16 research outputs found
Genetic variation and diversity of pearl millet [Pennisetum glaucum (L.)] genotypes assessed for millet head miner, Heliocheilus albipunctella resistance, in West Africa
Pearl millet (Pennisetum glaucum L.), the
major source of minerals and dietary energy for people
living in the semi-arid regions of Sahel, is regularly
damaged by millet head miner, Heliocheilus albipunctella.
In order to identify the plant-based resistance
sources for millet head miner along with high
grain Fe and Zn, we have screened forty pearl millet
genotypes, using an artificial infestation method.
Analysis of variance revealed significant differences
in the genotypes tested for head miner resistance. The
genotypes Gamoji, ICMP 177001, ICMP 177002,
ICMV 177003, ICMV IS 90311, LCIC9702, Souna 3,
ICMV IS 94206 and PE08043 exhibited antibiosis
resistance mechanism to Heliocheilus albipunctella
with appreciable agronomy and grain yield when
compared with the susceptible check ICMV IS 92222.
The genotypes Faringuero, ICMV 167005, ICMV IS
99001, Sadore local, SOSAT-C88, and ICMP 177004
exhibited tolerance to head miner damage with good
per se performance. The genotypes ICMP 177001,
ICMP 177002, ICMV 177003, and Moro exhibited
resistance to millet head miner and had consistent
grain Fe content across seasons (ranging from 44 to
70 ppm). Association between the head miner resistance
and morphological traits showed a positive and significant correlation of larval production index (%)
with head miner damage (r = 0.59**). Grain Fe and
Zn contents exhibited negative association with panicle
length and grain yield indicating proper care
should be taken in breeding for these traits. Hence, the
identified resistance sources can be effectively utilized
in breeding head miner resistant pearl millet OPV’s/
hybrids, with high grain yield including Fe and Zn
concentrations, to overcome the hunger and malnutrition
seen in populations living in the semi-arid tropics
Local Competition Between Foraging Relatives: Growth and Survival of Bruchid Beetle Larvae
Kin selection theory states that when resources are limited and all else is equal, individuals will direct competition away from kin. However, when competition between relatives is completely local, as is the case in granivorous insects whose larval stages spend their lives within a single seed, this can reduce or even negate the kin-selected benefits. Instead, an increase in competition may have the same detrimental effects on individuals that forage with kin as those that forage with non-kin. In a factorial experiment we assessed the effects of relatedness and competition over food on the survival and on fitness-related traits of the bruchid beetle Callosobruchus maculatus. Relatedness of competitors did not affect the survival of larvae. Larval survival substantially decreased with increasing larval density, and we found evidence that beetles maturing at a larger size were more adversely affected by competition, resulting in lower survival rates. Furthermore, females showed a reduction in their growth rate with increasing larval density, emerging smaller after the same development time. Males increased their growth rate, emerging earlier but at a similar size when food was more limited. Our results add to the growing number of studies that fail to show a relationship between relatedness and a reduction in competition between relatives in closed systems, and emphasize the importance of the scale at which competition between relatives occurs
Assessing the Impact of Rice Sector Policy Reforms on the Income Mobility of Rural Households in Nigeria
Loss of mating flight and shift in the pattern of carbohydrate storage in sexuals of ants (Hymenoptera; Formicidae)
In ants, energy for flying is derived from carbohydrates (glycogen and free sugars). The amount of these substrates was compared in sexuals participating or not participating in mating flights. Results show that in participating females (Lasius niger, L. flavus, Myrmica scabrinodis, Formica rufa, F. polyctena, F. lugubris), the amount of carbohydrates, especially glycogen, was higher than in non-participating females (Cataglyphis cursor, Iridomyrmex humilis). Similarly, male C. cursor and I. humilis which fly, exhibit a much higher carbohydrate content than do the non-flying females of these species. Furthermore, the quantity of carbohydrates stored was generally higher in males than in females for each species. These results are discussed with regard to the loss of the nuptial flight by some species of ants