to assess their status depending on occurrence and nature of damage. Of the species identified, there were seven lepidopterans, two homopterans, three heteropterans and coleopterans, each, and one dipteran, hymenopteran, isopteran and thysonopteran insects and jassids (Homoptera), cowbugs (Heteroptera), leaf Webbers and defoliators (Lepidoptera), leaf beetles (Coleoptera) and grasshoppers (Orthoptera). Seven identified species were new records on the crop in the country. The most commonly occurring species were Aphis craccivora (Koch), Helicoverpa armigera (Hub), Maruca testulalis (Geyer), Etiella zinckenella (Treitschke), Melanogromyza chalcosoma Spencer, Tanaostigmodes cajaninae LaSalle and Clavigralla sp

Comparative control of the banana weevil, Cosmopolites sordidus, by the fungal pathogen, Beauveria bassiana, and some insecticides when used in combination with pseudostem trapping

Field evaluation was made of the effect of the fungal pathogen, Beauveria bassiana (Bals.) Vuillemin (Isolate KB/91/3), and Dursban, Primicid and Furadan insecticides on the banana weevil, Cosmopolites sordidus Germar. When the treatments were combined with pseudostem trapping, population of the banana weevil declined sharply. In the first four weeks after application, B. bassiana did not cause significant mortality of the weevil, while high mortalities were recorded for the insecticides, particularly Dursban. Monitored over a longer period (2-5 months), however, all the treatments significantly (P<0.05) suppressed weevil population compared to the control. Beauveria bassiana was more persistent than the chemical insecticides, particularly when used without pseudostem traps. It is suggested that comprehensive field trials be carried out to confirm the findings of this study.Une evaluation a ete menee sur le champ sur l'effet du pathogene fungale, Beauveria bassiana (Bals.) Vuillemin (Isolate KB/9113), et les insecticides appelees Dursban, Primicide et Furadan utilisees sur les charancons de la banane, Germar cosmopolites sordidus. Quand les traitements etaient combines avec les signes du pseudostem, la population des charancons de la banane a connu un moindre declin. Au cours de la premiere semaine de la mise en application, B. Bassiana n'a pas cause de cas des mortalites considerables de charancons alors que des cas des mortalites elevees etaient remarques du cote insecticides, plus particulierement le Dursban. Apres un controle pendant une longue periode (de 2 a 5 mois), il ya eu cependant, tous les traitements qui ont considerablement domine la population des charancons (P<0.05). Le type Beauveria bassiana etait plus persistant que les autres produits chimiques d'insecticides, particulierement lors qu'ils sont utilises avec les pieges pseudostem. Il a ete conseille que les essaies complets soient menes pour determiner les resultats de cette recherche

Range and Occurance of Pigeonpea Pests in Central Uganda

A study was carried out at the Makerere University Agricultural Research Institute, Kabanyolo over four cropping seasons (1990-1992) to determine the range of pests attacking pigeonpeas ( Cajanus cajan (L) Millsp.) in Uganda, and to assess their status depending on occurrence and nature of damage. Of the species identified, there were seven lepidopterans, two homopterans, three heteropterans and coleopterans, each, and one dipteran, hymenopteran, isopteran and thysonopteran insects and jassids (Homoptera), cowbugs (Heteroptera), leaf Webbers and defoliators (Lepidoptera), leaf beetles (Coleoptera) and grasshoppers (Orthoptera). Seven identified species were new records on the crop in the country. The most commonly occurring species were Aphis craccivora (Koch), Helicoverpa armigera (Hub), Maruca testulalis (Geyer), Etiella zinckenella (Treitschke), Melanogromyza chalcosoma Spencer, Tanaostigmodes cajaninae LaSalle and Clavigralla sp

Relative Infestation and Damage of Some Pigeonpea Cultivars by Lepidopteran Pod Borers in Uganda

Infestation and damage of some pigeonpea ( Cajanus cajan [L.] Millsp.) cultivars by lepidopteran pod borers were evaluated over two cropping seasons during 1991 at the Makerere University Agricultural Research Institute, Kabanyolo. Significant (P≤0.05) cultivar differences were recorded in borer incidence and pod damage. Apio, the local cultivar, showed the highest infestation by Helicoverpa armigera (Hubner). ICPL 87104 had the greatest infestation by Maruca testlalis (Geyer), although in the second season it was not significantly higher than the rest. Etiella zinckenella (Treitschke) occurred in very low numbers, and cultivar differences were not significant (P > 0.05). Indexing larval counts to number of pods per plant showed that infestation pressure by both H. armigera and M. testulalis was not as different among cultivars as larval counts suggested. Pod damage was greatest on ICPL 87 and lowest on ICPL 87104

Use of Pseudostem and Coefficient of Infestation (PCI) for Assessing Banana Infestation and Damage by Cosmopolites sordidus Germar

The banana weevil borer, Cosmopolites sordidus Germar (Coleoptera: Curculionidae), is a nocturnal pest and larvae tunnel into banana rhizomes. Infestation and damage are assessed mainly by pseudostem trapping of adults, and the determination of coefficient of infestation. Deficiencies of these methods were identified and field experiments and destructive sampling of bananas carried out to answer some of the questions raised. Variations in trapping conditions, such as trap length, placement, duration of trapping, and soil moisture conditions significantly influenced weevil catches in pseudostem traps. The relationship between external rhizome tunneling, indexed as percent Coefficient of Infestation (PCI), and internal rhizome damage by C. sordidus varied among the banana types and with the parameters used to quantify damage. There was also a poor correlation between weevil trap catches and rhizome damage. For trap to be statistically comparable, trap size and trapping conditions should be defined and standardized. Proper use of the PCI requires that correlations between external tunneling and internal rhizome damage be established for a given banana type of cultivar.

