Control of Pine Beauty Moth by Fenitrothion in Scotland 1978 Edited by AVHolden and D Bevan Forestry Commission Forestry Commission ARCHIVE CONTENTS Page Preface ............................................................ 2 Summary and Main Conclusions ...................................... 3 Introduction ..................................................... 5 Chapter 1 The Pine beauty moth - its distribution, life cycle and importance as a pest in Scottish forests ........................................ 7 2 Discussion of aerial spraying techniques ........ 13 Preliminary Investigations 3 Selection of an insecticide for aerial application .................................... 25 4 Low volume and ultra-low volume spray trials from aircraft over Thetford Forest ............. 21 The Operation 5 Selection of spray technique and clearance procedure ...................................... 23 6 Getting off the ground .......................... 28 Results of Insecticide Application 7 Collection of spray droplets and chemical by larvae, foliage and ground deposition .......... 63 8 Larval mortality ................................ 81 Monitoring the Human Environment 9 Monitoring the pilot and aircraft ............... 84 10 Evaluation of risks to humans at ground level ... 91 Monitoring the Natural Environment 11 Deposition of fenitrothion at ground level ...... 95 12 Chemical and biological observations in streams ........................................ 103 13 The effects of fenitrothion on wildlife ......... 133 14 The effects of fenitrothion on bird populations .................................... 143 1 PREFACE This document is assembled from a series of individual reports written by scientists and technicians from a number of organisations which took part in an operation carried out at short notice, to monitor the spraying of forests in northern Scotland to control the outbreaks of Pine beauty moth. The operation was achieved with a limited number of available personnel and equipment for sampling, and with little opportunity for preliminary tests of experimental procedures. The unavoidable delay in commencing the spraying on the scheduled date resulted in additional difficulties for some organisations and, in view of the short notice given that spraying was to be carried out, it was not possible for adequate pre-spray observations to be made, such as would have provided the desired reference basis for the subsequent measurements. Notwithstanding these limitations, it has been suggested that the publication of the following reports in one volume will be of value to those who have the responsibility for authorising future aerial spraying operations in the United Kingdom, to control pests over relatively large areas. The experience gained by the various organisations involved has enabled them to reach certain conclusions regarding both the use of aerial spraying techniques and the environmental risks involved, and also to plan future monitoring operations, if necessary, with a greater ability to provide data which will give more confidence in assessing the environmental impact. The reports are presented with the minimum of editing, although duplication of essentially descriptive material has been avoided as far as possible, and an approach has been made to uniformity in the presentation of the data. The respective authors have presented all the information obtained during their investigations in the interest of providing as complete a record as possible, but it should be understood that both the acquisition of the field data and the provision of the reports were achieved with severe restrictions on the time available for planning and preparation, and with the minimum of staff for their accomplishment. It is to be hoped, however, that this document will be of value in planning future operations of a similar nature. 2 SUMMARY AND MAIN CONCLUSIONS The course of the current outbreak of Pine beauty, Panolis flawmea, is described, and the failure to control it with Bacillus thuringiensis in 1977 is recorded. The technical advantages of a target-specific ultra low volume aerial spraying over conventional low volume technique is considered. A comparative trial of the ULV and LV techniques is described and the results of assessments of deposits upon the ground, on the pine needles and on larvae are given for both the trial and the later spraying operation itself. It was clear that more insecticide arrived on the target larvae and needles in ULV applications and less upon the ground. The results of environmental monitoring are reported and are largely based on a limited number of samples and insufficient time for adequate pre-spray studies. Nevertheless it seems evident that in the terrestrial environment no major mortalities occurred during the period of study in species other than those of the primary target (Pine beauty moth) and the sawfly caterpillars on the same trees. Many other flying insects were seen among the trees some hours after spraying, and most bird species in the forests were unaffected, at least in the short term. No effects were found among the small mammals, although the time interval between spraying and sampling was too short to demonstrate any longer term effects. In the aquatic environment, while a significant effect was observed on many species of invertebrates, adequate representation of many of them was found in subsequent kick samples a month later. No effects were found on either wild or captive fish, and the residues found in them were much lower than were likely to be lethal. Concentrations in the water were mostly below 18 yyg/litre, and even the maximum observed (48 pg/litre) was only about 1 per cent of the 24-hour LC50 for salmon fry, although the duration of this peak was very brief. The aqueous concentrations decreased more rapidly after the ULV technique than after the LV spraying, but otherwise there was little difference between the methods. The possibility of long-term effects on the fish populations resulting from a decrease in the invertebrate food supply has not been investigated, although the likelihood of this is small. The concentrations of fenitrothion measured in the atmosphere in the vicinity of sprayed plantations were judged, by those responsible for the measurements, to present no risk to humans in the area. The pilot showed no evidence of cholinesterase reduction, although on one occasion some influence on pupil dilation was observed when the plane was forced to fly down wind into a previously sprayed area. This effect was not considered by the Medical Officer to be significant. Measurements were also made of the levels of fenitrothion in the cockpit atmosphere; on only one occasion were levels recorded high enough to cause concern, that is if threshold limit values for the very much more toxic methyl parathion are accepted as datum. The general assessment of the effects of the spraying on wildlife is that, within the limits of the observations made, these were small or unimportant. However, it is anticipated that in any future treatments some more detailed studies may be made to examine whether any more subtle effects, particularly those of a longer term nature, can be detected. If single treatments are made at long intervals, it seems unlikely that serious damage would be caused to non­ target species. The Group, who have only had the opportunity to study single treatments, expressed some reservations on repeated applications on the same area. Where the fresh waters are used for commercial purposes, as in fish farms, contamination could be less acceptable. 3 Despite the small measure of reported adverse environmental effects of this use of fenitrothion, as a single treatment over a large area, it is considered that caution over such operations should continue. The presence of rare species of birds or insects, for instance, might require special consideration, and consultations should take place with the appropriate wildlife authorities before spraying takes place. The ULV treatment would appear to have certain advantages and no disadvantages over the LV treatment, particularly those arising from the shorter period required to apply the required dose of insecticide, and the decreased risk of ground contamination. Editors:- A.V. Holden Officer-in-Charge Freshwater Fisheries Laboratory Department of Agriculture and Fisheries for Scotland. D. Bevan Principal Entomologist Forestry Commission 4 INTRODUCTION In 1976, outbreaks of Pine beauty moth were recorded on Lodgepole pine plantations in northern Scotland, and by 1977 it was found, following pupal surveys in a large number of plantations, that chemical control was urgently required if serious damage to large areas of Lodgepole pine forests was to be avoided. Aerial insecticide spraying on the scale required had not previously been employed in the United Kingdom, and the preferred ULV technique, which was less costly in both time and materials, had neither been tested nor approved for forestry use in this country. The first approach for permission to use fenitrothion spraying was made by the Forestry Commission to the Pesticides Safety Precautions Scheme (operated by the Ministry of Agriculture, Fisheries and Food) in March 1978, and following urgent discussions qualified approval was given, provided that the operation was monitored to assess the possible risks both to humans and to various wildlife species. Co-operation was sought from several organisations and laboratories, which had the responsibility for protecting human health