Contents - Faperta

Mechanisms and Inheritance of Resistance to Insect Pests 127
Number of eggs laid female –1
500
400
300
200
100
0
ICPL 98001 T 21 ICPL 87 ICPL 332
No-choice Multi-choice
FIGURE 5.2 Oviposition preference by the Helicoverpa armigera females on pigeonpea under no-choice and
multichoice conditions.
and frego-bract are nonpreferred by the cotton bollworm, Helicoverpa armigera (Hubner) for
egg laying than the genotypes with normal leaves (Wu, Cai, and Zhang, 1997). Oviposition
nonpreference is also a component of resistance to H. armigera in chickpea (Cowgill and
Lateef, 1996) and pigeonpea (Figure 5.2) (H.C. Sharma et al., 2001; Kumari, Sharma, and Reddy,
2005), and to Helicoverpa zea (Boddie) in tomato (Cosenza and Green, 1979). Both antixenosis
and antibiotic types of resistance have been observed against the pea weevil, Bruchus
pisorum L. (Clement et al., 1994). Nonpreference for feeding and nutritional antibiosis are
major components of resistance in soybean to Epilachna varivestis Mulsant (Kogan, 1982).
Antibiosis
Antibiosis is expressed in terms of larval mortality, decreased larval and pupal weights,
prolonged larval and pupal development, and reduced fecundity. Antibiosis effects are
also expressed in terms of sex ratio and proportion of insects entering diapause. The antibiotic
type of resistance prolongs the generation time, and can reduce the insect population
within a few generations through a cumulative effect on insect survival and development
(Coaker, 1959; Knipling, 1979; Jayaraj, 1982; H.C. Sharma, 1993). Both chemical and morphological
factors mediate antibiosis (Panda and Khush, 1995; H.C. Sharma and Nwanze,
1997; Smith, 2005). Lethal effects may be acute, often affecting young larvae, while chronic
effects lead to mortality of older larvae, pupae, and adults (H.C. Sharma, Vidyasagar, and
Subramanian, 1993; H.C. Sharma and Nwanze, 1997; H.C. Sharma et al., 2001; Smith, 2005;
Stevenson et al., 2005). Individuals surviving the direct effects of antibiosis may have
reduced body weight, a prolonged period of development, and reduced fecundity.
Antibiosis may also include subchronic effects, such as slow growth rates, poor utilization
of food, and reduced fecundity (Reese and Beck, 1976).
Antibiosis is an important component of resistance to H. armigera in cotton. Cotton genotypes
Suvin (Gossypium barbandense L.) and MCU 9 (G. hirsutum L.) are more suitable than
TKHe 44 (G. arboreum L.) for the growth and development of H. armigera (Nanthagopal and
Uthamasamy, 1989). Net reproductive rate, intrinsic rate of increase, and fecundity have
been found to be relatively lower on cotton genotypes LK 861 and LPS 141 as compared to
MCU 5 (Rao and Prasad, 1996). There is a large variation in larval survival, larval and
pupal weights, egg viability, and longevity of H. armigera adults when reared on different
chickpea genotypes (Srivastava and Srivastava, 1990). Life table analysis suggested that
there is considerable variation in net reproductive rate (142.1 to 268.6), mean generation