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Effects of diflubenzuron and penfluron on workers of Apis cerana indica F and Apis mellifera L Pr Gupta, Rs Chandel To cite this version: Pr Gupta, Rs Chandel. Effects of diflubenzuron and penfluron on workers of Apis cerana indicaF and Apis mellifera L. Apidologie, Springer Verlag, 1995, 26 (1), pp.3-10. hal-00891239 HAL Id: hal-00891239 https://hal.archives-ouvertes.fr/hal-00891239 Submitted on 1 Jan 1995 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Original article Effects of diflubenzuron and penfluron on workers of Apis cerana indica F and Apis mellifera L PR Gupta RS Chandel Department of Entomology, Dr YS Parmar University of Horticulture & Forestry, Nauni-173 230, Solan, India (Received 11 March 1994; accepted 29 August 1994) Summary — Newly emerged adult workers of Apis mellifera and A cerana indica tolerated a topically applied dose of 100 μg diflubenzuron (DF) and penfluron (PF) in acetone but the treated bees weighed less than control bees at 2 and 6 d of age. Oral administration of 100 μg DF (as Dimilin 25% wettable powder) in 10 μl sugar syrup proved fatal to A c indica. After 6 d of feeding 50 μg DF, hypopharyngeal gland development, measured as size of acini, was significantly suppressed in both bee species. The suppressed gland development in the treated group could be a consequence of poor gain in weight. Fora- gers of both bee species readily accepted DF-contaminated sugar syrup and, with increasing doses, there was decrease in time required to consume the contaminated sugar syrup in a dose-dependent manner. The treated bees weighed significantly less than the control bees. Thus, at higher doses chi- tin synthesis inhibitors may also prove harmful to adult bees. Apis mellifera / Apis cerana indica / toxicity / insecticide / diflubenzuron / penfluron INTRODUCTION 90 min to surfaces treated with as much as 10 000 ppm (10 g l-1) DF, there was no mor- tality. Except for this published work, no Diflubenzuron is recognized as an ecologi- information is available on the effect of DF cally safe and specific-action insecticide and another chitin inhibitor, owing to its chitin synthesis inhibition prop- potent synthesis erties. It is relatively safe to honey bees and penfluron (PF), on the 2 bee species. Short- term based on data when it was applied topically to the work- experiments mortality not true of of a ers of the European honeybee, Apis mellif- may give picture safety era L, a median lethal dose higher than 30 chemical to bees and, at sublethal doses, μg/bee was observed (Stevenson, 1978). the treatment may have latent effect as Usha and Kandasamy (1986) categorized demonstrated by El-Din et al (1990). The diflubenzuron (DF) as the safest insecticide toxicity of DF and PF to developing stages to the adult Indian bee, A cerana indica Fabr of A c indica and A mellifera has been and, following exposure of adult bees for reported by Chandel and Gupta (1992). This article reports the work conducted with glass slides. Gland development was determined young and foraging workers of the two bee by measuring the length and diameter of 10 acini species. of each gland at random under a microscope by an ocular lens precalibrated with a standard microm- eter. Each mean value of a treatment represented 200 measurements (10 acini/gland, 2 glands in a MATERIALS AND METHODS bee, and 10 bees as replicates). Six-day-old hive workers (10 in number) were also handled in the same way to compare their gland development Treatment of newly emerged bees with the laboratory-maintained 6-day-old bees. which were lethar- Newly emerged adult bees, Oral administration of diflubenzuron gic, dull in colour and had unprotrudable stings, to were removed from the hive, numbered on the foragers thorax by adhering a circular paper disk (4 mm diameter) bearing a number, and individually Outgoing foragers of both the bee-species were on the electronic balance. to weighed Twenty-five captured at the hive entrance in an insect collec- 30 bees of each were treated with 100 species μg tion net and, after an hour, each of the 30 bees DF or PF in acetone on their abdomen. Half of was fed 10 μl of 50% sugar syrup containing a the treated bees of each were species consigned known amount of DF through