Abstract:Avaliou-se a resposta funcional, o tempo de busca e de manuseio da presa pelo predador Scymnus (Pullus) argentinicus(Weise). Como alimento foram oferecidas ninfas de 3º e 4º ínstares do pulgão verde Schizaphis graminum (Rond.). O delineamento experimental foi o inteiramente casualizado, em esquema fatorial 3 x 5, em três densidades (10, 25 e 35) de ninfas do pulgão e quatro ínstares larvais e adulto do predador, em 10 repetições. Os insetos foram mantidos a 25 ± 1ºC, 70 ± 10% UR e fotofase de 14 horas. Tanto p… Show more
“…The study of the different types of functional response is important in understanding the underlining mechanisms in predator-prey interaction, in elucidating the practical role of coevolutionary relationships, and in contributing towards biological control using this kind of interaction (Houck & Strauss, 1985). In this context, many experiments about predaceous insects in agricultural systems have evaluated diverse aspects of the functional response: Veeravel & Baskaran (1997) and Vieira et al (1997) with coccinelids; Heimpel & Hough-Goldstein (1994), Saini et al (1997), and O' Neil (1997) with pentatomids; and Fonseca et al (2000) with neuropters.…”
This study evaluated the functional response of the predator Cosmoclopius nigroannulatus on first instar nymphae of Spartocera dentiventris, both species associated with Nicotina tabacum. The experiment was carried out in laboratory conditions: 27 +/- 1 degree C; 80 +/- 5%, RH; 12 h, photophase. Ten newly emerged adults of each sex of C. nigroannulatus were used in each of five densities (5, 15, 25, 35, and 45 individuals) of S. dentiventris nymphae. The predators were observed every 24 h for five days, when the number of dead and/or consumed nymphae was recorded. The results showed a positive correlation between the number of ingested nymphae and the increase in prey density. Females ingested more nymphae than the males. The estimated handling time per prey (Th) was higher in males (3.07 h) than in females (1.93 h), with total handling time (Th x Na) increased with density. Other components of the functional response, such as attack rate (a'), searching time (Ts), and search efficiency (E) showed, in neither males nor females, a negative correlation regarding density. The results indicated a higher predatory efficiency in the females. The components of the functional response fitted significantly the randomic model of the Holling discs equation (Na = N [1 - exp[- a'(T - ThNa)]]), evidencing a functional response of type II.
“…The study of the different types of functional response is important in understanding the underlining mechanisms in predator-prey interaction, in elucidating the practical role of coevolutionary relationships, and in contributing towards biological control using this kind of interaction (Houck & Strauss, 1985). In this context, many experiments about predaceous insects in agricultural systems have evaluated diverse aspects of the functional response: Veeravel & Baskaran (1997) and Vieira et al (1997) with coccinelids; Heimpel & Hough-Goldstein (1994), Saini et al (1997), and O' Neil (1997) with pentatomids; and Fonseca et al (2000) with neuropters.…”
This study evaluated the functional response of the predator Cosmoclopius nigroannulatus on first instar nymphae of Spartocera dentiventris, both species associated with Nicotina tabacum. The experiment was carried out in laboratory conditions: 27 +/- 1 degree C; 80 +/- 5%, RH; 12 h, photophase. Ten newly emerged adults of each sex of C. nigroannulatus were used in each of five densities (5, 15, 25, 35, and 45 individuals) of S. dentiventris nymphae. The predators were observed every 24 h for five days, when the number of dead and/or consumed nymphae was recorded. The results showed a positive correlation between the number of ingested nymphae and the increase in prey density. Females ingested more nymphae than the males. The estimated handling time per prey (Th) was higher in males (3.07 h) than in females (1.93 h), with total handling time (Th x Na) increased with density. Other components of the functional response, such as attack rate (a'), searching time (Ts), and search efficiency (E) showed, in neither males nor females, a negative correlation regarding density. The results indicated a higher predatory efficiency in the females. The components of the functional response fitted significantly the randomic model of the Holling discs equation (Na = N [1 - exp[- a'(T - ThNa)]]), evidencing a functional response of type II.
Predator species under field conditions can face different and variable densities of prey species. This work evaluated the functional response of the neotropical lady beetle Eriopis connexa(Coleoptera: Coccinellidae) subjected to different densities of the aphids Brevicoryne brassicaeand Aphis craccivora(Hemiptera: Aphididae). Thus, predation rates were analyzed of fourth-instar larvae and one-day old adults of the lady beetle preying upon the aphids at constant densities of 20, 40, 50, 60, and 70 aphids with 15 repetitions per density. The aphids were offered on 5 cm leaf discs of each plant host. The handling times and attack rates were 0.03 h-1and 0.27 h-1for larvae and 0.03 h-1and 0.15 h-1for adults fed B. brassicae and 0.59 h-1and 0.35 h-1for larvae and 0.70 h-1and 0.95 h-1for adults fed A. craccivora, respectively. Both larva and adult lady beetles increasedpredation rate as a function of prey density offered, with an estimated maximum number of prey consumed of 30.3 and 31.6 B. brassicae and 36.3 and 34.6 of A. craccivora by larva and adult lady beetles at the highest prey density, respectively. In conclusion, larvae and adults of E. connexaexhibited a type II functional response.
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