Agri-Entomology

A study was conducted at the Eco-toxicology laboratory in the Department of Agricultural Entomology, University of Agriculture Faisalabad, against three species Apis florea, A. dorsata and A. mellifera of honey bees, to check long-term survival of honeybees when exposed to different insecticides. In this study, we used a modeling approach regarding survival data of caged bees under chronic exposure to seven insecticides (Carbosulfan, Chlorpyrifos, Bifenthrin, Spinosad, Indoxacarb, Emamectin benzoate and Imidacloprid), having three replicates and four concentrations (1000, 500, 250, 125 and 0 ppm). We demonstrate the chronic toxicity induced by these insecticides. Laboratory bioassay of these insecticides showed that carbosulfan and imidacloprid were the most toxic at their high dose (1000 ppm) with LT50of 4 hours in each case for A. mellifera, chlorpyrifos and imidacloprid were the most toxic at their high dose (1000 ppm) with LT50 of 5 hours in each case for A. florea whereas chlorpyrifos was the most toxic at high dose (1000 ppm) with LT50 of 5 hours for A. dorsata. However, LT50 of spinosad was increased up to 18 hrs with decreasing concentrations at 125 ppm against A. mellifera, LT50 of spinosad was increased up to 15 hrs with decreasing concentrations at 125 ppm against A. florea as well as LT50 of spinosad and Emamectin benzoate was increased up to 20 hrs with decreasing concentrations at 125 ppm against A. dorsata. However, LT50 of all controlled species was 91-103 hrs.

Human health and environment are greatly affected by extensive used of synthetic insecticide, which is why the alternative way of pesticides, such as botanical pesticide consumption increase with the passage of time to control of insect pests. The insecticidal impact of Moringa (Moringa oleifera), Neem (Azadirachta indica) and Euclyptus (Eucalyptus globules) leaves extracts were investigated on Diurophous noxia (Hemiptera: Aphididae). This study was aimed to evaluate the efficiency of bio-pesticide instead of synthetic chemicals against D. noxia. Experimental results showed that the percentage of mortality fluctuate with the fluctuation of concentration with time intervals and have great impact on the population of D. noxia. Single, doubled and tripled combinations of leaves extract were tested at two different concentrations (25 and 50%). The results suggested and concluded that from all the application of single botanicals A. indica give better result as compared to other single application while application of double combination M. olerifera with A. indica give significance result instead of other double mixture, meanwhile the triple combination (M. olerifera, A. indica and E. globules) performed excellent result as the others triple mixtures. The study revealed that combine used of M. olerifera, A. indica and E. globules leaves extract were very effective against D. noxia and surge as an alternative way of pesticides instead of synthetic chemicals.

Human health and environment are greatly affected by extensive used of synthetic insecticide, which is why the alternative way of pesticides, such as botanical pesticide consumption increase with the passage of time to control of insect pests. The insecticidal impact of Moringa (Moringa oleifera), Neem (Azadirachta indica) and Euclyptus (Eucalyptus globules) leaves extracts were investigated on Diurophous noxia (Hemiptera: Aphididae). This study was aimed to evaluate the efficiency of bio-pesticide instead of synthetic chemicals against D. noxia. Experimental results showed that the percentage of mortality fluctuate with the fluctuation of concentration with time intervals and have great impact on the population of D. noxia. Single, doubled and tripled combinations of leaves extract were tested at two different concentrations (25 and 50%). The results suggested and concluded that from all the application of single botanicals A. indica give better result as compared to other single application while application of double combination M. olerifera with A. indica give significance result instead of other double mixture, meanwhile the triple combination (M. olerifera, A. indica and E. globules) performed excellent result as the others triple mixtures. The study revealed that combine used of M. olerifera, A. indica and E. globules leaves extract were very effective against D. noxia and surge as an alternative way of pesticides instead of synthetic chemicals.

