Laboratory studies of movement and microenvironment choices of engorged adult female Amblyomma maculatum (Acari: Ixodidae).

Microenvironmental factors affect ovipositional choices and behavior in ticks. In this study, engorged female Amblyomma maculatum Koch were released in an observation arena covered with garden soil. The arena was evenly split into wet and dry sides, each containing 5 different types of structures (totaling 10). Upon release, observations at particular time points were made over 2 days as to speed, distance, actual paths traveled, and ultimate site selection, presumably for oviposition. In addition, time-lapse videography was utilized to record the track of each individual tick. This scenario was replicated 3 times with different cohorts of ticks (n = 5 per replicate). Of the total 15 ticks released in the arena, all attained a final site selection by 24 h. These final sites were 7/15 (47%) edge of arena; 2/15 (13%) under bark; 2/15 (13%) open soil; 2/15 (13%) at or near release point; 1/15 (7%) tunnel with animal fur; and 1/15 (7%) tunnel with chicken feathers. At final site selection, 11/15 (73%) subsequently burrowed into the soil, 3 of which were completely buried. Time-lapse videography revealed that most ticks (80%) explored the arena in a "looping back" fashion. Overall, engorged Gulf Coast ticks moved at an average speed of 0.09 mm/s, and the total distance traversed by the ticks averaged 2.37 m.

An Odorant Receptor Expressed in Both Antennae and Ovipositors Regulates Benzothiazole-Induced Oviposition Behavior in Bactrocera dorsalis.

The oriental fruit fly,Bactrocera dorsalis (Hendel), is a notorious pest of fruit crops, causing severe damage to fleshy fruits during oviposition and larval feeding. Gravid females locate suitable oviposition sites by detecting the host volatiles. Here, the oviposition preference of antenna-removed females and the electrophysiological response of ovipositors to benzothiazole indicated that both antennae and ovipositors are involved in perceiving benzothiazole. Subsequently, odorant receptors (ORs) expressed in both antennae and ovipositors were screened, and BdorOR43a-1 was further identified to respond to benzothiazole using voltage-clamp recording. Furthermore, BdorOR43a-1-/- mutants were obtained using the CRISPR/Cas9 system and their oviposition preference to benzothiazole was found to be significantly altered compared to WT females, suggesting that BdorOR43a-1 is one of the important ORs for benzothiazole perception. Our results not only demonstrate the important role of antennae and ovipositors in benzothiazole-induced oviposition but also elucidate on the OR responsible for benzothiazole perception in B. dorsalis.

Biology and Ecology of Delia planipalpis (Stein) (Diptera: Anthomyiidae), an Emerging Pest of Broccoli in Mexico.

Delia planipalpis (Stein) (Diptera: Anthomyiidae) is a pest of crucifers, such as broccoli, radish, cauliflower, turnip and cabbage. It has been recently described in Mexico as a significant emerging pest of broccoli. Due the lack of knowledge of this pest, the present study aimed to determine its life cycle, female sexual maturation, copulation, oviposition behavior and adult longevity. The identity of the fly in Mexico was confirmed genetically by sequencing the cytochrome oxidase subunit 1 gene (COI). The mean development time of D. planipalpis was 32-33 days on radish at 24 °C under laboratory conditions. Females became sexually mature 1-2 days after emergence, and the highest incidence of matings was recorded on the second day (60%). Under choice conditions, D. planipalpis females preferred to oviposit on radish plants, rather than broccoli plants, possibly due to the use of radish for rearing the laboratory colony. Oviposition and the mean number of eggs laid varied among the broccoli varieties, with the highest oviposition observed on the Tlaloc variety. Repeated attempts to rear the laboratory colony on broccoli plants failed. Radish-reared insects of both sexes lived longer when individualized in the adult stage (14.5-22.5 days) than when adult flies were maintained in groups (10-11 days). This study contributes to the understanding of D. planipalpis biology and provides information that can be used to establish future control strategies against this pest.

Behavioral responses of different reproductive statuses and sexes in Hermetia illucens (L) adults to different attractants.

