scholarly journals Mealybug preference among clover cultivars: testing potential groundcover plants to dissociate mealybugs from grapevines

2018 ◽  
Vol 71 ◽  
pp. 248-254
Author(s):  
W.R. Manoharie Sandanayaka ◽  
Vicky A. Davis ◽  
Linley K. Jesson

The choice of groundcover plants used under grapevines may reduce the quantity of mealybugs found on grapevines in New Zealand vineyards. Preferences of Pseudococcus calceolariae and P. longispinus mealybugs on five clover cultivars were tested under ‘no-choice’ and ‘choice’ conditions. Two plants of each cultivar: ‘Karridale’(KS) (Trifolium subterraneum, L.), ‘Tripoli’ (TW), ‘Nomad’ (N) (T. repens), ‘Crimson cv’ (C) (T. incarnatum) and ‘Strawberry cv’ (S) (T. fragiferum) grown in pots, were arranged in randomised designs for the no-choice and choice tests and inoculated with newly emerged mealybugs. In the no-choice test, significantly more mealybugs (either species) were observed on KS and C than on TW, N, or S plants after 21 days. In the choice test, significantly more P. calceolariae were observed on KS than on TW, N, or S, while mealybug numbers on C were intermediate. Numbers of P. longispinus were significantly higher on KS and C than on TW, N or S. Mealybugs demonstrated preferences for KS and C over TW, N or S. These findings could aid development of recommendations for groundcover management in vineyards.

1960 ◽  
Vol 11 (5) ◽  
pp. 723 ◽  
Author(s):  
NW Grylls ◽  
JW Peak

Resistance to subterranean clover stunt virus was explored in 390 strains and named varieties of subterranean clover from the Mediterranean regions, England, France, the Iberian peninsula, New Zealand, and Australia. High levels of genetic resistance were shown in the Australian varieties Tallarook, Hill's Small, and Bass B. Resistance of a selected group of F2's was found to be midway between that of the parents. In selected groups of F4 generation hybrids, and in selected second and third generation backcrosses, resistance equal to that of Tallarook was shown. The apparent recovery of some plants during tests in the glass-house was shown to be a form of temporary tolerance to the virus.


2019 ◽  
Vol 65 (3) ◽  
pp. 305-316 ◽  
Author(s):  
Martin Plath ◽  
Kai Liu ◽  
Diane Umutoni ◽  
Guilherme Gomes-Silva ◽  
Jie-Fei Wei ◽  
...  

Abstract While many mating preferences have a genetic basis, the question remains as to whether and how learning/experience can modify individual mate choice decisions. We used wild-caught (predator-experienced) and F1 laboratory-reared (predator-naïve) invasive Western mosquitofish Gambusia affinis from China to test whether mating preferences (assessed in a first mate choice test) would change under immediate predation threat. The same individuals were tested in a second mate choice test during which 1 of 3 types of animated predators was presented: 1) a co-occurring predator, 2) a co-evolved but not currently co-occurring predator, and 3) a non-piscivorous species as control. We compared preference scores derived from both mate choice tests to separate innate from experiential effects of predation. We also asked whether predator-induced changes in mating preferences would differ between sexes or depend on the choosing individual’s personality type and/or body size. Wild-caught fish altered their mate choice decisions most when exposed to the co-occurring predator whereas laboratory-reared individuals responded most to the co-evolved predator, suggesting that both innate mechanisms and learning effects are involved. This behavior likely reduces individuals’ risk of falling victim to predation by temporarily moving away from high-quality (i.e., conspicuous) mating partners. Accordingly, effects were stronger in bolder than shyer, large- compared with small-bodied, and female compared with male focal individuals, likely because those phenotypes face an increased predation risk overall. Our study adds to the growing body of literature appreciating the complexity of the mate choice process, where an array of intrinsic and extrinsic factors interacts during decision-making.


Behaviour ◽  
1992 ◽  
Vol 123 (1-2) ◽  
pp. 121-143 ◽  
Author(s):  
Carlos R. Ruiz-Miranda

AbstractAlthough it is known that the young play an active role in the formation of mother-young attachment in ruminants, there is scant knowledge of how neonates identify their mothers. This research investigated the use of visual cues, particularly pelage pigmentation, in maternal recognition by domestic goat kids. Observations on the use of auditory cues were carried out secondarily. The findings of this study were: (1) The analysis of error patterns revealed that goat kids performed phenotype matching on the basis of pelage pigmentation when seeking their mothers in two- and six-choice tests, at a distance of 10 m. Presenting the kids with a choice between two females of the same colour resulted in more vacillation, and fewer kids were able to go to their mother directly than when the adults were of different colours. The phenomenon was not evident when the kids were 3 days old. Because it occurred at all other ages, regardless of whether the mother was absent, covered, or fully visible, colour-matching seems to be an important aspect of maternal recognition. (2) Visual cues were important for recognition, as evidenced by the performance of kids when maternal cues were limited (i.e. the mother was covered). (3) The efficiency measures did not correlate strongly with maternal vocalizations when visual cues from the mother were not completely present or when pelage pigmentation was not a good cue for discrimination. On the contrary, kids unexpectedly vocalized more in the conditions in which they could discriminate on the basis of visual cues, that is, when the mother was bare rather than covered, and when she was paired with a doe of a different colour category rather than one of the same colour category. (4) Five-day-old domestic goat kids recognized their mothers efficiently, even within a group, and at a distance of at least 10 m. Most 3-day-kids were not able to find their mothers efficiently in the six-choice test. Errors were made at all ages. The observed performance is consistent with the abilities required of kids under natural conditions.


