Development of a bioassay method to test activity of cry insecticidal proteins against Diatraea spp. (Lepidoptera: Crambidae) sugarcane stem borers

The genus Diatraea (Lepidoptera: Crambidae) includes stem borers representing the most critical sugarcane pests in the Americas. Colombia's most widely distributed and damaging Diatraea species include Diatraea saccharalis, D. indigenella, D. busckella, and D. tabernella. The reduced efficacy of biological tools commonly used in controlling several species highlights the importance of evaluating alternative management strategies, such as transgenic plants expressing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt). The selection of optimal Bt insecticidal proteins for Diatraea control depends on bioassays with purified Bt proteins. Because there is no described artificial diet for borer species other than D. saccharalis and availability of most purified Bt toxins is restricted, this study aimed at developing a bioassay method using fresh corn tissue and providing proof of concept by testing susceptibility to the Cry1Ac insecticidal protein from Bt. Toxicity was evaluated with a single Cry1Ac dose applied directly to corn discs. Stem borer mortality after seven days was higher than 90% for all four tested Diatraea species, while control mortality was below 8%. In addition, we observed that Cry1Ac caused more than 90% weight inhibition in all survivors and delayed development. These results validate the use of this method to determine mortality and growth inhibition due to the consumption of the Cry1Ac protein in each of the Diatraea species. Furthermore, this method could be used to assess other entomopathogenic substances to control these insect pests

Data from: Prey exploitation and dispersal strategies vary among natural populations of a predatory mite

When predators commonly overexploit local prey populations, dispersal drives the dynamics in local patches, which together form a metapopulation. Two extremes in a continuum of dispersal strategies are distinguished: the “Killer” strategy, where predators only start dispersing when all prey are eliminated, and the “Milker” strategy, in which predator dispersal occurs irrespective of prey availability. Theory shows that the Milker strategy is not evolutionarily stable if local populations are well connected by dispersal. Using strains of the predatory mite Phytoseiulus persimilis, collected from 11 native populations from coastal areas in Turkey and Sicily, we investigated whether these two strategies occur in nature. In small wind tunnels, we measured dispersal rates and population dynamics of all populations in a system consisting of detached rose leaves, spider mites (Tetranychus urticae) as prey, and P. persimilis. We found significant variation in the exploitation and dispersal strategies among predator populations, but none of the collected strains showed the extreme Killer or Milker strategy. The results suggest that there is genetic variation for prey exploitation and dispersal strategies. Thus, different dispersal strategies in the Milker–Killer continuum may be selected for under natural conditions. This may affect the predator–prey dynamics in local populations and is likely to determine persistence of predator–prey systems at the metapopulation level

Data from: Prey exploitation and dispersal strategies vary among natural populations of a predatory mite

When predators commonly overexploit local prey populations, dispersal drives the dynamics in local patches, which together form a metapopulation. Two extremes in a continuum of dispersal strategies are distinguished: the “Killer” strategy, where predators only start dispersing when all prey are eliminated, and the “Milker” strategy, in which predator dispersal occurs irrespective of prey availability. Theory shows that the Milker strategy is not evolutionarily stable if local populations are well connected by dispersal. Using strains of the predatory mite Phytoseiulus persimilis, collected from 11 native populations from coastal areas in Turkey and Sicily, we investigated whether these two strategies occur in nature. In small wind tunnels, we measured dispersal rates and population dynamics of all populations in a system consisting of detached rose leaves, spider mites (Tetranychus urticae) as prey, and P. persimilis. We found significant variation in the exploitation and dispersal strategies among predator populations, but none of the collected strains showed the extreme Killer or Milker strategy. The results suggest that there is genetic variation for prey exploitation and dispersal strategies. Thus, different dispersal strategies in the Milker–Killer continuum may be selected for under natural conditions. This may affect the predator–prey dynamics in local populations and is likely to determine persistence of predator–prey systems at the metapopulation level

Spit it out: extraction of saliva from the lychee erinose mite (Aceria litchi (Keifer) Acari: Eriophyidae)

N.A

Lethal and Sublethal Effects of Contact Insecticides and Horticultural Oils on the Hibiscus Bud Weevil, <i>Anthonomus testaceosquamosus</i> Linell (Coleoptera: Curculionidae)

