Pest In Florida Research Articles

Assessing the effectiveness of selected reduced-risk insecticides and malathion on blueberry gall midge (Diptera: Cecidomyiidae) and key parasitoids

The blueberry gall midge, Dasineura oxycoccana, is a major blueberry pest in Florida and North America, primarily controlled with insecticides. However, their efficacy on D. oxycoccana and impact on natural enemies are poorly documented. We compared the effects of seven reduced-risk insecticides with malathion on larval and adult D. oxycoccana in laboratory bioassays. Acetamiprid showed the highest larval mortality, similar to malathion. Imidacloprid was effective after 2 h, while spirotetramat was effective after 3 h. On adults, cyantraniliprole and acetamiprid were as effective as malathion. Flupyradifurone began showing comparable lethality at 3 h, while spirotetramat, imidacloprid, and tolfenpyrad began inducing comparable mortality 6 h post-application. The same insecticides were evaluated for their effects on D. oxycoccana and their key parasitoids in two southern highbush blueberry plantings in North-central and Central Florida. A wetter-spreader adjuvant was added to spirotetramat as a ninth treatment. Spirotetramat + adjuvant effectively reduced adults and larval densities by up to 100% in the first year and adults by 59% and larvae by 56% in the second year. Acetamiprid reduced adult densities by 65% in 2019. Spinetoram reduced adults by 77% and larvae by 100% in 2019, while flupyradifurone reduced adults by 77% and larvae by 37% in 2020. These insecticides had minimal adverse effects on Platygaster spp. and overall parasitoid densities for both years. Based on these findings, there is potential for incorporating spirotetramat + adjuvant, flupyradifurone, spinetoram, or acetamiprid into a strategic rotational program with minimal impacts on natural enemies of D. oxycoccana.

Susceptibility to insecticides of Megalurothrips usitatus (Bagnall) and Frankliniella insularis (Franklin) (Thysanoptera: Thripidae) infesting Lablab purpureus in Florida

Megalurothrips usitatus is a serious pest of leguminous crops that originates from the Asian tropics. Since 2020, it has become established in Florida, Mexico, parts of Central America, and parts of the Caribbean. In south Florida, M. usitatus has significantly impacted the snap bean (Phaseolus vulgaris) industry. It has also established in specialty legumes including lablab bean (Lablab purpureus), which supports high populations of Frankliniella insularis. In response to the establishment of M. usitatus in south Florida, populations of M. usitatus were collected from lablab bean and subjected to a maximum dose insecticide laboratory bioassay to determine susceptibility to eight insecticides. The top labeled rate of abamectin, acetamiprid, cyantraniliprole, flupyradifurone, lambda-cyhalothrin, methomyl, spinetoram, and tolfenpyrad was tested against seven populations of M. usitatus collected from farms managed by two different growers. Six populations of F. insularis collected from the same fields were subjected to the same bioassays. Overall, F. insularis, which is not documented as a pest in Florida, was more susceptible to insecticides than M. usitatus. Abamectin, cyantraniliprole, methomyl and spinetoram were effective against M. usitatus under the conditions of the bioassay, with survival ranging from 6.4% for spinetoram to 13.9% for abamectin. Percentage survival for either species treated with lambda-cyhalothrin did not differ significantly from the untreated control. Although one grower applied insecticides more intensively than the other, there was no statistical difference in survival among populations collected from the two different growers. Implications and priorities for managing newly established invasive thrips are discussed.

