Murderous plants: Victorian Gothic,Darwin and modern insights into vegetable carnivory

Darwin's interest in carnivorous plants was in keeping with the Victorian fascination with Gothic horrors, and his experiments on them were many and varied, ranging from what appears to be idle curiosity (e.g. what will happen if I place a human hair on a Drosera leaf?) to detailed investigations of mechanisms. Mechanisms for capture and digestion of prey vary greatly among the six (or more) lineages of flowering plants that have well‐developed carnivory, and some are much more active than others. Passive carnivory is common in some groups, and one, Roridula (Roridulaceae) from southern Africa, is so passively carnivorous that it requires the presence of an insect intermediate to derive any benefit from prey trapped on its leaves. Other groups not generally considered to be carnivores, such as Stylidium (Stylidiaceae), some species of Potentilla (Rosaceae), Proboscidea (Martyniaceae) and Geranium (Geraniaceae), that have been demonstrated to both produce digestive enzymes on their epidermal surfaces and be capable of absorbing the products, are putatively just as ‘carnivorous’ as Roridula. There is no clear way to discriminate between cases of passive and active carnivory and between non‐carnivorous and carnivorous plants – all intermediates exist. Here, we document the various angiosperm clades in which carnivory has evolved and the degree to which these plants have become ‘complete carnivores’. We also discuss the problems with definition of the terms used to describe carnivorous plants. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161 , 329–356.     

Seasonality of insect abundance in an Australian upland tropical rainforest

Monthly light and Malaise trap catches, taken over 31 months, were used to examine seasonal and annual changes in the abundance of predominant orders of upland tropical rainforest insects. Insect numbers and biomass increased during the late dry season, reached a peak during the wetter months, and declined during the early dry period. Fluctuations in insect abundance appeared to relate to (1) climatic factors such as length and severity of the dry season, or amount and period of rainfall; and (2) food availability such as an increase in the production of new leaves, or flowering and fruiting periodicity.     

The nesting biology of Archbold's Bowerbird Archboldia papuensis and a review of that of other bowerbirds (Ptilonorhynchidae)

Thirteen active and 14 old Archbold's Bowerbird Archboldia papuensis nests were studied in Tari Gap, Southern Highlands, Papua New Guinea. Clutch size was one egg. At two nests, only one-parent nest attendance was observed. Incubation and nestling periods were considerably longer and nestling growth slower than in other bowerbird species, possibly reflecting adaptation to a colder environment depauperate in insects. Of 382 identified nestling meals, 71% were exclusively fruit (14 spp. identified) and 29% were animal. Of 112 animal meals, 30% were skinks (Reptilia), 28% were small arthropods, 17% were beetles and the remainder (25%) were larger insects, pieces of nestling birds and unidentified items. Most active nests were built adjacent to older nests and the significance of this is discussed.     

Nesting biology of the Short-tailed Paradigalla Paradigalla brevicauda

Six nesting attempts of a ringed Short-tailed Paradigalla Paradigalla brevicauda between September 1986 and February 1989 in Papua New Guinea are reported. Nests are described and one illustrated. Previously undescribed eggs, of two single-egg clutches from the same female, lack broad longitudinal streaks typical of most Paradisaeinae eggs. The hatchling is naked, dark-skinned, with fully formed facial wattles. Fifty seven hours of observation at one nest confirmed single parent attendance. Of 66 identified nestling meals 65% were animal, including frogs and skinks, the remainder fruit. Growth and development of a nestling, that fledged at 26 days old, are described. Another young was fed by its parent 108 days after leaving the nest. Breeding and feeding of P. brevicauda are reviewed. The presumed female studied attended six nests within 100 m² over 29 months. Uniparental nesting suggests males are promiscuous, which is discussed with respect to proposed Paradigalla hybrids.     

Evolutionary implications of large-scale patterns in the ecology of Trinidadian guppies, Poecilia reticulata

Previous investigations of the guppy, Poecilia reticulata , in Trinidad have demonstrated rapid population differentiation at small geographic scales. However, most studies to date have focused on localities in Trinidad's Northern Range where barrier water falls mark sharp discontinuities in the selection regime and limit scope for gene flow. There is little information on the ecology of the guppy in the rest of the island even though its distribution amongst fish communities and habitats has important evolutionary implications. To determine how large-scale distribution patterns might affect the evolutionary potential of the guppy we surveyed 80 sites representative of a broad range of freshwater environments. We found guppies, which occurred in 80% of our samples, to be the most widely distributed freshwater fish in Trinidad. Guppies are common in predator-rich and turbid habitats, precisely those localities where female preferences are likely to be undermined. Moreover, the widespread distribution of this adaptable species, combined with its promiscuous mating system, may promote gene flow across geographical scales that transcend local selection regimes. These factors are likely to impede the evolution of reproductive isolation.     

