Development and rearing techniques of Palmistichus elaeisis (Hymenoptera: Eulophidae) in natural and alternative hosts / Desenvolvimento e técnicas de criação de Palmistichus elaeisis (Hymenoptera: Eulophidae) em hospedeiros natural e alternativo

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

This research was developed in the Laboratory of Biological Control of Insects of the Department of Animal Biology at the Federal University of Viçosa (UFV) in Viçosa, Minas Gerais State, Brazil. The objective was to evaluate the viability of pupae of Bombyx mori L., 1758 (Lepidoptera: Bombycidae) as an alternative host for Palmistichus elaeisis Delvare &LaSalle, 1993 (Hymenoptera: Eulophidae) aiming to optimize the production of this parasitoid in the laboratory for mass releasing against the brown eucalyptus caterpillar, Thyrinteina arnobia (Stoll, 1782) (Lepidoptera: Geometridae). The first study consisted of pupae of B. mori exposed to the parasitism by females of P. elaeisis at the densities of 1:1, 9:1, 18:1, 27:1, 36:1, 45:1 or 54:1 parasitoids-host, respectively. A total of 72.72% of these pupae were parasitized at the density of 1:1 and 100.00% with all others densities. Adults of P. elaeisis did not emerge at the densities of 1:1 and 9:1 and 100.00 and 54.54% of emergency of P. elaeisis was observed from pupae of B. mori at the densities of 45:1 and 54:1, respectively. The duration of the life cycle (egg-adult) of this parasitoid varied from 20 to 28 days, being inversely proportional to the increase of its density. The progeny of P. elaeisis varied from 49 to 589 descendants per pupa of B. mori at the densities of 18:1 to 45:1 parasitoids: host. This parasitoid presented lowest number of dead imature at the density of 45:1 and the sex rate of P. elaeisis varied from 0.93 0.01 to 0.97 0.01 without differences with the densities of 18:1, 27:1, 36:1, 45:1 and 54:1, parasitoids:host. The length of the body of females and males of P. elaeisis varied from 1.67 0.04 to 1.89 0.02 mm and of 1.34 0.01 to 1.54 0.03 mm, respectively. This parasitoid should be reared with the density of 45 females per pupa of B. mori. The second experiment studied the effect of the age of females of P. elaeisis and of pupae of the host B. mori in the biological characteristics of this parasitoid. Pupae of this host with 24, 48, 72 or 96 hours old were exposed to the parasitism by females of P. elaeisis with 24, 48, 72 or 96 hours old, respectively. The duration of the life cycle of P. elaeisis with 24, 48, 72 or 96 hours old B. mori pupae and parasitized by females of this parasitoid with 24, 48, 72 or 96 hours of age varied from 21 to 38, 22 to 31, 21 to 28 and 21 to 26 days, respectively. The parasitism of B. mori pupae was 100.00% with higher percentages of emerged individuals and sex rate of P. elaeisis for females of this parasitoid with 72 at 96 hours old with pupae of B. mori with 48 at 72 hours of age. In the third study, the influence of the period of storage of B. mori pupae at low temperature was evaluated on the progeny of P. elaeisis. Pupae of B. mori, with 48 and 72 hours old, were stored at 10 C during five, 10, 15 or 20 days and, later, exposed to the parasitism by females of P. elaeisis. The duration of the life cycle of P. elaeisis was shorter (19 and 20 days) with pupae of B. mori stored during 15 days. The parasitism of P. elaeisis reached 100.0% in pupae of B. mori after storage at 10 C in all periods with an emergency from 78.0 to 100.0% of this parasitoid. The progeny of P. elaeisis was larger (728 to 1.414 individuals) per pupa of B. mori stored during 15 days at 10 C. The sex rate and the longevity of this parasitoid varied from 0.92 to 0.98 and from three to 35 days, respectively, in pupae of B. mori with different storage periods. Pupae of B. mori can be stored at 10C for up to 15 days and to be used to rear P. elaeisis. In the last study, the most appropriate alternative host was selected to mass rearing P. elaeisis and its reproductive performance was evaluated on the host natural T. arnobia. Pupae of Anticarsia gemmatalis Hubner, 1818 (Lepidoptera: Noctuidae) and B. mori were exposed to the parasitism by females of P. elaeisis. The duration of the life cycle of P. elaeisis was 21.60 0.16 and 24.15 0.65 days with pupae of A. gemmatalis and B. mori, respectively, with 100.00% parasitism of these pupae and 71.42 and 100.00% of emergency of this parasitoid from the first and second hosts, respectively. The progeny of P. elaeisis was 511.00 49.70 and 110.20 19.37 from pupae of B. mori and A. gemmatalis, respectively. The largest progeny per female of P. elaeisis was obtained from pupae of A. gemmatalis with 17.68 3.15 descendants. The longevity of females and males of P. elaeisis emerged from pupae of B. mori and A. gemmatalis was 17.55 1.84 and 14.63 0.78 and of 16.40 2.26 and 13.70 1.50 days, respectively. The sex rate of P. elaeisis was higher with pupae of A. gemmatalis with a value of 0.96 0.01. The reproductive performance of P. elaeisis with pupae of T. arnobia (parasitism, emergency, progeny per pupa, size of the body and width of the cephalic capsule of females and males, longevity of females and males and sex rate) was not reduced after this parasitoid was reared during six generations with pupae of A. gemmatalis or B. mori. Therefore, these hosts can be used to mass rear P. elaeisis, but pupae of B. mori are more appropriate because they allow producing a larger number of individuals of this parasitoid per each one of them. The methodologies are appropriate to mass produce P. elaeisis in the laboratory. This can increase the possibilities of using this natural enemy in programs of biological control of eucalyptus Lepidoptera defoliators, mainly T. arnobia.

ASSUNTO(S)

controle biológico parasitoid thyrinteina arnobia entomologia agricola thyrinteina arnobia biological control bombyx mori parasitóide bombyx mori

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