Evaluation of Abamectin as a Potential Chemical Control for the Lychee Erinose Mite (Acari: Eriophyidae), a New Invasive Pest in Florida

The lychee erinose mite, Aceria litchii (Keifer) (Acari: Eriophyidae), is an important pest of lychee (Litchi chinensis Sonn.; Sapindaceae) trees. This minute mite prefers to feed on young, new flush causing the formation of galls called “erinea.” Chemical control to protect the new flush is the primary management approach that has been used to control this mite. Aceria litchii was detected recently in Lee County, Florida, USA, and there is an urgent need to identify an acaricide that can control mite populations. Among the acaricides registered for use on lychee in Florida, abamectin was reported to be effective against A. litchii from other parts of the world. However, it remains unknown whether this acaricide can control the mites inside the erinea effectively and protect the new flush. We investigated whether abamectin alone or in combination with an organosilicone surfactant could control an existing mite infestation. Lychee leaflets that had erinea were sprayed with acaricides, then placed on uninfested plants and monitored for symptom development. One mo after placing treated leaflets on uninfested plants, the same treatment was applied to the whole plants and monitored for erinea development on the new flush. Our results showed that none of the treatments were able to control the mites inside the erinea and protect the new flush. The methods described here can be used for more precise evaluations of other acaricides that are urgently needed to control A. litchii in Florida.

The Horntail Snail (Macrochlamys indica): A New Invasive Pest in Florida

The horntail snail was detected, in August 2020, in Miami-Dade County. This snail is considered of quarantine importance in the United States because it can become an agricultural pest and potentially host parasitic nematodes of medical significance. A program to survey, control, and eradicate the horntail snail has been implemented by the Florida Department of Agriculture and Consumer Services, Division of Plant Industry. A version of this article has been posted on the UF/IFAS Tropical REC website prior to EDIS publication at https://trec.ifas.ufl.edu/media/trecifasufledu/pdf-docs/Horntail-Snail-Extension-10-13-2020.pdf

Characterization of Frankliniella occidentalis and Frankliniella bispinosa (Thysanoptera: Thripidae) Injury to Strawberry.

Frankliniella flower thrips are pests of numerous fruit and vegetable crops as they feed and reproduce in the flowers and fruits. The invasive Frankliniella occidentalis (Pergande) from the Southwestern United States, an economic pest in Florida since 2005, and the native Frankliniella bispinosa Morgan are both found in Florida strawberries. The objective of this research was to characterize injury to strawberry fruit from these species. Densities of 0, 2, 4, 8, 16, or 32 adult females of each species were caged on a strawberry plant with one flower. The cages were removed after 2, 5, or 10 d, and the number of surviving adults and the number of larvae determined. Injury was quantified on the mature fruit 21 d after thrips were introduced onto the experimental plant. Initial densities as low as two adult F. occidentalis females per flower decreased fruit set and increased cat-facing on the fruits that developed. There were no significant effects on fruit set and cat-facing by any initial density of F. bispinosa. Feeding by thrips on the small, green fruit affected the size and shape of the mature fruit: the diameters were decreased as a linear function of increased feeding by F. bispinosa, and the weights were decreased as a linear function of increased feeding by F. occidentalis. Overall, results showed that F. occidentalis was more damaging to strawberry than F. bispinosa. The differences in pest status between these common flower thrips species in Florida presents challenges to management programs.

Secondary hosts of the Asian citrus psyllid, Diaphorina citri Kuwayama: Survivorship and preference

AbstractThe Asian citrus psyllid, Diaphorina citri Kuwayama, is the most economically important and difficult to manage citrus pest in Florida due to its role as vector of huanglongbing or citrus greening disease. Spread of the disease is a function of dispersal patterns and thus influenced by availability of suitable hosts. Young leaves of citrus or related plants are required for reproduction, but in their absence, secondary hosts may provide needed resources to enhance survival. Therefore, survivorship on and preference for three abundant weed species was investigated. The suitability of potential secondary host plants Bidens alba (L.), DC, Ludwigia octovalvis (Jacqu.) P. H. Raven, and Eupatorium capillifolium (Lam.) Small was compared to a reproductive host, Murraya paniculata (L.) Jack, in no‐choice tests by assessing survivorship of D. citri adults confined to these plants in cages. Preference was evaluated by choice tests where D. citri adults were released into cages containing all three secondary hosts alone or with M. paniculata. Both B. alba and E. capillifolium increased D. citri survivorship by twofold compared to starvation conditions with only water available. Choice trials revealed no difference in initial selection between true and secondary hosts; however, the true host was favoured over time. This result suggested that hosts were selected initially by sight, and only later by taste and/or smell. While secondary hosts are unable to support reproduction or long‐term survival, these findings establish the ability of D. citri to use secondary hosts that are ubiquitous in Florida citrus groves as temporary reservoirs for food and moisture when ideal host conditions are scarce or absent.

