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Pirimicarb, an aphid selective insecticide, adversely affects demographic parameters of the aphid predator Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae)

100%

Rahmani S., Bandani A. R.

Journal of Plant Protection Research

2016

tom 56

nr 4

Demographic toxicology is recommended for toxicity determination of the long term effects of a pesticide since it gives a more accurate and efficient measure of the effect of a pesticide. Thus, in the current study the sublethal effects of pirimicarb (carbamate insecticide) two concentrations of LC30 and LC10 were used against third instar larvae of Hippodamia variegata (Goeze) in order to determine the effects of the pesticide on demographic parameters of the predator under laboratory conditions. Results showed that pirimicarb did not affect individual life parameters such as development time of larva, pupa, adult longevity, female and male longevity, adult preoviposition period (APOP), and total preoviposition period (TPOP). However, population parameters such as intrinsic rate of increase (r), net reproductive rate (R0), mean generation time (T), and finite rate of increase (λ) was affected by sublethal treatment. For example, intrinsic rate of increase (r) was 0.18 day–1 in the controls but it was 0.13 and 0.14 day–1 in the treated insects with LC10 and LC30 concentrations, respectively. Also, there were significant differences between mean generation time (T) of the treatments and the controls i.e. mean generation time of the controls was 29.03 days while mean generation time in the two treatments of LC10 and LC30 was 33.93 and 31.66 days, respectively. The finite rate of increase was also significantly affected by sublethal effects of the pesticide. The results showed that pirimicarb, even at low concentrations, has potential to adversely affect the predatory ladybird, therefore care should be taken when this insecticide is used in the Integrated Pest Management (IPM) program.

Seasonal dynamics of: the pea aphid, Acyrthosiphon pisum (Harris), its natural enemies the seven spotted lady beetle Coccinella septempunctata Linnaeus and variegated lady beetle Hippodamia variegata Goeze, and their parasitoid Dinocampus coccinellae (Schrank)

80%

Soleimani S., Madadi H.

Journal of Plant Protection Research

2015

tom 55

nr 4

Two important lady beetle species commonly found in alfalfa fields in Iran are the variegated lady beetle Hippodamia variegata Goeze and the seven spotted lady beetle Coccinella septempunctata (Linnaeus, 1758) (Coleoptera: Coccinellidae). These two species attack many aphid species including the pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae). In this study, the seasonal population changes of A. pisum, H. variegata, C. septempunctata and the parasitoid, Dinocampus coccinellae (Schrank) (Hymenoptera: Braconidae) were studied in alfalfa fields in the 2012 and 2013 seasonal periods. The highest ladybird densities were noted on July 5, 2012 and on September 6, 2013 (17.2±2.8 and 13.4±1.6) individuals per 20 sweeps, respectively. Parasitism rates by D. coccinellae ranged from approximately 3 to 6% in two subsequent years, respectively. Parasitism was higher early in the growing season. Most parasitised ladybirds were females. There was no significant relationship between the temperature and relative humidity with pea aphid populations, although the aphid populations declined during the hot summer period. In contrast, the relationship between temperature and the H. variegata population was significant and positive in both years of the study. It has been shown that these lady beetle species have a major role in reducing the pea aphid populations in alfalfa fields. Due to the relatively low percentage of field parasitism by D. coccinellae, this parasite might not reduce the biocontrol efficiency of lady beetle species.

Ograniczanie wyników

2 Journal of Plant Protection Research

1 Bandani A. R.

1 Madadi H.

1 Rahmani S.

1 Soleimani S.

1 2016

1 2015

Wyniki wyszukiwania

Pirimicarb, an aphid selective insecticide, adversely affects demographic parameters of the aphid predator Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae)

Seasonal dynamics of: the pea aphid, Acyrthosiphon pisum (Harris), its natural enemies the seven spotted lady beetle Coccinella septempunctata Linnaeus and variegated lady beetle Hippodamia variegata Goeze, and their parasitoid Dinocampus coccinellae (Schrank)