Biological Control of Sciarid flies (Bradysia spp.) with Entompathogenic Nematode Steinernema feltiae on Greenhouse Propagated Poinsettia (Euphorbia pulcherima) in Ethiopia

Abstract

Sciarid flies (Bradysia spp.) are major insect pests of gre enhouse -grown
horticultural crops mainly due to the direct feeding damage caused by the larvae,
and the ability of larvae to transmit certain soil-borne plant pathogens. Currently,
insecticides and biological control agents are being used successively to deal with
Sciarid flies populations in greenhouse production systems. Sciarid flies are very
important constraints of flowers in general and particularly Poinsettia. Biological
control of sciarid flies is a safe alternative to chemical control. The
entompa thogenic nematode, Ste ine rnema feltiae was applied at the rate of 50
million nema todes /1 0 0m”; sprayed two times per season at weekly interval. On the
other hand, the conventional insecticide nomoult and tap water were used as
positive and negative controls, respectively. Three separate greenhouses were used
for each treatment. The exper iment was conducted two times and the results were
combined for analysis. Adult sciarid flies were monitored for six we eks by using
yellow sticks trap suspended over the crop. Plant mortality, root development, root
d amage and number of sciarid fly maggots recovered atter six weeks o f trial period
were assessed by using destructive sampling. The result revealed that as compared
to the untreated control. S. feltiae has resulted to 66% reduction of the deve lopment
of sciarid fly adult. Similarly, the application of S. feltiae increased the root
deve lopment by 38.55 %. Besides, from our visual observation of the plant, injury
caused by the insect in the negative control plots resulted in yellowing and wilting
o f leaves and loss of plant vigor.