calibrated capillary to a cage (13.5 x 11 x 13 cm) with a hole at the tubes. The time taken by a worker bee (N = 15) to top through which gravity feeder containing 50% consume the provided sugar syrup was recorded sugar syrup was inserted half an hour after the with the help of a chronometer. Each cage was fit- treatment. Thus, each treatment was represented ted with a gravity feeder containing a known vol- by 2 cages. All the test cages were maintained in ume of sugar syrup. Test cages were maintained an incubator at 29 ± 1°C. Observations on the for 4 d and the weight gain of experimental bees in were recorded 2 and 6 d after the gain weight was recorded. Data were to F- and t-tests treatment. subject and treatment responses were compared by using Experiments with oral feeding of the chemi- the least significant difference concept (LSD) as cal were restricted to DF (used as Dimilin, 25% outlined by Gomez and Gomez (1984). wettable powder), since formulated material of PF was not available. Per os administration of 100 and 50 DF was made 1 h after the cap- μg RESULTS ture to each of the 30 newly fledged bees of both species through 10 μl of sugar syrup with the help of calibrated capillary tubes. These were han- dled as described above and maintained for 6 d, Weight gain in topically treated bees until the acini of hypopharyngeal gland were well developed in the normal bees taken from the hive. Ten bees of each treatment set were made immo- Newly emerged workers of A mellifera (aver- bile by cold treatment in the refrigerator for 15 age weight 82.03 mg ± 1.96 SE) were min and dissected in saline con- physiological approximately 1.5 times heavier than A c taining 0.145 M NaCl, 0.006 M KCI, 0.002 M indica (56.23 mg ± 1.37 SE) but both bee CaCl2 and 0.002 M NaHCO3 to expose the hypopharyngeal glands in situ. The cut-open head species tolerated doses of DF and PF as of the bee was charged with 10% V/V formal high as 100 μg per imago. Within 2 d, the saline (saline with 10% formaldehyde) for 1 h, effect of the treatment at this dose was evi- the glands were removed and washed thoroughly dent (table I) and the treated bees weighed with water to eliminate the formal saline. These significantly less than the controls.The were stained in borax carmine for 15-20 min, of the treated bees was washed in water, dehydrated through ascending weight gain signifi- series of alcohol (15 min in each grade), cleared cantly lower in 6-day-old bees (119.6 and in clove oil and xylene, and mounted in DPX® 121.7% of the initial weight of A mellifera (Glaxo L aboratories India Ltd, Bombay, India) on and A c indica in the control against 110.5 and 108.3% with DF and 116.8 and 117.5% Size of acini of hypopharyngeal glands with PF treatment). In the control and treated in nurse bees fed diflubenzuron lots, the percentage mortality recorded 6 d after the treatment did not vary significantly In the the diameter and but higher mortality was registered with DF laboratory control, (23.3 and 16.7% for A mellifera and A c length of acini were 22.1 and 11.8% smaller indica) than with PF (0 and 6.7%) or con- in A mellifera and 33.4 and 34.7% smaller in trol (16.7 and 7.1 %). A c indica than in those taken from the hive (table II). Acini of nurse bees from the colony with 13.7 s (r = -0.988) and 13.16s had opaque and pale appearance but these (r=-0.999) in their respective controls (table were translucent and whitish in the labora- III). tory-maintained control. Thus, even the con- The foragers of both bee species fed with hive conditions and in trol bees under cages DF weighed significantly lower than the con- in the sizes of showed significant differences trol bees (table IV). A mellifera tolerated a acini. bees in the control Although laboratory dose as high as 100 μg but most of A c with the from were also provided pollen indica bees died at 100 μg. The weight in combs, feeding was negligible. A mellifera was significantly lower at 12.5 In A mellifera taken from the hive and and 25 μg doses (4.9 and 11.1 % less than fed with 100 and 50 μg DF per bee, the acini the control). However, at 100 μg DF, there were significantly smaller than in the labo- was a minimal weight of the forager (21.4% ratory control (table II).

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