CONSUMPTION OF AMPHIPODS BY THE NEW ZEALAND LAND SNAIL WAINUIA URNULA (PULMONATA: RHYTIDIDAE)

An unusual carnivorous diet was documented for the rhytididsnail Wainuia urnula urnula (Pfeiffer) from the southern North Island,New Zealand. Eighty-two percent of 315 samples of faeces or gutcontents contained remains of landhoppers (Crustacea: Amphipoda).Earthworms (Oligochaeta) were the second most common food typeidentified, but occurred in only 4 percent of samples. In the laboratory,W. urnula urnula captured landhoppers by rapidly everting theTVU-section odontophore beneath the prey and immediately drawingit into the mouth in a single action. Diet samples from the allopatriccongeners W. edwardi (Suter) (n 5 51) and W. clarki Powell (n5 7) contained no remains of landhoppers, and these snails didnot eat landhoppers in the laboratory. The diet of these specieswas dominated by earthworms. The subspecies W. u. nasuta ateboth earthworms and amphipods with similar frequency (n 5 40).Individual teeth on the radula of W. urnula urnula had a simpleblade-like cusp like other Wainuia species, but there were fewerteeth per row and fewer rows on the whole radula than in otherspecies. W. u. nasuta had a similar number of rows of teethto W. clarki and W. edwardi, but the number of teeth per rowwas intermediate between these species and W. u. urnula. Recordsof pulmonate species preying on arthropods are rare, yet inthe case of W. urnula this specialization has been accompaniedby minimal morphological change. (Received 22 December 1998; accepted 11 March 1999)     

A rapid technique for analysing diets of invertebrate predators by electrophoresis

A technique has been developed for the rapid determination of some species of prey consumed by mites and insects. The method detects prey enzymes within the gut of a predator by polyacrylamide gradient gel electrophoresis and subsequent staining for esterase activity. It is sufficiently sensitive to detect fruit tree red spider mite (Panonychus ulmi) esterases within the gut of a single predacious mite (Typhlodromus pyri) for at least 31 h after feeding. The method has been used to demonstrate feeding relationships among a range of insect and mite predator and prey species in the laboratory and in the field.     

The distribution of wood-ants (Formica lugubris Zetterstedt) in a northern English forest

Abstract. 1. A survey of 202 ha of planted forest in Langdale Forest, North Yorkshire, in 1972 discovered 326 occupied and thirty-eight deserted nests of Formica lugubris Zetterstedt. The average density of occupied nests was therefore 1.61 ha^-1.
2. Nests were associated with most crop trees and wild trees present, but were most abundant near to plantation margins and regenerating natural scrub.
3. In planted areas 76% of nests were found 5 m or less from the plantation boundary. More nests were found on the south and west border of plantations than on the north and east respectively, and most nests were not shaded from the south or southeast.
4. An analysis of nearest neighbour measurements showed that the dispersion of nests was not random but contagious (clumped). Nest mounds were higher in shaded situations than in unshaded.
5. The diameter of nest mounds was greater in areas planted with trees before 1945 than in areas planted since 1945.
6. The present population of F.lugubris appears to have spread into planted areas from nests present in marginal natural woodland which escaped the disturbance of the area at the time of planting.     

The Mouse p (pink‐eyed dilution) and Human P Genes,Oculocutaneous Albinism Type 2 (OCA2), and Melanosomal pH

Recessive mutations of the mouse p (pink‐eyed dilution) gene lead to hypopigmentation of the eyes, skin, and fur. Mice lacking a functional p protein have pink eyes and light gray fur (if non‐agouti) or cream‐colored fur (if agouti). The human orthologue is the P protein. Humans lacking a functional P protein have oculocutaneous albinism type 2 (OCA2). Melanocytes from p‐deficient mice or OCA2 individuals contain small, minimally pigmented melanosomes. The mouse and human proteins are predicted to have 12 membrane spanning domains and possess significant sequence homology to a number of membrane transport proteins, some of which are involved in the transport of anions. The p protein has been localized to the melanosome membrane. Recently, it has been shown that melanosomes from p protein‐deficient melanocytes have an abnormal pH. Melanosomes in cultured melanocytes derived from wild‐type mice are typically acidic, whereas melanosomes from p protein‐deficient mice are non‐acidic. Melanosomes and related endosome‐derived organelles (i.e., lysosomes) are thought to have an adenosine triphosphate (ATP)‐driven proton pump that helps to generate an acidic lumen. To compensate for the charge of these protons, anions must also be transported to the lumen of the melanosome. In light of these observations, a model of p protein function is presented in which the p protein, together with the ATP‐driven proton pump, regulates the pH of the melanosome.