The zoophytophagous predator,
Nesidiocoris tenuis
(Reuter) (Hemiptera: Miridae), is an important biological control agent. To maintain this insect, several non-crop host plants are used as banker ...plants in greenhouse crop systems. To optimize the efficiency of the predator-banker plant interaction, it is necessary to investigate how individual predators move between banker plants and crops. However, the movement is difficult to quantify under field conditions. Therefore, we investigated the movement of
N. tenuis
between tomato plants (
Solanum lycopersicum
L., Solanales: Solanaceae) and three banker plants (
Cleome hassleriana
Chod., Brassicales: Cleomaceae;
Sesamum indicum
L., Lamiales: Pedaliaceae; and
Verbena × hybrida
Voss, Lamiales: Verbenaceae) in a greenhouse by conducting PCR using plant-species-specific primers. Laboratory analysis results showed that our molecular method could detect
N. tenuis
activity within a relatively short time (≤ 24 h). In addition,
N. tenuis
predation on a pest species was unlikely to result in false detection of plant DNA in the pest (suggesting that
N. tenuis
had been on the plants). Multiple plant species were detected in adult insects collected from the greenhouse plants, indicating that
N. tenuis
frequently moved across the mentioned plant species. The movement patterns of
N. tenuis
between plant species varied substantially based on the plant species from which they were collected, which suggested each of the plant species had different functions for
N. tenuis
. Our findings revealed that planting multiple host plants would stabilize the
N. tenuis
population in biological control programs.
The spider mite sub-family Tetranychinae includes many agricultural pests. The internal transcribed spacer (ITS) region of nuclear ribosomal RNA genes and the cytochrome c oxidase subunit I (COI) ...gene of mitochondrial DNA have been used for species identification and phylogenetic reconstruction within the sub-family Tetranychinae, although they have not always been successful. The 18S and 28S rRNA genes should be more suitable for resolving higher levels of phylogeny, such as tribes or genera of Tetranychinae because these genes evolve more slowly and are made up of conserved regions and divergent domains. Therefore, we used both the 18S (1,825-1,901 bp) and 28S (the 5' end of 646-743 bp) rRNA genes to infer phylogenetic relationships within the sub-family Tetranychinae with a focus on the tribe Tetranychini. Then, we compared the phylogenetic tree of the 18S and 28S genes with that of the mitochondrial COI gene (618 bp). As observed in previous studies, our phylogeny based on the COI gene was not resolved because of the low bootstrap values for most nodes of the tree. On the other hand, our phylogenetic tree of the 18S and 28S genes revealed several well-supported clades within the sub-family Tetranychinae. The 18S and 28S phylogenetic trees suggest that the tribes Bryobiini, Petrobiini and Eurytetranychini are monophyletic and that the tribe Tetranychini is polyphyletic. At the genus level, six genera for which more than two species were sampled appear to be monophyletic, while four genera (Oligonychus, Tetranychus, Schizotetranychus and Eotetranychus) appear to be polyphyletic. The topology presented here does not fully agree with the current morphology-based taxonomy, so that the diagnostic morphological characters of Tetranychinae need to be reconsidered.
To monitor and control the Japanese orange fly
Bactrocera tsuneonis
(Miyake) (Diptera: Tephritidae), it is important to determine their dispersal ability. Therefore, to determine the genetic ...structure of this species, we developed microsatellite markers at 17 loci for
B. tsuneonis.
A total of 80 adult females and males randomly collected from abandoned orchards in the Oita and Yamaguchi Prefectures, in the western part of Japan, were used for polymorphism analysis using the microsatellite markers. The average number of alleles was 2.65 for the 17 loci, in which two loci did not show polymorphism. The expected heterozygosity ranged from 0 to 0.663, although the observed heterozygosity was relatively low between 0 and 0.105. The null allele frequencies varied among populations. Moreover, no polymorphism was found in the three larval populations collected in the Oita Prefecture. These results suggested a high degree of inbreeding for this species. Significant genetic differentiation between females and males of the same population was not observed, although it was observed between the Oita and Yamaguchi populations. A bottleneck effect was detected in Yamaguchi but not in Oita, and this is congruent with the history of an expanding distribution in this species. These markers could be used for population discrimination and to expand the geographic history of this species, potentially contributing to the pest management of
B. tsuneonis
.
We examined the genetic variation in the sequences of cytochrome
c
oxidase subunit I gene (DNA barcode region) and some other regions of mitochondrial DNA of sweet potato weevil,
Cylas formicarius
...(Fabricius, 1798) (Coleoptera: Brentidae), and West Indian sweet potato weevil,
Euscepes postfasciatus
(Fairmaire, 1849) (Coleoptera: Curculionidae), in Japan. In the DNA barcode region of
C. formicarius
, 139 haplotypes were detected from 1705 individuals belonging to 46 geographical populations. In the maximum likelihood phylogenetic tree, haplotypes found in Japan were mainly divided into three clades. In the DNA barcode region of
E. postfasciatus
, two haplotypes were detected from 82 individuals belonging to eight geographical populations. Of those haplotypes, Hap 1 was detected from the Nansei Islands, Fiji, Samoa, and Tonga, while Hap 2 was detected from the Nansei Islands and Samoa. These results suggest that the Japanese populations of both the species were derived from several foreign countries. Based on the haplotype network analyses of some other gene regions, those regions may be useful for a more detailed estimation of the origin of an accidentally collected individual in non-distribution area in Japan.
