Screening for broad mite susceptibility in Rhododendron simsii hybrids

Broad mite Polyphagotarsonemus latus, is a key pest of pot azalea (Rhododendron simsii Planch hybrids). No information on variation in susceptibility or potential tolerance within these plants is available to date. We evaluated a selection of 32 Rhododendron cultivars, mainly Rhododendron simsii hybrids, for susceptibility to broad mite. The plants were artificially infested in a greenhouse by surrounding each azalea with four broad mite-infested English ivy plants (Hedera helix). Broad mite infestation was evaluated by counting the number of broad mites per shoot tip and assigning a damage rate. Results indicated a comparable infestation rate expressed as the number of mites on all cultivars at the initial stage of the experiments. Correlations between the average damage rate and the number of broad mites per shoot tip on all cultivars at different time intervals were significantly positive, although low, in each experiment, with R-2-values of 0.14 and 0.61. At the end of the experiments significant differences in susceptibility between the evaluated cultivars were observed. The cultivars, 'Emil De Coninck' and 'Mont Blanc' were rated as the most susceptible, whereas 'Mistral' and its bud sport 'Elien' were tolerant towards the broad mite, because damage rates were low and very few broad mites were found

Insecticide effect of zeolites on the tomato leafminer Tuta absoluta (Lepidoptera: Gelechiidae)

(1) Background: The tomato leafminer Tuta absoluta (Lepidoptera: Gelechiidae) is a key tomato insect pest. At present, it is considered to be a serious threat in various countries in Europe, North Africa, and Middle East. The extensive use and the developed resistance of T. absoluta to spinosad causes some concern, which leads to the need for alternative products. (2) Materials and Methods: Several laboratory experiments were conducted to investigate the ovicidal properties of a zeolite particle film on T. absoluta. The toxicity of three different zeolites and six zeolite formulations to T. absoluta eggs and larvae was determined using different exposure methods. (3) Results: In general, the formulated zeolites yielded higher egg and larvae mortality values, especially when the zeolite particle film was residually applied. Notable differences in mortality rates from exposure to zeolites compared to other products, such as kaolin, its formulated product Surround, and the insecticide spinosad, were observed. Kaolin and Surround exhibited little or no effect for both application methods, while the hatch rate was reduced by 95% when spinosad was applied topically. Spinosad yielded egg and larvae mortality rates of 100% for both application methods. Additionally, increased oviposition activity was observed in adults exposed to the wettable powder (WP) formulations. These WP formulations increased egg deposition, while Surround and spinosad elicited a negative oviposition response. (4) Conclusions: It can be derived that the tested products, zeolites BEA (Beta polymorph A), FAU (Faujasite), LTA (Linde type A), and their formulations, had no real insecticidal activity against the eggs of T. absoluta. Nevertheless, egg exposure to zeolites seemed to affect the development process by weakening the first instar larvae and increasing their mortality. Subsequently, based on the choice test, no significant difference was observed between the number of eggs laid on the treated leaves and control leaves

Influence of male age and diet on reproductive potential of orius laevigatus (hemiptera: anthocoridae)

When assessing the reproductive potential of laboratory-reared predatory insects, the role of males is often neglected, although they may have a significant impact on the reproductive output of their female mates. The current study investigated the effect of age and diet of males on the reproductive capacity of the anthocorid predator Onus laevigatus (Fieber) (Hemiptera: Anthocoridae). The tested diets consisted of eggs of Anagasta kuehniella (Zeller) and an egg yolk-based artificial diet. Regardless of their diet, virgin females did not produce any mature oocytes, indicating that mating is required to complete ovarian development. Food source and age of the males affected the reproductive potential of their female mates. When both males and females were offered the artificial diet, male age had a significant effect on female oocyte counts. Virgin females that were mated with 0-d-old virgin males produced fewer offspring than those mated with 8-d-old virgin males. In contrast, male age did not affect fecundity when the males were fed A. kuehniella eggs. The implications of the findings for the mass production of O. laevigatus are discussed

Temperature-dependent development of the two-spotted ladybeetle, Adalia bipunctata, on the green peach aphid, Myzus persicae, and a factitious food under constant temperatures