Background: The odor of various fermented organic materials acts as an attractant for oviposition by gravid females of the black soldier fly (BSF) to find larval food sources. Females display oviposition site selection on various organic materials, but little work has been done on the response to substrate attractants under caged conditions similar to those in a BSF farm production system. Methods: Fifty of each reproductive status (mated and virgin) and sex (males and females) of BSF adults were marked and then exposed to one of five different oviposition attractants in a transparent acrylic chamber: no substrate (control) plus pineapple, mixed vegetables, okara, and fermented fish to represent fruit-, vegetable-, plant protein-, and animal protein-based substrates, respectively. The frequency of the perching activity on the oviposition apparatus and flying behavior under the LED illumination, including the laid egg weight, were recorded. Results: The sexually-related activities of BSF adults were clearly observed. A majority of the females preferred to perch on the oviposition apparatus and fly around the illuminated area compared to the very low activities of the mated males. The BSF adults displayed different behavioral responses to the different tested attractants. While active flying was common when using plant protein- and animal protein-based substrates, mated females showed the greatest perching preference for plant-based substrates (fruit and vegetables) and this correlated with the laid egg weight. Discussion: Egg-laying was more likely to happen on the plant-based substrate than on the animal protein-based substrate. However, the strong smell of the animal protein-based substrate could strongly trigger lekking behavior, which is an important part of mating behavior. This knowledge can support egg trapping in nature and also improve the efficiency of egg production in mass-rearing facilities.

Behavioral and Electrophysiological Study on Eight Japanese Papilio Species with Five Hostplant Volatiles and Linalool.

An electroantennogram (EAG) technique compared the antennal olfactory responses by both sexes of eight Japanese Papilio species with known host plants in laboratory experiments. Papilio species were collected from Honshû and Kyûshû (Japanese islands). The behavioral responses to volatile leaf substances from Citrus deliciosa, Zanthoxylum ailanthoides, Phellodendron amurense, Orixa japonica, and Foeniculum vulgare were examined in laboratory experiments. Individual EAG reactions were recorded. The results were very similar to the empirical field observations. The electrophysiological results of both sexes showed that the volatile substances released from non-preferred plants mainly elicited more significant EAG responses than the volatile substances from preferred host plants. Moreover, we performed behavioral experiments using eight female butterflies and their responses to five host plant species. An association between host plant selection behavior and taxonomical classification exists within the Papilio genus. The EAG responses were small when exposed to the plants with high scores in the behavioral experiments. Host plant preference patterns seem to be related to the volatile substances within the host plants. The butterflies responded to Linalool in both the behavioral and electrophysiological experiments.

The Role of Tire Leachate in Condition-Specific Competition and the Persistence of a Resident Mosquito from a Competitively Superior Invader.

(1) Background: Condition-specific competition, when the outcome of competition varies with abiotic conditions, can facilitate species coexistence in spatially or temporally variable environments. Discarded vehicle tires degrade to leach contaminants into collected rainwater that provide habitats for competing mosquito species. We tested the hypothesis that more highly degraded tires that contain greater tire leachate alters interspecific mosquito competition to produce a condition-specific advantage for the resident, Culex pipiens, by altering the outcome of competition with the competitively superior invasive Aedes albopictus. (2) Methods: In a competition trial, varying densities of newly hatched Ae. albopictus and Cx. pipiens larvae were added to tires that had been exposed to three different ultraviolet (UV)-B conditions that mimicked full-sun, shade, or no UV-B conditions in the field. We also measured Cx. pipiens and Ae. albopictus oviposition preference among four treatments with varying tire leachate (high and low) and resources (high and low) amounts to determine if adult gravid females avoided habitats with higher tire leachate. (3) Results: We found stronger competitive effects of Cx. pipiens on the population performance and survival of Ae. albopictus in tires exposed to shade and full-sun conditions that had higher concentrations of contaminants. Further, zinc concentration was higher in emergent adults of Ae. albopictus than Cx. pipiens. Oviposition by these species was similar between tire leachate treatments but not by resource amount. (4) Conclusions: These results suggest that degraded tires with higher tire leachate may promote condition-specific competition by reducing the competitive advantage of invasive Ae. albopictus over resident Cx. pipiens and, combined with Cx. pipiens' preferential oviposition in higher resource sites, contribute to the persistence of the resident species.

