Factors Influencing Reproduction

A variety of interacting factors are known to have an impact on the reproduction of female cockroaches, including food availability, body size, mating status, social contacts, and age (reviewed by Engelmann, 1970; Roth, 1970b). The presence of conspecifics accelerates reproduction in B. germanica, not only by influencing food in take but also via a more direct effect on juvenile hormone synthesis (Holbrook et al., 2000a). In N. cinerea maternal age is negatively correlated with fertility and lifetime fecundity. Old females take significantly longer than young ones to produce a first clutch. They also include fewer eggs per ootheca, and those eggs are slower to develop. Maternal age does not affect hatch rate, viability, nymphal development, or the reproductive potential of these nymphs when they became adults. While age does affect maternal fitness, then, it has no effect on the fitness of the offspring older females produce (Moore and Moore, 2001; Moore and Harris, 2003).

Species are differentially dependent on stored reserves for their first oviposition, varying from complete dependence (e.g., R. maderae—Roth, 1964b), to complete independence (e.g., Pycnoscelus—Roth and Stay, 1962a) (Table 7.3). Reproduction in relatively small blattellids can be closely tied to food availability. Females of B. germanica invest 34% of their pre-oviposition dry weight and 26% of their nitrogen into their first ootheca (Mullins et al., 1992). Female Parc. fulvescens typically store sufficient reserves to produce just one egg case, constituting 15-20% of her body weight (Cochran, 1986a; Lembke and Cochran, 1990). In larger species like Peri-planeta, food intake is not necessary to mature the first batch of eggs, and females can produce up to five oothe-cae without feeding between successive ovipositions (Kunkel, 1966). Oothecae are just 7% of the weight of the unstarved female (Weaver and Pratt, 1981). Mating and feeding seem to have a synergistic effect in N. cinerea and R. maderae, since both stimuli are usually required for the

Table 7.3. Effect of starvation during the first preoviposition period in virgin and mated female cockroaches. See Roth (1970b) for citations of original work.

Oocyte development1

Fed Starved

Table 7.3. Effect of starvation during the first preoviposition period in virgin and mated female cockroaches. See Roth (1970b) for citations of original work.

Oocyte development1

Fed Starved

Species

Virgins

Mated

Virgins

Mated

Blattella germanica

+

+++

-

Blattella vaga

+

+++

-

Blaberus craniifer

+

+++

+

Byrsotria fumigata

+

+++

+

Eublaberus posticus

+ -

+++

+-

+++

Nauphoeta cinerea

+

+++

+-

+++

Rhyparobia maderae

+-

+++

-

-

Pycnoscelus indicus

+++

+++

+++

+++

Pycnoscelus surinamensis

+++

+++

+++

+++

Diploptera punctata

-

+++

-

+++

1(+ + +) develop and mature rapidly;(+) develop and mature;(+—) may or may not develop; (—) do not develop.

1(+ + +) develop and mature rapidly;(+) develop and mature;(+—) may or may not develop; (—) do not develop.

maximum rate of yolk deposition (Roth, 1964a, 1964b). Mating is necessary for initiation of yolk deposition in D. punctata (Engelmann, 1960; Roth and Stay, 1961),but has no effect on yolk deposition in Byr. fumigata, Pyc. indicus, or B. germanica (Roth and Stay, 1962a). Stimuli from feeding, drinking, mating, and social contact are required for the highest rates of yolk deposition in P. americana. A graded series of "sexually suppressed" females can be produced by withholding one or more of these stimuli (Weaver, 1984; Pipa, 1985).

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