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Title: FEEDING SITE SELECTION ON SOYBEAN BY THE FACULTATIVELY PHYTOPHAGOUS PREDATOR ORIUS INSIDIOSUS

Author
item ARMER, C - ENTOMOLOGY UI URBANA
item WIEDENMANN, R - NATURAL HISTORY SURVEY IL
item BUSH, DANIEL

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Biological control is emerging as an important tool in an integrated approach for pest management in modern agriculture. The ability of beneficial predator insects to use limited plant feeding as a mechanism to maintain their populations during periods of prey scarcity may enhance their efficacy in the field. In the results reported here, we labeled the plant's vascular system with dyes and tagged metabolites to show that one beneficial predator, Orius insidiosus, obtains moisture and limited nutrients during plant feeding. The use of these resources should extend the life expectancy of this predator during periods of scarce prey. Knowledge of plant feeding site selection and the nature of the nutrients obtained during feeding may lead to better management practices.

Technical Abstract: Experiments were conducted to test whether the facultatively phytophagous predator Orius insidiosus (Say)(Heteroptera: Anthocoridae) ingested phloem, xylem or mesophyll contents while feeding on soybean (Glycine max L.). Phloem sap uptake was examined by radiolabeling photosynthate with 14-C carbon dioxide and then measuring radiolabeled metabolite accumulation in feeding animals. No appreciable levels of radiolabeled phloem sap were ingested by Orius insidiosus observed feeding on labeled plants. In contrast, well known phloem feeding insects used as positive controls accumulated substantial levels of labeled metabolites. The insects did feed on xylem contents, as shown by ingestion of safranin-labeled xylem fluid. A few of the insects ingested chloroplasts, indicating mesophyll feeding. The small diameter of the food canal may have limited the frequency of mesophyll feeding. This insect appears to be feeding on plants primarily for moisture found in the xylem. Feeding site determines the nutrients ingested during phytophagy. The results presented here show that Orius insidiosus obtains water from the xylem, and may ingest small levels of starches, sugars, and amino acids from the mesophyll. Thus, facultative phytophagy may help the predator survive periods when prey are scarce.