The effects of starvation on development and reproductive potential of apterous virginoparae of vetch aphid, Megoura viciae

Abstract

Apterous virginoparae of Megoura viciae Buckton starved during the fourth instar lost weight but nevertheless completed their development, showing that growth and development could proceed independently. Their weight at the end of starvation was a function of initial weight. Aphids used considerable amounts of lipid during starvation, and if allowed to feed on becoming adult showed a delayed onset to reproduction. Starvation in the fourth instar arrested embryogenesis, and in small aphids resulted in degeneration of gonadal and somatic tissues.

Aphid individual performance may not predict population responses to elevated CO2 or O3

“…1f), changes in resource allocation within the developing aphid (perhaps associated with nutrient stress (e.g. Brough & Dixon, 1990) do not explain these results. Aphids reared at elevated CO 2 and/or O 3 may either have been unable to maintain embryo maturation once their initial complement of mature embryos were born, or have resorbed the youngest undifferentiated embryos in response to low host plant quality (e.g.…”

“…Because both CO 2 and O 3 affect plant quality, it may not be possible to make reliable predictions about the future fecundity of herbivorous insects without directly measuring the number of offspring produced. Similarly, recent studies (Bezemer et al , 1999; Percy et al , 2002) suggest that the performance of individual herbivores may not predict population responses to elevated CO 2 or O 3 .…”

“…Aphids are a very useful model system for comparisons between individual and population responses to global change, since their biology is well understood (Dixon, 1998) and they develop rapidly and may have several generations in a single growing season. Several recent studies have investigated the independent effects of both CO 2 (Salt et al , 1996; Docherty et al , 1997; Bezemer et al , 1998, 1999; Diaz et al , 1998; Awmack & Harrington, 2000; Hughes & Bazzaz, 2001) and O 3 (Whittaker et al , 1989; Salt & Whittaker, 1995) on aphid populations. We are not aware of any investigations linking the interacting effects of CO 2 and O 3 on the performance of individual herbivores to the performance of aphid populations.…”

The effect of starvation and subsequent feeding on the reproductive potential of the grain aphid, Sitobion avenae

“…A population may react and adapt to stressful conditions by developing biological strategies for acclimatization or by evolving more resistant macromolecules to retain functional efficiency in the altered environment (Karan & David, 2000). Many studies have reported that the ability to arrest or resorb oocytes in insects is a reproductive strategy that enables their shortterm tolerance of a lack of food, a lack of oviposition sites, or other stresses (reviewed in Bell & Bohm, 1975;Brough & Dixon, 1990).…”

“…Starved aphids adopt a quite different strategy of resorption. The smallest embryos were resorbed and the largest embryo in each ovariole continued to mature, which to a limited extent, enables it to adjust its reproductive biomass during starvation (Ward & Dixon, 1982;Brough & Dixon, 1990). Leather et al (1983) reported that starvation could cause a decreased total fecundity in apterous Aphis fabae Scopoli adults.…”