Eggs
The eggs are cemented to the surface of pulses and are smooth, domed structures with oval, flat bases.
Larva and Pupa
The larvae and pupae are normally only found in cells bored within the seeds of pulses. For descriptions and a key including C. maculatus larvae, see Prevett (1971) and Vats (1974).
Adult
C. maculatus adults are 2.0-3.5 mm long. The antennae of both sexes are slightly serrate (for details of antennal and sensilla structure see Mbata et al. (1997)). Females often have strong markings on the elytra consisting of two large lateral dark patches mid-way along the elytra and smaller patches at the anterior and posterior ends, leaving a paler brown cross-shaped area covering the rest. The males are much less distinctly marked. In common with other species of Callosobruchus, C. maculatus has a pair of distinct ridges (inner and outer) on the ventral side of each hind femur, and each ridge bears a tooth near the apical end. The inner tooth is triangular, and equal to (or slightly longer than) the outer tooth. A unique chordotonal structure in the fore coxae of adult C. maculatus and C. subinnotatus was described by Ramaswamy and Monroe (1997). The location and ultrastructure of sex pheromone glands in female C. maculatus is described by Pierre et al. (1996).
Several workers have described an active- or flight-form of adult C. maculatus which is apparently more active and is more strongly marked, with a white pygidium (Utida, 1953). The function of this form, which appears in populations as a result of genetic and environmental factors, is not understood.
No particular detection or inspection methods for Callosobruchus spp. have been developed.
The potential exists for the development of population monitoring by use of sex pheromones. The female-produced sex pheromone has been isolated and identified (Phillips et al., 1996);and the behavioural and electroantennogram (EAG) response to pheremonal components by males was recorded by Shu et al. (1996).
Related invasive species
- Callosobruchus maculatus
Related Farm Practice
- Development
- Pests
- Hosts
- Rest
- Host plants
C. maculatus is a major pest of cowpeas, green gram and lentils. For a complete list of host plants, see Udayagiri and Wadhi (1989), and Desroches et al. (1997). Host plants vary considerably in their suitability for larval development (Wijeratne, 1998). Alpha-amylase inhibitors prevent development of C. maculatus on a number of legumes (Blanco-Labra et al., 1996;Reis et al., 1997;Ishimoto et al., 1999;Janarthanan et al., 1999) including Phaseolus vulgaris, but not the development of the bruchids Acanthoscelides obtectus and Zabrotes subfasciatus (Ishimoto and Chrispeels, 1996).
There have been many studies of host preference in C. maculatus and its ability to adapt to using hosts less suitable for larval development, for example Huignard et al. (1996);Taheri (1996);Sulehrie et al. (1998). Inheritance of aspects of host plant choice were observed by Messina and Slade (1997).