Technomyrmex difficilis (Hymenoptera: Formicidae), an Old World Arboreal ant, in red Mangroves (Malpighiales: Rhizophora mangle) on West Indian Islands

Technomyrmex difficilis is an Old World arboreal ant that is becoming a major pest in the US and the West Indies. After its first records in the New World in 1986 from Florida, T. difficilis was soon reported from other parts of the New World, including eight West Indian islands (Puerto Rico, New Providence, Grand Cayman, St Croix, St Thomas, Antigua, Nevis, and Jamaica) and Honduras. In Florida, T. difficilis has become one of the most common species found nesting in red mangroves (Rhizophora mangle). Here, we report records of T. difficilis nesting in red mangroves at 16 sites on eight West Indian islands, including four islands with no previously reports of this species (Grand Bahama, St Maarten, Roatan, and Trinidad). It is probable that over the next few years T. difficilis will become increasingly important as a pest in Florida and the West Indies.

Pest Identification Guide: Solanum (Pepper) Whitefly, Aleurotrachelus trachoides

Considered an emerging pest in Florida, the solanum whitefly has been in the state since at least the 1960s. It eats pepper, eggplant, and tomato, as well as other food crops, ornamental plants, and weeds. Learn to identify the little pest with this handy, 2-page guide written by Nicole A. Casuso and Hugh A. Smith and published by the UF/IFAS Entomology and Nematology Department.https://edis.ifas.ufl.edu/in1201

Pest Identification Guide: Ficus Whitefly: Singhiella simplex

Ficus whitefly (Singhiella simplex) is found on ficus species, especially weeping fig. It is a major pest in Florida. Learn to identify these tiny flies with this handy, 2-page guide written by Nicole A. Casuso and Hugh A. Smith and published by the UF/IFAS Entomology and Nematology Department.https://edis.ifas.ufl.edu/in1203

Pest Identification Guide: Rugose Spiraling Whitefly, Aleurodicus rugioperculatus

Rugose spiraling whitefly (Aleurodicus rugioperculatus) feeds on over 118 hosts including coconut palm, gumbo limbo, and other fruits and ornamentals. It is a major pest in Florida. Learn to identify these tiny flies with this handy, 2-page guide written by Nicole A. Casuso and Hugh A. Smith and published by the UF/IFAS Entomology and Nematology Department.https://edis.ifas.ufl.edu/in1202

Pest Identification Guide: Bondar’s Nesting Whitefly: Paraleyrodes bondari

Bondar’s nesting whitefly (Paraleyrodes bondari) is an emerging pest in Florida that targets ficus species, hibiscus, sugar apple, guava, and citrus, among others. Learn to identify these tiny flies with this handy, 2-page guide written by Nicole A. Casuso and Hugh A. Smith and published by the UF/IFAS Entomology and Nematology Department.https://edis.ifas.ufl.edu/in1204

Rapid Detection of Insecticide Resistance inDiaphorina citri(Hemiptera: Liviidae) Populations, using a Bottle Bioassay

