James J. Mathers

Population Development of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) under Simulated UK Glasshouse Conditions.

Tomato leafminer Tuta absoluta (Meyrick) is a major pest of tomato plants in South America. It was first recorded in the UK in 2009 where it has been subjected to eradication policies. The current work outlines T. absoluta development under various UK glasshouse temperatures. The optimum temperature for Tuta development ranged from 19–23 °C. At 19 °C, there was 52% survival of T. absoluta from egg to adult. As temperature increased (23 °C and above) development time of the moth would appear to decrease. Population development ceases between 7 and 10 °C. Only 17% of eggs hatched at 10 °C but no larvae developed through to adult moths. No eggs hatched when maintained at 7 °C. Under laboratory conditions the total lifespan of the moth was longest (72 days) at 13 °C and shortest (35 days) at both 23 and 25 °C. Development from egg to adult took 58 days at 13 °C; 37 days at 19 °C and 23 days at 25 °C. High mortality of larvae occurred under all temperatures tested. First instar larvae were exposed on the leaf surface for approximately 82 minutes before fully tunnelling into the leaf. Adult longevity was longest at 10 °C with moths living for 40 days and shortest at 19 °C where they survived for 16 days. Generally more males than females were produced. The potential of Tuta absoluta to establish populations within UK protected horticulture is discussed.

The integrated use of chemical insecticides and the entomopathogenic nematode, Steinernema carpocapsae (Nematoda: Steinernematidae), for the control of sweetpotato whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae)

The integration of chemical insecticides and infective juveniles of the entomopathogenic nematode Steinernema carpocapsae (Wesier) (Nematoda: Steinernematidae), to control second instars of the sweetpotato whitefly, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) was investigated. Using a sand bioassay, the effects of direct exposure of S. carpocapsae for 24 h to field rate dilutions of four insecticides (spiromesifen, thiacloprid, imidacloprid and pymetrozine) on infectivity to Galleria mellonella larvae were tested. Although all chemicals tested, except spiromesifen, produced acceptable nematode infectivity rates, they were all significantly less than the water control. The effect of insecticide treatment (dry residues of spiromesifen, thiacloprid and pymetrozine and soil drench of imidacloprid) on the efficacy of the nematode against B. tabaci was also investigated. Nematodes in combination with thiacloprid and spiromesifen gave higher B. tabaci mortality (86.5% and 94.3% respectively) compared to using nematodes alone (75.2%) on tomato plants. There was no significant difference in B. tabaci mortality when using the chemicals imidacloprid, pymetrozine and spiromesifen in conjunction with nematodes compared to using the chemicals alone. However, using thiacloprid in combination with the nematodes produced significantly higher B. tabaci mortality than using the chemical alone. The integration of S. carpocapsae and these chemical agents into current integrated pest management programmes for the control of B. tabaci is discussed.

Prey consumption rates and compatibility with pesticides of four predatory mites from the family Phytoseiidae attacking Thrips palmi Karny (Thysanoptera: Thripidae).

BACKGROUND Predatory mites (Amblyseius swirskii Athias-Henriot, Typhlodromips montdorensis Schicha, Neoseiulus cucumeris (Oudemans) and Iphiseius degenerans Berlese) were investigated for their potential to act as control agents for Thrips palmi Karny. Prey consumption rates and compatibility with pesticides were assessed. RESULTS Second-instar larvae were the preferred life stage. Typhlodromips montdorensis consumed the most larvae (2.8) and also an average of 1.2 adult T. palmi per 5 day period. Both 24 and 48 h assessments following application of abamectin, spinosad and imazalil demonstrated mortality of predatory mites (across all species), which was significantly higher than with the other treatments (P < 0.001). Spraying with pymetrozine did not provide any increased mortality when compared with the water control. Application of thiacloprid proved detrimental only to I. degenerans. Following indirect exposure of predatory mites to pymetrozine and imazalil, no significant differences in mite mortality were obtained. Indirect exposure to spinosad was identified as the most detrimental treatment (P < 0.001) to all mites. Abamectin also proved detrimental, with only T. montdorensis showing any potential tolerance. CONCLUSION All predatory mites investigated offer potential for controlling T. palmi. Compatibility with chemicals varied between the mites. The potential of incorporating the mites into eradication strategies for T. palmi is discussed.

Environmental evaluation of hot water treatments to control Liriomyza huidobrensis infesting plant material in transit

Though quarantine disinfestation treatments have been exempt from the methyl bromide phase out, it is still required to research and develop alternative treatments for fumigation of plant material in transit. This study investigated the ability of both the egg and pupal stages of the quarantine pest, South Americian leafminer, Liriomyza huidobrensis to survive submersion in water heated to temperatures between 40 and 50 °C for varying periods of time. Large reductions in egg viability were recorded. However, the treatments also resulted in unacceptable levels of damage to the host plant material. Damage was uneconomically viable. Pupae were all killed exposure to water at 44 °C for 20 min. Incubation of insect and plant material at either 5 or 20 /dgC for 24 h before submersion in the hot water did not significantly alter the pests’ ability to survive the treatments. The potential of hot water treatments to act as an alternative to methyl bromide fumigation for disinfecting plants in transit is discussed.

Feeding responses of adult seven-spotted ladybirds, Coccinella septempunctata (Coleoptera, Coccinellidae), to insecticide contaminated prey in laboratory arenas

Abstract The behavioural responses previously reported from Coccinella septempunctata to the organophosphate, dimethoate, have implications for the effective development of integrated pest management (IPM) strategies. Through a series of simple tests, coccinellids’ consumption rates were measured from live pesticide-resistant aphids, treated with five insecticides from three chemical classes: carbamates, organophosphates and pyrethroids. This study quantifies for the first time the doses of ingested insecticide to which C. septempunctata responds, and demonstrates that a number of insecticides can cause C. septempunctata to change its feeding behaviour. Females were confirmed to eat more than males, and responses to insecticides were observed more frequently in females. Aphid consumption was reduced most in the pyrethroid treatment groups, but choice tests found no preference for either treated or untreated prey in any group. The results are discussed in terms of the mechanism by which coccinellids detect insecticides, and the consequences for IPM.

Screening Commercially Available Entomopathogenic Biocontrol Agents for the Control of Aethina tumida (Coleoptera: Nitidulidae) in the UK

The Small hive beetle, Aethina tumida, is an invasive pest of honey bees. Indigenous to sub-Saharan Africa, it has now become established in North America and Australia. It represents a serious threat to European honey bees. Commercially available entomopathogenic agents were screened for their potential to control beetle larvae. Entomopathogenic fungi investigated had minimal impact. The nematodes Steinernema kraussei and S. carpocapsae provided excellent control with 100% mortality of larvae being obtained. Sequential applications of the nematodes following larvae entering sand to pupate also provided excellent control for up to 3 weeks. The information gained supports the development of contingency plans to deal with A. tumida should it occur in the UK, and is relevant to the management of Small hive beetle where it is already present.