Flow and polypide distribution in the cheilostome bryozoan Bugula and their inference in Archimedes

Cilia-generated flow in the absence of ambient current is directed from frontal to reverse sides of branches in Bugula turrita, B. turbinata, B. neritina , and B. stolonifera , whether axes of feeding lophophores are perpendicular to the basal plane of branches or are tilted toward distal ends of branches. Ambient current less than 5 cm per second interacts with cilia-generated flow, but ambient flow of 15 cm per second destroys self-generated colonial flow and severely hampers feeding. Polypides are located in the more distal, younger portions of colonies, in species with and without polypide recycling, whereas zooids in the more proximal, older portions are senesced. Presence of feeding polypides in distal but not in proximal portions of the larger spiralled colonies of B. turrita and B. turbinata results in downward, slightly radially directed flow through the colony. The colonial flow passes directly from one whorl to the next-proximal so that water exits from low around the colony perimeter, and a proximally expanding conical stagnant zone occupies the interior of the colony. A substantial percentage of zooecia in distal whorls of well-preserved Archimedes is filled by sediment and inferred to have been occupied by actively feeding polypides. whereas spar-filled zooecia capped by terminal diaphragms were apparently senesced during the latter part of a colony's existence. The capped zooecia constitute an increasing percentage of the total in more proximal whorls. Generally similar colony form and inferred similarity in distribution of current-generating polypides in spiralled colonies of Bugula and in Archimedes suggest that colony-generated flow in Archimedes was similar to that in Bugula , passing downward and then outward, and only through the distal whorls of the colonies.     

A preliminary study of insect abundance on West Island,Aldabra Atoll,Indian Ocean

• 1 Heath and Rothamsted light traps and a Johnson-Taylor suction trap were used to sample flying insects on Aldabra Atoll.
• 2 The present study extended over two wet seasons. The pattern of relative monthly insect activity resembled the rainfall pattern. Catches were greatest during the months when there was a sudden marked increase in precipitation.
• 3 Lepidoptera dominated light trap catches and Diptera suction trap catches, the total monthly insect numbers therefore reflecting the abundance of these two orders. Hemiptera, Coleoptera and Hymenoptera were also common.
• 4 Predominant families were represented by only a few or even only one dominant species. These species were present throughout the study period although their monthly totals varied considerably, different species dominating the catches during different months.
• 5 The composition and size of catches in the three light traps was affected by the type of light source and surrounding vegetation.
• 6 A comprehensive list of families and selected common species is given with their relative monthly abundance in the light traps.
• 7 Suction trap catches were segregated on an hourly basis to give a broad indication of insect flight periodicity.

     

Behavioural and chemical mechanisms of plant‐mediated deterrence and attraction among frugivorous insects

1. Herbivory often induces systemic plant responses that affect the host choice of subsequent herbivores, either deterring or attracting them, with implications for the performance of both herbivore and host plant. Combining measures of herbivore movement and consumption can efficiently provide insights into the induced plant responses that are most important for determining choice behaviour. 2. The preferences of two frugivorous stink bug species, Nezara viridula and Euschistus servus between cotton plants left undamaged or damaged by Helicoverpa zea and Heliothis virescens larvae were investigated. A novel consumer movement model was used to investigate if attraction rates or leaving rates determined preferences. Stink bug consumption rates were measured using salivary sheath flanges. Finally, the systemic induction of selected phenolic‐based and terpenoid secondary metabolites were measured from heliothine herbivory on developing cotton bolls, to investigate if they explained stink bug feeding responses. 3. Heliothine herbivory did not affect the N. viridula feeding preference. However, we found opposing effects of H. zea and H. virescens herbivory on the behaviour of E. servus. Avoidance of H. zea‐damaged plants is not obviously related to phenolic or terpenoid induction in cotton bolls; whereas a preference for H. virescens‐damaged plants may be related to reductions in chlorogenic acid in boll carpel walls. 4. The present results highlight the inferential power of measuring both consumer movement and consumption in preference experiments and combining behavioural responses with phytochemical responses. Furthermore, while plant‐mediated interactions among herbivorous insects are well studied, interactions among frugivorous species specifically have been poorly documented.