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a major pest of citrus crops worldwide. A large number of insecticides have been used to manage D. citri in Florida. Therefore, insecticide resistance could become an important problem facing citrus production. Monitoring insecticide susceptibility in populations of D. citri and providing a technique to use as an early warning is needed so citrus producers can modify chemical control strategies for this pest in Florida. The objective of this study was to develop a simple and fast tool to determine insecticide resistance in D. citri and apply it to commercial citrus production in Florida. LC50 and LC95 estimates were determined for 8 commonly used insecticides on a susceptible laboratory population of D. citri 24 h after treatment in a residual contact bottle assay. Five to 7 concentrations of each insecticide were tested. The LC50 values (and 95% fiducial limits) ranged from 0.06 (0.02–0.26) to 0.80 (0.26–2.46) ng/μL for each insecticide tested. Exposure time—mortality indices were determined for 0, 10, 100, 1,000, and 10,000 ng/μL concentrations of each insecticide in a laboratory susceptible strain. Knockdown was assessed after 15, 30, 45, 60, 75, 90, 105, and 120 min. Complete knockdown (100.0%) occurred within 60 min for dimethoate, fenpropathrin, imidacloprid, bifenthrin, and flupyradifurone at the 10,000 ng/μL concentration. For spinetoram, 86.7% knockdown occurred within 120 min at 10,000 ng/μL. For sulfoxaflor and cyantraniliprole, 44.0 and 42.6% knockdown, respectively, occurred within 120 min at 1,000 ng/μL. We also developed a bottle bioassay to survey field populations of D. citri for insecticide resistance in central Florida. Exposure time—mortality indices developed in the laboratory were used to assess susceptibility of 1 laboratory and 4 field populations of D. citri after 15, 30, 50, 75, 90, 105, and 120 min of exposure at the 10,000 ng/μL concentration of various insecticides. Little to no evidence of resistance was detected for bifenthrin, dimethoate, imidacloprid, and fenpropathrin in central Florida. Our investigation demonstrated that a bottle bioassay is suitable for assaying insecticide resistance in D. citri adults under laboratory and field conditions. It should be a flexible tool for rapid testing of insecticide resistance in possible cases of insecticide failure. Its simplicity should allow trained professionals to rapidly monitor for insecticide resistance in commercial settings where “hot spots” of D. citri populations may occur.

Control of Sweetpotato Whitefly with Insecticides Applied to Soil and Foliage of TYLCV Tolerant and Susceptible Staked Tomatoes, 2015

Bemisia tabaci is the most damaging tomato pest in Florida due primarily to its role as a vector of tomato yellow leaf curl virus (TYLCV), although moderate populations can cause irregular ripening syndrome. This trial evaluated the effectiveness of different insecticide rotations and application methods to control SWF and reduce yield losses caused by both pest and virus in TYLCV-tolerant and -susceptible cultivars. Two sets of three raised beds 420 ft long were prepared at the Southwest Florida Research and Education Center in Immokalee, FL, on 6-inch centers incorporating ∼50% of the necessary fertilizer (10-2-10 NPK). Two drip tapes with 8-inch emitter spacing and flow rate of 0.67 gpm/100 ft were laid on each bed which was then covered with black polyethylene film. Chemigation was then used to fumigate beds with 300 lb/acre PicClor 60 EC 10 on 19 Feb. Seedlings of a TYLCV-tolerant variety ‘Ridge Runner’ and a susceptible variety ‘Rocky Top’ obtained from a commercial greenhouse were transplanted 18 inches apart on 6 Mar 2014, and the rest of the fertilizer requirement was injected through the drip over the course of the …

Control of Sweetpotato Whitefly With Foliar Insecticides on Staked Tomatoes, Fall 2013

SWF biotype B continues to be a destructive tomato pest in Florida, mostly due to its role as a vector of tomato yellow leaf curl virus. Affected plants yield little or no fruit when infected young. For this trial, two sets of three beds 420 ft in length were prepared on 15 Aug at the Southwest Florida Research and Education Center in Immokalee, FL. Dry fertilizer (10-2-10 NPK) was incorporated at a rate of 1,000 lb/acre, beds were fumigated with PicClor 60 EC at 240 lbs/acre, and each bed received two drip tapes with 8-inch emitter spacing and was covered with black polyethylene film mulch. Seedlings of ‘Soraya’ obtained from a commercial greenhouse were transplanted 18 inches apart on 6 Sep. Fertilizer was injected during the course of the growing season as liquid 7-2-7 through the drip, and Actigard (0.33–0.50 oz/acre), …

Bionomics of Asian Citrus Psyllid (Hemiptera: Liviidae) Associated with Orange Jasmine Hedges in Southeast Central Florida, with Special Reference to Biological Control by Tamarixia radiata.

