Portman S L, Frank J H, McSorley R, Leppla N C
Department of Biology, Penn State University, University Park, PA 16802, USA.
Environ Entomol. 2010 Jun;39(3):939-43. doi: 10.1603/EN09268.
Larra bicolor F. (Hymenoptera: Crabronidae) is a specialist parasitoid of Scapteriscus (Orthoptera: Gryllotalpidae) mole crickets, attacking adults and medium to large nymphs of the hosts. Adult wasps derive energy from plant nectars. In replicated trials in pastures in northern Florida, many more wasps fed on nectar of Spermacoce verticillata F. (Rubiaceae), a non-native plant, than on nectar of the native plants Spermacoce prostrata Aubl. or Spermacoce remota Lamarck. Few of them fed on the native plant Solidago fistulosa Michx. (Asteraceae). About as many fed on the native plant Chamaecrista fasciculata (Michx) Greene as on S. verticillata in the autumn months until the native plant ceased flowering by October. In contrast, S. verticillata continues flowering until the first hard freeze, which typically occurs in December, so overall, it is a more reliable nectar source in northern Florida and may be still more reliable in frost-free areas of southern Florida where it may flower year-round. The number of immature wasps (eggs and larvae) parasitizing mole crickets was positively related to host density but also declined with distance from a plot of S. verticillata out to 200 m, based on samples of pitfall trap-collected mole crickets. The occurrence of parasitized mole crickets at a 200-m distance suggests that female wasps recruited to a plot of S. verticillata forage for hosts out to at least 200 m. This in turn suggests that mole cricket populations might be diminished by planting plots of S. verticillata at least 400 m apart when L. bicolor wasps are present.
双色拉瑞黄蜂（膜翅目：蛛蜂科）是短腹蝼蛄（直翅目：蝼蛄科）的专一性寄生蜂，攻击寄主的成虫以及中大型若虫。成年黄蜂从植物花蜜中获取能量。在佛罗里达州北部牧场进行的重复试验中，取食外来植物垂花蛇根草（茜草科）花蜜的黄蜂数量，比取食本地植物平卧蛇根草或远距蛇根草花蜜的黄蜂数量多得多。很少有黄蜂取食本地植物细叶一枝黄花（菊科）的花蜜。在秋季，取食本地植物束花山扁豆的黄蜂数量与取食垂花蛇根草的黄蜂数量大致相同，直到本地植物在10月停止开花。相比之下，垂花蛇根草会一直开花到12月通常出现的首次严重霜冻，所以总体而言，在佛罗里达州北部它是更可靠的花蜜来源，在佛罗里达州南部无霜地区可能更可靠，因为在那里它可能全年开花。根据陷阱诱捕收集的蝼蛄样本，寄生蝼蛄的未成熟黄蜂（卵和幼虫）数量与寄主密度呈正相关，但也随着距垂花蛇根草地块距离增加至200米而减少。在200米距离处出现被寄生的蝼蛄表明，被吸引到垂花蛇根草地块的雌蜂会在至少200米范围内搜寻寄主。这反过来表明，当存在双色拉瑞黄蜂时，将垂花蛇根草地块相隔至少400米种植，蝼蛄种群数量可能会减少。
