Intraspecific genetic variation in arthropods is often studied in the context of evolution and ecology. Such knowledge, however, can also be very usefully applied to biological pest control. ...Selection of genotypes with optimal trait values may be a powerful tool to develop more effective biocontrol agents. Although it has repeatedly been proposed, this approach is still hardly applied in the current commercial development of arthropod agents for pest control. In this perspective study, we call to take advantage of the increasing knowledge on the genetics underlying intraspecific variation to improve biological control agents. We argue that it is timely now because at present both the need and the technical possibilities for implementation exist, as there is (1) increased economic importance of biocontrol, (2) reduced availability of exotic biocontrol agents due to stricter legislation, and (3) increased availability of genetic information on non‐model species. We present a step‐by‐step approach towards the exploitation of intraspecific genetic variation for biocontrol, outline that knowledge of the underlying genetic mechanisms is essential for success, and indicate how new molecular techniques can facilitate this. Finally, we exemplify this procedure by two case studies, one focussing on a target trait – offspring sex ratio – across species of hymenopteran parasitoids, and the other on a target species – the two‐spot ladybird beetle – where wing length and body colouration can be optimized for aphid control. With this overview, we aim to inspire scientific researchers and biocontrol agent producers to start collaborating on the use of genetic variation for the improvement of natural enemies.
The invasive white mango scale (Aulacaspis tubercularis) was introduced accidentally to Ethiopia in 2010 (through plant materials) and to Bahir Dar area, north western Ethiopia, in 2017. Its ...population dynamics was studied from October to May 2018/19 on randomly selected mango trees from which number of scales and their natural enemies were recorded using leaves as samples. Analysis of variance, correlation and regression were used for data analysis. Significantly more male colonies, live males, live females and number of eggs were recorded in October than in other months. The number of dead female scales was significantly and positively correlated with rainfall (r = 0.6), maximum temperature (r = 0.34), minimum temperature (r = 0.70) and wind (r = 0.5). Regression analyses showed significant association of weather variable and live females (r
2
=0.75), adult predators and Aphytis spp. (r
2
=0.48), dead females (r
2
=0.62) and eggs (r
2
=0.68). Four species of natural enemies, i.e., Cryptolaemus montrouzieri, Chilocorus stigma, Chilocorus bipustulatus larvae, Chrysoperla carnea and an unknown lady beetle larvae were found preying on white mango scale. Scale population varied with time and space, and different developmental stages responded differently to weather variables and predators.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, GIS, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Fruit and vegetable crops are affected by numerous arthropods, including aphids and thrips. Hoverfly adults are important pollinators, and their larvae are mainly aphid predators. Molecular studies ...on the stomach contents of larvae allowed to associate hoverflies with the consumption of other soft‐bodied arthropods, including thrips, with few records found in Neotropical hoverfly species. Allograpta exotica (Wiedemann) (Diptera: Syrphidae), a species widely distributed in the Americas, from the USA to Argentinian Patagonia, has been associated with numerous crops mainly affected by aphids, and to a lesser extent with whiteflies. The objective of this work was to assess the consumption and preference rates of various instars of A. exotica as biocontrol agents for two major insect pests, Myzus persicae (Sulzer) (Hemiptera: Aphididae) and Frankliniella gemina (Bagnall) (Thysanoptera: Thripidae), under controlled laboratory conditions. Additionally, we morphologically characterized the three larval stages of A. exotica. We determined that all three instars of A. exotica consume both M. persicae and F. gemina, and that they kill more thrips than aphids. Still, A. exotica preferred M. persicae over F. gemina, even when the relative aphid availability decreased compared to F. gemina, although consumption of both prey types remained high. Interestingly, A. exotica second instars consumed four times more thrips than aphids. This study explored the potential use of one of the most common hoverfly species in fruit and vegetable crops as a biocontrol agent of aphids and thrips. Further laboratory and field studies should explore more deeply the potential of this Neotropical beneficial dipteran.
Allograpta exotica (Diptera: Syrphidae) is broadly distributed in the Americas. We evaluated the consumption and preference rates of A. exotica instars on Myzus persicae (Hemiptera: Aphididae) aphids and Frankliniella gemina (Thysanoptera: Thripidae) thrips, under laboratory conditions. All instars consumed much of both pests, although they preferred aphids. The hoverfly could control both pests. These results shed light on the feeding habits of A. exotica and its role as a biological controller of soft‐bodied arthropods in agroecosystems.
Cydalima perspectalis (Lepidoptera: Crambidae), a species native to East Asia, has been especially devastating in the Mediterranean region and Catalonia, northeast Spain, where Buxus sempervirens is ...an essential component of the natural forest. As an invasive species, the lack of biotic mortality factors in the arrival region has been one of the main factors allowing its expansion. Therefore, this study aimed to collect and identify possible indigenous natural enemies adapting to the new species in the boxwood of the southwest Mediterranean region. Later, the efficacy of some of the collected species for controlling C. perspectalis larvae was tested in laboratory conditions. The larval collection was carried out in successive years in the boxwood of the region. Several collected larvae were infected with an entomopathogen, Beauveria bassiana, or parasitized by Compsilura concinnata, both common in native Lepidoptera caterpillars. The B. bassiana strain was found to be highly virulent against the developed larvae of C. perspectalis, which suggests that B. bassiana may be an effective treatment in parks and gardens when the first overwintering larvae are detected. The biology of the parasitoid identified is not very well known in Europe, which suggests the necessity of studying its biology and alternative hosts in the region in order to improve its population.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Hyperaspis trifurcata
(Coleoptera: Coccinellidae) is a native predator of the wild cochineal scale,
Dactylopius opuntiae
(Hemiptera: Dactylopiidae) in North America. Here we have determined its life ...cycle and voracity when reared on first instar nymphs of
D. opuntiae
and estimated its population parameters using five diets based on different developmental stages of its prey: (a) first instar nymphs, (b) second instar nymphs, (c) young adults, (d) gravid adult females, and (e) a mixed diet which included all the developmental stages. The tests were conducted under laboratory conditions: 25 ± 2 °C, 60 ± 10 % RH and 12:12 (L:D) h.
