Satiation and the functional response: a test of a new model

Abstract. 1. A model of the functional response to prey density is derived to include the reduction in time available for search, T_s , resulting from predator satiation.
2. For larger prey items predator satiation occurs at each prey capture and T_s is reduced by the attack time and digestive pause of a series of attack cycles. For small prey items predator foraging is continuous at low densities with T_s reduced solely by attack time. At higher densities predator satiation occurs after the capture of several small prey items and T_s is reduced by the attack time and digestive pause of a series of foraging cycles.
3. A comparison of the predicted asymptotic level of prey capture using experimentally estimated parameter values, with the maximum consumption of aphids by larval and adult coccinellids provides a test of the satiation model.
4. The limitation of prey capture by predator satiation is discussed with reference to handling time and the success of coccinellids in biological control.     

Glitoria yellow vein virus, a tymovirus from Kenya

Clitoria yellow vein virus (CYW) was found in Clitoria ternatea and Abrus precatorius in coastal districts of Kenya, but was not detected in food legume crops. When transmitted by inoculation of sap, CYW infected many species in the Papilionaceae, commonly causing yellowing of secondary and smaller leaf veins. All the economically important food legumes grown in the area of occurrence were very susceptible, so that CYW is potentially very important. The virus also infected okra (Hibiscus esculentus) and species in the Solanaceae, but none of many species of Cucurbitaceae. CYW is serologically closely related to cocoa yellow mosaic and kennedya yellow mottle viruses, and more distantly to okra mosaic and desmodium yellow mottle viruses. Other properties of CYW^ typical of the tymoviruses include particle morphology (particle diameter c. 28 nm; two components) with sedimentation coefficients of 50S (top) and 109S (bottom); molecular weight of protein sub-units c. 20000; thermal inactivation point c. 72 ^oC; and longevity in vitro c. 3 wk.