Biology and host specificity of Gonatocerus deleoni (Hymenoptera: Mymaridae), a potential biocontrol agent of Homalodisca vitripennis (Hemiptera: Cicadellidae) in California, USA

Senecio brasiliensis (Spreng.) Less quando ingerido por bovinos e eqüinos causa uma séria intoxicação, a seneciose. Devido a significativa perda econômica para a pecuária é interessante o controle com uso de insetos. Através de coletas sistêmicas e contínuas na planta observou-se que Phaedon confinis Klug, causa sérios danos à planta apresentando grande potencial como biocontrolador. O objetivo foi ampliar a 52 plantas os testes de especificidade hospedeira com larvas de 1º instar e adultos do crisomelídeo. Os insetos foram submetidos aos testes “sem chance de escolha” e de “múltipla escolha”. Os seguintes resultados foram obtidos: “SEM CHANCE DE ESCOLHA” L1 - 52 plantas testadas: dano nulo 90,39%; exploratório 5,77%; fraco 1,92%; e normal apenas no S. brasiliensis 1,92%, onde 31,67% das larvas atingiram a fase adulta. “SEM CHANCE DE ESCOLHA” ADULTOS - 46 plantas testadas: em 82,60% o dano foi nulo; 13,04% exploratório; 2,17% fraco; 2,17% normal S. brasiliensis. O crisomelídeo ovipositou durante os dias de observação somente nas folhas de S. brasiliensis, 615 ovos com viabilidade de 73,01%. No teste “MÚLTIPLA ESCOLHA” LARVAS - Nove plantas testadas: 66,67% dano nulo; 11,11% fraco; 11,11% exploratório; e 11,11% normal S. brasiliensis. Os resultados indicam que a alimentação normal, oviposição, sobrevivência e desenvolvimento de P. confinis estão restritos ao S. brasiliensis e contribuem para confirmar o seu potencial como agente de biocontrole. Host Specificity Test of Phaedon confinis (Coleoptera, Chrysomelidae), a Potential Biocontrol Agent of Senecio brasiliensis (Asteraceae) Abstract. Senecio brasiliensis (Spreng.) Less when ingested by cattle and horses, the plant causes seneciosis, a serious poisoning. Due to the great financial losses to cattle ranchers, controlling the plant using insects has become attractive. Systematic survey efforts have revealed that Phaedon confinis Klug causes serious damage to the plant, and may be a great biocontrol agent. The object was to extend the tests of host specificity to 52 plants using 1st larval instar and adult chrysomelid bettles. The insects were submitted to “no-choice” and “multiple-choice” tests. The following results were obtained: “NO-CHOICE” L1 – 52 plants tested: null 90.39%; negligible damage 5.77%; light 1.92%; and normal in only S. brasiliensis 1.92%, where 31.67% of larvae obtained an adult phase. “NO-CHOICE” ADULTS – 46 plants. Null damage was recorded in 82.60%; 13.04% showed negligible damage; 2.17% light; 2.17% normal in S. brasiliensis. The chysomelids oviposited during observation days only on S. brasiliensis leaves. 615 eggs were oviposited with 73.01% viability. “MULTIPLE CHOICE” LARVAE – nine plants tested. 66.67% null; 11.11% weak; 11.11% negligible damage; and 11.11% normal in S. brasiliensis. The results indicate that the normal diet, oviposition, survival and development of P. confinis is restricted to S. brasiliensis and corroborates its potential as a biocontrol agent.

Download Full-text

Insecticidal control of Melanterius servulus (Coleoptera: Curculionidae), a potential biocontrol agent of Paraserianthes lophantha (Leguminosae), in commercial seed orchards of black wattle, Acacia mearnsii(Leguminosae)

Bulletin of Entomological Research ◽

10.1017/s0007485300051725 ◽

1992 ◽

Vol 82 (2) ◽

pp. 197-202 ◽

Cited By ~ 2

Author(s):

D. Donnelly ◽

F.J. Calitz ◽

I.M.R. Van Aarde

Keyword(s):

South Africa ◽

Host Specificity ◽

Biocontrol Agent ◽

Field Trials ◽

Acacia Mearnsii ◽

Pyrethroid Insecticides ◽

Seed Orchards ◽

Potential Biocontrol Agent ◽

Black Wattle ◽

Two Stages

AbstractA seed-feeding weevil, Melanterius servulus Pascoe, is considered suitable for release against the weed Paraserianthes lophantha. However, host specificity tests have indicated that M. servulus may also develop on the seeds of Acacia mearnsii (black wattle), which is both a weed and a crop plant in South Africa. Seed orchards, which supply the black wattle industry, may therefore need to be protected. The aim of this study was to determine whether the two pyrethroid insecticides presently used in wattle plantations against the wattle bagworm (Kotochalia junodi Heylaerts (Lepidoptera: Psychidae)) are effective against M. servulus. Since M. servulus has not yet been released in South Africa, field trials were not possible, and evidence that black wattle seed orchards can be protected from M. servulus was obtained indirectly, in two stages. Firstly, field trials showed that the two insecticides effectively protect the weed Acacia longifolia from a closely related weevil, Melanterius ventralis Lea, which has already been established as a biocontrol agent. Secondly, quarantine laboratory trials demonstrated that M. ventralis and M. servulus showed similar avoidance responses and similar levels of mortality when exposed to the insecticides. All the evidence indicates that the chemical protection of A. mearnsii seed orchards from M. servulus is possible.

Download Full-text