Population dynamics of weevil Hypolixus pica, the natural enemy of wild amaranth, Amaranthus retroflexus, in citrus orchards and identification of its parasitoids in Dezful

Subject Areas : Plant Protection

Rajabali  Pourtaherzari ¹ ()
Parviz  Shishehbor ² ()
Rahim  Islamizadeh ³ ()

Received: 2010-07-14 Accepted : 2011-04-11 Published : 2009-12-22

Keywords:

Abstract :

Wild amaranth, Amaranthus retroflexus L. is one of the dominant summer weeds of citrus orchards in Dezful. Adults and larvae of snout beetle, Hypolixus pica (F.) feed on this weed and decrease its growth and reproduction. Population dynamics of H. pica was studied during the growing period of wild amaranth in a citrus orchard in Dezful. Every two weeks 30 plants (replications) were sampled and developmental stages of weevil were counted. The population of eggs started at the beginning of May and peaked in mid-July (23 eggs in 30 plants). In early November no eggs were observed. The population of larvae started in mid- May, increased gradually and peaked at the beginning of November (103 larvae in 30 plants). Pupae population started in mid-July and peaked in mid-September (24 pupae in 30 plants). Peak of adult female population was observed in the mid-September while adult male population had two peaks in early October and November. The population of parasitoids started at the beginning of June. The lowest and the peak number of parasitoids occured  in early May and mid-August, respectively. The parasitoids Habrobracon hebetor, Eurytoma curculionum and Cyrtoptx sp. had feeding activity on larvae.

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