Abstract
Because nutrients accrued during larval stages represent the major limiting factor for egg production, the use of adult feeding to enhance the reproductive output in moths is considered to be largely weight-dependent. It is hypothesized, however, that feeding by adults could be adaptive and an effective means of increasing their reproductive success. In order to test this, the calling behaviour of Spodoptera littoralis females that differed in body weight and whether they had fed or not were recorded. Two experiments were carried out. In the first, the calling behaviour of food-deprived females of different body weights was recorded. A strong positive correlation was found between body weight at emergence and the total duration of calling of females on the second to the fifth night after emergence. In the second experiment, groups of female moths that varied in body weight were given access to water or sucrose. Feeding on sucrose significantly reduced the pre-calling period and increased the total time spent calling on the six nights after emergence. The increase in time spent calling associated with ingesting sucrose were proportionately similar for both small and large females, implying that feeding by adults can result in an increase in the time spent calling by moths irrespective of larval nutritional status. Female longevity was also correlated with moth weight at emergence and/or sucrose availability. It is concluded that it is advantageous for female S. littoralis to be large and/or have access to sucrose-rich food in the adult stage as they can spend more time attracting a mate, which increases their chances of mating in early adult life, and their longer adult life may indirectly result in an increase in fecundity.
Highlights
Body weight is one of the most important factors shaping biological processes in insects (Reavey, 1993)
Female longevity was significantly correlated with body weight at emergence (Fig. 2)
From nights 1 to 4 the time spent calling by L-SF was significantly longer than by L-WF and sucrose-fed females” (S-SF), which spent significantly more time calling than S-WF
Summary
Body weight is one of the most important factors shaping biological processes in insects (Reavey, 1993). Large female insects are generally thought to be potentially very fecund (Honek, 1993; Tammaru et al, 2002; Xu & Wang, 2009). Various aspects of the reproductive physiology and behaviour of moths, e.g. sexual selection (Jaffe et al, 2007; Xu & Wang, 2009; Harari et al, 2011), propensity for re-mating (Torres-Vila et al, 1997) and investment by males (Teng & Zhang, 2009) are affected by body weight. In which females release sex pheromones to attract males, is a prerequisite for mating in moths. Many studies have shown that calling is affected by endogenous and exogenous factors, including temperature (Mozuraitis & Buda, 2006), photoperiod (Gomez & Rojas, 2006), age (Ambrogi et al, 2009), mating status (McNamara et al, 2009), presence of host or non-host plant leaves (Sadek & Anderson, 2007) and perception of the pheromone produced by conspecifics (Lim et al, 2007). The effect of body weight on calling behaviour has rarely been addressed
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