To develop an augmentative biological control programme for
Bemisia tabaci
(Gennadius) (Hemiptera: Aleyrodidae) and
Thrips palmi
Karny (Thysanoptera: Thripidae) using
Nesidiocoris tenuis
(Reuter) ...(Hemiptera: Miridae), we studied the life history traits of a Japanese strain of
N. tenuis
reared on
B. tabaci
and
T. palmi
in controlled environments. The lower developmental threshold during the nymphal period was far higher than those estimated for Spanish, Moroccan, and Iranian strains, indicating that the Japanese strain is better adapted to higher temperatures than the other three strains tested. The intrinsic rate of increase
r
m
was highest at 30 °C and lowest at 20 °C. The
r
m
value for individuals reared on
T. palmi
at 25 °C was lower than that for individuals reared on
B. tabaci
at the same temperature. Implications of these results for the biological control of
B. tabaci
and
T. palmi
in greenhouses are discussed.
Slow-release sachets of predatory mites are widely employed for controlling small pest arthropods in protected crops. However, environmental stresses can adversely affect the performance of such ...sachets. To solve this problem, we developed plant-attached shelters that hold sachets of
Neoseiulus californicus
(McGregor) or
Amblyseius swirskii
(Athias-Henriot). We conducted laboratory experiments to reveal whether sheltered sachets can protect predators against pesticides and drenching. The numbers of each predator in unsheltered sachets were drastically decreased after spraying with a non-selective pesticide (methidathion), and after continuous spraying (four days) with water, whereas the numbers in the sheltered sachets were not seriously affected by these factors. We also found that more predators (at least for
N. californicus
) were released from sheltered sachets at different temperatures (25 and 17 °C) than from unsheltered sachets. These results indicate sheltered sachets to be potentially useful for protecting predatory mites against environmental stresses and enhancing their release to crops.
We examined the utility of a non-destructive DNA extraction method for identification of
Bradysia odoriphaga
Yang and Zhang, 1985 (Diptera: Sciaridae) based on PCR using species-specific primers and ...DNA barcoding targeting the mitochondrial cytochrome
c
oxidase subunit I gene. Using species-specific primers, PCR success rates for adults and pupae were more than 90%, while those for larvae and eggs were 51% and 13%, respectively. The success rates of PCR for DNA barcode region were slightly higher than those of PCR using species-specific primers. In all sequenced samples, the 658 bp of sequences in the DNA barcode region were identical to the sequences from
B
.
odoriphaga
that we previously obtained using a destructive DNA extraction method. The adults were successfully identified based on morphological characters after non-destructive DNA extraction. The non-destructive DNA extraction method examined in this study is useful for the identification of adults and pupae of
B
.
odoriphaga
collected in the fields.
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•We have four important insect predator groups of pest spider mites.•Rearing these insect predators is difficult due to the lack of suitable host plants.•Prey spider mites can be ...efficiently maintained on komatsuna plants (Brassica rapa).•The insect predators can be efficiently reared on prey-infested komatsuna plants.
Establishing effective methods of rearing natural enemies can facilitate basic and applied studies on their use in biological pest control. Insect predators of four genera (Oligota, Stethorus, Scolothrips and Feltiella) and predatory mites are important natural enemies of pest spider mites in agricultural crops. However, fewer laboratory studies have focused on insect predators due to the difficulty of their rearing. To establish a simple rearing method, we compared the rearing efficiency of four insect predator groups (Oligota spp., Stethorus spp., Scolothrips takahashii and Feltiella acarisuga) on potted komatsuna plants (Brassica rapa) infested with the two-spotted spider mite Tetranychus urticae, a new plant-prey combination for predator rearing in large containers, with that on potted bean plants infested with T. urticae. Significantly more Feltiella acarisuga and Stethorus spp. adults were obtained when offered T. urticae-infested komatsuna plants than infested lima bean or kidney bean plants (Feltiella: 70, 9 and 0 adults, respectively; Stethorus: 72, 3 and 0 adults, respectively). More adults of S. takahashii and Oligota spp. were obtained on T. urticae-infested komatsuna than on infested lima bean (Scolothrips: 181 and 27 adults, respectively; Oligota: 152 and 16 adults, respectively). Many individuals of all four predator groups such as larvae of F. acarisuga and Stethorus spp. were entrapped by the hooked trichomes on lima and kidney bean leaves, whereas no entrapped predators were observed on the komatsuna plants. These results show potted komatsuna plants infested with T. urticae to be suitable for efficient rearing of all four predator groups.
PCR is a useful technique to detect mutations in insecticide resistance genes or to analyze gene flow in pest insects.
Plutella xylostella
(L.) is one of the most important pests that develops ...insecticide resistance, and it is desirable to make efficient use of specimens obtained from pheromone-baited sticky traps. To estimate the period of DNA preservation in moths collected on traps in the field, we analyzed the probability of PCR success using mtCOI and microsatellite primers. The results suggested that moths caught by sticky traps would maintain DNA of sufficient quality for PCR analysis when the trap was changed weekly. DNA degradation was greater in moth specimens on traps exposed to ultraviolet (UV) radiation in direct sunlight than in the shade. DNA degeneration was greater in moths exposed to direct sunlight in summer than in winter. Therefore, setting traps in shade or using a UV light-shielding barrier over the trap might be an effective approach to prevent DNA degradation.
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