Field studies of foraging behaviour of an intertidal beetle

Abstract. 1. Adult staphylinid beetles Thinopinus pictus LeC. are noct turnal predators of sand beach amphipods, Orchestoidea califomiana (Brandt). I made continuous observations of Thinopinus near the drift patches on which amphipods feed.
2. Thinopinus alternated between active and ambush foraging modes.
3. Thinopinus had greater attack rates and captured smaller amphipods while in active foraging mode.
4. Thinopinus attacked 0.147 amphipods/min, and captured 9.1% of the amphipods attacked. The attack rate on amphipods increased with the proportion of time spent by Thinopinus in active mode.
5. Thinopinus remained longer near types of drift patches which were more attractive to amphipods.     

Effects of Root Restriction, Root Pruning and 6-Benzylaminopurine on the Growth of Peach Seedlings

Peach seedlings were grown in aerated nutrient solution in small(15 cm³) or large (500 cm³) containers. Subsequently some plantswere removed from the small to the large containers or werestressed by root pruning. Half the plants received a foliarspray of 6-benzylaminopurine (BAP) every 4 days. Root restriction eventually impaired growth rates and ultimatelyplant size. The effect of root pruning was quickly overcomeby a redistribution of growth in favour of the roots. When restrictedplants were transferred into large containers there was an accompanyingrapid root growth and plants attained a comparable size to unrestrictedplants. BAP applied to the leaves to some extent overcame thereduced growth of restricted plants, however, its major effectwas on the distribution of dry matter. Restriction and BAP application,in general, reduced the levels of mineral nutrients in the leaves. It is argued that the limit set by the roots on top growth involvesan internal regulation by the root, in particular the productionand supply of growth substances. The evidence suggests thatthis is related to root morphology and must be taken into accountwhen studying top:root inter-relationships. The experiment highlights the importance of root restrictionas a technique for manipulating root growth and studying rootfunction and its interaction with the top. Some implicationsof controlled root growth in the field are discussed.     

Proleptusmackenzieisp.n. (Nematoda, Spirurida) from Raja fyllae in the Barents Sea

Previous work on species of Proleptus Dujardin, 1845 and related genera is briefly reviewed. Proleptus mackenziei sp.n. is described and figured. P. mackenziei is close to P. obtusus, P. acutus and P. malayi but differs from them in the host, position of the vulva which is 2/5/ of the body length from the anus and in the detailed arrangements of the papillae on the male tail.