Students Tackle Problems Of Importance

Press, Volume CIV, Issue 30739, 1 May 1965, Page 10

Students Tackle Problems Of Importance

Students at Lincoln College who are doing research in entomology for theses for their masters’ degrees are generally making investigations into specific problems affecting agriculture and while the prime aim of this study is to train them in the'correct approach to research and methods of making such an investigation, they may also make some contribution to solving these problems.

Dr, R. A. Harrison, reader in agricultural zoology at the college, said this week that students who had done the bachelor course at Lincoln had a good knowledge of the problems of agriculture in New Zealand and appreciating the economics and significance of these problems were able to begin investigations of them.

The problems of an enitomological nature could be tackled within the framework of a general plan: (1) By investigating or surveying the problem to determine its economic significance; (2) by investigating the biology or ecology of the insects involved; and (3) by investigating control measures. Students doing research in entomology as their chosen field at Lincoln had been attracted to all of these sections of research. Including an important course of reading as well as the practical research work, the course for the masterate usually took about two years.

What could the trained entomologist leaving Lincoln at the close of that course expect to do? He or she could enter an entomological research unit like the Entomology Division of the Department of Scientific and Industrial Research, which two had done last year, or the Department of Agriculture and Forest Service which employed entomologists. They could enter industry where in both New Zealand and Australia there was a growing demand for people trained for work with insecticides and insect pest control, and they could take up university positions where they would be encouraged to seek further qualifications at the doctorate of philosophy level, preferably at an overseas university. Dr. Harrison said that one Lincoln masterate graduate was now at the University of California and another would soon be going to the East-West Centre at Hawaii. Once such men had their doctorates they could virtually pick their jobs in research organisations or in the uni-

versittes. The present director of the Entomology Division of the D.S.I.R. in New Zealand, Dr. J. M. Hoy, was a graduate of Lincoln.

Dr. Harrison then proceeded to discuss the sort of work either recently tackled by Lincoln masterate students or actually under way at the moment

Mr E. G. White, he said, had completed a survey of the insects of the tussock country with the object of determining what insects occurred generally, with particular reference to those that were pests or potential pests of tussock grasses or inter-tussock plant communities on improved or semi-improved areas, as well as in the pastoral area generally. In this work 150,000 insects had been collected, examined and recorded and this knowledge of the fauna of a fairly typical grassland tussock environment could now form the basis of more specific studies of the more important insects involved. Traps In his work Mr White used sticky traps, large wind nets up to 4ft to sft in diameter, light traps that could be automaticaly turned on at intervals in places like Mount Gog and Sugar Loaf in the Cass area, and pitfail traps in the soil. Dr. Harrison said that while the porina caterpillar occurred in numbers in the tussock lands, Mr White’s work seemed to indicate it was not as important in these areas as on the plains, and caterpillars of other native species were at least as significant in damaging the tussock and inter-tussock species as the porina. In the soil itself he had confirmed that the grass grub was probably the most important of the root eating insects, but various relatives of the grass grub were playing a significant part as well. Mr A. Spain, with the aid of a grant from the Forest Service, was in the process of making a survey of the insect fauna of Olearia Colensoi

and associated plants in the sub-alpine scrublands. Many of the stands of the Olearia were dying back and preliminary thought on this problem indicated that it might be a condition resulting from the browsing of deer and other mammals, and insect damage. Mr Spain’s particular interest was to see if insects were implicated and his work was now well under way. He had found insects that destroyed the developing buds, insects that were stem borers and others that were defoliators. Already the work had indicated potential damaging insects and it was hoped that by the end of next season that the significance, if any, of these three groups would be determined. Biology Looking into the biology of an insect pest has been Mr J. Brown who has now completed his work. He has been working on the green manuka beetle, a close relative of the grass grub with similar habits, and as a result of Mr Brown’s work Dr. Harrison said it was now possible to be more certain that it was a pest of some significance in some areas. In the sandy soils of the Manawatu it was the most important grass grub pest and it was also of some significance in the tussock grasslands, but not quite as important as the grass grub.

Dr. Harrison said Mr Brown’s investigations into the breeding cycle of the insect and its behaviour at the various seasons of the year had added a great amount to the knowledge of what was a relatively unknown insect. A lot of Mr Brown’s work had been related to the taxonomy or classification of this insect in the general pattern of insects and it was now possible for an entomologist, to identify the grubs of this beetle and to separate them from closely related species, which was quite difficult to do before this investigation.

Another biological study is being undertaken by Mr R. A. French. His subject is the Ilspotted ladybird, which is the most common ladybird in

Canterbury. In general it is known that these ladybirds are predators of aphids and one of the most important aspects of Mr French’s work is to determine how important they are as predators of aphids on Canterbury crops. His method of approach has been to do laboratory trials on the feeding potential of the ladybird at each of its life stages, using aphids marked with radioactive isotopes. In association with this in the field Mr French is examining the migration ability of the insect—how far it will travel —how it survives the winter and whether it will breed up in the spring and breed up quickly enough to cope with the build-up of aphids. Mr French’s preliminary investigations indicate that the ladybird may not be very useful in the early part of the season when the aphids are higher up on brassica and

chou moeliier plants and they feed on those that drop off these plants, but they be more effective later in the season on clover crops. Still another biological Investigation is being undertaken by Miss G. Kellock. Her subject is a small predations mite known to occur in apple orchards in particular and suspected of being of great significance in the control of populations of pest species of mites. This work fits, well into investigations being made in Nelson, under the Entomology Division, into the integrated control of insect pests. Nothing at all at present is known about the habits and biology of this mite and in order that the Nelson workers can develop their theories on integrated control it is necessary that they should have full details of the biology of this mite and other potential predators.