Factors Affecting Progeny Production and Sex Ratio of Gryon aetherium (Hymenoptera: Scelionidae), a Candidate Biological Control Agent for Bagrada hilaris (Hemiptera: Pentatomidae).

Manipulating the factors that influence progeny production and sex ratio in parasitoids can help maximize the production of quarantine bioassays and/or mass releases. In a series of experiments, we studied the effects of several factors on offspring production and sex ratio in the parasitoid Gryon aetherium (Hymenoptera: Scelionidae), a candidate biological control agent for Bagrada hilaris (Hemiptera: Pentatomidae). Progeny production was influenced by maternal age and dropped when females were 24 or 28 days old and decreased on the second day of exposure. Overall, the offspring sex ratio was highly variable in G. aetherium and was affected by the duration of exposure, with higher proportions of females emerging after one day of exposure than after two days, but was not affected by female density, female age/host deprivation, or temperature during oviposition. Progeny production was affected by the temperature during oviposition and was highest at 26.6 °C. The results indicate that production of G. aetherium can be maximized at one day of exposure, using females that are less than 24 d old, and at temperatures of around 26 °C.

Dynamic expression analysis of Vitelloin-related genes in Zeugodacus cucurbitae (Coquillett) driven by short-term high-temperature stress.

Zeugodacus cucurbitae (Coquillett) is an important pest of fruit and vegetable crops in tropical and subtropical regions. Previous studies have shown that short-term high-temperature stress has a significant effect on the oviposition behavior of three successive generations (F1 -F3 ) of Z. cucurbitae (Coquillett). For the clarification of the molecular response of the oviposition behavior of Z. cucurbitae (Coquillett) to short-term high-temperature stress, three Vitellogenin (Vg) genes, namely, Vg-1, Vg-2, and Vg-3, and one Vitellogenin receptor (VgR) gene were selected; 25°C was used as the control treatment; and 33°C, 37°C, 41°C, and 45°C were set as the high-temperature treatments. Newly emerged adults of the F1 generation were treated for 1 h, and the expression dynamics of the target genes were analyzed 7 days after the emergence of three successive generations of adults. Results showed that the expression of the Vg gene in the 33°C and 37°C groups was upregulated compared with that in the control group, and the difference among the 41°C, 45°C, and control groups was small. VgR gene expression level gradually increased in each treatment group with the increase in the number of days and peaked on Days 6 and 7. Compared with the control group, the expression of VgR gene in the F1 generation was downregulated in the high-temperature treatment group over 7 days. On Day 7, the expression level of the VgR gene in the F2 and F3 generations in the 37°C and 45°C groups was significantly higher than that in the F2 and F3 generations in the control group. In conclusion, Vg and VgR are transformed and utilized differently after short-term high-temperature treatment.

The predatory bug Orius strigicollis shows a preference for egg-laying sites based on plant topography.

BACKGROUND: Oviposition site selection is an important factor in determining the success of insect populations. Orius spp. are widely used in the biological control of a wide range of soft-bodied insect pests such as thrips, aphids, and mites. Orius strigicollis (Heteroptera: Anthocoridae) is the dominant Orius species in southern China; however, what factor drives its selection of an oviposition site after mating currently remains unknown. METHODS: Here, kidney bean pods (KBPs) were chosen as the oviposition substrate, and choice and nonchoice experiments were conducted to determine the preferences concerning oviposition sites on the KBPs of O. strigicollis. The mechanism of oviposition behavior was revealed through observation and measurement of oviposition action, the egg hatching rate, and the oviposition time. RESULTS: We found that O. strigicollis preferred the seams of the pods for oviposition, especially the seams at the tips of the KBPs. Choice and nonchoice experiments showed that females did not lay eggs when the KBP tail parts were unavailable. The rates of egg hatching on different KBP parts were not significantly different, but the time required for females to lay eggs on the tip seam was significantly lower. Decreased oviposition time is achieved on the tip seam because the insect can exploit support points found there and gain leverage for insertion of the ovipositor. DISCUSSION: The preferences for oviposition sites of O. strigicollis are significantly influenced by the topography of the KBP surface. Revealing such behavior and mechanisms will provide an important scientific basis for the mass rearing of predatory bugs.

