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Rhynchophorus ferrugineus (Olivier) (Coleoptera: Dryophthoridae) is an economically important, internally feeding pest of ornamental and fruit-producing palms in many subtropical regions. A related weevil, Rhynchophorus cruentatus (Fabricius) (Coleoptera: Dryophthoridae), is an internally feeding palm pest in the southeastern USA. Acoustic methods for detection of early instars hidden in palms in field environments have been investigated for both species. Acoustic methods also have been used to examine the effectiveness of physical, biological, and other control treatments. This report addresses several physical, physiological, and behavioral factors that influence the spectral and temporal patterns of sounds produced by palm weevil larvae under different laboratory and field experiment conditions, which must be considered carefully in interpreting larval sound production. Such factors include the leakage of fluid from the palm tree tissues into tunnels scraped out by larvae as they move and feed within the tree trunk, as well as occurrences of molting between periods of feeding activity, and frequency-dependent damping that distorts signals as the distance between insects and sensors increases. Methods are discussed that combine effects of environmental, physiological, and behavioral variability to facilitate reliable interpretations of Rhynchophorus and other insect larval acoustic activity in hidden environments.

Pepper weevil, Anthonomus eugenii Cano (Coleoptera: Curculionidae), is a most serious pest of peppers in North Florida. To analyze A. eugenii infestation levels on jalapeño peppers as a reference for effectively controlling pepper weevil, we investigated infestation and population dynamics of A. eugenii, and influence of plant direction, layer, and spacing in open fields in North Florida. The results showed that adult pepper weevil infestation started in late Apr when plants started to produce buds and flowers. Three infestation peaks were recorded on 9 Jun, 24 Jul, and 11 Sep. The second peak showed the highest infestation level (14.6 ± 2.7 infested fruits per plant). The density curve of A. eugenii larvae within fruits lagged about 2 to 4 wk behind the curve of infestation level in the field. Three peaks occurred on 10 Jul, 21 Aug, and 25 Sep. Fruits on the eastern part and top third of pepper plants had the lowest infestation levels, as did plants spaced 40 cm apart. This study, focusing on the preferred locations of A. eugenii, will help improve sampling technique and pest management applications, and thus enhance the effectiveness of pesticide application, and ultimately reduce ecological damage.

Myllocerus undecimpustulatus undatus Marshall (Coleoptera: Curculionidae), also known as the Sri Lankan weevil, is becoming a major pest of ornamentals and tropical fruit trees in the southern USA, including Florida. Recent findings of this species in Florida citrus groves justify research into its biology and ecology. We studied morphological and sexually dimorphic characters of this species as an aid to rapid separation of sexes for studies aiming to identify semiochemicals that may be of value in management. Female weevils collected from the field in southeastern Florida were significantly larger than males in length of head, abdomen, and overall length. Females, but not males, have a characteristic black-gray marking extending from the ventral mesosternum to the second abdominal segment. Scanning electron microscopic images revealed that females had fewer ovate-to-obovate scales in this region of characteristic black-gray marking, and more plumose scales compared with males. Host choice and oviposition studies showed that Sri Lankan weevils prefer peach plants over weeds or grasses in peach orchards. Electroantennogram recordings with different peach volatiles identified peach odorants that can elicit significantly higher antennal responses. Both male and female Sri Lankan weevil antennae were highly responsive to these volatiles. Behavioral assays in olfactometers are underway to identify those semiochemicals that could be used as attractants or disruptants.

Parapantomorus fluctuosus (Boheman) and Pantomorus cinerosus (Boheman) (both Coleoptera: Curculionidae) are parthenogenetic broad-nosed weevils native to South America, and they damage citrus in Argentina and Brazil. The objectives of this contribution are to apply ecological niche modelling to compare the suitable areas of occurrence of these species with those of other parthenogenetic Naupactini distributed in similar areas, and to analyze their potential range in relation to the distribution of citrus groves, mainly in Argentina and Brazil. Pantomorus cinerosus and P. fluctuosus were predicted to be distributed in tropical and subtropical South America, Mexico, Central America, Cuba, southeastern USA (Florida), southern Africa, Madagascar, eastern Australia, and southern China. However, neither has colonized other countries outside the native range. The potential distribution of P. fluctuosus is broader than that of P. cinerosus, and the predicted areas of both species are partially coincident with main production areas of citrus in Argentina, Brazil, and throughout the world. Although ecological niche modelling is an effective tool for predicting the potential spread and colonization of weevils in distant cultivated areas, weevil establishment is most likely the result of multiple factors.