The Asian citrus psyllid, Diaphorina citri Kuwayama, is an important pest in Florida because it transmits bacteria responsible for citrus huanglongbing disease. In addition to infesting citrus, orange jasmine (Murraya exotica L.) is one of Asian citrus psyllid's preferred host plants and is widely grown as an ornamental hedge. We report on Asian citrus psyllid bionomics over three years at five urban plantings of orange jasmine and on biological control of Asian citrus psyllid by a parasitoid Tamarixia radiata (Waterston). T. radiata had been released in Florida shortly after Asian citrus psyllid was first found, and the parasitoid was known to be established at each planting. Additionally, three new T. radiata haplotypes were released every 3 wk at three plantings during the first study year (one haplotype per planting, over all releases an average of 17 parasitoids per linear meter of hedge); all three haplotypes were released at a fourth planting beginning midway through the study (over all releases, an average combined total of 202 parasitoids per linear meter of hedge). Asian citrus psyllid populations were present year-round at each planting, often at large levels. Such plantings may pose risk to commercial citrus as Asian citrus psyllid reservoirs. Releases of the new haplotypes did not cause any measurable reduction in Asian citrus psyllid population levels during the study, and ironically percentage parasitism was generally highest at a planting where no releases were made. Higher release rates might have been more effective. The probability is discussed that repetitive pruning of orange jasmine reduced the full potential of T. radiata against Asian citrus psyllid in this study.

Bermudagrass Stem Maggot—A New Pest in Florida

Bermudagrass is a dominant hay crop in Florida. Now, hay producers are facing a new emerging pest problem in bermudagrass and stargrass production fields. The bermudagrass stem maggot is a new exotic invasive fly. It was first discovered damaging bermudagrass pasture and hay fields in Georgia. The identification of the fly was the first record of this species in North America, and it has the potential to become a serious pest of bermudagrass and stargrass in Florida. This 2-page fact sheet was written by Ann Blount, Tim Wilson, Jay Ferrell, Russ Mizell, and Jonael Bosques, and published by the UF Department of Agronomy, June 2014.
 SS-AGR-379/AG384: Bermudagrass Stem Maggot—A New Pest in Florida (ufl.edu)

Ultrastructural and chemical studies on waxy secretions and wax-producing structures on the integument of the woolly oak aphid Stegophylla brevirostris Quednau (Hemiptera: Aphididae)

The woolly oak aphid (WOA), Stegophylla brevirostris Quednau, is a recently described oak pest in Florida, USA. Colonies of WOA on live-oak trees are distinguished by a thick layer of white filamentous waxy material covering most individuals. Nymphs and apterous adults have several long waxy threads/bundles extending from their head, thorax and especially from their abdomen. We used scanning electron microscopy of ‘naturally waxed’ and ‘dewaxed’ aphids to study the ultrastructure and distribution of wax-producing structures on the cuticle. Two types of ‘wax pores’ and smaller wax ‘pits’ were found clustered in wax pore plates around dorsal setae on the head, thorax and abdomen. The larger, type-1, wax pores produce short or long wax columns with honeycomb interior; the smaller, type-2, wax pores produce short or long hollow wax tubes; whereas wax pits produce the shorter and more loosely net tufts of wax filaments covering most of the body dorsally. Wax columns or tubes produced by clusters of types-1 and 2 wax pores aggregate together forming the longer and thicker wax bundles that extend dorsally and laterally from the cuticle, especially near the posterior end of the abdomen. Type-2 wax pores and wax pits were also found on parts of the legs and antennae. Infrared spectroscopy indicated that wax esters, containing saturated fatty acids and fatty alcohols, are the major constituents of WOA waxy secretions. The possible roles of these secretions, especially in avoiding contamination with honeydew and providing some protection against natural enemies and adverse climatic conditions, are discussed.