Bracon wasps for ecological pest control-a laboratory experiment.

Biological control of pest insects by natural enemies may be an effective, cheap and environmentally friendly alternative to synthetic pesticides. The cosmopolitan parasitoid wasp species Bracon brevicornis Wesmael and B. hebetor Say (Hymenoptera: Braconidae) use lepidopteran species as hosts, including insect pests like Ephestia kuehniella or Ostrinia nubilalis. Here, we compare the reproductive success of both Bracon species on E. kuehniella in a laboratory experiment. We asked (1) how the reproductive success on a single host larva changes with temperature, (2) how it changes with temperature when more host larvae are present and (3) how temperature and availability of host larvae influence the efficacy of Bracon species as biological control agents. In general, differences between B. brevicornis and B. hebetor have been small. For rearing both Bracon species in the laboratory on one host larva, a temperature between 20-27 °C seems appropriate to obtain the highest number of offspring with a female-biased sex ratio. Rearing the braconid wasps on more than one host larva revealed a higher number of total offspring but less offspring per host larva on average. Again, highest numbers of offspring hatched at 27 °C and the sex ratio was independent from temperature. Although no parasitoids hatched at 12 °C and only few at 36 °C, host larvae were still paralyzed. The efficacy of B. brevicornis was higher than 80% at all numbers of host larvae presented at all temperatures while the efficacy of B. hebetor was less than 80% at 12 °C and 27 °C at low numbers of host larvae presented. In conclusion, practitioners can use either B. brevicornis or B. hebetor at low and high temperatures and at varying host densities to achieve high pest control efficacy.

[Effects of water quality on the reproductive behavior and capacity of Andrias davidianus under tourism disturbance.] / æ— æ¸¸å¹²æ‰°ä¸‹æ°´è´¨å¯¹å¤§é²µç¹æ®–è¡Œä¸ºä¸Žç¹æ®–åŠ›çš„å½±å“.

Water quality under tourism disturbance was simulated through controlling the water intake of the ecological breeding ponds of Chinese giant salamander (Andrias davidianus, CGS). Both the reproductive behavior (oviposition and parental care) and capacity (relative egg production, fertilizing rate of eggs, and hatching rate of fertilized eggs) of CGS were examined using a real-time infrared digital monitoring system. The relationships among reproductive behavior, capacity, and the corresponding parameters of water quality were analyzed, to understand how water quality under tourism disturbance would affect the reproductive behavior and capacity of CGS. The examined oviposition behavior and capacity of CGS showed no variation in general, but the parental care behavior such as tail fanning and agitation time of the male CGS were prolonged significantly in the groups under tourism disturbance. Such prolonged behaviors would help increase the content of dissolved oxygen (DO) to meet the high demands of DO during embryonic development of CGS. In addition, the overall hatching time of fertilized eggs was increased significantly under disturbance conditions when it compared with the control, which would ensure the overall hatching rate among these comparative groups unaffected. In summary, the prolongations of some reproductive behavior (tail fanning and agitation of the male CGS and the development time of fertilized egg) would be a kind of positive actions of CGS in response to the changes of water quality resulted from tourism disturbance.

Morphological and molecular characterization of adult hairworms (Phylum Nematomorpha) from Iceland and the Faroe Islands, and documentation of their non-adult stages and hosts.

