Life History and Sex Determination in the Diaspine Scale,Pseudaulacaspis pentagona(Targ.) (Coccoidea)

Abstract

The increasing body of knowledge about the armored scales is beginning to reveal manv unique aspects in the life cycles of these highly specialized insects. Such information is not only of value to the entomologist and those concerned with the control of scales but is also becoming important in such diverse fields as genetics, ecology, cytology, and physiology; armored scales may well find an expanding place in the laboratory as subjects for researches in a variety of fields. Pseudaulacaspis pentagona (Targ.) has one of the most unusual, yet to date one of the best understood life cycles of the armored scales. Various aspects of its biology have been described by Berlese (1910), Smit (1953), Dustan (1953), and Monti (1955). Accounts of its natural enemies or biological control programs have been given by Berlese (1910) for Italy, by Ogilvie (1928) and Simmonds (1955) for Bermuda, by Bennett (1956) for Trinidad, and Clausen (1956) for Florida. P. pentagona is a pest of economic importance on a wide variety of hosts throughout an extekive geographic distribution (Anon., 1956), and has been cultured extensively in the biological control laboratory for the mass-rearing of scale parasites and predators. Recent investirzations of the sex determining mechanik and chromosome behaviour (Brown and Bennett, 1957) have arain shown unusual processes and relationships, some of which appear to occur in many other species of armored scales. It is the purpose of this paper to describe the life cycle of P. pentagona as it is known from field and laboratory studies and from cytological and genetic investigations.

Genetic evidence for biparental males in haplo-diploid predator mites (Acarina: Phytoseiidae)

“…The claim for haploidy of phytoseiid males is therefore without any doubt. In order to explain the biparental origin of haploid males in both phytoseiid species, attention is drawn to the peculiar genetic system in armoured scale insects (Diaspididae), as studied by Brown & De Lotto (1959), Brown & Bennett (1957), Bennett & Brown (1958) and Brown (1958). In most of the diaspidid species males are haploid, but arise from fertilized eggs.…”

The population dynamics of the white peach scale and its parasitoids in a mulberry orchard in Campania, Italy

“…Male adults are winged and go through two instars and a 'prepupal' and 'pupal' stage before moulting to the winged adult stage. The male: female sex ratio of the scale is typically 1:1 (Tremblay, 1959;Hanks & Denno, 1993a) becoming more male-biased if mating is delayed (Bennett & Brown, 1958;Tremblay, 1958). In southern Italy, the scale completes three generations per year and overwinters as an adult female.…”

Chromosome Behaviour in <i>Laccifer lacca</i> (Kerr) Lacciferidae-Coccoidea

“…lacca in possessing two kinds of chromosomes viz. euchromatic and heterochromatic has been totally ignored by Tulsyan 1963, since the heterochromatic nuclei have been mistermed as 'nuclear matter' and with no reference to the euchro matic nuclei which alone give rise to the sperms (Bennett and Brown 1958, Brown 1959, Dikshith 1963, Hughes-Schrader 1935, 1948, Schrader 1921, 1929. Moreover while studying the 'spermatogenesis' Tulsyan (1963) has not taken into account the important features of the Lecanoid system such as i) the division of the gonial cells ii) the formation of the monopolar spindle iii) suppression of the second cytoplasmic division iv) formation of binucleate and quadrinucleate spermatids v) fate and role of the heterochro matic nuclei and their contribution in the restoration of the physiological haploidy of the male L. lacca.…”