Efficacy of different insecticides for the management of stemborers of maize in Uganda

Evaluation was made of the efficacy of commonly available insecticides for control of stemborers on maize. Insecticide application influenced the occurrence and extent of stemborer damage on maize. In the early stages of crop development, the lowest stemborer incidence was recorded on Furadan treated plots, although its efficacy decreased with time. Overall, Sevin treatments effected better control compared to other treatments. A well timed granular application of Sevin could fit well in the integrated stemborer management system and reduce maize yield losses caused by these pests.L'efficacite des insecticides communement disponibles dans la lutte contre les insectes terebrants des tiges du mais a ete evaluee dans la presente etude. L'application de l'insecticide a influence l'existence et l'importance des degets causes par les insectes terebrants sur le mais. Au cours des premiers stades de developpment de la culture, la plus faible incidence de l'insecte terebrant a ete enregistree sur les parcelles traitees avec du furadan, bien que son efficacite ait diminue avec le temps. Dans l'ensemble, les traitements avec du sevin ont produit un meilleur control par rapport a d'autres traitements. Une application granulaire du sevin mieux chronometree conviendrait mieux dans le systeme integre de la gestion de l'insecte terebrant et reduisait les pertes de la productivite du mais causees par ces pestes

Relative Infestation and Damage of Some Pigeonpea Cultivars by Lepidopteran Pod Borers in Uganda

Infestation and damage of some pigeonpea ( Cajanus cajan [L.] Millsp.) cultivars by lepidopteran pod borers were evaluated over two cropping seasons during 1991 at the Makerere University Agricultural Research Institute, Kabanyolo. Significant (P 640.05) cultivar differences were recorded in borer incidence and pod damage. Apio, the local cultivar, showed the highest infestation by Helicoverpa armigera (Hubner). ICPL 87104 had the greatest infestation by Maruca testlalis (Geyer), although in the second season it was not significantly higher than the rest. Etiella zinckenella (Treitschke) occurred in very low numbers, and cultivar differences were not significant (P > 0.05). Indexing larval counts to number of pods per plant showed that infestation pressure by both H. armigera and M. testulalis was not as different among cultivars as larval counts suggested. Pod damage was greatest on ICPL 87 and lowest on ICPL 87104

Seasonal fluctuations and damage of lepidopteran stemborers of maize in a major agroecozone of Uganda

The distribution and damage of stemborers of maize, Chilo partellus (Swinhoe), Busseola fusca (Fuller), Eldana saccharina Walker, and Sesamia calamistis Hampson, were studied in two locations in Uganda. The species composition of the stemborers was influenced by crop phenology. Distribution of stem borer larvae in the plant was similar at both locations. At 2-3 weeks after plant emergence (WAE), 100% of larvae recovered was from the funnel of the plant with the proportion decreasing as the stem elongated. Busseola fusca and Chilo partellus were more injurious as indicated by the extent of leaf and stem injury. Sesamia calamistis predominantly attacked the maize ears. This phenological relationship of variation in stemborer incidence and damage to crop phenology is crucial in devising management strategies of the pests.La distribution et les degets causes par les insectes terebrants (stemborers) des tiges du mais, Chillo partellus (Swinhoe), Busseola fusca (Fuller), Eldama Saccharina Walker, et Sesamia calamistis Hampson, ont ete etudies dans deux endroits en Ouganda. La composition specifique des insectes terebrants a ete influencee par la phenologie de la culture. La distribution des larves des insectes terebrants dans la plantes s'est revelee semblable dans les deux sites. Deux a trois semaines apres l'emergence de la plante (WAE), 100% des larves retrouvees provenaient de la cheminee de la plante avec une proportion decroissant avec l'elongation de la tige. Busseola fusca et Chilo partellus etaient plus agressives comme l'indiquaient l'etendue de la feuille et la blessure de la tige. Sesamia calamistis attaquait surtout les epis du mais. Cette relation phenologique de la variation dans l'incidence des insectes terebrants sur les tiges et les degets causee a la phenologie de la culture est cruciale dans les strategies combinees du controle des pestes

Factors Influencing the Incidence of the Black Bean Aphid, Aphis fabae Scop., on Common beans intercropped with maize

The incidence of the black bean aphid, Aphis fabae scop. (Homoptera: Aphididae), and its colonization of common beans (phaseolus vulgaris L.) grown as sole crop and as intercrops with maize ( Zea mays L.) of varying growth stages was evaluated in the field and glasshouse. Modification of bean micro-climate and its effects on A. fabae, and the species range and abundance of coccinellid predators (Coleoptera: Coccinellidae) of the aphid were also assessed. Results showed that A. fabae infestation of beans was greatly reduced when intercropped with older and taller maize plants. Larger maize plants interfered with aphid colonization of beans and only small proportions of beans were infested by the aphid. Shading by older maize plants significantly (P≤ 0.01) reduced the level of solar radiation reaching intercropped beans; this reduced the build-up of A. fabae populations. Intercropping also reduced the number and diversity of coccinellid predators on beans, contrary to the prediction based on the "enemies hypothesis". Reduced aphid incidence on intercrop beans was attributed to maize interference with aphid host finding behavior and bean colonization and, to a lesser extent, to reduced build-up of A. fabae populations due to shading