No species of freshwater Nematomorpha have been described from Iceland, but they have been identified anecdotally. Recent surveys in Iceland using freshwater gastropods as biodiversity indicators resulted in the collection of adult free-living hairworms and their non-adult stages including cysts in snail paratenic hosts and juvenile worms in ground beetle definitive hosts. Additionally, specimens acquired from the Icelandic Institute of Natural History indicate nematomorphs are common in Iceland. A single specimen from the Faroe Islands National Museum represents a new species record. Our morphological and molecular characterization indicated all the samples belong to the species Gordionus wolterstorffii, a common nematomorph found throughout Europe. Also, we provide the first descriptions of the cyst stage for the genus Gordionus. Molecular phylogenetic analysis based on 10 species of Gordionus and one species of the closely related genus Parachordodes indicates that Gordionus is not monophyletic. Combining our morphological and phylogenetic investigations, we discuss the lack of clarity in diagnostic morphological characters and the need for additional global collections to clarify the taxonomy of Gordionus.

Host Patch Use and Potential Competitive Interactions Between Two Egg Parasitoids From the Family Scelionidae, Candidate Biological Control Agents of Bagrada hilaris (Hemiptera: Pentatomidae).

Two egg parasitoids from Pakistan, Gryon sp. nr. gonikopalense Sharma (Hymenoptera: Scelionidae) and Trissolcus hyalinipennis Rajmohana & Narendran (Hymenoptera: Scelionidae), are currently being investigated as potential classical biocontrol agents for Bagrada hilaris Burmeister. The former is the most promising because of its ability to attack B. hilaris eggs in soil, but the latter was recently discovered in California. This study detailed the patch use and oviposition behavior of both species and assessed their relative foraging efficiency. We also investigated possible competitive interactions by assessing 1) the occurrence of intra- and interspecific host discrimination, 2) mutual interference between females (extrinsic competition), 3) the outcome of multiparasitism (intrinsic competition), and 4) the effect of competition on host suppression. Our results showed that T. hyalinipennis females tended to probe repeatedly in the same hosts leading to longer host patch time and lower foraging efficiency. Both species avoided conspecific superparasitism, but not multiparasitism. When the two species foraged simultaneously, G. sp. nr. gonikopalense seemed to be slightly superior in extrinsic competition, while neither species seemed to have an advantage in intrinsic competition. Also, neither species could develop as a facultative hyperparasitoid, but they inflicted non-reproductive mortality on eggs containing 4-d-old larvae of their competitor. Lastly, host mortality inflicted by G. sp. nr. gonikopalense and T. hyalinipennis when acting together appeared to be additive. These results suggest that the presence of T. hyalinipennis in California is unlikely to reduce G. sp. nr. gonikopalense efficiency, but will instead improve the biological control of B. hilaris.

Time-dependent oviposition deterrence by an oviposition mark in a fungus-farming lizard beetle.

In insects, the selection of a suitable oviposition site is critical for offspring performance. Avoiding hosts already occupied by conspecific immatures in oviposition is one of the mechanisms to reduce intraspecific competition. The avoidance of such hosts by ovipositing females has been well-documented in parasitoid wasps and phytophagous insects but remains unknown in mycophagous insects. Here, we report that oviposition marks (OMs) of the fungus-farming lizard beetle, Doubledaya bucculenta (Coleoptera: Erotylidae: Languriinae), deter conspecific females from oviposition. The females excavate a wall of host bamboo internodes to access cavities for oviposition and plug the holes with excised bamboo fibers after oviposition. A larva completes its development within a single internode. To determine what types of OMs function as oviposition deterrents and how the oviposition-deterring pattern associates with offspring survival, we examined the oviposition behaviors, egg-period lengths, and reactions of larvae to eggs. When a single internode was provided, most females laid eggs in internodes with no OMs, incomplete OMs, or plug-removed completed OMs (COMs), but fewer females laid in internodes with fresh COMs and no females laid in those with old COMs. When eggs were reared under constant temperatures, egg-period lengths varied, suggesting that later-laid eggs sometimes hatch earlier than earlier-laid eggs. When a larva encountered an egg, all eggs were killed shortly. These results suggest that the females avoid internodes associated with high offspring mortality and that the COM's plug contains an oviposition-deterring cue. Given that larvae of oviposition-deterring insects including D. bucculenta inhabit spatiotemporally-limited sites and have limited mobility, high resource competition in the larval stage may have driven the evolution of oviposition deterrence.

