BIOLOGICAL ASPECTS AND INSECTICIDE ACTION OF PLANT SPECIES ON EGGS AND NYMPHS OF CITRUS BLACK FLY (Aleurocanthus woglumi Ashby - Aleyrodidae)AT LABORATORY LEVEL

Abstract

ABSTRACT Aleurocanthus woglumi Ashby (Hemiptera: Aleyrodidae) is an important pest of many plant species in particular citrus species. The aims of this study were: (1) to observe ;'in vitro'; biological aspects in three hosts and (2) to evaluate the bioactivity of plant species on immature A.woglum. Aqueous neem extract (Meliaceae), cassava wastewater, pepper sauce and gravy peduncle floral carnation guinea button and commercial neem were used in the experiment. Egg viability (%), nymphal period duration, nymphal mortality (%), puparium stage duration and pupae viability (%) were evaluated in 50 egg positions, with minimum of five eggs in "Pera" orange, mango and malay apple leaves obtained in the field. The insecticide effect (translaminar action and direct spray) at different concentrations on immature A.woglumi was evaluated. The first bioassay conducted to evaluate the bioactivity of species by translaminar action, each sample unit corresponded to three leaves, with minimum of 20 eggs and 20 1st instar nymphs, the variables were unviable eggs and nymph mortality (%); the experiment had a completely randomized design with four replications. In the second bioassay, fully infected branches were sprayed on upper and lower face of leaves with all treatments. Leaves with at least 40 eggs and 40 1st instar nymphs were marked, and mortality (%) and emergence (%) of adults were evaluated for seven days; each sample unit was represented by 40 eggs and 40 1st instar nymphs and the experiment had a completely randomized design with four replications. The average duration of the nymphal period ranged from 7.76 to 24.18 days in 'Pera'; orange, and from 8.86 to 25.20 days in mango. There was no significant difference between the viability of eggs and nymphs in ;'Pera'; orange and mango or pupae viability between ;'Pera'; orange and malay apple. Treatment efficiency was evaluated using the Abbott's formula [E(%) = T-I/T x 100], where E ( % ) = efficiency percentage, T = number of live insects in the control treatment and I = number of live insects in treatment with insecticide. Therefore, in the first bioassay conducted to evaluate the bioactivity of species by translaminar action, all treatments showed efficiency greater than 50%. In the second bioassay by direct spraying to cassava wastewater (100% and 50 %) and commercial neem oil (1%), treatment had nymphal mortality efficiency greater than 80%.