2017 ◽  
Vol 41 (4) ◽  
pp. 439-446 ◽  
Author(s):  
Guilherme Vieira Pimentel ◽  
Adriano Cirino Tomaz ◽  
Bruno Portela Brasileiro ◽  
Luiz Alexandre Peternelli ◽  
Márcio Henrique Pereira Barbosa

ABSTRACT The sugarcane borer Diatraea saccharalis Fabr. (Lepidoptera: Crambidae) is one of the most important pests of sugarcane in the Americas. The purpose of this study was to assess multiple resistance traits in eight sugarcane genotypes against D. saccharalis, including five commercial cultivars and three exotic germplasm with potential to serve as resistance sources against this pest. The oviposition preference was assessed by using both free-choice and non-choice tests. The performance of both early stage larvae feeding on the leaves and late stages larvae feeding within the stalks were also assessed. There were differences among genotypes for number of both eggs and egg cluster in the free-choice test while no differences in non-choice test were observed. There were also differences in survival of early stage larvae feeding on the leaves, foliar injury rating and stalk damage. The genotype IM76-228 was the least preferred for oviposition and it seems that leaf width had some influence on adults’ preference rather than greening of the leaves. IM76-228 and RB867515 causes higher mortality of early stage larvae feeding in the stalks while IM76-228 and RB985523 had lower damage in both leaves and stalks. The genotype IM76-228 was the most resistant to D. saccharalis and could serve as genes sources for resistance in sugarcane breeding programs.


2004 ◽  
Vol 129 (3) ◽  
pp. 383-388 ◽  
Author(s):  
Beiquan Mou ◽  
Yong-Biao Liu

Leafminer (Liriomyza spp.) is a major insect pest of many important agricultural crops including lettuce (Lactuca sativa L.). The goals of this study were to evaluate lettuce genotypes for resistance to leafminers and to estimate the heritabilities of leafminer-resistant traits in the field, to examine the association among different resistant traits, and to study the mechanism of leafminer resistance in lettuce. Seventy-eight lettuce accessions and 232 F2 plants of crosses were evaluated for leafminer stings and the production of pupae and flies in the field in 2001 and 2002, and resistant genotypes were subjected to no-choice test. Wild species (Lactuca serriola L., L. saligna L., and L. virosa L.) had significantly fewer stings than cultivated lettuces. Among cultivated lettuces, sting densities were lowest on leaf lettuce and highest on romaine types. The sting results from the field were highly correlated with the results from insect cages (r = 0.770 and 0.756 for 2001 and 2002 tests, respectively), suggesting that a cage test can be used to screen for resistance in the field. Broad-sense heritability estimates for stings per unit leaf area in the field were 81.6% and 67.4% for 2001 and 2002 tests, respectively. The number of pupae produced per plant or per leaf was moderately correlated with sting density but was not correlated with leaf weight. Results suggest that both antixenosis and antibiosis exist in lettuce germplasm and resistant genotypes from choice tests remain resistant under no-choice conditions. These findings suggest that genetic improvement of cultivated lettuce for leafminer resistance is feasible.


Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 1020 ◽  
Author(s):  
Xiong ◽  
Cai ◽  
Chen ◽  
Liang ◽  
Wen ◽  
...  

The black-winged subterranean termite, Odontotermes formosanus Shiraki, is a severe pest of plantations and forests in China. This termite cultures symbiotic Termitomyces in the fungal combs, which are challenged by antagonistic microbes such as Trichoderma fungi. In a previous study we showed that O. formosanus workers made significantly fewer tunnels in sand containing commercially formulated conidia of Trichoderma viride Pers. ex Fries compared with untreated sand. Herein, we hypothesize that fungi in the genus Trichoderma exert repellent effects on O. formosanus. Different choice tests were conducted to evaluate the tunneling and aggregation behaviors of O. formosanus workers reacting to sand/soil containing the unformulated conidia of seven Trichoderma fungi (Trichoderma longibrachiatum Rifai, Trichoderma koningii Oud., Trichoderma harzianum Rifai, Trichoderma hamatum (Bon.) Bain, Trichoderma atroviride Karsten, Trichoderma spirale Indira and Kamala, and T. viride). We also investigated the colony-initiation preference of paired O. formosanus adults to soil treated with Trichoderma conidia (T. koningii or T. longibrachiatum) versus untreated soil. Tunneling-choice tests showed that sand containing conidia of nearly all Trichoderma fungi tested (except T. harzianum) significantly decreased tunneling activity in O. formosanus workers compared with untreated sand. Aggregation-choice test showed that T. koningii, T. atroviride and T. spirale repelled O. formosanus workers, whereas T. longibrachiatum and T. hamatum attracted termites. There was no significant difference in proportions of paired adults that stayed and laid eggs in the soil blocks treated with conidia of Trichoderma fungi and untreated ones. Our study showed that Trichoderma fungi generally repelled tunneling in O. formosanus, but may exert varied effects on aggregation preference by workers.


