Influence of prey availability on reproduction and prey consumption ofPhytoseiulus persimilis, Amblyseius californicusandMetaseiulus occidentalis(Acarina: Phytoseiidae)

Abstract

As the level of prey availability was increased predators expressed corresponding increases in fecundity per reproductive period, in daily ovipositional rate, in total number of prey killed per reproductive period, in daily number of prey killed per reproductive period and in female:male sex ratio. The number of prey kills per predator egg produced initially increased with increasing prey availability but levelled off at higher levels of prey availability. The total number of reproductive days also increased initially but then declined at the higher levels of prey availability.

Evolution of pseudo-arrhenotoky

“…This is exemplified by the decrease in sex ratio and oviposition rate (1) in the data presented in Fig. 1; (2) with decreasing prey density (Table 1; Veltkamp, 1968;Friese and Gilstrap, 1982), (3) with increasing predator density (see Tables 2 and 3); (4) with temperatures decreasing below 20 ~ C (e.g. Amblyseius chilenensis Dosse (Ma and Laing, 1973); T. occidentalis (Tanigoshi et al, 1975;Wiegers, 1981), and A. hibisci Chant (Tanigoshi et al, 1981)); and (5) just after food deprivation of the predator female, in P. persimilis (Amano and Chant, 1978).…”

“…Influence of prey availability total fecundity, oviposition rate and sex ratio of three phytoseiid species at 26 ~ __ 2.6~ (data from Friese and Gilstrap, 1982) (1930) predicted equal investment in both sexes in terms of maternal resources and the costs of producing a son or a daughter are unlikely to be exactly the same. For example, if egg weight reflects maternal investment, sons are cheaper than daughters.…”

“…Nagelkerke and K. Hofker, unpublished data, 1987;C.J. Nagelkerke (unpublished data, 1987, using a strain from Morocco) ); Tfl, Typhlodromus floridanus (Tanigoshi and McMurtry, 1977); T1, T. longipilus (Burrell and McCormick, 1964); Tin, T. mcgegori (Croft and Jorgensen, 1969 ); To, T. occidentalis (Tanigoshi et al, 1975;Friese and Gilstrap, 1982;Hoy, 1984;Sabelis, 1985); Tr, T. rickeri (McMurtry and Scriven, 1964); Tpi, T. pini (Charlet and McMurtry, 1977); Tpy, T. pyri (Overmeer, 1981); Tvo T. validus (Charlet and McMurtry, 1977). dispersal, population mixing is largely determined by the oviposition behaviour of the phytoseiid females.…”

“…Whenever the isolated state of the ovipositing females was uncertain (incomplete methods description), the sex ratios are indicated by open circles instead of dark points. The drawn line corresponds to the regression of the sex ratio (y) on the oviposition rate (x) after logarithmic transformation of x (r --0.844): y = 0.538 + 0.208 x. Abbreviated and complete scientific nomenclature of the phytoseiid species are given below together with references used to construct the figure: Aa, Amblyseius andersoni (Amano and Chant, 1978); Aan, A. anonymus (Dinh et al, 1988); Abi, A. bibens (Blommers, 1976);Abr, A. brazilii (E1-Banhawy, 1975); Aca, A. californicus (Friese and Gilstrap, 1982); Aci, A. citrifolius (De Moraes and McMurtry, 1981 ); Ach, A. chiIenensis (Ma and Laing, 1973); Ad, A. degenerans (Takafuji and Chant, 1976); Afa, A. faIlacis (Ballard, 1954); Aft, A. finlandicus (M.W. Sabelis, unpublished data, 1982); Afu, A. fustis (Ezulike and Odebiyi, 1985); Ag, A. gossypi (Rasmy and E1-Banhawy, 1975); Ah, A. hibisci (Tanigoshi et al, 1981); Ai, A. idaeus (Dinh et al, 1988); Ala, A. largoensis (Tanaka and Kashio, 1977); Aio, A. longispinosus (Shih and Shieh, 1979;Mallik and Channabasavanna, 1983); Am, A. masiaka (Blommers, 1974); Ap, A. potentillae (Sabelis, 1981 ); Apl, A. pseudolongispinosus (Xin et al, 1984); As, A. scutalis (Bounfour and McMurtry, 1987); Au, A. umbraticus (Knisley and Swift, 1971 ); Avz, A. vazimba (Blommers, 1974); Ph, Phytoseius hawaiiensis (Sanderson and McMurtry, 1984); P1, Phytoseiulus longipes (Badii and McMurtry, 1984); Pro, P. macropilis (Prasad, 1967;; Pp, P. persimilis (Takafuji and Chant, 1976;Friese and Gilstrap, 1982; M.W.…”

“…There also exists evidence of equal investment in the sexes for phytoseiids with a diet of high-density prey types when current prey density is low. Veltkamp (1968) and Friese and Gilstrap (1982) collected eggs deposited by phytoseiids at various prey densities and reared them to adulthood at high prey density for determination of sex. The sex ratios measured in this way appeared to be female-biased at high prey density, but they approached unity at the lowest prey densities, where random mating is expected to be the rule (Table 1).…”