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Life cycle of the aquatic moth Cataclysta lemnata (Lepidoptera: Crambidae) was studied in laboratory conditions to obtain a basic biological knowledge useful for predicting the possible success of the herbivorous larvae of this insect as potential control agents in limiting the spread of the invasive American duckweed Lemna minuta (Alismatales: Araceae) in Italy. The multivoltinism of C. lemnata, as well as the high overall emergence from the pupal stage (85%), the high success in mating among the formed couples (>90%), and the high number of larvae born from each egg laying (on average 310 individuals), suggest that the insect can be successfully bred in the laboratory for the purposes of an augmentative biological control. Under experimental conditions, larvae developed in 23 days (through six larval instars, distinguishable by cephalic capsule dimensions) and pupae in 10, with no difference in duration between females and males. The larval phase resulted longer than the adult one (23 vs 10 days); therefore, it can be considered the most suitable stage for releasing the insect in the field for biocontrol purposes. Indeed, the larvae having a herbivorous diet might consume a large amount of the invasive plant, contrarily to the adult phase which is focused exclusively on reproduction. Our results not only contribute to the knowledge of aquatic Lepidoptera that are scarcely known, but also support the effectiveness of a possible protocol for an augmentative biological control of the invasive alien duckweed L. minuta. [ABSTRACT FROM AUTHOR]

Aquatic habitats are vulnerable to the invasion of alien species, so early warning protocols are necessary for eradication. The presence in Italy of two alien duckweeds in freshwaters has been documented: Lemna minuta, that showed high invasivity, and L. valdiviana, still confined to south Lazio. These two species may be mistaken for each other and for the domestic L. minor and L. gibba due to morphological variation. Here, we assess the applicability of DNA barcoding as a complement to morphological analysis for monitoring the spread of alien Lemna. We chose two chloroplast genome sequences for their ability to discriminate all Lemna species: the 5' intron of the trnK gene and the matK gene. Among 48 samples of Lemna collected at 20 sites in Central Italy, 20 were identified as L. minor, 19 as L. minuta, five as L. trisulca and four as L. gibba. L. minuta was present at most sampling sites; in particular, at six locations of Lake Trasimeno, eight L. minuta samples were found. We demonstrate that DNA sequence analyses with cost-effective barcoding techniques can effectively support expert efforts in species determination for an early alert system of invasive Lemna species. [ABSTRACT FROM AUTHOR]

The American duckweed Lemna minuta is invasive in freshwater habitats across much of Europe, often causing serious ecological impacts. To date, few studies have addressed how to halt its expansion. However, encouraging empirical evidence of L. minuta control by the aquatic herbivorous larvae of the insect Cataclysta lemnata is emerging. To better understand the biocontrol capacity of C. lemnata, information on overlap in the phenology and the growth conditions in nature of both species is fundamental. In this study, L. minuta and C. lemnata populations were analyzed in the field to define (i) their phenological features, (ii) the main environmental characteristics where the two species occur, and (iii) any overlap or difference in phenology and ecological requirements. The seasonal occurrence of the two species and environmental data were collected from 31 wetlands in central Italy. The two species showed a large phenological overlap and ecological similarities. Populations of L. minuta and C. lemnata were found all year long, although abundances were greater in spring and summer. Both species preferred waters that were shallow, circumneutral, with moderately high conductivity and trophic level and with low dissolved oxygen. The phenology and ecology of the two species were shown to be compatible, suggesting the insect could be released in natural sites invaded by the alien L. minuta where could act as potential biocontrol agent of it. [ABSTRACT FROM AUTHOR]

• Ability in consuming alien Lemna minuta by native herbivorous larvae was tested. • Larvae of Cataclysta lemnata proved to consume and accept L. minuta as host plant. • Larvae effectively consume as much the native Lemna minor as the alien L. minuta. • Late-instar larvae were most efficient in consuming both Lemna species. • C. lemnata could help to contain the spread of the highly invasive alien L. minuta. Alien plant invasion is a serious threat for biodiversity conservation. Most theories on the mechanisms regulating the expansion of an alien species, agree that herbivory is one of the main factors affecting the success or failure of these species. One worrying example in Europe is the American duckweed Lemna minuta that, since its arrival in the 1940s, has become wide spread throughout many countries. This study focused on determining and quantifying the herbivorous nature of the larvae of the moth Cataclysta lemnata (native to Europe) with regards to L. minuta. On the premise that, if a native herbivore feeds on an alien plant species, it could help to contain its expansion. We tested the effectiveness of larvae at three different instars in consuming L. minuta under laboratory conditions. Laval preference for the alien L. minuta and the native L. minor was determined by quantifying the removal of monolayer mats of these two duckweeds. Firstly, we found that C. lemnata larvae was able to use L. minuta as a trophic resource and also to build protective cases. Moreover, they feed effectively, and seemingly without preference, on both the native and the alien species, contrary to the Enemy Release Hypothesis, which assumes that native consumers are better adapted to consume native species than alien ones. In addition, C. lemnata late-instar larvae were more efficient in Lemna consumption. This study suggests that where C. lemnata is a native herbivore the spread of L. minuta could be effectively contained. [ABSTRACT FROM AUTHOR]