Male Investment Uric Acid

Dog Food Secrets

How to Choose Healthy Dog Food

Get Instant Access

Roth and Willis (1952a) were the first to note that in B. germanica, a chalk-white secretion composed of uric acid oozes from male uricose glands (utriculi majores) and covers the spermatophore just before copulating pairs separate (Fig. 6.9). Subsequent surveys made evident that uricose glands are unique to a relatively small subset of Blattaria. Within the Blaberoidea, the glands are common in the Pseudophyllodromiinae, less frequent in the Blat-tellinae, and in the Blaberidae occur only in some Epil-amprinae. They are absent in Blattoidea (Roth and Dateo, 1965; Roth, 1967c).

Several hypotheses addressing the functional significance of uric acid expulsion via uricose glands have been offered. Because uric acid is the characteristic end prod uct of nitrogen metabolism in terrestrial insects (Cochran, 1985), initially it was thought that mating served as an accessory means of excretion in these species (Roth and Dateo, 1964). The glands of males denied mating partners become tremendously swollen with uric acid (Roth and Willis, 1952a), like cows that need milking. These excessive accumulations can result in increased male mortality (Haydak, 1953; Roth and Dateo, 1965). Field observations of cockroaches seeking out and ingesting uric acid from bird and reptile droppings (Fig. 5.2), however, weaken the excretion hypothesis. It would also be unusual for males of a species to have a waste elim-

Fig. 6.9 Scanning electron micrograph of the edge of an emptied spermatophore with adhering spherical urate granules of varying diameter (Blattella germanica). From Mullins and Keil (1980), courtesy of Donald Mullins, and with copyright permission from the journal Nature (www.nature.com/).

Fig. 6.9 Scanning electron micrograph of the edge of an emptied spermatophore with adhering spherical urate granules of varying diameter (Blattella germanica). From Mullins and Keil (1980), courtesy of Donald Mullins, and with copyright permission from the journal Nature (www.nature.com/).

Dog food 5% protein

Diet

Fig. 6.10 Comparison of total radiolabel content of Blattella germanica females and the oothecae they produced while feeding on either a dog food (25% crude protein) or a 5% protein diet; these females were mated to virgin males that had been simultaneously injected with 3H leucine (a representative amino acid) and 14C hypoxanthine (a purine converted to uric acid in vivo). Dog food fed-females and their oothecae contained 17% of the male contributed radiolabel. Those on the low-protein diet contained 63% of the radiolabel made available to them at mating. Values are mean ± SEM. a vs. b, p = 0.005; c vs. d, p = 0.027; e vs. f, p = 0.007 (Student's t-test). From Mullins et al. (1992), courtesy of Donald Mullins and with permission from the Journal of Experimental Biology.

Dog food 5% protein

Diet

Fig. 6.10 Comparison of total radiolabel content of Blattella germanica females and the oothecae they produced while feeding on either a dog food (25% crude protein) or a 5% protein diet; these females were mated to virgin males that had been simultaneously injected with 3H leucine (a representative amino acid) and 14C hypoxanthine (a purine converted to uric acid in vivo). Dog food fed-females and their oothecae contained 17% of the male contributed radiolabel. Those on the low-protein diet contained 63% of the radiolabel made available to them at mating. Values are mean ± SEM. a vs. b, p = 0.005; c vs. d, p = 0.027; e vs. f, p = 0.007 (Student's t-test). From Mullins et al. (1992), courtesy of Donald Mullins and with permission from the Journal of Experimental Biology.

ination system unavailable to females and juveniles. From the female perspective, it was suggested that a sper-matophore slathered with an excretory product would be an unattractive meal, and prevent her from consuming it before the sperm moved into storage (Roth, 1967,1970a). An alternative suggestion was that the uric acid may function as a mating plug that deters additional inseminations (Cornwell, 1968). In species such as Miriamrothschildia (= Onychostylus) notulatus, Lophoblatta sp., Cariblatta minima, Amazonina sp., and Dendroblatta sobrina, so much uric acid is applied by males that the female genital segments gape open (Roth, 1967c).

The most strongly supported hypothesis is that the uric acid transferred during mating acts as a nuptial gift. In B. germanica, radiolabeled uric acid can be traced from the male to the female, and subsequently to her oocytes; the transfer occurs more readily when the female is maintained on a low-nitrogen diet (Fig. 6.10). The urates are probably ingested by the female, along with the sper-matophore, but it is possible that a small fraction may enter via her genital tract (Mullins and Keil, 1980). An analogous urate transfer and incorporation occurs in X. hamata. In this case, the female turns, post-copulation, and feeds on a urate-containing slurry produced and offered by the male (Schal and Bell, 1982). After copulation the male raises his wings, telescopes his abdomen, widens the genital chamber, exposes a white urate secretion, and directs it toward the female, who ingests it. Females feed for about 3.5 min. As in B. germanica, females on nitrogen-deficient diets transfer to their maturing oocytes more male-derived uric acid than do females on highprotein diets. The magnitude of the gift offered by males of these two species depends on a combination of male age, size, diet, and frequency of mating. The uricose glands of newly emerged male B. germanica contain little or no secretion; they become filled in one or two days (Roth and Dateo, 1964). The glands are nearly emptied at each copulation (Roth and Willis, 1952a).

Male to female transfer of uric acid probably occurs in all cockroach species that possess male uricose glands. A recently mated female Blattella humbertiana was observed removing excess uric acid with her hind legs, then eating some of the material before it hardened (Graves, pers, comm. to LMR in Roth, 1967c). In three species of Latiblattella the male's genitalia and posterior abdominal segments are covered with "chalky white secretion" after mating, and females of Lat. angustifrons have been observed applying their mouthparts to it after mating (Willis, 1970).

Was this article helpful?

0 0
Pamper Your Dog

Pamper Your Dog

The cookbook that your dog and dogs everywhere have been waiting for has finally arrived. Pamper Your Dog unleashes 130 recipes for tasty treats and meals for your canine friend that are sure to have your dog salivating. You cook for yourself and your family, so don't ignore your most faithful of friends. Pamper Your Dog will show you how to prepare tasty and healthful treats and main meals for their dogs without a lot of cost or work. This great collection of recipes features 130 tempting and tasty treats for your dog.

Get My Free Ebook


Post a comment