H. trifurcata
developmental times were 5.9, 3.1, 3.6, 3.1, 8.9 and 11.4 days for the eggs, first, second, third and fourth instar larvae, and pupae, respectively. Overall there were 36.6 days from egg to adult emergence. Females consumed a mean of 5293 ± 361 first instar
D. opuntiae
nymphs during their lifetime, and there was no significant difference in developmental time between males and females.
H. trifurcata
could complete its life cycle when reared on any developmental stage of
D. opuntiae
. Nevertheless, the highest fecundity (237.4 ± 25.8 eggs) was obtained when they were fed the mixed diet, and the lowest fecundity and fertility were obtained when they were fed first or second instar nymphs, with a fecundity of 57.8 ± 10 and 140.5 ± 13 eggs and a fertility of 72 and 80 %, respectively. Moreover, the mixed diet increased the net reproduction rate (R
o
= 112) and prolonged the generation time (T = 68.4 days) compared with females reared on first or second instar nymphs where R
o
= 27.3 and 66.3 and T = 56.2 and 62.4 days, respectively. These parameters indicate that
H. trifurcata
has potential as a biological control agent of
D. opuntiae
.
Laboratory tests were conducted in Italy to evaluate the acceptance and suitability of the alien butterfly Cacyreus marshalli Butler as host for three indigenous parasitoids, Trichogramma brassicae ...(Bezdenko), Exorista larvarum (L.) and Brachymeria tibialis (Walker). Only E. larvarum and B. tibialis showed potential to adapt to C. marshalli. Their contribution to biological control appeared to be especially related to host mortality due to incomplete parasitoid development.
La efectividad del insecticida ometoato (Folimat® 1000) y de enemigos naturales nativos para controlar al psílido asiático de los cítricos, fue comparada en Río Bravo, Tamaulipas, durante 2010. Los ...resultados indicaron que ometoato fue más efectivo y no se observaron ninfas o adultos a las 264 h después de la aplicación; por otra parte, a las 72 h en el tratamiento de enemigos naturales, la población de ninfas fue reducida y similar al tratamiento con ometoato. En el testigo absoluto, la población de ninfas se incrementó a más 100% a las 264 h.
A survey of parasitoids of the pepper weevil (Anthonomus eugenii Cano), one of the most important pests of peppers in North America, was conducted in Mexico as part of a search for biological control ...agents of this pest. Surveys were conducted in different years on the Pacific and Atlantic Coasts in Mexico. We recovered parasitoid species belonging to 7 genera: Triaspis eugenii Wharton & López-Martínez, Urosigalphus sp., Bracon spp.; Catolaccus hunteri Crawford; Eurytoma spp.; Eupelmus sp.; and Ceratoneura sp. The latter species might be a newly recorded genus for this pest. Catolaccus hunteri, T. eugenii, and Urosigalphus sp. represented 96% of all recovered specimens. Triaspis eugenii was collected only in Nayarit, and Urosigalphus sp. predominated in Oaxaca; both locations are on the Pacific Coast. Catolaccus hunteri was present at every sample site. The biology of the braconids T. eugenii and Urosigalphus sp. would seem to make them best suited for biological control of pepper weevil due to their presumed host specificity and habit of attacking the host egg.
To identify the predator complex of the invasive thrips, Klambothrips myopori, on its ornamental host plant Myoporum laetum, field surveys were conducted at three sites in southern California over ...the period of 1 y. Five insect orders and five spider families were represented in the survey. Although the most abundant groups differed among collection sites, syrphid larvae, anthocorids, Chrysoperla spp., Franklinothrips orizabensis Johansen (Thysanoptera: Aeolothripidae), and one spider family (Salticidae) were all collected at each site. Based on the field surveys, Orius spp. and Chrysoperla spp. were identified as possible key natural enemies of K. myopori. Laboratory studies were then conducted to determine the consumption rates of Orius insidiosus Say (Hemiptera: Anthocoridae) and Chrysoperla rufilabris Burmeister (Neuroptera: Chrysopidae) at constant densities of K. myopori and to define the functional responses of the predators. Both predators consumed more second-instar larvae than other prey stages. Orius insidious displayed a type II functional response, while C. rufilabris displayed both type II and type III depending on prey stage. Generally speaking, O. insidiosus and C. rufilabris consumed a higher proportion of prey at lower pest densities, implying that in an augmentative control program using these commercially available natural enemies, predators could be released early in the year when host plants begin to flush and thrips populations are low to suppress population growth.
PDF
