Lincoln University Digital Thesis Copyright Statement The digital copy of this thesis is protected by the Copyright Act 1994 (New Zealand). This thesis may be consulted by you, provided you comply with the provisions of the Act and the following conditions of use: you will use the copy only for the purposes of research or private study you will recognise the author's right to be identified as the author of the thesis and due acknowledgement will be made to the author where appropriate you will obtain the author's permission before publishing any material from the thesis. PEST MANAGEMENT OF THE NEW ZEALAND FLOWER THRIPS THRIPS OBSCURATUS (CRAWFORD) (THYSANOPTERA: THRIPIDAE) ON STONEFRUIT IN CANTERBURY, NEW ZEALAND. A THESIS SUBMITTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF CANTERBURY D. A. J. TEULON LINCOLN COLLEGE 1988 DEDICATED TO JOHN FRANCIS BRUGES 1957-1987 Abstract of a thesis submitted in partial fulfilment of the requirements for the degree of Ph.D. PEST MANAGEMENT OF THE NEW ZEALAND FLOWER THRIPS THRIPS OBSCURATUS (CRAWFORD) (THYSANOPTERA: THRIPIDAE) ON STONEFRUIT IN CANTERBURY, NEW ZEALAND. by D.AJ. TEULON The New Zealand flower thrips (Thrips obscuratus (Crawford» is an important pest of stonefruit during flowering and at harvest in New Zealand. The biology and control of this species fonned the basis for this study. A simple method for laboratory rearing is described that facilitated studies on the bionomics of T. obscuratus. Aspects of reproduction, fecundity, requirements for oviposition and development, development rates, temperature thresholds, thennal constants, and lifespan are detailed. T. obscuratus has been reported from at least 223 eqdemic and introduced plant species. Larvae were taken from 49 species around Canterbury. Adults were usually found on flowers but were also common on leaves and fruits. All larvae were on flowers except for two records from the fruit of stonefruit. The number and species of thrips infesting sprayed and unsprayed stonefruit flowers and fruit were detennined. Adults and larvae were almost all T. obscuratus and adults were mostly female. Adults and larvae of thrips were found in stonefruit flowers from pink to shuck fall. Adults were found in similar numbers throughout flower development. Larvae were almost entirely absent at pink; numbers were small at full bloom and peaked at or just after petal fall. Thrips adults, eggs and larvae were all common on peaches, nectarines and apricots. Thrips were most numerous on ripe fruit, although they were found on fruit for the local market up to three weeks before harvest. Thrips numbers were highest on stonefruit varieties ripening during December and January and lowest on varieties ripening during February, March and April, and were higher on peaches than apricots and nectarines. Sources of T. obscuratus infestations were probably from flowers in the vicinity of the orchard. Pupation sites for T. obscuratus were established as including the soil and litter beneath a flowering cabbage tree (Cordyline australis). Female T. obscuratus were parasitised and sterilised by a nematode thought to be Howardula aptini. Flying thrips were sampled inside and outside stonefruit blocks from September 1984 to August 1987. Several species including T. obscuratus, Thrips tabaci, Limothrips cerealium and Haplothrips niger were common. A broad pattern of the seasonal abundance of T. obscuratus was apparent from water trap samples. Thrips numbers were lowest in winter and low in spring, but increased gradually during summer. Numbers peaked in midsummer but declined suddenly in mid to late January. Numbers remained moderate to low throughout late summer and autumn. Seasonal abundance could be.1argely explained by the interrelationship of temperature, soil moisture and availability of host plants. Flight take-off thresholds of 150 C were established from weekly water trap samples for both male and female T. obscuratus adults. Both adults and larvae of T. obscuratus were found on hosts throughout the year, but were most common in early summer. There was no reproductive diapause for T. obscuratus females collected from the field in winter. In field experiments T. obscuratus males and females showed a preference for white without U.V., and to a It:sser extent yellow, compared to green, blue, black and red. Traps baited with ethyl nicotinate caught significantly more T. obscuratus males and females than traps baited with anisaldehyde, benzaldehyde, peach juice, peach fruit and unbaited traps. An insecticide trial investigated the protection of nectarine flowers from thrips infestation and damage,using the insecticides fluvalinate or phosalone (low toxicity to bees) applied at full bloom as supplements to the current recommended spray