No abstract

Sticky traps with a total of 20 different colours and shades were tested with a view to finding the optimum shade of colour for a sticky trap to attract the western flower thrips, Frankliniella occidentalis (Pergande), in glasshouses. A blue shade was found best for attracting F. occidentalis. Stick traps in this shade are an efficient tool for detecting initial attacks of F. occidentalis in glasszouses.

Laboratory experiments were performed with adult female Macrolophus caliginosus Wagner (Heteroptera: Miridae) at 22°C on bean plants to determine the functional response towards whiteflies, as well as the preference and switching capacity between the two prey species: whiteflies and spider mites. Predation of females presented with first instars of Trialeurodes vaporariorum Westwood (Homoptera: Aleyrodidae) was of a Type III functional response. The observed maximum predation was approximately 75 first instars at high prey densities within a 24‐h period. The preference of M. caliginosus females between eggs of T. vaporariorum and Tetranychus urticae Koch (Acarina: Tetranychidae) changed with the ratio of offered prey. The preference for T. vaporariorum eggs increased non‐linearly with increasing proportions of this prey type. The average maximum predation of whitefly and spider mite eggs were approximately 166 and 111 eggs per day, respectively, at the highest ratio of the two preys. The proportion of M. caliginosus females found on the test plants at the end of the experiment increased with prey density suggesting that this mirid spends more time in areas with high prey density. Macrolophus caliginosus females are voracious predators of eggs and first instars of T. vaporariorum as well as of spider mite eggs and may thus be a valuable addition to existing methods of biological control of T. vaporariorum and T. urticae.

The life table characteristics of the polyphagous mirid Macrolophus caliginosus Wagner (Heteroptera: Miridae) preying on various stages of Tetranychus urticae Koch (Acari: Tetranychidae) with tomato as host plant were described at 22 °C. The following average parameters were obtained: Female longevity: 28.7 days; fecundity: 0.7 eggs/female/day; egg mortality: 2.6%; pre‐oviposition period: 5.5 days; oviposition period: 18.1 days; post‐oviposition period: 3.2 days; juvenile development time: 26.8 days; juvenile mortality: 34.9%; and sex ratio (♀/(♀+♂)) 0.46. Life table parameters were estimated as net reproduction rate (R0): 6.15; intrinsic rate of increase (rm): 0.031 day−1; finite rate of increase (≤): 1.032; mean generation time (Tc): 58.17 days; and doubling time (T2) 22.2 days. The parameters obtained were in accordance with those reported for M. caliginosus fed on another mite species (T. turkestani Ugarov & Nikolski (Acari: Tetranychidae)). However, compared to the performance of M. caliginosus fed on common glasshouse insect pests, a diet consisting of only mites appeared to be inferior. However, being a voracious predator, M. caliginosus may be a valuable addition to existing methods of mite control.

The biology of Hypoaspis miles Berlese (Acarina: Hypoaspidae) fed on mushroom sciarid larvae (Lycoriella solani Winnertz) (Diptera: Lycoriidae) and mould mites (Tyrophagus putrescentiae Schrank) (Acari: Acaridae), was investigated by laboratory experiments at 20 °C, 75% r.h. and LD16:D8 hours. H. miles had a significantly shorter development time and a significantly lower juvenile mortality when fed on sciarid larvae than on mould mites, the development time being 14.5 days and the mortality 3.5% on the former prey. The preoviposition and postoviposition periods of H. miles were not uninfluenced by the prey species and were 5–9 and 32–37 days, respectively. Oviposition periods of 53.2 and 68.5 days and female longevities of 82 and 109.6 days were observed on diets of sciarid larvae and mould mites, respectively. Male longevity (168–219 days) was uninfluenced by the prey species. The egg production of H. miles on sciarid larvae was estimated to be 44.4 ± 4.33 eggs per female, as compared to 22.43 ± 1.79 eggs per female on mould mites. The sex‐ratio of the offspring was significantly influenced by the prey species, the ratios (♀/(♀+♂)) being 0.66 on sciarid larvae and 0.54 on mould mites. The net reproductive rate (R0) for H. miles fed on sciarid larvae was approximately 27 which was three times higher than for mites feeding on mould mites. The innate capacity of increase (rm) was highest (0.0747 day−1) when sciarid larvae served as food, giving a doubling time of 9.3 days as compared to 12.8 days on mould mites. The generation times were 44.28 on sciarid larvae and 40.67 days on mould mites. The daily food consumption rate of juvenile and adult H. miles was 0.24 and 0.86 sciarid larvae and 10.8 and 21.7 mould mites, respectively. In terms of weight consumed, however, the consumption of sciarid larvae was 2–3.5 times the weight of mould mites. The ratio of females to males influenced the oviposition period and egg production of H. miles, with virgin females laying fewer eggs over a longer period of time as compared with females with access to males. The egg production in relation to the sex‐ratio was described by models predicting a maximum number of eggs per female of 22.3 to be attained at a sex ratio of 0.69 (♀/(♀+♂)) and a maximum daily number of eggs per female of 0.33 to be attained at a sex ratio of 0.37 (♀/(♀+♂)).

