An experiment was conducted to compare the predation efficiency of the coccinellids Harmonia axyridis and Coleomegilla maculata on potato plants, Solanum tuberosum, and on a wild aphid-resistant species, Solanum tarijense. Harmonia axyridis females reduced aphid populations more than C. maculata females. Aphid predation by the predators was reduced on S. tarijense compared to S. tuberosum. Coleomegilla maculata spent less time on S. tarijense than on S. tuberosum. Harmonia axyridis spent the same amount of time on both plant species. The plant species did not affect IGP between larvae. Compared to S. tuberosum, the resistant plant offers M. persicae an enemy-free space against both coccinellid predators., Bruno Fréchette ... [et al.]., and Obsahuje seznam literatury
The effects of imidacloprid on 1-day-old third instars of Harmonia axyridis were assessed by topical treatment and contact with treated glass plates in laboratory bioassays. When 5 µl of imidacloprid solutions were applied topically, the LD50 was 0.085 g/l per insect after 24 h. Contact with imidacloprid-treated plates had little effect on the number of third instars that became adults. Average duration of larval development was not significantly affected by duration of contact and imidacloprid concentrations. There were no significant differences in maximal larval weight, weight gain and day at maximum larval weight. There were significant differences in average weight gain per day (from third instar to prepupa) after treatments with different imidacloprid concentrations. A temporary knockdown effect was observed with higher concentrations and longer durations of contact with treated plates. Compared with untreated third instars, contact with imidacloprid-treated plates caused an increase in time spent (in seconds) on the glass plates resulting from an increase in number of stops (per second) and angular speed (degrees per second) and a decrease in linear speed, excluding stops (mm/second). The changes in locomotory behavior (i.e., duration of stay on untreated plate, number of stops and angular speed) lasted up to 24 h after contact with imidacloprid-treated plates.
Until recently, the Canadian distribution of the blueberry maggot, Rhagoletis mendax Curran (Diptera: Tephritidae), was restricted to Nova Scotia, Prince Edward Island and New Brunswick. The insect was first mentioned in southern Quebec in 1996 and, to date, it has not reached the Lac St-Jean region, where 34% of Canadian blueberry acreage is located. Two questions concerning the northern limit of distribution of the blueberry maggot in Quebec were addressed. First, are wild plants suitable hosts for larval development? We collected the fruit of five wild plants, (e.g. Vaccinium corymbosum, Vaccinium angustifolium, Vaccinium myrtilloides, Gaylussacia baccata, and Aronia melanocarpa) growing in southern Quebec and allowed larvae to complete their development into pupae. Blueberry maggot pupae were recovered from Vaccinium corymbosum, Vaccinium angustifolium, and Gaylussacia baccata, indicating that these plants are suitable for larval development. Second, are harsh winter temperatures a factor limiting the northern distribution of the blueberry maggot? Pupae collected in Quebec and Nova Scotia were put in the soil in the fall and were brought back to the laboratory to determine their supercooling points at different times during winter. The supercooling points of pupae collected in Quebec and Nova Scotia averaged -22.6°C. In natural conditions, air temperatures <-20°C are frequently observed in Quebec in January, February and March. However, due to snow cover, soil temperatures are rarely <-12°C. If -22.6°C constitutes the lower limit for the survival, then winter temperatures are probably not a limiting factor to its northern distribution in Quebec, because blueberry maggot pupae overwinter in the soil., Charles Vincent, Pierre Lemoyne, Sonia Gaul, Kenna Mackenzie., and Obsahuje bibliografii
The parasitoid, Anagyrus kamali Moursi (Hymenoptera: Encyrtidae), has been recently introduced into the Caribbean as a biological control agent against the hibiscus mealybug (HMB), Maconellicoccus hirsutus Green (Homoptera: Pseudococcidae). Storage of A. kamali that is essential for its use in biological control did not affect the longevity of female and male parasitoids (40.3 ± 14.07 and 31.7 ± 9.57 days, respectively) when kept at 20 ± 2°C in absence of hosts and fed ad libitum with droplets of pure honey. At a storage temperature of 27 ± 2°C the longevity decreased by about 10 days. Fed females did not resorb eggs during the first two weeks of storage at 20 ± 2°. Parasitoid ovogenesis ceased when ovarioles/lateral oviducts were full. The lifetime fecundity was not significantly affected by a storage at 20 ± 2°C of up to 14 days. Foraging activities and oviposition were the main factors influencing the lifespan of female A. kamali.
The multicolored Asian ladybeetle, Harmonia axyridis (Coleoptera: Coccinellidae), was first reported in southern Canada in 1994. In this study, we examined the status of the ladybeetle in Quebec agroecosystems seven to ten years after its arrival. We integrated the findings from eight independent field studies carried out in pome fruit, grapes, medicinal crops, field corn, sweet corn, sweet pepper, lettuce, and soybean. Nine aphidophagous and 6 coccidophagous coccinellid species were sampled on these crops. Among these aphidophagous species, three invasive (H. axyridis, Coccinella septempunctata and Propylea quatuordecimpunctata) as well as one indigenous species (Coleomegilla maculata lengi) were consistently present. Higher richness was observed in perennial crops, where the 6 coccidophagous coccinellids were almost exclusively present. Higher abundance of aphidophagous coccinellids was observed in field and sweet corn. The multicolored Asian ladybeetle was a dominant species of the coccinellid assemblage in all crops monitored.