2019 ◽  
Vol 112 (4) ◽  
pp. 1695-1704 ◽  
Author(s):  
Scott H Graham ◽  
Fred M Musser ◽  
Alana L Jacobson ◽  
Anitha Chitturi ◽  
Beverly Catchot ◽  
...  

Abstract Thrips (Thysanoptera: Thripidae) and tarnished plant bug, Lygus lineolaris (Hemiptera: Miridae), are among the most important insect pests of cotton, Gosssypium hirsutum, in the mid-southern United States. These pests are currently managed primarily by insecticides; however, a new Bt toxin, Cry51Aa2.834_16 is under evaluation for control of thrips and tarnished plant bug. Experiments were conducted to evaluate the behavioral response of thrips and tarnished plant bug to Bt Cry51Aa2.834_16. Adult thrips avoided Bt Cry51Aa2.834_16 cotton in field choice tests and in separate field tests of Bt and non-Bt cotton not treated with insecticides. In a greenhouse choice test, approximately twice as many adult thrips and eggs were found on non-Bt compared with Bt Cry51Aa2.834_16 cotton. Similarly, in a field test of nontreated Bt Cry51Aa2.834_16 and non-Bt cotton, 68% of adult thrips collected were found on non-Bt cotton. In cotton that was not sprayed with insecticides, Bt Cry51Aa2.834_16 did not affect the distribution of tarnished plant bug within the canopy, although more square and flower injury was caused by tarnished plant bug in non-Bt cotton. Adult tarnished plant bug exhibited a nonpreference for diet containing lyophilized Bt Cry51Aa2.834_16 leaves and for excised Bt Cry51Aa2.834_16 squares in choice tests with non-Bt squares. The behavioral responses of these pests when exposed to this new Bt toxin will play a key role in the efficacy and potential resistance management strategies if this new technology is incorporated in an overall cotton insect pest management system.


1988 ◽  
Vol 120 (6) ◽  
pp. 593-600 ◽  
Author(s):  
Diether P. Peschken ◽  
Jo-Anne L. Derby

AbstractLiriomyza sonchi Hendel was screened for its host specificity as a potential biological control agent against sow-thistles (Sonchus spp.). Recent literature indicated that L. sonchi is recorded frequently from Sonchus spp., but also from Arnoseris minima Schweigger and Koerte and Reichardia arabicum Hochstetter and Steudel. A total of 78 plant species were tested, including 37 species in the Cichorieae (Compositae). In no-choice tests, feeding punctures were observed on species in the closely related genera Aetheorrhiza, Crepis, Lactuca, and Taraxacum, and such distantly related species as Helichrysum bracteatum Andrews var. monstrosum Hortorum (Inuleae tribe, Compositae) and Pisum sativum L. (Leguminosae). From 0.04 to 0.67 adults per female were produced on Aetheorrhiza bulbosa (L.), Crepis dioscordis L., C. rubra L., Leontodon hispidus L., and Taraxacum officinale Weber as compared with about 23 per female on its host, Sonchus arvensis L. No species in these genera other than Sonchus are reported as hosts in the field in Europe and they are therefore considered to be cage-induced hosts. Because of its economic importance, 10 cultivars of lettuce, Lactuca sativa L., were exposed to a total of 837 females in no-choice tests. One puparium and one adult (0.006 per female) were produced. In one replicated choice test with 150 females, no mines were produced on lettuce. It is concluded that the field host range of L. sonchi is restricted to Sonchus spp.


1971 ◽  
Vol 11 (49) ◽  
pp. 202 ◽  
Author(s):  
WR Scott

Six cultivars of subterranean clover, Geraldton, Yarloop, Woogenellup, Clare, Mount Barker, and Tallarook, were grown as ungrazed swards at 1,700 feet a.s.1. in the Mackenzie Country of South Canterbury, New Zealand. In this very frosty environment seed yields tended to increase with increasing lateness of flowering although Clare and perhaps Tallarook appeared to be more frost susceptible than the other cultivars. It is suggested that the deleterious effects of frosts in reducing the seed yields of subterranean clover may have been overemphasized in the past and that the trend for seed yields to increase with increasing lateness of flowering can be partially explained by differences in runner production.


Author(s):  
V. L. Kiselev ◽  
V. V. Maretskaya ◽  
O. V. Spiridonov

Testing is one of the most effective ways for monitoring of students՚ current academic performance. Multiple choice tests are the most common and most often used tasks in the practical activities of higher education teachers. The approaches to the test development are shown and examples of test tasks for students of engineering specialties of highereducational institution are presented in the article.


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