We explored the relative importance of temporal vs. spatial variability to the conditionality of a mutualism between the treehopper Publilia modesta and the ant Formica obscuripes. The effect of the ants on the membracids varied considerably among years. When the effect of the ants on the membracids was estimated in five sites spread over 5 km there was mixed evidence for spatial conditionality in the mutualism. Using repeated surveys of nymph number we found that the effect of the ants on nymph number varied among sites through time. When total new adult production was examined, however, no such interaction between ants and location was evident. Aggregations displayed strong negative density‐dependent adult production. Thus, while in some sites ants had a greater positive effect on nymph survivorship, aggregations at those sites produced proportionately fewer adults because of negative density dependence. Density dependence reduced or eliminated spatial differences in the effect of the ants on the membracids. Differences among sites did not explain spatial variation in the effect of ants on nymphs or new adult production. We conclude that temporal variability is much more important than spatial variability in generating conditionality in the mutualism. Corresponding Editor: P. Nonacs

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Marking biological control agents facilitates studies of dispersal and predation. This study examines the feasibility of marking the various life stages of a weed biological control agent, Diorhabda carinulata (Desbrochers) (Coleoptera: Chrysomelidae), by submersion in rabbit or chicken immunoglobulin G (IgG) protein solutions. We determined whether externally applied IgGs are effective labels of the various lifestages, whether IgGs can be retained between D. carinulata lifestages, and to what extent abiotic factors associated with field conditions mediate label retention. The presence of the labels on the various lifestages of the beetles was detected by IgG‐specific enzyme‐linked immunosorbent assays. Duration of each immunolabel was measured on eggs and larvae in laboratory studies and on adults in laboratory and field studies. For adults, both labels showed high (>80%) retention for ca. 14 days after marking under field and laboratory conditions. Temperature and type of label (rabbit or chicken) had only a minimal effect on marker retention. Externally marked eggs exhibited high (100%) retention for both proteins over the entire duration of the egg stage. Interestingly, some larvae emerging from externally labeled eggs contained both external and internal IgG marks. To our knowledge, this is the first case of an IgG being transferred from the egg to larva of an insect. Age of eggs at the time of label application affected the intensity of the external label on neonates. For instance, larvae that emerged from eggs that were >1 day old when labeled exhibited stronger label retention than larvae that emerged from eggs that were 1 day old when labeled. For larvae, retention of rabbit IgG was greater than retention of chicken IgG. Label retention declined as larvae aged; larvae >3 days old retained significantly less label than did neonate larvae. Both IgG labels were retained from the first to second instar, but at a very low rate of <10%. Overall, our study demonstrates that protein‐marking technology has potential for use in studies of dispersal and predator–prey associations for D. carinulata.

Marking biological control agents facilitates studies of dispersal and predation. This study examines the effect of a biological solvent, dimethyl sulfoxide (DMSO), on retention of immunoglobulin G (IgG) protein solutions applied to Diorhabda carinulata (Desbrochers) (Coleoptera: Chrysomelidae), an important biological control agent of saltcedar, either internally by feeding them protein‐labeled foliage or externally by immersing them in a protein solution. In addition, we determined whether internally or externally marked DMSO‐IgG labels could be transferred via feeding from marked D. carinulata to its predator, Perillus bioculatus (Fabricius) (Heteroptera: Pentatomidae). The presence of rabbit and chicken IgG proteins was detected by IgG‐specific enzyme‐linked immunosorbent assays (ELISA). DMSO‐IgG treatments showed greater label retention than IgG treatments alone, and this effect was stronger for rabbit IgG than for chicken IgG. Fourteen days after marking, beetles immersed in rabbit IgG showed 100% internal retention of label, whereas beetles immersed in chicken IgG showed 65% internal retention. Immersion led to greater initial (time 0) label values, and longer label retention, than feeding beetles labeled foliage. The DMSO‐IgG label was readily transferred to P. bioculatus after feeding on a single marked prey insect. This investigation shows that addition of DMSO enhances retention of IgG labels, and demonstrates that protein marking technology has potential for use in dispersal and predator–prey studies with D. carinulata. Moreover, our observation of P. bioculatus feeding on D. carinulata is, to our knowledge, a new predator–prey association for the stink bug.

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