Use of Life Tables in a Bioclimatic Study of an Experimental Aphid‐Braconid Wasp Host‐Parasite System

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org. This content downloaded from 128.235.251.160 on TueHOST-PARASITE LIFE TABLES 119 to environmental extremes of drought and flash floods. 2. The natural life span for most Rhinichthys oscults in the Chiricahua Mountains is less than 3 years. None was found to reach 4 years.3. High mortality rates during summer drought must be interpreted, in part, as an acceleration of death among older fish since most fish are expected to die before they are 3 years old. Among younger fish, drought directly elevates the mortality rate.4. Mortalities during a drought are caused directly by the disappearance of water and indirectly by starvation of the fish which are crowded into reduced habitat with inadequate food. 5. Flash floods are an important cause of mortality among fish of the year if they occur while the fish are very small. The greatest potential loss of fish of the year occurs in late summer when the initial flash flood induces major reproduction and is then followed by another flash flood.6. Flash floods are not a significant cause of mortality among older fish. 7. Temporary waters may persist in some sections through a period of wet years. The populations of fish inhabiting them are derived from upstream sections during a flash flood. All fish that were located in downstream temporary sections in the spring of 1960, were one-year-olds. 8. Temperatures do not rise to lethal levels in any of the flowing streams. In exposed shallow isolated pools, the temperatures may become lethal for oldcr fish, but not for fish of the year. 9. Predators play a minor role. Only one, the garter snake, Thamnophtis cyrtopsis, is common and apparently important.10. Although fish populations are greatly reduced by a year of drought, there is no immediate threat of their local extinction. ACKNOWVLEDGMENTSThese studies were made possible . 1946. Lethal temperature relations for a sample of young speckled trout (Salvelinus fontinalis). Univ. Toronto Stud. Biol. Ser. 54; Pub. Ont. Fish. Res. Lab. 66. Hart, J. S. 1952. Geographic variations of some physiological and morphological characters in certain freshwater fish. Univ. Toronto Biol. Ser. 60; Pub. Ont. Fish. Res. Lab. 72. John, K. R. 1963. The effect of torrential rains on the reproductive cycle of Rhinichthys osculus (Girard) in the Chiricahua Mts., Arizona. Copeia, 1963 (2): in press.

Praon volucre (Hymenoptera: Braconidae: Aphidiinae), a natural enemy of Macrosiphum euphorbiae (Hemiptera: Aphididae): Life table and intrinsic rate of population increase

“…The rates and patterns of oviposition recorded for P. volucre parasitizing M. euphorbiae are similar to those reported by Messenger (1964) for Praon palitans Muesebeck (Hymenoptera: Braconidae: Aphidiinae) parasitizing Therioaphis trifolii form maculata (Buckton) (Hemiptera: Aphididae). Both parasitoids oviposit for periods exceeding 15 days and approximately 50% of the eggs are laid within the first four days of a female's life.…”

“…Both parasitoids oviposit for periods exceeding 15 days and approximately 50% of the eggs are laid within the first four days of a female's life. However, P. volucre has a higher total fertility (504 eggs) than P. palitans (298.8 eggs;Messenger, 1964). In other Aphidiinae, such as A. colemani and Lysiphlebus testaceipes (Cresson) (Hymenoptera: Braconidae: Aphidiinae), about 85-90% of the offspring is produced during the first three days after female emergence and females oviposit for an average of 8 days (Rodrigues et al, 2003;Torres et al, 2007;Silva et al, 2008b).…”

The Phenology and Distribution of Aphids in California Alfalfa as Modified by Ladybird Beetle Predation (Coleoptera: Coccinellidae)

“…Blue alfalfa aphid was most abundant during late winter -early spring, while pea aphid and spotted alfalfa aphid populations increased only during late summer -early fall. Numerous studies have shown that pea aphid, in contrast to spotted alfalfa aphid, does not do well during the hot summer in the San Joaquin Valley, where daily temperatures often exceed 40°C (Messenger 1964;Gutierrez and van den Bosch 1970). Blue alfalfa aphid would likewise be expected to perform poorly in this area, as its response to high temperature is very similar to that of pea aphid.…”

Geographic Distribution and Relative Abundance of the Invasive Glassy-Winged Sharpshooter: Effects of Temperature and Egg Parasitoids

“…However, this delicate balance can be disrupted by climate change. Among the pioneering works on the effects of weather in entomology were those of Messenger (1964Messenger ( , 1968, while a recent review of climate change on plant diseases is that of Coakley et al (1999). In their edited volume, Reddy and Hodges (2001) review many aspects of current thinking on the effects of climate change in agriculture.…”