Identifying the Biological Characteristics Associated with Oviposition Behavior of Tea Leafhopper Empoasca onukii Matsuda Using the Blue Light Detection Method.

Tea leafhopper (Empoasca onukii Matsuda) is amongst the key pests in tea plantations around the East Asian region. Stereomicroscopy is a conventional method used for detecting tea leafhopper eggs by dissecting the tender tissues. However, there is a need for a faster and more efficient method to directly observe and investigate intact eggs within tea shoots. The absence of a proven method limits research efforts for determining the oviposition behavior of E. onukii. Herein, we applied the blue light detection method (BLDM), a technique recently developed for other species, in order to detect E. onukii eggs directly and non-destructively within the tender shoot. In addition, we compared BLDM against the traditional stereomicroscope detection method (SMDM) for four tea cultivars. Notably, our results revealed that BLDM was precise and effective in measuring the egg laying quantity of E. onukii on intact tea shoots. Neither tea cultivars nor egg density in the tender shoot significantly affected the accuracy of BLDM. Furthermore, biological characteristics that have rarely been reported previously for E. onukii were investigated using the BLDM, including zygote duration, ovipositional rhythm, egg distribution within the tender shoot, and in different leaf positions, numbers of eggs laid by a single female daily, and laid by the entire generation. Therefore, these findings provide insights into the basic and theoretical evidence for the strategy and mechanism associated with the oviposition behavior of E. onukii.

The egg and larval pheromone dodecanoic acid mediates density-dependent oviposition of Phlebotomus papatasi.

BACKGROUND: Gravid females assess the conditions of oviposition sites to secure the growth and survival of their offspring. Conspecific-occupied sites may signal suitable oviposition sites but may also impose risk due to competition or cannibalism at high population density or heterogeneous larval stage structure, respectively. Chemicals in the habitat, including chemicals emitted from other organisms, serve as cues for females to assess habitat conditions. Here, we investigated the attraction and oviposition preference of the Old World cutaneous leishmaniasis vector, Phlebotomus papatasi, to young and old conspecific stages, including eggs and evaluated the effect of a semiochemical associated with eggs and neonate larvae. METHODS: Attraction and oviposition preference of Ph. papatasi to each of various life stages (eggs, first-, second-, third-, fourth-instar larvae, pupae and male and female adults) was investigated using cage and oviposition jar behavioral assays. Identification of organic chemical compounds extracted from eggs was performed using GC-MS and chemicals were tested in the same behavioral assays in a dose-response manner. Behavioral responses were statistically analyzed using logistic models. RESULTS: Gravid Ph. papatasi females were significantly attracted to and preferred to oviposit on medium containing young life stages (eggs and first instars). This preference decreased towards older life stages. Dose effect of eggs indicated a hump-shaped response with respect to attraction but a concave-up pattern with respect to oviposition. Chemical analysis of semiochemicals from eggs and first-instar larvae revealed the presence of dodecanoic acid (DA) and isovaleric acid. Sand flies were attracted to and laid more eggs at the lowest DA dose tested followed by a negative dose-response. CONCLUSIONS: Findings corroborated our hypothesis that gravid sand flies should prefer early colonized oviposition sites as indicators of site suitability but avoid sites containing older stages as indicators of potential competition. Findings also supported the predictions of our hump-shaped oviposition regulation (HSR) model, with attraction to conspecific eggs at low-medium densities and switching to repellence at high egg densities. This oviposition behavior is mediated by DA that was identified from surface extracts of both eggs and first-instar larvae. Isovaleric acid was also found in extracts of both stages.

Investigation of the ability of the oviposition-stimulant lectin from Moringa oleifera seeds (WSMoL) to bind with membrane proteins present in the legs of Aedes aegypti.