In 2017, the hibiscus bud weevil (HBW), Anthonomus testaceosquamosus Linell (Coleoptera: Curculionidae), was found outside of its native range of Mexico and Texas, infesting hibiscus plants in Florida. Therefore, we selected 21 different insecticide and horticultural oil products to evaluate their effects on the reproductive rate, feeding, and oviposition behavior of the HBW. In laboratory experiments, significant mortality was observed in adult weevils exposed to diflubenzuron-treated hibiscus leaves and buds, and hibiscus buds treated with diflubenzuron contained the fewest number of eggs and feeding/oviposition holes. Among horticultural oil products, significant mortality was only observed in experiments in which adult weevils were directly sprayed (direct experiments). Pyrethrins and spinetoram plus sulfoxaflor reduced the oviposition rate and caused significant mortality in direct experiments. Diflubenzuron, pyrethrins, spinetoram plus sulfoxaflor, and spirotetramat were further tested via contact toxicity experiments and greenhouse experiments. Contact toxicity experiments demonstrated that the tested insecticides (except diflubenzuron) were highly toxic to HBW adults. In greenhouse experiments, only those hibiscus plants treated with pyrethrins had significantly fewer feeding/oviposition holes and larvae within their flower buds when compared to control (water-treated) plants. These results constitute an important first step in the identification of effective chemical control options for the HBW

Biology of Anthonomus testaceosquamosus Linell, 1897 (Coleoptera: Curculionidae): A New Pest of Tropical Hibiscus

Originating in northeastern Mexico and southern Texas, the hibiscus bud weevil (HBW), Anthonomus testaceosquamosus Linell 1897, was discovered infesting China rose hibiscus (Hibiscus rosa-sinensis L.) in south Florida in May 2017. Although the biologies of the congeneric boll weevil, A. grandis Boheman 1843, and pepper weevil, A. eugenii Cano 1894 are well documented, no data are available regarding the biology of HBW. Here, we present a comprehensive study on the biology of this pest when reared at 10, 15, 27 and 34 &deg;C and on different food sources. This weevil has three larval instars and its life cycle was completed only at 27 &plusmn; 1 &deg;C. Weevil development was similar on an artificial diet when compared with a diet of hibiscus buds. Adult HBW could survive solely on pollen, but reproduction did not occur. Without water, HBW survived for &asymp;15 days; survival times reached nearly 30 days when water was accessible. Our results suggest that if left unmanaged, HBW has the potential to cause significant economic damage to the hibiscus industry. Given that a comprehensive understanding of a pest&rsquo;s biology is critical for development of effective integrated pest management, our results provide a foundation for future research endeavors to mitigate the impact of this weevil in south Florida

Detection of the Lychee Erinose Mite, Aceria litchii (Keifer) (Acari: Eriophyidae) in Florida, USA: A Comparison with Other Alien Populations

The lychee erinose mite (LEM), Aceria litchii (Keifer) is a serious pest of lychee (Litchi chinensis Sonn.). LEM causes a type of gall called &lsquo;erineum&rsquo; (abnormal felty growth of trichomes from the epidermis), where it feeds, reproduces and protects itself from biotic and abiotic adversities. In February of 2018, LEM was found in a commercial lychee orchard on Pine Island, Florida. Infestations were recorded on young leaves, stems, and inflorescences of approximately 30 young trees (1.5&ndash;3.0 yrs.) of three lychee varieties presenting abundant new growth. Although LEM is present in Hawaii, this mite is a prioritized quarantine pest in the continental USA and its territories. Florida LEM specimens showed small morphological differences from the original taxonomic descriptions of Keifer (1943) and Huang (2008). The observed differences are probably an artifact of the drawings in the original descriptions. Molecular comparisons were conducted on the DNA of LEM specimens from India, Hawaii, Brazil, Taiwan, Australia and Florida. The amplified COI fragment showed very low nucleotide variation among the locations and thus, could be used for accurate LEM identification. The ITS1 sequences and partial 5.8S fragments displayed no nucleotide differences for specimens from any of the locations except Australia. Consistent differences were observed in the ITS2 and 28S fragments. The ITS1-ITS2 concatenated phylogeny yielded two lineages, with Australia in one group and Hawaii, India, Brazil, Florida and Taiwan in another. Specimens from Taiwan and Florida present identical ITS and rDNA segments, suggesting a common origin; however, analysis of additional sequences is needed to confirm the origin of the Florida population