Seasonal Abundance and Population Fluctuation of Leucaena Tree Beetle, Acanthoscelides macrophthalmus (Schaeffer) (Coleoptera: Chrysomelidae: Bruchinae) and its Accompaniment Parasitoids

Document Type : Original Article

Authors

1 Plant Protection Research Institute, Agricultural Research Centre, Dokki, Giza, Egypt.

2 Plant Protection Research Institute, Agricultural Research Centre, Dokki, Giza, Egypt

Abstract

The data presented in this study provide some basic information regarding seasonal abundance and population fluctuation, the influence of temperature and relative humidity, monthly population and emergence percentages, time and peacks number, and emergence ratios of population density of each leucaena pods and seeds beetle, Acanthoscelides macrophthalmus and its accompaniment parasitoids (Dinarmus basalis Rondani and Lyrcus sp.) emerged from infested Leucaena leucocephala trees.
             Insects are abundant throughout the year. The highest monthly population of beetles recorded during November, followed by May and December, the highest population of parasitoids observed during February, followed by March and January (D. basalis) also January and August (Lyrcus sp.).Nine peaks for beetles are recoded, the higher peak observed at 4th week Nov. followed by 3rd week of May, then 4th week of January, the same number of peaks recorded for D. basalis parasitoid, the highest peak noticed at 3rd week of Jan. and March, whereas Lyrcus sp. parasitoid has 8 peaks, the higher found at 3rd week of Jan.General ratio of insect’s emergence was 1:0.384:0.047 (beetles: Dinarmus: lyrcus). Highest ratios between beetles: parasitoids noticed during February (1:2), July (1:1.774) and March. (1:1.287). The dominant weather factors (MaxTemp., Min.Temp. & RH%.) evidently showed effective changes in the population density of beetles and parasitoids during annual activity months. The correlation between parasitoids and beetles population differed during the different seasons.  
The current work shows that Dinarmus basalis (26.8% seasonal emergence) and Lyrcus sp. (3.3% seasonal emergence) parasitoids develop within infested leucaena seeds with A. macrophthalmus beetle. Numerous numbers of each beetle (69.9% seasonal emergence) and parasitoids (31.3% seasonal emergence) were observed throughout the year, therefore A. macrophthalmus beetles can be used as a substitute host for mass rearing of D. basalisparasitoids, which are biological agent to control stored seed bruchids.

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