Successful invasion of a species into novel, marginal areas often requires the ability to face different ecological characteristics than those prevailing in its native environment. In insects, one of the factors that affect invasiveness is the reproductive system. Unisexuality provides advantages because a single specimen can initiate a new population. Unisexual reproduction precludes breakup of genetic combinations that promote ecological specialization, although it may limit evolutionary potential for colonization. In order to assess the importance of the reproductive mode in the colonization ability of the weevils that are native to South America, we compared 1 bisexual and 2 parthenogenetic species that expanded their ranges in the last 2 centuries. First, for parthenogenetic species we tested clonality of the sample. Second, we proposed central and marginal areas through phylogeographic and habitat modeling analyses, and identified the pathways of dispersal for each species. Bisexual Naupactus xanthographus (Germar) (Coleoptera: Curculionidae) expanded its range westward to areas with similar environmental constraints than in its native ecosystem. Conversely, parthenogenetic Naupactus leucoloma Boheman and Naupactus cervinus Boheman (both Coleoptera: Curculionidae) invaded other continents where they had low to null predicted habitat suitability. While a single clone of N. cervinus successfully established around the world in areas with apparently adverse conditions, clones of N. leucoloma expanded their range to areas only moderately suitable. We conclude that parthenogenesis is a driver in these particular species for colonization of marginal habitats. However, N. cervinus also would have pre-existing adaptations that allowed it to establish in areas with apparently low potential to survive.

Mexico is a center of New World crop origins with many insect species associated with the wild crop relatives, some of which have become pests of cultivated plants. Many of these indigenous pests of Mexico are weevils (Coleoptera: Curculionidae), and some represent potential quarantine pests. In the present work, we present some of the most important species of weevils considered as crop pests, which are presently restricted primarily to Mexico with the potential to invade other regions. We also present species of weevils exotic to Mexico, considered by national quarantine authorities to be possible threats to Mexican agriculture. Potential quarantine weevil pests for avocado include Conotrachelus aguacatae Barber, Conotrachelus perseae Barber, Heilipus lauri Boheman, Heilipus albopictus Champion, and Copturus aguacatae Kissinger (all Coleoptera: Curculionidae). For guava, species include Conotrachelus dimidiatus Champion and Conotrachelus copalensis Salas-Araiza and Romero-Nápoles (both Coleoptera: Curculionidae). Weevil pests reported with quarantine importance for sugar cane are Sphenophorus incurrens Gyllenhal (Coleoptera: Dryophthoridae), Apinocis angustus (Casey), and Apinocis subnudus (Buchanan) (both Coleoptera: Curculionidae). The weevil Rhyssomatus nigerrimus Fåhraeus (Coleoptera: Dryophthoridae) recently has been observed damaging soybeans in northern and southern Mexico. Cactophagus spinolae Gyllenhal (Coleoptera: Dryophthoridae) is a generalist cactus pest. Scyphophorus acupunctatus Gyllenhal (Coleoptera: Dryophthoridae) is a well-known pest of cultivated and wild agaves. Several species of Epicaerus (Coleoptera: Curculionidae) have been reported on various crops in restricted areas including, among others, Epicaerus operculatus (Say) on garlic, and Epicaerus cognatus Sharp (both Coleoptera: Curculionidae) on potato. Amphidees latifrons (Sharp) (Coleoptera: Curculionidae) has been reported from apples in localized regions of northern Coahuila. Weevils exotic to Mexico of quarantine concern are Naupactus cervinus Boheman, Diaprepes abbreviatus (L.) (both Coleoptera: Curculionidae), and Rhynchophorus ferrugineus (Olivier) (Coleoptera: Dryophthoridae).

The cowpea curculio, Chalcodermus aeneus Boheman (Coleoptera: Curculionidae), was first described from samples collected by Chevrolat in Mexico in 1837. Cowpea, Vigna unguiculata (L.) Walp. (Fabaceae), has nothing to do with the original hosts of this curculio species, because cowpea is from the Old World, specifically Africa, and C. aeneus has never been reported in the Old World. Cowpea curculio has been reported as a major pest of cowpea in the southeastern USA for well over a century. The distribution of C. aeneus in the US in 1910 was reported to be in the states of Texas, Louisiana, Alabama, Florida, Georgia, South Carolina, North Carolina, Oklahoma, Maryland, and Missouri. Outside of the US, C. aeneus is found in Mexico, Belize, Guatemala, Honduras, Nicaragua, and Peru. This curculio causes tremendous damage to cowpea, so much so that it can render cowpea production unsustainable in a curculio-infested region. Recent deficiencies in viable commercial insecticide controls have led to repeated collapses of acreage in Georgia. In experiments reported here, as much as 60% yield loss occurred with only moderate C. aeneus infestations. Heavy curculio pressure shut down cowpea production in our test, even with fairly effective foliar insecticides. Fortunately, C. aeneus is not easily transported in cowpea shipments around the world because it reproduces only in green pods, from which it leaves to pupate in the soil before the grain dries. This curculio can be quarantined effectively from large scale movement via shipping due to its reproductive biology, but spreads easily via a land to cowpea crop “bridge.” In the southeastern US, research efforts are underway to identify means to reduce the overwintering populations, with the goal of regional eradication sometime in the future.

