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Effect of Cassava Variety on the Biology of Bemisia Afer (Priesner & Hosny) (Hemiptera: Aleyrodidae)

  • D. C. Munthali
Research Article

Abstract

The biology of Bemisia afer (Prisner & Hosny) reared in clip cages on leaves of 15 varieties of cassava, Manihotesculenta (Crantz)(Euphorbiaceae) was studied under field conditions during the cold months of June—August and during the warm months of September—October. Both variety and time of the year significantly affected the developmental period, the rate of population increase and the mortality.

The longest mean developmental period (59.5 days) occurred on the MH108 leaves during the cold months (at 20°C and 62.9% r.h.), while the shortest (27.1 days) was on the Kithekere variety during the warm months (at 25°C and 53% r.h.).

The pest population increased most rapidly on MH84 (at 5.4 eggs per female per day) and slowest on the Nigerian 3057/1 (at 0.9 eggs per female per day). The mortality of the pest indicated that Chitembwere had the greatest killing power (K = 2.555) and Nigerian 3057/1 had the least (K = 0.0760).

The combined use of the developmental periods, rate of population Increase and mortality indicated that Gomani was the most resistant while Kithekere was the least resistant variety to B. afer. Other varieties with high resistance properties included MH108, Chitembwere and Mbundumali. Of the three biological characteristics used, the developmental period was the most powerful while the rate of population increase was the least.

Pubescence of a cassava variety was only weakly associated with resistance to B. afer (r = 0.48) suggesting that other factors are more responsible for resistance to this pest than hairiness.

Key Words

Bemisia afer biology cassava varieties 

Résumé

La biologie de Bemisia afer (Priesner & Hosny) élevée dans des cages en plastique sur les feuilles de manioc de quinze variétés, Manihot esculenta (Crantz) (Euphorbiaceae) était étudié sous les conditions de terrain pendant la saison froide du mois de juin au mois d’aûut et pendant des mois chauds de septembre à octobre. La variéte ainsi que le temps de l’année ont influencé de façon significative la période de développement, le taux de croissance de la population et la mortalité.

La moyenne la plus longue de la période de développement (de 59.5 jours) a eu lieu sur les feuilles de MH108 pendant les mois froids (à 20°C et 62.9% h.r.), alors que la plus courte (de 27.1 jours) était sur la variété de Kithekere pendant les mois chauds (à 25°C et 53% h.r.).

La population parasitaire augmenta le plus rapidement sur MH84 (à 5.4 oeufs par femelle par jour) et augmenta le moins vite sur le Nigerian 3057/1 (à 0.9 oeufs par femelle par jour). La mortalité des insectes indiquait que Chitembwere avait le plus grand pouvoir de tuer (K = 2.555) et le Nigerian 3057/1 avait le pouvoir le plus faible (K = 0.760).

L’utilisation à la fois des périodes développementales, le taux de croissance de la population et la mortalité indiquèrent que Gomani était la plus résistante alors que Kithekere était la variété la moins résistante à B. afer. D’autres variétés avec de hautes propriétés de résistance comprenait MH108, Chitembwere et Mbundumali. Des trois caractéristiques biologiques employées, la période développementale était la plus puissante tandis que le taux de la croissance de la population était la motndre.

Les poils d’une variété de cassave n’était que faiblement associés à la résistance à B. afer (r = 0.48) suggérant le fait que d’autres facteurs sont plus responsables pour la resistance centre ce parasite que la présence des poils.

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Copyright information

© ICIPE 1992

Authors and Affiliations

  • D. C. Munthali
    • 1
  1. 1.University of MalawiZombaMalawi

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