ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1937.tb08497.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1937.tb08498.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

摘要:

Summary1McAtee has tried to show that protective adaptations in insects are non‐effective against the predations of birds, and his corollary is that predation in birds is proportional to availability. His methods and deductions are shown to be faulty.2Predation is clearlyinfluencedby availability, but there is no proof that it is exactly proportional to availability. Given the extent to which predation is proportional to availability, one would still not be in a position to deny the selective value of alleged protective adaptations, since the percentage protection necessary for selective value is not known. It is very difficult to establish the numbers of available food animals in a district accurately because the presence of the observer himself upsets the numbers which existed before his arrival. The best chance would appear to be in a desert or polar region.3The stomachs from Jidda form a nucleus for such a study, and, pending an ecological survey of the Jidda region, an attempt has been made to see how far McAtee's assertions may be proved or disproved from internal evidence alone,i. e., from considerations of the stomach‐contents. The results do not show anything conclusive, but from the abundance of “protected” forms it appears the percentage protection referred to in 2 must be very small.The following insects, usually considered to be protected, formed the bulk of the food: —Ants.—Eaten as a staple food by 47 per cent. of the birds (30 out of 44 species). These were nearly all workers and soldiers, and over 50 per cent, of the ants wereMyrmecines(which have a sting).Coleoptera.—The chief families found were Curculionidæ, Tenebrionidæ, and Histeridæ, all of them considered distasteful to birds on account of their hardness.Hymenoptera(other than ants).—Were very plentiful, stings being found frequently.4The individual tastes of birds of the same species were considered. Most species exhibit a basic preference which may be overruled by special abundance of other prey, but this other prey is not necessarily of a kind considered unpalatable, merely not so usual in the diet. Hence the feeding, though to a certain extent influenced by availability, is not entirely dictated by it.5The work of sorting the débris from a stomach was facilitated by having a trough whose width was the same as the diameter of the field of the binocular microscope. In this way the stomach‐contents could be examined in alcohol with the certainty that nothing was missed and that no part of the contents was looked at more than once.Lepidoptera fared worse than other insects in the stomachs, and often the only trace of lepidopterous food was a few wing‐scales floating on the surfàce of the alcohol. These could often be detected only with a good binocular, and since they are out of the focal plane of the rest of the stomach‐contents (which do not float), they might easily be missed. This may account for the fact that McAtee only found Lepidoptera in 87 out of 80,000 stomachs, whereas they occurred in nearly 121/2per c

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1937.tb08499.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1937.tb08500.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1937.tb08501.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1937.tb08502.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

摘要:

SummaryAn attempt has been made to discover whether eating can be made to recur after the animal is satiated with food. This has been found to be the case under certain rather complicated conditions, the essential feature apparently being that the conditions arouse a certain state of excitement in the animals. It, was discovered, further, that those conditions which will start eating after satiation will prevent it when the animals are hungry.It is suggested that. this is similar to the Pavlovian “external inhibition” and “dismhibition” respectively. From this it is concluded that satiation must involve some mechanism similar to Pavlov's “internal in

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1937.tb08503.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

摘要:

Summary1All immature stages and adults of both sexes ofCimex lectulariusL. will feed on man, mouse, and domestic fowl. The insect can be bred to the adult stage on any of these hosts, and such adults will mate and produce fertile eggs.2The speed of development from egg to adult is slightly greater on mouse than on man or fowl under the conditions of the experiments. Given equal opportunity for feeding once in every instar, a greater proportion of bugs reach maturity on mouse than on man, the lowest proportion with any of the three hosts occurring on fowl.3Facts are brought forward to show that the shorter period for development on mouse is correlated with a relatively heavy blood‐meal. Also, adults bred on mouse are heavier than those bred on fowl or on man. Although bugs fed on fowl develop more quickly than on man, they do not always take heavier meals.4Bugs bred on mouse produce more eggs at the first feed than bugs bred on man or fowl. This increased egg‐production is associated with the greater body‐weight of mouse‐bred bugs: but there appears to be also another factor which makes mouse a better host for the production of bed‐bug eggs.5Mated adults and 2nd‐instar nymphs, when starved on a single blood‐meal, live longer on man than on either mouse or fowl. This is not obvious on the unmated adults until the variation in length of life associated with weight of meal is eliminated: then it is seen that unmated bugs, too, live longest when fed on mouse.6The blood of man, when dried, contains a greater proportion of dry material than the blood of either mouse or fowl, This may account for the longer life of bugs starved on human blood.7The differences in the life of bed‐bugs bred on the fowl and on man are small. Those fed on man, however, appear to be slightly better fitted for survival on one meal from the host under the conditions of the experiments than bugs fed on fowl.8The aerences in the life of bed‐bugs living on different hosts—man, mouse, and fowl—in nature are more likely to be due, primarily, to differences in the behaviour of the insects in the presence of those hosts rather than to thephysical effects of the meals taken from them. It is thought that the slitly different results with insects fed on the two human hosts may be due rather to differences in feeding behaviour of the insect than to the effe

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1937.tb08504.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY

ISSN:0370-2774    

DOI:10.1111/j.1469-7998.1937.tb08505.x

出版商:Blackwell Publishing Ltd    

年代:1937

数据来源: WILEY