Host suitability, respiration rate and the outcome of larval competition in strains of the cowpea weevil, Callosobruchus maculatus

Abstract

Abstract. Variation between strains of Callosobruchus maculatus in several lifehistory traits is well known. Differences in functional anatomy of egg pores and larval respiration rates have also been reported in strains from Brazil and Yemen. The response of five strains of C. maculatus to seeds of two host species, cowpea (Vigna unguiculata) and mung bean (Vigna radiata), was measured along with the larval respiration rates of the same strains on both hosts. There was significant variability of response to the two hosts. Strains with higher larval respiration rate (mL O 2 /insect/day) showed higher seed consumption, which significantly affected adult emergence per seed on both hosts. This finding provides support for the hypothesis that differential feeding rate is an important mechanistic component of the larval competition outcome observed in strains of C. maculatus.

The effect of temperature on the diapause and cold hardiness of Dendrolimus tabulaeformis (Lepidoptera: Lasiocampidae)

“…Before each measurement larvae were weighed using an electronic balance (sensitivity: 0.1 mg, Sartorius, R200 D.A.G., Göttingen, Gernamy). The respiration rate was calculated as the amount of O2 uptake per fresh weight per hour (µl O2 / mg / h) (Daniel & Smith, 1994;Guedes et al, 2003;Gao et al, 2008). Each measurement was replicated six times.…”

“…Oxygen uptake was measured in a Gilson Differential Respirometer (Gilson, 1963) using methods adapted from Daniel & Smith (1994), Guedes et al (2003) and Gao et al (2008). A series of 13 ml flasks was used for each measurement, with each flask containing 1 to 2 diapausing larvae that had been dried using filter paper.…”

Enhanced tolerance to water stress in adults of the South India strain of the seed beetle, Callosobruchus maculatus (Coleoptera: Bruchidae), as a product of large body size

“…In fact, these respiratory rates of the larva represent the extremes with South India being the highest and Brazil the lowest when larvae of other strains of C. maculatus are compared (Guedes et al, 2003). Increased seed consumption necessitates increased rates of respiration and leads to larger emerging adults for the South India strain (Guedes et al, 2003).…”

“…Females have stripes on the pygidium and are black, whereas males lack stripes and are brown with a smaller pygidium (Bandara & Saxena, 1995). To rule out differences due to diet, both strains were reared on cowpea for two generations (Guedes et al, 2003). After emergence of the second generation, beetles were stored individually in 1.5 cc mesh-covered chambers for 48 h, as adults do not require food or liquid water (Mitchell, 1975).…”

“…The South India strain has a contest (attack) behavioral process of larval competition and a contest outcome where one, or few, adults emerge per seed. Brazil strain of this same species has a scramble process of competition where several to only one adult emerges per single seed (Smith & Lessels, 1985;Guedes et al, 2003). Because how these beetles are reared is reminiscent of the storage facilities that they inhabit (dry, air-tight containers at room temperature and low relative humidity), laboratory observations likely reflect what occurs in nature (Messina & Mitchell, 1989).…”