Reproductive status of Megacopta cribraria (Hemiptera: Plataspidae) sampled with cross-vane traps and sweep nets in soybean

The invasive plataspid Megacopta cribraria (Fabricius) (Hemiptera: Plataspidae) can infest soybean fields in the southeastern United States. Current sampling methods rely on beat cloths, sweep nets and visual observations of the soybean canopy. Cross-vane traps have been suggested as a useful tool for initial detection and determining relative abundance of the insect. The relationship between cross vane trap and sweep net sampling and the effect of distance from soybean field edges on densities of M. cribraria was studied. Late-planted soybean fields were sampled weekly using cross-vane traps and sweep net sampling in 2013 and 2014 along three transects at 0, 10, 20 and 40 m from the outer field edge.  Reproductive status of M. cribraria females in relation to season and plant phenology was examined to assess the overall structure of adult female field populations. Across all fields, in 2013, densities averaged 2.2 adults per trap and 2.4 adults and 0.9 nymphs per 20 sweeps. In 2014, densities averaged 7.8 adults per trap and 14.3 and 9.9 nymphs per 20 sweeps. Regression analysis determined no significant relationship between the two sampling methods. Analysis of variance showed a decrease in insect count with distance from the field edge for both sweep net sampling and trapping. Results, when coupled with M. cribraria reproductive biology studies, will provide researchers, growers, crop consultants and farm managers useful information on another possible sampling method for the plataspid and an understanding of the female population migration patterns.