E. Alan Cameron

Colour and odour responses of flying western flower thrips: wind tunnel and greenhouse experiments

The behavioural responses of flying western flower thrips (Frankliniella occidentalis Pergande) (Thysanoptera: Thripidae) to the colour yellow and the odour anisaldehyde were examined. In a wind tunnel, upwind flight by female thrips was common in an airflow of 0.11 m s−1 but was impeded at 0.22 m s−1. In the absence of anisaldehyde, flying female thrips exhibited an oriented response towards a yellow cue in the wind tunnel at a wind speed of 0.11 m s−1. The main response of females to anisaldehyde in the wind tunnel was flight inhibition. There was no evidence of an odour‐induced visual response, an odour‐induced anemotactic response or chemotaxis by female thrips to anisaldehyde in wind tunnel bioassays, but chemokinesis was implicated. With a matrix of yellow or black water traps with and without anisaldehyde in a greenhouse sweet pepper crop, yellow traps with anisaldehyde caught more thrips adults than yellow traps without anisaldehyde, black traps with anisaldehyde and black traps without anisaldehyde (1.3, 28 and 721 times for males respectively and 2.4, 9 and 117 times for females, respectively). Differences between respective traps were statistically significant in almost all cases. Trapping experiments using a centre‐baited trap design to reduce the interaction of anisaldehyde between baited and unbaited traps were undertaken in tomato and sweet pepper greenhouse crops. When the spatial distribution of the thrips adult population within the greenhouse was taken into account, yellow water traps with anisaldehyde caught between 11 and 15 times more female and 3 and 20 times more male F. occidentalis adults than yellow traps without anisaldehyde.

Disruption of gypsy moth mating with microencapsulated disparlure.

Broadcast applications of microencapsulated disparlure at rates of 2.5 to 15.0 grams per hectare are capable of reducing successful mating of wild gypsy moths under field conditions. In test plots, population densities were as high as 32 pairs of pupae in an area of about 700 square meters.

Sexual Activity of the Gypsy Moth" 2

Female moths that had begun to deposit unfertilized eggs (spewing females) did attract males and were mated. However, only females that had spewed fewer than 10 eggs before matingf were likely to deposit fertile eggs after mating. Males in a natural infestation did not discriminate between mated, virgin, spewing and nonspewing females. Both sexes of the gypsy moth were capable of mating several times in 24 hr. About 1/3 of the males in a dense population were mating with pre- viously mated females. In the microencapsulated,. disparlure-treated plots, only 1- to 4-day-old females were mated. In untreated plots, 1- to 8-day- old females were mated. Furthernore, fewer females tethered in the litter in the treated plots were mated than those females tethered in the litter in control plots. The disparlure treatment reduced the incidence of mating. In treated plots, more females tethered on the tree at 2 m were mated than females tethered in the litter. Videotaped activity of males in a dense population revealed that males orient to vertical silhou- ettes initially, and not to specific pheromone sources.

Simulations on the role of the egg parasite, Ooencyrtus kuvanae (Howard), in the population dynamics of the gypsy moth

Abstract Computer simulations were run to examine the effects of Ooencrytus kuvanae (Howard) parasitism on gypsy moth populations. Two difference equation models were used, one, a simple theoretical model containing only a few important components, the other, a more comprehensive model with component functions based on field data. The simulations of the first model showed that O. Kuvanae cannot control gypsy moth populations by itself. Egg parasitism was most important during the outbreak and collapse phase of the gypsy moth population cycle, and was of little importance in the endemic phase. The endemic phase was, however, lower and lasted longer with O. kuvanae parasitism than without. Simulations with the second model generally supported these conclusions. The second set of simulations also demonstrated that due to the non-linearity of the density dependence of O. kuvanae parasitism, they gypsy moth populations could be forced into a chaotic regime (unstable, aperiodic population behavior). The variation in parasitism rate from the simulations was compared with that of field populations and found to be essentially the same, indicating that the simulation models are realistic.

Parasitoids in the Management of Sirex noctilio: Looking Back and Looking Ahead

The control of the woodwasp Sirex noctilio can be visualized as a three-legged stool. Silvicultural practices to reduce tree competition and stress and biological control using the nematode Deladenus siricidicola are two important legs. The third, and equally important, component of a total control program for this pest is the use of parasitoid wasps. Parasitoids were the first form of control used against S. noctilio in the Southern Hemisphere and remain important, especially as a constant repressor at low population levels. However, there is significant variation in the effect and application of the various parasitoid wasps in different regions. There is evidently scope for renewed efforts to better understand and optimize the use of parasitoids to achieve stable, long lasting population repression of invasive S. noctilio populations.

Apparent long-term bodily contamination by disparlure, the gypsy moth (Lymantria dispar) Attractant.

Positive attraction of male gypsy moths to the body of the author, now four years after his last known direct contact with disparlure, the synthetic pheromone, is documented. A designed test showed that moths responded to him in highly significantly greater numbers than to others who had had less or no previous exposure to the insect and / or disparlure. The data present persuasive evidence of bodily contamination with disparlure and suggest that the material is very persistent.

The discovery of a new species of Ceranisus from southwestern Turkey

An explorative trip was made to southwesternTurkey in April 1995 in search of pear thrips,Taeniothrips inconsequens (Uzel)(Thysanoptera: Thripidae), and its naturalenemies. Forty-three females and 13 males of apreviously undescribed species of the genusCeranisus Walker (Hymenoptera:Eulophidae) were found, mainly in floweringArbutus andrachne L. Although theparasitoid was found in association withseveral thrips species, but especially T.inconsequens adults and larvae, its host orhosts were not determined. The parasitoid isdescribed and given the name Ceranisusantalyacus S. Triapitsyn.

Effect of p-Anisaldehyde and a Yellow Color on Behavior and Capture of Western Flower Thrips

Observations in a flight chamber olfactometer and in glasshouses of sweet pepper or tomato suggest a chemokinetic response by western flower thrips (WFT) to p-anisaldehyde rather than a response based on anemotaxis, chemotaxis, or an odor-induced visual response. Yellow water traps baited with p-anisaldehyde increased capture of WFT >10-fold over non-baited yellow traps, and >100-fold over non-baited black traps. Evidence of baited trap interference with nearby non-baited traps was detected, suggesting a need for caution in interpretation of baited versus non-baited trap catches under glasshouse conditions where traps are not adequately spaced.

On the persistence of disparlure in the human body.

Response of male gypsy moths from a sparse infestation in Italy to an observer apparently contaminated with disparlure at least two years previously is reported. Other examples of pheromone contamination of people or things are also recorded.

Position and Abundance of Pear Thrips Eggs in Sugar Maple Flowering and Vegetative Buds

Bud samples were taken from flowering sugar maple, Acer saccharum (Marsh.), during budburst to determine the position and abundance of pear thrips, Taeniothrips inconsequens, eggs in 1992. Buds were stained with acid fuchsin to observe eggs. Peak numbers of eggs were found in mixed male and female flowering buds and exclusively male flowering buds collected on 1 May, and in vegetative buds collected on 14 May. No female flowering buds were collected. Most eggs were located in the petioles of flowering buds and in the leaf veins of vegetative buds. Factors influencing the position and abundance of eggs and the significance of flowering on the population dynamics of pear thrips are discussed.