Numerous weevil species are serious pests on agricultural crops in the Caribbean basin and the USA. These pests include native and exotic weevil (Coleoptera: Curculionoidea) species. Among them, some weevil species are easy to identify, and others need training and expertise in taxonomy in order to identify them properly. Commodity-based identification and training tools are extremely important and critical. For example, the citrus root weevil, Diaprepes abbreviatus (L.) (Coleoptera: Curculionidae) was established in the US nearly 50 yr ago, and costs millions of dollars annually in control attempts in Florida alone. Other species such as the red palm weevil, Rhynchophorus ferrugineus (Olivier) (Coleoptera: Dryophthoridae); the South American palm weevil, Rhynchophorus palmarum (L.) (Coleoptera: Dryophthoridae); and the Jamaican weevil, Exophthalmus vittatus L. (Coleoptera: Curculionidae), are potential threats to fruits, vegetables, and ornamental crops. Adults of these weevils display various coloration, and patterns of red, blue, black, green, yellow, orange, and white. Some species have more than 2 color forms; male and female weevils may show major variations in their morphological characters. Regulatory agencies at the local, regional, and international levels are strengthening collaboration on offshore mitigation of these pests. Strict enforcement of regulatory guidelines and procedures is being adopted at the ports of entry into the US. Indeed, training on the identification and screening of these species, and other potential crop pests, is critically important for food security in the region. Training and capacity building to design, develop, and deploy keys, tools, and resources are major components of successful implementation of digital identification tools. The team at the Center for Biological Control is part of the digital resource consortium building tools on invasive beetles on economically important crops. To build capacity in digital insect identification, we have not only modified the contents of graduate and undergraduate insect systematics curriculum, but also have trained numerous students in these new skills.

Alien (exotic) insects threaten trees, landscapes, and ecosystem stability. Bark and ambrosia beetles (Coleoptera: Curculionidae: Scolytinae) are saproxylic beetles that spend most of their life cycles under bark, and often are introduced to new locations through wooden packing materials used in international trade. This project reports the identification of 4 alien species reared on the Osa Peninsula of Costa Rica. Bait branches from 41 trees were exposed to saproxylic beetles in a mosaic of old growth and secondary forest. The branches yielded 6,578 scolytines in 33 species. Four of these were alien species: Coccotrypes cyperi Beeson, Premnobius cavipennis Eichhoff, Xylosandrus crassiusculus Motschulsky, and Xylosandrus morigerus Blandford (all Coleoptera: Curculionidae). At least 1 of the alien species, Premnobius cavipennis, was the most abundant scolytine, represented by 1,476 individuals, and it emerged from almost half of the trees sampled. It was reared from the plant families Lecythidaceae, Sapotaceae, and Fabaceae. Most individuals emerged from bait branches in old growth forest, and were disproportionately abundant at canopy stratum. Only 46 individuals of the economic pest X. crassiusculus were reared from bait branches. Two of the 4 alien scolytines were reared commonly from branches in old growth forest, even though mature forest typically resists invasions of alien species. Unfertilized females can disperse and found colonies by mating with haploid sons, and intra-colony mating promotes rapid population growth; therefore, these life history traits facilitate invasion.

The significance of ecological non-monotonicity (a function whose first derivative changes signs) in shaping the structure and functions of the ecosystem has recently been recognized, but such studies involving high-order interactions are rare. Here, we have proposed a three-trophic conceptual diagram on interactions among trees, rodents, and insects in mast and non-mast years and tested the hypothesis that oak ( Quercus wutaishanica ) masting could result in increased mutualism and less predation in an oak-weevil-rodent system in a warm temperate forest of China. Our 14-year dataset revealed that mast years coincided with a relatively low rodent abundance but a high weevil abundance. Masting not only benefited seedling recruitment of oaks through increased dispersal by rodents but also a decrease in predation by rodents and weevils, as well as an increase in the overwintering survival of rodents. Masting appeared to have increased weevil survival by reducing predation of infested acorns by rodents. These results suggest that masting benefits all participants in the plant-insect-rodent system by increasing mutualism and reducing predation behavior (i.e., a non-monotonic function). Our study highlights the significance of masting in maintaining the diversity and function of the forest ecosystem by facilitating the transformation from predation to mutualism among trophic species.