The ability of a natural enemy to tolerate a wide temperature range is a critical factor in the evaluation of its suitability as a biological control agent. In the current study, temperature-dependent development of the two-spotted ladybeetle A. bipunctata L. (Coleoptera: Coccinellidae) was evaluated on Myzus persicae (Sulzer) (Hemiptera: Aphididae) and a factitious food consisting of moist bee pollen and Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs under six constant temperatures ranging from 15 to 35 degrees C. On both diets, the developmental rate of A. bipunctata showed a positive linear relationship with temperature in the range of 15-30 degrees C, but the ladybird failed to develop to the adult stage at 35 degrees C. Total immature mortality in the temperature range of 15-30 degrees C ranged from 24.30-69.40% and 40.47-76.15% on the aphid prey and factitious food, respectively. One linear and two nonlinear models were fitted to the data. The linear model successfully predicted the lower developmental thresholds and thermal constants of the predator. The non-linear models of Lactin and Briere overestimated the upper developmental thresholds of A. bipunctata on both diets. Furthermore, in some cases, there were marked differences among models in estimates of the lower developmental threshold (t(min)). Depending on the model, t(min) values for total development ranged from 10.06 to 10.47 degrees C and from 9.39 to 11.31 degrees C on M. persicae and factitious food, respectively. Similar thermal constants of 267.9DD (on the aphid diet) and 266.3DD (on the factitious food) were calculated for the total development of A. bipunctata, indicating the nutritional value of the factitious food

Impact of Artificial Rearing Systems on the Developmental and Reproductive Fitness of the Predatory Bug, Orius laevigatus

This study investigated the effect of several substrate types and moisture sources on the developmental and reproductive fitness of the zoophytophagous predator Orius laevigatus (Fieber) (Hemiptera: Anthocoridae) when fed a factitious prey (i.e. unnatural prey) Ephestia kuehniella (Zeller) eggs, or a meridic artificial diet based on hen's egg yolk. O. laevigatus is known to feed on plants as an alternative food source and to oviposit in plants. E. kuehniella eggs were superior to the artificial diet. Supplementary feeding on plant materials did not compensate for the nutritional shortcomings of the artificial diet. Survival rates showed that oviposition substrates such as bean pods or lipophilic surfaces such as wax paper and plastic were more suitable for rearing O. laevigatus than household paper. The use of green bean pods as a plant substrate did not have a beneficial effect on O. laevigatus. The results indicated that O. laevigatus can successfully complete its nymphal development and realize its full reproductive potential in the absence of plant material. However, plant materials would still be required for oviposition, unless a reliable and cost-effective artificial oviposition substrate were made available. The omission of plant materials from the rearing procedures may reduce production cost of this species and other heteropteran predators

Influence of diet on the predation rate of Orius laevigatus on Frankliniella occidentalis

The predation rate of fifth instars and female adults of Orius laevigatus (Fieber) fed honeybee pollen, Ephestia kuehniella Zeller eggs or an egg yolk based artificial diet on second instars of the western flower thrips Frankliniella occidentalis (Pergande) was examined in the laboratory. Predation rate of both fifth instars and female adults was not influenced by their diet. Despite a lower body weight, O. laevigatus reared on artificial diet or pollen killed as many prey as their peers reared on E. kuehniella eggs, suggesting that body weight is not a reliable predictor of predation rate. The use of non-prey foods for O. laevigatus for mass production or as a supplementary food to sustain its populations in the field when prey are scarce is discussed

Effects of selected insecticides on osmotically treated entomopathogenic nematodes

Combining environmentally friendly insecticides with entomopathogenic nematodes may constitute an effective alternative to conventional chemical control of many insect pests. The objective of this laboratory study was to evaluate the effects of selected insecticides which are commonly used for pest control in vegetables in China on osmotically treated and untreated infective juveniles of Steinernema carpocapsae strain All. The insecticides azadirachtin, chlorpyrifos, cypermethrin, fipronil, imidacloprid, malathion, thiamethoxam and chlorantraniliprole-thiamethoxam had no adverse effects on nematode survival and infectivity. In contrast, bisultap, emamectin benzoate, phoxim and rotenone proved harmful to S. carpocapsae All mainly by reducing infectivity of the infective juveniles to larvae of the greater wax moth, Galleria mellonella. Osmotic induction is a promising way to induce entomopathogenic nematodes into partial anhydrobiosis and thus increase environmental stress tolerance of the nematodes as well as their shelf life after production. The present results showed that osmotic treatment did not adversely affect fitness of the nematode in terms of its susceptibility to insecticides and even increased its tolerance to chlorpyrifos and rotenone. The results of this laboratory study indicate that several of the tested insecticides can be safely combined with S. carpocapsae All within an integrated pest management approach