| The cotton mirids Apolygus lucorum (Meyer-Dür) and Adelphocoris suturalis Jakovlev (Hemiptera: Miridae) are two key species of insect pests in cotton growing regions of North China. These two species are both polyphagous with the ability of surviving and damaging on many species of host plants, and lack of effective natural enemy control in the field. Area wide outbreaks of the two species and subsequent heavy losses of cotton production were recorded in Henan, Hebei and Shandong provinces in recent years. To understand their mobility and seasonal migration among host plants in the field, the species of overwintering host plants and predatory natural enemies is the base of monitoring and controlling populations of these two pests with ecological principles.In the present study, the mobility, seasonal migration and predatory natural enemies of these two species were preliminarily investigated using mark-recapture method with trace element Rb, aerial sticky cards and trajectory simulation of HYSPLIT. Main results are as follows:1. Spraying 2000 ppm RbCl solution on the host plants with A. lucorum and A. suturalis could effectively mark the two species of plant bugs and their host plants. The Rb could reside in plant bug body up to 6 to7 days and in host plants up to 10 days. The residuals in plant bugs did not influence the survival and flight ability of plant bugs. Thus, 2000ppm was the optimum concentration of RbCl for marking cotton mirids.2. Mark recapture experiments indicated that these two species of cotton mirids immigrated into cotton fields from overwintering sites during spring. Both species exhibited a strong ability of movement with A. lucorum displaced at least 2560 m with 2 days and A. suturalis displaced 5120 m with 6 days, the maximum distance of recapture, away from the overwintering site during spring in Nanyang of Henan province.3. The mark recapture experiment indicated that the cotton mirid A. lucorum emmigrated from cotton field to weeds for overwintering. The A. lucorum could displace at least 2560 m, the maximum distance of recapture, away from the overwintering site within a week during autumn in Yuanyang of Henan province. The weeds Artemisia argyi and Humulus scandens were main overwintering hosts of A. lucorum. 4. The cotton mirid A. lucorum was captured at altitude of about 60 m and 200 m above ground with series of stick cards carried by a helium filled balloon. This indicated that the A. lucorum might have taken long-distance windborne migration. Simulated forward trajectories with the HYSPLIT model indicated that the A. lucorum might displace 80 to 190 km within 10 hours.5. The predatory natural enemies of the two species of bugs in the fields were Xysticus hedini, Pirata subpiraticus, Misumenops tricuspidatus, Propylea japonica, Xysticus Saganus, Ummeliata tokyoensis, Theridion miradile and Clubiona pseudogermanica with the first four species dominant.
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