Efficacy of Spoladea recurvalis as biological control agent against the weed Trianthema portulacastrum L.

Issue Date

10-2004

Abstract

The effects of larval density of Spoladea recurvalis on Trianthema portulacastrum L. (horse purslane) at different growth stages were determined in pot studies from May 2002 to January 2003. The life cycle of S. recurvalis ranged from 31 to 33 days. The eggs hatched within 4 days, the larval period was 15 days covering five instars, and pupal period was 10 days. Increasing numbers of larvae (1.5.10,15 and 20) were released on caged T. portulacastrum plants. Twenty larvae of S. recurvalis consumed 36% of leaves of the plants within 24 hours. At 14 days after release, 86% of leaves were consumed by 20 larvae. Also, the number of flowers and capsules produced by the plants were significantly reduced. S. recurvalis larvae consumed and greatly damaged the young (15-39 days old) but caused little damage to mature 60-day old plants. All the leaves of 15-day-old plants were consumed within 24 hours after insect release and 81% of leaves of 30-day-old plants were consumed within 24 hours after insect release and 81% of leaves of 30-day-old plants was consumed 14 days after larvae were released. Of the 13 crops and 5 weeds tested for host specificity, the insect fed and completed its life cycle only on Amaranthus viridis and Portulaca oleracea.

Source or Periodical Title

Philippine Entomologist

ISSN

0048-3753

Volume

18

Issue

2

Page

174

Document Type

Article

Frequency

semi-annually

Language

English

En – AGROVOC descriptors

TRIANTHEMA; AMARANTHUS VIRIDIS; BIOLOGICAL CONTROL AGENTS; LIFECYCLE; ANIMAL DEVELOPMENTAL STAGES; PEST CONTROL

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