Effects of plant density on abundance of diamondback moth (Lepidoptera: Plutellidae) and Diadegma insulare (Cresson) (Hymenoptera: Ichneumonidae)

Idris Abd. Ghani, E. Grafius

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The effects of plant density of broccoli (Brassica oleracea L. var. italica) on the abundance of diamondback moth (DBM), Plutella xylostella (L.), and its parasitoid, Diadegma insulare (Cresson), were studied. There were no significant differences in the number of small DBM larvae (first and second instars) per plant across treatments (three different plant densities and three different spacings between plants) and sampling dates. The number of large larvae (third and fourth instars) and D. insulare pupae per plant were significantly influenced by plant density, sampling dates and the interaction of these two factors. However, the number of DBM pupae was not significantly different among treatments. Percentage parasitism of DBM larvae by D. insulare per plant did not vary significantly with either plant density or sampling date. Percentage parasitism of DBM larvae (field and laboratory-reared) per plant in the upper or lower one-third of the plant canopy was not significantly different among treatments and was not influenced by the interaction of plant density and height. This suggests that the host-searching ability of D. insulare is not constrained either by plant density or height. The secondary (female to male) sex ratio of D. insulare and the number of D. insulare adults caught per trap (a measure of diurnal flight activity) were not significantly influenced by plant density and sampling date. However, the total catches of adults (both sexes) were significantly higher in the higher than in the lower plant density. Based on our results, we suggest that broccoli plant density should be chosen only when proven to have a negative impact on DBM population abundance.

Original languageEnglish
Pages (from-to)103-107
Number of pages5
JournalInternational Journal of Pest Management
Volume47
Issue number2
DOIs
Publication statusPublished - Apr 2001

Fingerprint

Diadegma insulare
Plutellidae
Ichneumonidae
Plutella xylostella
plant density
Hymenoptera
Lepidoptera
insect larvae
broccoli
pupae
parasitism
instars
sampling
host seeking
Brassica oleracea
sex ratio
flight
traps
spatial distribution

Keywords

  • Diadegma insulare
  • Diamondback moth
  • Diurnal flight activity
  • Parasitoid
  • Percentage parasitism
  • Plant density

ASJC Scopus subject areas

  • Insect Science

Cite this

Effects of plant density on abundance of diamondback moth (Lepidoptera : Plutellidae) and Diadegma insulare (Cresson) (Hymenoptera: Ichneumonidae). / Abd. Ghani, Idris; Grafius, E.

In: International Journal of Pest Management, Vol. 47, No. 2, 04.2001, p. 103-107.

Research output: Contribution to journalArticle

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