-An environmental concern regarding the cultivation of transgenic crop plants is their effect on non-target organisms. Honey bees are obvious non-target arthropods to be included in a risk assessment procedure but due to their complex social behaviour, testing transgene products on individual bees is not possible in bee colonies. We employed a laboratory larval rearing technique to test the impacts of such transgene products on honey bees. A serine proteinase inhibitor (Kunitz Soybean Trypsin Inhibitor, SBTI), that is a source of insect resistance in transgenic plants, was used as a model insecticidal protein on honey bee larvae reared individually in the laboratory. The addition of 1.0% SBTI (w:w of total protein) to the larval diet created significant additional larval mortality, slowed juvenile development and significantly decreased adult body mass. Our results suggest that the larval rearing technique can be used to monitor direct side-effects of transgene products on individual honey bee larvae.Apis mellifera / risk assessment / larval rearing / transgenic plants / proteinase inhibitor

The mortality of honey bee larvae and pupae reared in vitro caused by various combinations of oral inoculation with Paenibacillus larvae larvae spores, acute paralysis virus (APV), and infestation with Varroa jacobsoni was studied. The effect of the mite itself and the mite acting as a vector of APV on the mortality of larvae and pupae was investigated. Mortality caused by P. l. larvae ranged from 25 to 55% depending on spore dose. Oral inoculation with APV caused 9% mortality, which was not additive to the mortality caused by P. l. larvae. P. l. larvae did not induce the activation of APV infection. The mortality caused by V. jacobsoni itself was 25%, and by mites transmitting APV, 55%. Neither the mites themselves or the mites transmitting APV had an additive effect on mortality caused by P. l. larvae. The study suggests that APV transmitted by mites is the most significant cause of mortality of the treatment combinations tested. The results do not suggest that the mite itself or the mites transmitting APV act as a stress factor provoking clinical symptoms of American foulbrood (AFB) in individual larvae in the in vitro rearing system.

In many glasshouse ornamental crops, daylength is controlled in order to regulate plant growth. To investi ate whether short daylength influences the bionomics of Frankliniella occidentahs (Pergande), life tabfe parameters of F. occzdenralis reared on bean leaves at 25°C and photoperiods of 420, 8:16 or 16:s (L:D) h were calculated. The immature developmental time significantly increased with decreasing daylength from 13.15 to 14.75 days at 16:s and 4:20 (L:D) h photo eriod, respectively. The effect was expressed primarily in second larval instars. The immature mortalt y increased with decreasing daylength from 67.3 % to 87.5 % at photoperiods of 1 6 3 and 4:20 (L:D) h, respectively. Female adult longevity was significantly Ion est with 13.3 days at 4:20 (L:D) photoperiod. However, mean preoviposition period and fertility $id not differ among different daylengths. Life table parameters differed between photoperiods of 16:s; 8:16 and 4:20 (L:D) as follows: Net reproductive rate (R,)= 12.2; 7.6 and 3.7 (generation I); intrinsic rate of increase (rm) = 0.14; 0.1 1 and 0.06 (day-I); mean generation time (T) = 17.9; 18.3 and 21.1 (days), and doubling time (DT) = 5.0; 6.3 and 11.2 (days), respectively. This study shows that short daylength at 25°C reduces reproductive fitness of F. occidentalis but does not induce reproductive diapause in this species. 2 Materials and methods Adult F. occidentalis were collected from a stock culture reared on bean plants (Phaseolus vulgaris L.) at 23°C and a photoperiod of 16:s (