programme. Thrips numbers were reduced, and export packout (based on russet only) was 10% higher for trees treated at full bloom than for those treated only with the recommended spray programme. Several varieties of ripe stonefruit picked at maturity for the local market and which had received only periodic applications of carbaryl were infested with adults, eggs and larvae. The application of low rates of fluvalinate for preharvest control of thrips on peach fruit was investigated. Peaches were sampled for thrips at local market maturity ('Redhaven') and export market maturity ('Flamecrest'). Low rates of fluvalinate (20% to 5% of field rates) reduced thrips infestation on both varieties. On 'Flamecrest' one application of fluvalinate at 10% field rate, 15 days before harvest, was more effective at reducing thrips infestation than the current recommended spray programme. The management of T. obscuratus on stonefruit in Canterbury is reviewed in relation to previous research and knowledge gained from this study. KEYWORDS: Thrips obscuratus, Thysanoptera, Thripidae, thrips, rearing, bionomics, biology, ecology, pest, pest management, stonefruit, nectarine, peach, flower, fruit, New Zealand. TABLE OF CONTENTS Chapter. Page. I GENERAL INTRODUCTION 1 n LITERATURE REVIEW 5 1 INTRODUCTION 5 2 TAXONOMY 5 3 BIOLOGY AND ECOLOGY OF THRIPS ....................................................................... 6 3.1 MORPHOLOGY 6 3.2 DISTRIBUTION .......................................................................................... .. 6 3.3 HOSTS 6 3.4 FEEDING BEHA VIOUR .................................................................................. 7 3.5 UFE HISTORY .......................................................................................... .. 9 3.6 REQUIREMENTS FOR DEVELOPMENT..................................................... 10 3.7 FUGHTTAKE-OFFTEMPERATURETHRESHOLDS AND DIURNAL ACTIVITY .......................................................................................... .. 11 3.8 SEASONAUTY .......................................................................................... .. 11 3.9 NATURAL ENEMIES ..................................................................................... .. 12 4 ECONOMIC IMPORTANCE .......................................................................................... .. 13 4.1 THRIPS AS BENEFICIAL INSECTS. ............................................................ .. 13 4.2 THRIPS AS PESTS OF CULTIVATED PLANTS .......................................... 14 4.3 THRIPS AS PESTS OF STONEFRUIT ........................................................... 15 5 CONTROL STRATEGIES ........................................................................................... 19 5.1 CHEMICAL CONTROL .......... ·........................................................................ 19 5.2 BIOLOGICAL CONTROL ............................................................................... 21 5.3 CULTURAL CONTROL ................................................................................. .. 21 5.4 NATURAL CONTROL ..................................................................... ;.............. 21 6 PEACH AND NECTARINE CULTIVATION................................................................. 22 6.1 PRODUCTION 22 6.2 MANAGEMENT .......................................................................................... .. 23 6.3 PEST AND DISEASES ..................................................................................... 23 6.4 FLOWER AND FRUIT DEVELOPMENT...................................................... 25 Chapter. Page. ill LABORATORY REARING OF THE NEW ZEALAND FLOWER THRIPS....................... .. 28 1 INTRODUCTION 28 2 MATERIALS AND METHODS ....................................................................................... 29 2.1 OVIPOSmON 31 2.1.1 EFFECf OF POLLEN AND NUTRIENT MEDIUM............................. 31 2.1.2 EFFECT OF POLLEN AND OTHER PLANT TISSUE......................... 32 2.1.3 EFFECT OF TEMPERATURF................................................................. 32 2.2 LARV AL DEVELOPMENT............................................................................. 33 2.2.1 EFFECT OF POLLEN AND NUTRIEN MEDIUM .............................. 33 2.2.2 EFFECT OF POLLEN AND OTHER PLANT TISSUE......................... 33 2.2.3 EFFECT OF POLLEN TYPE................................................................... 34 2.3 DEVELOPMENT AT CONSTANT TEMPERATURES ................................ 34 2.4 REPRODUCTION .......................................................................................... .. 35 3 RESULTS 36 3.1 OVIPOSmON ............................................................................................