Reproductive Diapause in North American Populations of the Introduced Lady Beetle Hippodamia variegata (Coleoptera: Coccinellidae)

2018 ◽  
Vol 47 (5) ◽  
pp. 1337-1343 ◽  
Author(s):  
John J Obrycki
2020 ◽  
Vol 49 (5) ◽  
pp. 1164-1170
Author(s):  
John J Obrycki

Abstract Quantifying responses of three congeneric species of lady beetles, Hippodamia parenthesis (Say), Hippodamia convergens (Guerin), and Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae), to abiotic factors that influence their seasonal biology provides an understanding of the phenology of these species in North America. The developmental response and the induction and duration of adult hibernal diapause in four North American populations of H. parenthesis, collected between 40° N and 44° N latitude, was determined when beetles were reared at four photoperiods (L:D 16:8, 14:10, 12;12, and 10:14) at 22°C. Preimaginal development of the four H. parenthesis populations reared at the photoperiods was affected by population, photoperiod, and the interaction between population and photoperiod. Fifteen to 19% of H. parenthesis females reared at L:D 16:8 entered diapause, whereas shorter photoperiods (L:D 12:12 and 10:14) induced diapause in all females. Variation in response to L:D 14:10 was observed among the four populations of H. parenthesis, similar to the response observed in H. convergens and H. variegata. In contrast to the response of H. parenthesis females, in which four individuals oviposited at L:D 12:12 or 10:14 within 120 d, the duration of reproductive diapause in H. convergens and H. variegata females at L:D 12:12 and 10:14 showed a prolonged quantitative response to photoperiod. Comparisons of the responses (days to first oviposition) to photoperiod of H. parenthesis and H. variegata from the same collection sites showed significant differences at most photoperiods. Similarly, responses at all photoperiods varied between H. parenthesis and H. convergens from similar latitudes in Iowa.


2013 ◽  
Vol 53 (2) ◽  
pp. 143-147 ◽  
Author(s):  
Ali Almasi ◽  
Qodrat Sabahi ◽  
Khalil Talebi ◽  
Ardavan Mardani

Abstract The implementation of an Integrated Pest Management (IPM) program requires selecting and using chemicals which are least harmful to natural enemies. In this study, the acute toxicity of the recommended field concentration of four conventional insecticides was evaluated in reference to the different life stages (L3, L4 and adult) of the variegated lady beetle Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae). The evaluated insecticides were Proteus, pymetrozine, deltamethrin, and pirimicarb. A completely randomized design (CRD) with four replications was used as the experimental design. The means were separated by the least significant difference (LSD). The mortalities of those predators treated with the field recommended concentrations of various insecticides, were significantly different. Proteus showed strong toxicity toward the different life stages of the predator. However, pymetrozine and pirimicarb caused less than a 50% mortality. Based on the lethal concentration (LC50) values at 24 h after treatment, the adult predator was the most susceptible to proteus, followed by deltamethrin, pymetrozine, and pirimicarb values of 35.977, 358.757, 915.667, and 2616.113. Based on sublethal concentrations (LC30), these values were 22.718, 261.957, 569.879, and 1521.424. Based on International Organization of Biological Control (IOBC) classification, the insecticides pirimicarb and pymetrozine were both categorized as having a Class 1 toxicity level (harmless), deltamethrin as having a Class 2 level (slightly harmful), and Proteus, a Class 4 toxicity level (harmful).


2015 ◽  
Vol 55 (4) ◽  
pp. 421-428 ◽  
Author(s):  
Safura Soleimani ◽  
Hossein Madadi

Abstract Two important lady beetle species commonly found in alfalfa fields in Iran are the variegated lady beetle Hippodamia variegata Goeze and the seven spotted lady beetle Coccinella septempunctata (Linnaeus, 1758) (Coleoptera: Coccinellidae). These two species attack many aphid species including the pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae). In this study, the seasonal population changes of A. pisum, H. variegata, C. septempunctata and the parasitoid, Dinocampus coccinellae (Schrank) (Hymenoptera: Braconidae) were studied in alfalfa fields in the 2012 and 2013 seasonal periods. The highest ladybird densities were noted on July 5, 2012 and on September 6, 2013 (17.2±2.8 and 13.4±1.6) individuals per 20 sweeps, respectively. Parasitism rates by D. coccinellae ranged from approximately 3 to 6% in two subsequent years, respectively. Parasitism was higher early in the growing season. Most parasitised ladybirds were females. There was no significant relationship between the temperature and relative humidity with pea aphid populations, although the aphid populations declined during the hot summer period. In contrast, the relationship between temperature and the H. variegata population was significant and positive in both years of the study. It has been shown that these lady beetle species have a major role in reducing the pea aphid populations in alfalfa fields. Due to the relatively low percentage of field parasitism by D. coccinellae, this parasite might not reduce the biocontrol efficiency of lady beetle species.


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