The mosquito Aedes aegypti L. is a vector transmitting diseases such as dengue, chikungunya and Zika virus fever. The water-soluble lectin from Moringa oleifera Lam. seeds (WSMoL) is larvicidal, ovicidal and can stimulate oviposition in A. aegypti. This study aimed to investigate whether WSMoL could bind to membrane proteins from A. aegypti legs. Initially, proteins from the legs were extracted using sodium deoxycholate, digitonin, dodecyl sodium sulfate (SDS) or Triton X-100. The protein concentration was found to be higher in the extract obtained using Triton X-100, which was applied to a WSMoL-Sepharose column. The adsorbed proteins were evaluated using gel filtration chromatography and polyacrylamide gel electrophoresis (PAGE) in presence of SDS. The similarity in the sequences of adsorbed proteins with those available in databases was determined. The proteins adsorbed on the matrix were eluted forming a single peak. Gel filtration chromatography and SDS-PAGE revealed the presence of proteins with molecular masses of approximately 20 kDa and polypeptide bands of 17.0 and 23.7 kDa, respectively. MS/MS analysis indicated similarity between these proteins and ABC carriers, which are expressed in the legs of mosquitos. WSMoL could bind to membrane proteins in the legs of A. aegypti females and induce oviposition through these interactions.

Cryptic Diversity in the Aphid-Parasitizing Wasp Protaphidius nawaii (Hymenoptera: Braconidae): Discovery of Two Attendant-Ant-Specific mtDNA Lineages.

The parasitoid wasp Protaphidius nawaii parasitizes the aphid Stomaphis japonica, which is obligatorily attended by several species of ants of genus Lasius. Subgenus Lasius or Dendrolasius ants use different defense strategies to protect the aphids that they attend (Lasius, shelter building; Dendrolasius, aggressive attack). We performed molecular phylogenetic analysis based on partial mitochondrial DNA sequences of P. nawaii and found that the parasitoid wasp consists of two highly differentiated genetic lineages. Although these two lineages distributed sympatrically, one tends to parasitize aphids attended by ants of subgenus Lasius, and the other parasitizes aphids attended by ants of subgenus Dendrolasius. The two lineages of P. nawaii appear to exhibit different oviposition behaviors adapted to the different aphid-protection strategies of the two ant subgenera.

Overlooked side effects of organic farming inputs attract soil insect crop pests.

Organic farming has been praised for many sound reasons, but there are some negative effects of organic practices. Research on the interactions between soil insect pests and organic farming practices is still scarce, although such interactions might sometimes lead to severe crop damage. Here, we explore the influences of organic farming inputs and key host crops on the oviposition behavior of soil insect pests likely to infest crops. We also shed light on the factors driving this behavior and analyze 4 yr of data from an on-farm investigation. Our study offers clear support to the idea that decomposing organic matter and legume crops affect oviposition behavior and provides evidence that butyric acid and 1-hexanol are major attractants. The results suggest that poor management or returning decomposing organic matter to the field is risky. The silver lining, however, is that oviposition behavior can be disrupted by the identified key attractants to benefit crop protection.

Role of egg-laying behavior, virulence and local adaptation in a parasitoid's chances of reproducing in a new host.

Understanding the ability of parasitoid insects to succeed in new host populations is a relevant question for biological control and adaptive mechanisms. Cotesia typhae is an African parasitoid specialized on the moth Sesamiae nonagrioides, also called the Mediterranean corn borer. Two Kenyan strains of C. typhae differ in their virulence against a new host population from France. We explored behavioral and physiological hypotheses about this differentiation. Cotesia genus belongs to a group of Hymenoptera in which females inject a domesticated virus in their host to overcome its resistance. Since viral particles are injected along with eggs and since the strain with the higher virulence injects more eggs, we hypothesized that virulence could be explained by the quantity of virus injected. To test this assumption, we measured the injected quantities of eggs and viral particles (estimated by viral DNA segments) of each parasitoid strain along several ovipositions, to vary these quantities. Unexpectedly, results showed that virulence against the French host was not correlated to the injected quantities of eggs or viral segments, indicating that virulence differentiation is explained by other causes. The virulence against the respective natural hosts of the two C. typhae strains was also measured, and results suggest that local adaptation to a more resistant natural host may explain the pre-adaptation of one strain to the new host population. We also identified a differentiation of oviposition strategy and subsequent offspring number between the parasitoid strains, which is important in a biocontrol perspective.