The Red Palm Weevil is a serious problem of the date palm in Pakistan. The sole and combine application effects of Beauveria bassiana (Balsamo) Vuillemin (Hyphomycetes) and sub-lethal dosages of Imidacloprid against the second and fourth instar larvae of Rhynchophorus ferrugineus Olivier was investigated in laboratory. Additionally, the in vitro hyphal growth of B. bassiana amended with three different concentrations (50, 250, 500 µl L-1) of Confidor® 200 SL was also assessed. The results showed significantly higher mortality for the second and fourth instar larvae of RPWrnwhen B. bassiana and Imidacloprid applied together compared to their sole application. The highest mortality level (100%) for the second instar was recorded after 15 days of treatment with B. bassiana (1×106 conidia/ml) and Imidacloprid (1 µl L-1) in combination, while for the fourth instar larvae it was achieved after 20 days of application. However, the presence of Imidacloprid did not significantly affect the hyphal growth of B. bassiana on Sabouraud Dextrose Agar (SDA), and greater colony sizes compared to untreated control were recorded in all cases. The maximum number of sporulation (173, 159.83 conidia ml-1) and percentage (89.15, 79.4%) of mycosed R. ferrugineus cadavers was observed at lower dose rate (1×106 conidia/ml) of B. bassiana, exhibited the potential to be exploited for the control of RPW.

The present study was conducted to evaluate the susceptibility of Rhizoglyphus tritici against the comparative potential of ether extracts from Azadirachta indica, Eucalyptus sp., Citrullus colocynthis, Allium sativum, Nicotiana tabacum, Curcuma longa, Nerium indicum, Syzygium aromaticum, Ocimum tenuiflorum and Cassia fistula. The whole trial was executed under laboratory conditions with five concentrations from T1-T5 (0.5%, 1%, 2%, 4% and 8%), and four exposure periods (7, 14, 21 and 28 days). The percentage inhibition of mite population was both time-dependent and concentration-dependent. All the plant extracts exhibited significant acaricidal potential for adult mite as compared to control. The significant population inhibition percentage trend was observed of C. longa 91%, 95.54%, 94.97% and 97.46% and S. aromaticum 88.06%, 92.17%, 95.27% and 96.67% followed by C. fistula 92.03%, 93.27%, 93.22% and 92.07% while least population inhibition percentage was observed of N. tabacum 84.70%, 85..08%, 90.70% and 93.14% after 7, 14, 21 and 28 days. The median lethal concentrations were also calculated for all extracts, and it was observed that S. aromaticum was highly toxic to mites at lowest concentration 0.128, 0.028, 0.006 and 0.005 followed by C. longa 0.071, 0.036, 0.027 and 0.016 while least toxicity was observed in C. colocynthis 0.047, 0.030, 0.009 and 0.009 against R. tritici, and lethal concentration (LC50) decreased with an increasing time of exposure of the R. tritici to the ether extract. It was concluded that acaricidal potential of plants is directly proportional to time exposure and during first and second week C. fistula and S. aromaticum followed C. longa but suddenly after two weeks acaricidal potential of S. aromaticum was boost up and it was concluded that C. fistula, S. aromaticum and C. longa proved to be more effective gainst stored grain mites as compared to the others plant extracts. Perhaps, this new study will provide the basis for further investigation in order to develop new and safer acaricides in field conditions.

Herbivore-induced plant volatiles (HIPVs) are clues that help predatory insects search for food. The hypothesis that entomopathogenic fungi, which protect plants, benefit from the release of HIPVs was tested. The plant Arabidopsis thaliana was used as the source of HIPVs. The insect herbivore Lipaphis erysimi (Kaltenbach) was used as the inducer, and the fungal pathogen of the aphid Lecanicillium lecanii was exposed to HIPVs to test our hypothesis. When exposed to aphid-induced A. thaliana volatiles, the mortality of aphids pre-treated with a conidial suspension of L. lecanii, the conidial germination and the appres-sorial formation were significantly increased compared with the control. The decan-3-ol and 4-methylpentyl isothiocyanate that were detected in the headspace seemed to have positive and negative affection, respectively. Moreover, HIPVs generated from groups of eight aphids per plant promoted significantly increased conidial germination and appressorial formation compared with HIPVs from groups of one, two and four aphids per plant. Our results demonstrated that the pathogenicity of the entomopathogenic fungus L. lecanii was enhanced when exposed to HIPVs and that the HIPVs were affected by the number of insect herbivores that induced them.