Technomyrmex difficilis (Hymenoptera: Formicidae) in thE West Indies

Abstract Technomyrmex difficilis Forel is an Old World ant often misidentified as the white-footed ant, Technomyrmex albipes (Smith). The earliest New World records of T. difficilis are from Miami-Dade County, Florida, collected beginning in 1986. Since then, it has been found in at least 22 Florida counties. Here, I report T. difficilis from 5 West Indian islands: Antigua, Nevis, Puerto Rico, St. Croix, and St. Thomas. Colonies were widespread only on St. Croix. It is probable that over the next few years T. difficilis will become increasingly important as a pest in Florida and the West Indies.

Parasitoids of Paratachardina lobata (Hem., Kerriidae): surveys for biological control of the invasive lobate lac scale

Abstract Paratachardina lobata is an invasive pest in southern Florida, threatening a great number of economically important and native plants. The lobate lac scale does not cause problems in its area of origin, India and Sri Lanka, presumably due to various parasitoid wasps. In an attempt to discover promising parasitoids for biological control against the invasive pest in Florida, P. lobata infesting Pongamia pinnata (Fabaceae) was collected bimonthly from August 2005 to June 2006 at 14 sites in southern India. Four parasitoids were demonstrably associated with P. lobata: a eulophid Aprostocetus bangaloricus Narendran, an encyrtid Ooencyrtus kerriae Hayat and two aphelinids, Marietta leopardina Motschulsky and an undescribed Coccophagus Westwood sp. These chalcidoid wasps were found regularly at all heavily infested sites with an average emergence number per collection period of 62.8, 31.7, 11.9 and 90.5 respectively. The mean number emerged 20–28 days after the collection date, excluding the Coccophagus sp., which occurred significantly later, on average 41 days after collection. Species emergence was examined and parasitized scales dissected. Parasitoid remains were interpreted to understand the mode of parasitism. The Coccophagus sp. was found to be a secondary parasitoid. Marietta leopardina occurred as a primary parasitoid, but only in low number and this species is also known to be hyperparasitic on chalcidoid wasps. Aprostocetus bangaloricus and O. kerriae are promising candidates for the lobate lac scale control in Florida. They are primary parasitoids of P. lobata and occurred at almost every collection site, especially where P. lobata was very abundant.

Contribution of predation and parasitism to mortality of citrus leafminer Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) populations in Florida

The citrus leafminer (CLM), Phyllocnistis citrella Stainton, is native to southern Asia and regarded as an important pest in nurseries and young or top-worked citrus trees in Florida. Damage to the leaf cuticle increases susceptibility to citrus canker disease and further aids spread by increasing inoculum loads. Biological control agents are known to play an important role in regulating pest populations. We evaluated individual contributions of predation and parasitisation to cohorts of P. citrella by exclusion and by direct observation of leaf mines in the field. Predation, particularly by ants, was the largest single cause of P. citrella mortality, accounting for more than 30% of all deaths by natural enemies, and 60% of all deaths by predators. First and second instars of P. citrella were most subject to ant predation. Ageniaspis citricola was the most important parasitoid of P. citrella and caused 8.2–28.6% mortality compared to 9.6–14.7% from indigenous parasitoids. The total biotic mortality of P. citrella observed in exclusion experiments was 52–85%. These results were in basic agreement with 89% mortality, predominantly by predation, obtained by reconstructing a cohort from observations of recently mined leaves. A partial life table based on these data predicted an innate rate of increase (Ro) of 2.8 and thus an almost 3-fold increase per generation. These results indicate that, while biotic mortality takes considerable toll of P. citrella populations, the predominance of predation suggests that the parasitoid complex on this exotic pest in Florida is depauperate and would likely be improved by additional introductions.