Demographic parameters of the turnip aphid, Lipaphis erysimi Kaltenbach (Hemiptera: Aphididae), which is a serious pest of Brassica crops worldwide, were evaluated on five major Brassica vegetables (three varieties of Brassica oleraceae; kohlrabi, cabbage and ornamental cabbage, and two subspecies of Brassica rapa; Chinese cabbage and bak choi). The study was carried out under laboratory conditions at 25 ± 1°C, 70 ± 5% RH and 16:8 (L:D) h. Preadult developmental time, survival rate, female longevity, reproduction, and life table parameters were evaluated according to the age-stage specific life table method. The highest population growth parameters, i.e., net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) were recorded on kohlrabi (R0 = 30.45 offspring, r = 0.2174 d-1, λ = 1.2429 d-1). These parameters were the lowest on Chinese cabbage (R0 = 13.00 offspring, r = 0.1503 d-1, and λ = 1.1621 d-1) and bak choi (R0 = 16.30 offspring, r = 0.1614 d-1, λ = 1.1752 d-1). The results attained from population growth parameters, together with population projection estimation based on the age-stage, two-sex life table theory, indicated that both Chinese cabbage and bak choi were less suitable hosts for turnip aphids and should be considered as a possible source for developing resistance in breeding programs and integrated pest management strategies.

Citrus limonoids, nomilin and limonin, were used for larvicidal assay against Aedes albopictus utilizing WHO methodology. LC(50s) were 305.83, 176.08, and 136.07 μM for nomilin and 850.09, 600.72, and 407.09 μM for limonin after 24, 48, and 72 h, respectively. LT(50) assays exhibited that Savage citrange oil was the best at all concentrations (400, 500, 600, and 700 ppm) while Fairchild and Cassa grande were the weakest oils at 400 ppm, but at 500, 600, and 700 ppm, Carrizo citrange remained at the bottom with highest LT(50) values. Results exhibited that nomilin was more toxic than limonin and therefore provided a clear indication that limonoids in sample oils influenced the potential of respective oil. Out of the 10 tested citrus seed oils, Savage citrange (Citrus sinensis) comprised the maximum amount of limonin (2823.59 μg/ml) followed by grapefruit, Sacaton citrumelo, and Jaffa. When this oil (Savage citrange) was evaluated for bioassay against larvae of Ae. albopictus, it reflected complete dominance (LC(50) and LT(50)) as compared to rest of the oils. Although Jaffa (Citrus paradisi) was found to contain nomilin and limonin, it was found less effective as compared to Savage citrange. The oils from Minneola and Chinese lime did not contain limonin and nomilin, and were therefore weak in terms of LC(50) values. Presence of limonin and nomilin in plant products is therefore a significant indicator of the pest control that needs to be exploited in other plants as well.

No abstract

The house fly, Musca domestica, is a serious pest of public health importance with the ability to develop insecticide resistance. The focus of the present study was to evaluate toxicity and resistance of the field collected house flies from Punjab, Pakistan, against insect growth regulator (IGR) insecticides. House flies collected from six different localities exhibited very low levels of resistance to cyromazine, triflumuron, and methoxyfenozide compared with the Lab-susceptible reference strain, with resistance ratios (RRs) ranging between 3.56- to 8.19-fold, 1.45- to 3.68-fold, and 2.20- to 8.60-fold, respectively. However, very low to low levels of resistance were observed for pyriproxyfen and very low to moderate levels for lufenuron with RRs ranged from 4.13- to 11.63-fold to 8.57- to 22.75-fold, respectively. There was a significant correlation between RRs of cyromazine and triflumuron (r = 0.976, p < 0.001), suggesting the possibility for cross-resistance. Susceptibility status of different IGRs in Pakistani strains of house flies is reported here for the first time. The trend observed in decreasing susceptibility towards different IGR insecticides tested will continue unless resistance management practices are followed.

No abstract

No abstract

To evaluate the efficacy of the essential oils extracted from the branches and leaves of eucalyptus (Eucalyptus globules Labill.), neem (Azadirachta indica A. Juss), peppermint (Mentha piperita L.), basil (Ocimum basilicum L.) and from rhizome of ginger (Zingiber officinale Rosc.) against the larvae and pupae of Aedes aegypti L. The essential oils were extracted with Soxhlet apparatus using petroleum ether as a solvent. The oils were evaluated against 1 th instar larvae and the pupae of Ae. aegypti following WHO protocol. The dead individuals in all stages were counted after 8, 16, 24 and 48 hours in treatments of different concentrations (100, 200, 300 and 400 ppm). The percent mortality in each stage was determined and consequently LC 50 s were also calculated by Probit analysis. A control treatment was also run by using petroleum ether in which mortality (<6%) of different life stages of Aedes mosquitoes was observed. Results showed that higher mortality was observed in early life stages than later ones. Ginger was more effective having lowest LC 50 after 8 h (142 ppm) and 16 h (8.5 ppm) against 1 st instar larvae followed by peppermint, basil, eucalyptus and neem. However, eucalyptus and peppermint were efficacious after 24 h (66 and 84 ppm) and 48 h (19.5 and 17 ppm), respectively. Ginger oil showed high efficacy in short period of the time (8 and 16 h) followed by peppermint, basil, eucalyptus and neem, whereas eucalyptus oil exhibited its lethality after 24 h, whilst peppermint has longer potency and persistence (48 h) than other plant oils. For pupal stage, peppermint had knockdown effect (8 h) followed by eucalyptus (16 h), basil (24 h) and neem (48 h). From these results, it can be concluded that the oils of E. globules and M. piperita were effective larvicide against the immature stages of Ae. aegypti.

No abstract